CN115473196A - Converter type power supply power system short circuit calculation method, system, medium and equipment - Google Patents

Abstract

The invention discloses a short-circuit calculation method, system, medium and equipment of a converter-type power supply power system, which incorporates the switching of the control mode of the converter-type power supply under system failure into the scope of short-circuit calculation, and based on the obtained constraints and network The fault equation proposes an alternate iterative method, which can quickly solve the short-circuit calculation problem of the power system with converter-type power supply and has high accuracy, and can also summarize the factors that affect the output short-circuit current of the converter-type power supply. A reference is provided for the setup and design of the controller.

Description

Short-circuit calculation method, system, medium and equipment of converter-type power supply power system

technical field

The invention belongs to the field of electric power technology, and in particular relates to a short-circuit calculation method, system, medium and equipment of a converter-type power supply power system.

Background technique

With the large-scale application of renewable energy and the rapid development of converter technology, Converter Interfaced Generations (CIGs) have gradually become one of the mainstream forms of power generation in contemporary power systems. Compared with the traditional synchronous generators (Synchronous Generators, SGs), the new energy generation technology fed by the voltage source converter (Voltage Sourced Converter, VSC) can realize the rapid decoupling of active power and reactive power, and It provides important support for the stable operation of the system. At the same time, the short-circuit characteristics of the new energy generator set are affected by the control function, which is obviously different from the traditional synchronous generator set. Therefore, it is necessary to analyze the impact and contribution level of the converter-type power supply on the short-circuit current of the system in detail.

The existing literature mainly focuses on the dynamic characteristics of the short-circuit current injected by the converter-type power supply to the fault point under the grid fault, the calculation method of the short-circuit current and the measures to limit the level of the short-circuit current. For example, when the filter inductance of the converter or the limit value of the overcurrent protection is large, and the reactive power support requirement is high during the fault ride-through period, the output current of the converter may not be able to track the command value during the fault ride-through period. However, few articles consider the influence of converter control mode switching on the short-circuit current level of the system during the transient process of system faults.

Contents of the invention

The technical problem to be solved by the present invention is to provide a short-circuit calculation method, system, medium and equipment for a converter-type power supply power system to solve the problems of relay protection setting and The technical problem that the circuit breaker and protection equipment of the new energy power system cannot be selected.

The present invention adopts following technical scheme:

A short-circuit calculation method for a converter-type power supply power system, comprising the following steps:

S1. Establish the control model of the converter-type power supply, and obtain that the converter-type power supply does not provide reactive power support, and the converter-type power supply provides reactive power support for the system without triggering the current limiting control. The q-axis component of the output current of the converter-type power supply follows the reference value, the d-axis component of the output current of the converter-type power supply is smaller than the reference value, and the converter-type power supply provides reactive power for the system with the maximum allowable current to support the commutation in the control mode device type power constraints;

S2. Establishing a fault network model of a power system with a converter-type power supply;

S3. Based on the fault network model obtained in step S2 and the constraints of the converter-type power supply under different control modes obtained in step S1, realize short-circuit calculation applicable to power systems containing converter-type power supplies.

Specifically, in step S1, the constraints of the converter-type power supply are as follows:

Converter-type power supply does not provide reactive power support control mode U ₁ :

The converter-type power supply provides reactive power support control mode U ₂ for the system without triggering the current limiting control:

The q-axis component of the output current of the converter-type power supply follows the reference value, and the d-axis component of the output current of the converter-type power supply is less than the reference value Control mode U ₃ :

The converter-type power supply provides reactive power support control mode U ₄ for the system with the maximum allowable current:

分别为系统PCC点电压、低电压穿越控制的启动电压、系统额定电压以及模式三与模式四切换点的临界电压，I_c、

以及I_n分别表示换流器型电源输出的短路电流、换流器型电源所允许的最大短路电流以及系统的额定电流，

表示换流器型电源输出有功功率的参考值，

为由低电压穿越控制提供的换流器型电源输出电流相角，kv表示低电压穿越控制的无功功率支撑系数，P_c为换流器型电源实际输出的有功功率。Among them, V _p , V _t , V _n and

are respectively the system PCC point voltage, the starting voltage of low voltage ride through control, the system rated voltage and the critical voltage of mode 3 and mode 4 switching points, I _c ,

and In respectively represent the short _- circuit current output by the converter-type power supply, the maximum allowable short-circuit current of the converter-type power supply and the rated current of the system,

Indicates the reference value of the output active power of the converter-type power supply,

is the output current phase angle of the converter-type power supply provided by the low-voltage ride-through control, kv represents the reactive power support coefficient of the low-voltage ride-through control, and _Pc is the actual output active power of the converter-type power supply.

Specifically, in step S2, the fault network model of the power system including the converter-type power supply is specifically:

以及

分别表示同步电机节点电压相量列向量、系统PCC点电压相量列向量以及负荷节点电压相量列向量，

和

分别为换流器型电源输出电流相量列向量和同步电机节点此暂态电流相量列向量，Z_s和K_s分别为等效同步阻抗矩阵阵以及等效同步系数矩阵，Y_p和K_p分别表示PCC点等效导纳阵和PCC点等效系数矩阵，Y_ab表示系统导纳阵中对应的分块矩阵，a，b＝1，2，3。in,

as well as

Respectively represent the synchronous motor node voltage phasor column vector, the system PCC point voltage phasor column vector and the load node voltage phasor column vector,

with

are the output current phasor column vector of the converter-type power supply and the transient current phasor column vector of the synchronous motor node, Z _s and K _s are the equivalent synchronous impedance matrix and the equivalent synchronous coefficient matrix respectively, Y _p and K _p represents the PCC point equivalent admittance matrix and PCC point equivalent coefficient matrix respectively, Y _ab represents the corresponding block matrix in the system admittance matrix, a, b=1, 2, 3.

Further, the definition of each parameter in the fault network equation is as follows:

Specifically, in step S3, the short-circuit calculation result of the power system including the converter-type power supply is as follows:

为PCC点电压向量，V_p∠θ_c为换流器型电源输出短路电流向量，Y_p和K_p分别为PCC点等效导纳阵和PCC点等效系数矩阵，

为同步电机节点暂态电流相量列向量。in,

is the PCC point voltage vector, V _p ∠θ _c is the output short-circuit current vector of the converter power supply, Y _p and K _p are the PCC point equivalent admittance matrix and PCC point equivalent coefficient matrix, respectively,

is the column vector of the synchronous motor node transient current phasor.

为：Further, the PCC point current vector

for:

为第k台换流器型电源由低电压穿越控制提供的短路电流相角，下标k表示电力系统中所包含的换流器型电源的总台数，j表示虚数单位，T为矩阵转置符号。Among them, I _ck is the short-circuit current output by the k-th converter-type power supply, θ _c is the short-circuit current phase angle vector provided by the phase-locked loop control, and θ _ck is the k-th converter-type power supply controlled by the phase-locked loop Provided the short-circuit current phase angle,

is the short-circuit current phase angle provided by the low-voltage ride-through control of the k-th converter-type power supply, the subscript k indicates the total number of converter-type power supplies included in the power system, j indicates the imaginary number unit, and T is the matrix transposition symbol.

Furthermore, the output short-circuit voltage vector V _p ∠θ _c of the converter-type power supply is:

为第k台换流器型电源的PCC点电压相角的指数表达形式，下标k表示电力系统中所包含的换流器型电源的总台数，j表示虚数单位，T为矩阵转置符号。Among them, θ _c represents the short-circuit current phase angle vector provided by the phase-locked loop control, c represents the PCC point voltage phase angle vector provided by the phase-locked loop control, V _pk is the PCC point voltage amplitude of the k-th converter-type power supply value,

is the exponential expression form of the PCC point voltage phase angle of the k-th converter-type power supply, the subscript k indicates the total number of converter-type power supplies included in the power system, j indicates the imaginary number unit, and T is the matrix transposition symbol .

In the second aspect, an embodiment of the present invention provides a short-circuit calculation system for a converter-type power supply power system, including:

Constraint module, establish the control model of the converter-type power supply, obtain the converter-type power supply does not provide reactive power support, the converter-type power supply provides reactive power support for the system on the premise of not triggering the current limit control. The q-axis component of the output current of the converter-type power supply follows the reference value, the d-axis component of the output current of the converter-type power supply is smaller than the reference value, and the converter-type power supply provides reactive power support for the system with the maximum allowable current. converter-type power constraints;

The modeling module is used to establish the fault network model of the power system with converter type power supply;

The calculation module, based on the fault network model obtained by the modeling module and the constraints of the converter-type power supply under different control modes obtained by the constraint module, realizes the short-circuit calculation applicable to the power system containing the converter-type power supply.

In a third aspect, a computer device includes a memory, a processor, and a computer program stored in the memory and operable on the processor. When the processor executes the computer program, the above-mentioned converter-type Steps in the calculation method for the short circuit of the power supply system.

In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, including a computer program. When the computer program is executed by a processor, the steps of the above-mentioned short-circuit calculation method for a converter-type power supply system are implemented.

Compared with the prior art, the present invention has at least the following beneficial effects:

The present invention is a short-circuit calculation method of a converter-type power supply power system, which includes the switching of the control mode of the converter-type power supply under system failure into the consideration of the short-circuit calculation, and proposes an alternate iterative method based on the obtained constraint conditions and network failure equations The algorithm can quickly solve the short-circuit calculation problem of the power system with converter-type power supply and has high accuracy. It can also summarize the factors that affect the output short-circuit current of the converter-type power supply, and provide a basis for the setting and design of the controller. For reference, please combine.

Furthermore, based on the commonly used control equations of the converter-type power supply, the constraints of the converter-type power supply under different control modes are derived.

Furthermore, based on the fault network model of the traditional power system, the fault network model of the power system with converter type power supply is derived. Based on this network model, an alternate iterative algorithm that can quickly and accurately calculate the short-circuit problem of the power system with converter-type power supply is given, and the factors that affect the short-circuit current level of the converter-type power supply are summarized.

Furthermore, based on the system parameters of the power system with converter-type power supply, the parameters in the fault network equation are derived to quickly solve the short-circuit calculation results.

Further, based on the derived fault network equation, the calculation results of the short-circuit current of the converter-type power supply power system are obtained, that is, the output short-circuit current of the converter-type power supply and the voltage of the PCC point, which are used for relay protection setting and circuit break of the new energy power system It provides the basis for the selection of the device and protection equipment.

Furthermore, based on the proposed alternate iterative algorithm, the amplitude and phase angle of the output short-circuit current of the converter-type power supply can be obtained, and the relay protection setting of the new energy power system can be performed based on the obtained results. .

Furthermore, based on the proposed alternate iterative algorithm, the voltage amplitude and phase angle of the PCC point of the converter-type power supply can be obtained, and the selection of circuit breakers and protection equipment for new energy power systems can be performed based on the obtained results.

It can be understood that, for the beneficial effects of the above-mentioned second aspect to the third aspect, reference may be made to relevant descriptions in the above-mentioned first aspect, and details are not repeated here.

In summary, the present invention summarizes the key factors affecting the short-circuit current level of the converter-type power supply, and based on the obtained calculation results of the short-circuit of the power system with the converter-type power supply, it can quickly and accurately calculate the short-circuit problem of the power system with the converter-type power supply , which lays a theoretical foundation for the rapid relay protection setting of the new energy power system and the selection of circuit breakers and protection equipment for the new energy power system.

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a flowchart of the present invention;

Fig. 2 is the equivalent circuit schematic diagram of converter type power supply;

Figure 3 is a schematic diagram of an equivalent network of a power system with a converter-type power supply;

Fig. 4 is the flow chart of alternate iterative algorithm for short-circuit calculation;

Figure 5 is an analysis diagram of the node voltage error of the system under different transition resistances;

Figure 6 is an analysis diagram of the node voltage error of the system under different fault locations.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In the description of the present invention, it should be understood that the terms "comprising" and "comprising" indicate the presence of described features, integers, steps, operations, elements and/or components, but do not exclude one or more other features, Presence or addition of wholes, steps, operations, elements, components and/or collections thereof.

It should also be understood that the terminology used in the description of the present invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the present invention. As used in this specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural referents unless the context clearly dictates otherwise.

It should also be further understood that the term "and/or" used in the description of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations , for example, A and/or B, may mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" in this article generally indicates that the contextual objects are an "or" relationship.

It should be understood that although the terms first, second, third, etc. may be used in the embodiments of the present invention to describe preset ranges, etc., these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be called the second preset range, and similarly, the second preset range may also be called the first preset range.

Depending on the context, the word "if" as used herein may be interpreted as "at" or "when" or "in response to determining" or "in response to detecting". Similarly, depending on the context, the phrases "if determined" or "if detected (the stated condition or event)" could be interpreted as "when determined" or "in response to the determination" or "when detected (the stated condition or event) )" or "in response to detection of (a stated condition or event)".

Various structural schematic diagrams according to the disclosed embodiments of the present invention are shown in the accompanying drawings. The figures are not drawn to scale, with certain details exaggerated and possibly omitted for clarity of presentation. The shapes of various regions and layers shown in the figure and their relative sizes and positional relationships are only exemplary, and may deviate due to manufacturing tolerances or technical limitations in practice, and those skilled in the art may Regions/layers with different shapes, sizes, and relative positions can be additionally designed as needed.

The invention provides a short-circuit calculation method of a converter-type power supply power system. Firstly, a control model of the converter-type power supply is established, and constraints of the converter-type power supply under different control modes are determined. On this basis, the fault network model of the power system with converter-type power supply is established, and the equations that can quickly calculate the fault power flow of the system are further derived, and finally an alternate iterative algorithm for system short-circuit calculation is obtained. This method provides an alternate iterative algorithm that can quickly solve the fault power flow of the system and has high accuracy. The results of the algorithm show that the short-circuit current that the converter-type power supply can provide is closely related to factors such as the control mode of the converter, the location of the fault, and the transition resistance.

Please refer to Fig. 1, a short-circuit calculation method of a converter-type power supply power system of the present invention, based on the fault network model of the power system containing a converter-type power supply, combined with the actual parameters of the system, the short-circuit problem of the system can be quickly and accurately calculated, Specific steps are as follows:

S1. Establish the control model of the converter-type power supply, and obtain the constraints of the converter-type power supply under different control modes;

The converter-type power constraints for different control modes are described by the following equations:

分别为系统PCC点电压、低电压穿越控制的启动电压、系统额定电压以及模式三与模式四切换点的临界电压；I_c、

以及I_n分别表示换流器型电源输出的短路电流、换流器型电源所允许的最大短路电流以及系统的额定电流；

表示换流器型电源输出有功功率的参考值；

为由低电压穿越控制提供的换流器型电源输出电流相角；k_v表示低电压穿越控制的无功功率支撑系数；U₁、U₂、U₃和U₄分别对应换流器型电源四种控制模式的集合。Among them, V _p , V _t , V _n and

They are respectively the system PCC point voltage, the starting voltage of low voltage ride through control, the system rated voltage and the critical voltage of mode 3 and mode 4 switching points; I _c ,

and In respectively represent the short _- circuit current output by the converter-type power supply, the maximum allowable short-circuit current of the converter-type power supply and the rated current of the system;

Indicates the reference value of the output active power of the converter-type power supply;

is the output current phase angle of the converter-type power supply provided by the low-voltage ride-through control; k _v represents the reactive power support coefficient of the low-voltage ride-through control; U ₁ , U ₂ , U ₃ and U ₄ respectively correspond to the converter-type power supply A collection of four control modes.

Please refer to Figure 2, the schematic diagram of the equivalent circuit of the converter type power supply in Figure 2;

The commonly used control equations (excluding inner and outer loops) for converter-type power supplies are:

Low voltage ride through control:

Current limit control:

和

分别表示换流器型电源输出电流的d轴分量和q轴分量；

和

分别表示换流器型电源输出电流参考值的d轴分量和q轴分量；

为换流器型电源所能允许的最大短路电流；V_p、V_t以及V_n分别表示系统PCC点电压、低电压穿越控制的启动电压以及系统额定电压；k_v表示低电压穿越控制的无功功率支撑系数。in,

with

represent the d-axis component and q-axis component of the output current of the converter-type power supply, respectively;

with

Respectively represent the d-axis component and the q-axis component of the output current reference value of the converter-type power supply;

is the maximum allowable short-circuit current of the converter-type power supply; V _p , V _t and _{V n} represent the PCC point voltage of the system, the starting voltage of the low voltage ride-through control and the rated voltage of the system respectively; Work power support factor.

Based on formula (1) and formula (2), it is concluded that the converter-type power supply with low-voltage fault ride-through capability can be switched to one of the following four control modes during power system failure.

Mode 1 (U ₁ ): when the voltage at the PCC point is still higher than the starting voltage of the LVRT control, the converter-type power supply does not provide reactive power support. At this time, the active power output by the converter-type power supply is adjusted to the set reference value.

分别表示换流器型电源输出的有功功率及其参考值；

为由低电压穿越控制提供的换流器型电源输出电流相角。Among them, P _c and

Respectively represent the active power output by the converter-type power supply and its reference value;

is the phase angle of the output current of the converter-type power supply provided by the low voltage ride through control.

Mode 2 (U ₂ ): When the PCC point voltage is lower than the start-up voltage of LVRT control, the converter-type power supply can provide reactive power support for the system without triggering the current limiting control.

Mode 3 (U ₃ ): When the PCC point voltage is lower than the starting voltage of the low voltage ride-through control and the converter current limiting control is started, the q-axis component of the output current of the converter-type power supply can follow its reference value, while The d-axis component of the output current of the converter-type power supply is smaller than the reference value due to the effect of the current limiting control.

Mode 4 (U ₄ ): When the PCC point voltage is lower than the critical voltage, the converter-type power supply can only provide reactive power support for the system with its maximum allowable current.

为模式三U₃与模式四U₄切换点的临界电压。in,

It is the critical voltage of the switching point of mode three U ₃ and mode four U ₄ .

At this time, the converter-type power supply needs to meet the following constraints:

S2. Establishing a fault network model of a power system with a converter-type power supply;

Please refer to FIG. 3 . FIG. 3 is a schematic diagram of an equivalent network of a power system including a converter-type power supply. Following the fault network form of the traditional power system, the fault network model of the power system with converter type power supply is written.

和

分别表示系统所有节点的电压相量列向量以及电流相量列向量；

以及

分别表示同步电机节点电压相量列向量、系统PCC点电压相量列向量以及负荷节点电压相量列向量；

和

分别表示同步电机节点电流相量列向量以及换流器型电源输出电流相量列向量；Y_f为故障网络方程的导纳阵。in,

with

Respectively represent the voltage phasor column vector and the current phasor column vector of all nodes in the system;

as well as

Respectively represent the synchronous motor node voltage phasor column vector, the system PCC point voltage phasor column vector and the load node voltage phasor column vector;

with

Respectively represent the synchronous motor node current phasor column vector and the converter type power supply output current phasor column vector; Y _f is the admittance matrix of the fault network equation.

In practical short-circuit calculations, however, the synchronous motor dynamics are described by the following equations:

表示同步发电机的次暂态电动势；

表示同步发电机的次暂态电流；x″表示同步发电机的次暂态电抗；y_g表示同步发电机的等效导纳；

和

分别表示同步发电机端口的输出电压及输出电流。in,

Indicates the subtransient electromotive force of the synchronous generator;

represents the subtransient current of the synchronous generator; x″ represents the subtransient reactance of the synchronous generator; y _g represents the equivalent admittance of the synchronous generator;

with

Respectively represent the output voltage and output current of the synchronous generator port.

Substituting formula (9) into formula (8), the optimized fault network equation is obtained:

表示同步电机节点次暂态电流相量列向量；Y_ab(a，b＝1，2，3)表示系统导纳阵中对应的分块矩阵。in,

represents the column vector of the synchronous motor node subtransient current phasor; Y _ab (a, b=1, 2, 3) represents the corresponding block matrix in the system admittance matrix.

Based on equation (10), the fault network model of the power system with converter-type power supply is described by the following equation:

以及

分别表示同步电机节点电压相量列向量、系统PCC点电压相量列向量以及负荷节点电压相量列向量；

和

分别为换流器型电源输出电流相量列向量和同步电机节点此暂态电流相量列向量；Z_s和K_s分别为等效同步阻抗矩阵阵以及等效同步系数矩阵；Y_p和K_p分别表示PCC点等效导纳阵和PCC点等效系数矩阵；Y_ab(a，b＝1，2，3)表示系统导纳阵中对应的分块矩阵。in,

as well as

Respectively represent the synchronous motor node voltage phasor column vector, the system PCC point voltage phasor column vector and the load node voltage phasor column vector;

with

are the output current phasor column vector of the converter-type power supply and the transient current phasor column vector of the synchronous motor node; Z _s and K _s are the equivalent synchronous impedance matrix and the equivalent synchronous coefficient matrix respectively; Y _p and K _p represents the PCC point equivalent admittance matrix and the PCC point equivalent coefficient matrix respectively; Y _ab (a, b=1, 2, 3) represents the corresponding block matrix in the system admittance matrix.

The specific definition of each parameter in the fault network equation is as follows:

Wherein, Y _ab (a, b=1, 2, 3) represents the corresponding block matrix in the system admittance matrix.

S3. Based on the fault network model obtained in step S2 and the constraints of the converter-type power supply under different control modes obtained in step S1, realize short-circuit calculation applicable to power systems containing converter-type power supplies.

According to formula (11), the short-circuit calculation results of the power system with converter-type power supply are obtained as follows:

Among them, the specific definitions of the PCC point voltage vector and the output short-circuit current vector of the converter-type power supply are as follows:

Among them, c represents the PCC point voltage phase angle vector provided by the phase-locked loop control; the subscript k represents the total number of converter-type power supplies included in the power system; the subscript i represents the ith converter-type power supply; j represents the imaginary unit.

Based on Equation (12), Equation (13) and the equation constraints of the converter-type power supply under different control modes in step S1, the short-circuit calculation problem of the studied system is quickly solved; through the calculation of the converter-type power supply under different control modes Inequality constraints can be used to determine whether the desired result is correct.

Please refer to Figure 4, the alternate iterative algorithm flow of short-circuit calculation is as follows:

k_v，I_n，V_t，形成导纳阵Y_f，并计算

Z_p(没找到这个符号)，Z_s，K_p，K_s，设置U₁＝U₂＝U₃＝φ，U₄＝U，联立式(23)和(24)，计算得到V_p，I_c，θ_c，

利用公式P_ci＝V_piI_ci计算每个CIG的有功功率输出：enter

_{k v} , In , V _t , form the admittance matrix Y _f , and calculate

Z _p (can't find this symbol), Z _s , K _p , K _s , set U ₁ ＝U ₂ ＝U ₃ ＝φ, U ₄ ＝U, combine equations (23) and (24), and calculate V _p , I _c , θ _c ,

Use the formula P _ci =V _pi I _ci to calculate the active power output of each CIG:

中；When V _pi ≥ V _ti , the CIG belongs to control mode 1, so its node number i is stored in the set

middle;

时，该CIG属于控制模式四，故将其节点编号i存入集合

中；When V _pi < V _ti and

, the CIG belongs to control mode 4, so its node number i is stored in the set

middle;

时，此时需要比较各CIG的实际输出功率与其输出功率的参考值来确定其所处的控制模式；When V _pi < V _ti and

At this time, it is necessary to compare the actual output power of each CIG with its output power reference value to determine the control mode it is in;

时，该CIG属于控制模式三，故将其节点编号i存入集合

中；when

, the CIG belongs to control mode 3, so its node number i is stored in the set

middle;

中；随后，判断一次计算前集合中的元素与一次计算后集合中的元素是否一致；若一致，则计算V_p、V_l，并输出V_p、V_g、V_l的计算结果；若不一致，则重新计算V_p，I_c，θ_c，

的值并重复上述判断过程直至计算前集合中的元素与计算后集合中的元素相同。If the power does not satisfy the above inequality, the CIG belongs to control mode 2, so its node number is stored in the set

Then, judge whether the elements in the set before a calculation are consistent with the elements in the set after a calculation; if they are consistent, calculate V _p , V _l , and output the calculation results of V _p , V _g , V _l ; if they are not consistent , then recalculate V _p , I _c , θ _c ,

value and repeat the above judgment process until the elements in the set before calculation are the same as the elements in the set after calculation.

In yet another embodiment of the present invention, a short-circuit calculation system for a converter-type power supply power system is provided, which can be used to implement the above-mentioned short-circuit calculation method for a converter-type power supply power system. Specifically, the converter-type power supply power system The system short-circuit calculation system includes a constraint module, a modeling module and a calculation module.

Among them, the constraint module establishes the control model of the converter-type power supply, and obtains that the converter-type power supply does not provide reactive power support, and the converter-type power supply provides reactive power support for the system without triggering the current limiting control , The q-axis component of the output current of the converter-type power supply follows the reference value, the d-axis component of the output current of the converter-type power supply is less than the reference value, and the converter-type power supply provides reactive power support for the system with the maximum allowable current under the control mode The converter-type power constraint of ;

The modeling module is used to establish the fault network model of the power system with converter type power supply;

The calculation module, based on the fault network model obtained by the modeling module and the constraints of the converter-type power supply under different control modes obtained by the constraint module, realizes the short-circuit calculation applicable to the power system containing the converter-type power supply.

In yet another embodiment of the present invention, a terminal device is provided, the terminal device includes a processor and a memory, the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the computer The program instructions stored in the storage medium. The processor may be a central processing unit (Central Processing Unit, CPU), or other general-purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), off-the-shelf programmable gates Array (Field-Programmable GateArray, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc., which are the computing core and control core of the terminal, are suitable for implementing one or more instructions, and are specifically suitable for To load and execute one or more instructions so as to realize the corresponding method flow or corresponding functions; the processor described in the embodiment of the present invention can be used for the operation of the short-circuit calculation method of the converter-type power supply power system, including:

The control model of the converter-type power supply is established, and it is obtained that the converter-type power supply does not provide reactive power support, the converter-type power supply provides reactive power support for the system without triggering the current limit control, and the converter-type power supply The q-axis component of the output current of the power supply follows the reference value, the d-axis component of the output current of the converter-type power supply is smaller than the reference value, and the converter-type power supply provides reactive power for the system with the maximum allowable current. Power supply constraints; establish a fault network model of the power system with converter-type power supply; based on the fault network model and the constraints of the converter-type power supply under different control modes, realize the short-circuit calculation suitable for the power system with converter-type power supply.

In yet another embodiment of the present invention, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory). The computer-readable storage medium is a memory device in a terminal device for storing programs and data. . It can be understood that the computer-readable storage medium here may include a built-in storage medium in the terminal device, and certainly may include an extended storage medium supported by the terminal device. The computer-readable storage medium provides storage space, and the storage space stores the operating system of the terminal. Moreover, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions may be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here may be a high-speed RAM memory, or a non-volatile memory (Non-Volatile Memory), such as at least one magnetic disk memory.

One or more instructions stored in the computer-readable storage medium can be loaded and executed by the processor, so as to realize the corresponding steps in the method for calculating the short circuit of the converter-type power supply system in the above-mentioned embodiments; one or more instructions in the computer-readable storage medium One or more instructions are loaded by the processor and executed in the following steps:

The control model of the converter-type power supply is established, and it is obtained that the converter-type power supply does not provide reactive power support, the converter-type power supply provides reactive power support for the system without triggering the current limit control, and the converter-type power supply The q-axis component of the output current of the power supply follows the reference value, the d-axis component of the output current of the converter-type power supply is smaller than the reference value, and the converter-type power supply provides reactive power for the system with the maximum allowable current. Power supply constraints; establish a fault network model of the power system with converter-type power supply; based on the fault network model and the constraints of the converter-type power supply under different control modes, realize the short-circuit calculation suitable for the power system with converter-type power supply.

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Please refer to Table 1, Table 1 is the relevant parameters of the test system.

Table 1

Please refer to Table 2, from the results in Table 2, the calculation results of the PCC point voltage of the converter-type power supply under four different control modes can be obtained. These calculation and simulation results show that the method proposed in the present invention for distinguishing the control mode of the converter-type power supply when the system fails is correct. In addition, comparing the simulation results and the calculation results of the algorithm, it is not difficult to see that the final results obtained by the proposed algorithm are very similar to the numerical simulation results through the simulation platform, and the error is not more than 1.5%. This effectively demonstrates the effectiveness and accuracy of the present invention, which can well set the parameters of the relay protection of the new energy power system, and lays a theoretical foundation for the selection of circuit breakers and protection equipment in the new energy power system.

Table 2 Calculation results of PCC point voltage of each converter type power supply

Please refer to FIG. 5, which is an analysis diagram of the node voltage error of the system under different transition resistances. It can be seen that the error of the proposed algorithm is slightly different under different transition resistances; the larger the transition resistance is, the smaller the node voltage amplitude error is, and the larger the node voltage phase angle error is. Also, since the true value is very close to zero, the phase angle error is generally larger than the magnitude error, but not more than 4%. This also verifies that the proposed algorithm has high accuracy.

Please refer to FIG. 6, which is an analysis diagram of the node voltage error of the system under different fault locations. It can be seen that the difference in the fault location of the system will not have a great impact on the accuracy of the proposed algorithm. The size of the error between the two is mainly caused by its own characteristics, and it does not exceed 2%. It is verified that the method of the present invention has high accuracy.

To sum up, the present invention provides a short-circuit calculation method, system, medium, and equipment for a converter-type power supply power system, which takes the control mode switching of the converter-type power supply under system failure into consideration in the short-circuit calculation, and based on the obtained constraints The condition and network fault equation propose an alternate iterative method, which can quickly solve the short-circuit calculation problem of the power system with converter-type power supply and has high accuracy. The factors provide a reference for the setting and design of the controller.

Those skilled in the art should understand that the embodiments of the present application may be provided as methods, systems, or computer program products. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowcharts and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow diagram procedure or procedures and/or block diagram procedures or blocks.

The above content is only to illustrate the technical ideas of the present invention, and cannot limit the protection scope of the present invention. Any changes made on the basis of the technical solutions according to the technical ideas proposed in the present invention shall fall within the scope of the claims of the present invention. within the scope of protection.

Claims (10)

1. The short-circuit calculation method of converter type power supply power system, is characterized in that, comprises the following steps: S1. Establish the control model of the converter-type power supply, and obtain that the converter-type power supply does not provide reactive power support, and the converter-type power supply provides reactive power support for the system without triggering the current limiting control. The q-axis component of the output current of the converter-type power supply follows the reference value, the d-axis component of the output current of the converter-type power supply is smaller than the reference value, and the converter-type power supply provides reactive power for the system with the maximum allowable current to support the commutation in the control mode device type power constraints; S2. Establishing a fault network model of a power system with a converter-type power supply; S3. Based on the fault network model obtained in step S2 and the constraints of the converter-type power supply under different control modes obtained in step S1, realize short-circuit calculation applicable to power systems containing converter-type power supplies. 2. The short-circuit calculation method of the converter-type power supply power system according to claim 1, characterized in that, in step S1, the constraints of the converter-type power supply are specifically as follows: Converter-type power supply does not provide reactive power support control mode U ₁ :

The converter-type power supply provides reactive power support control mode U ₂ for the system without triggering the current limiting control:

The q-axis component of the output current of the converter-type power supply follows the reference value, and the d-axis component of the output current of the converter-type power supply is less than the reference value Control mode U ₃ :

The converter-type power supply provides reactive power support control mode U ₄ for the system with the maximum allowable current:

Among them, V _p , V _t , V _n and

are respectively the system PCC point voltage, the starting voltage of low voltage ride through control, the system rated voltage and the critical voltage of mode 3 and mode 4 switching points, I _c ,

and In respectively represent the short _- circuit current output by the converter-type power supply, the maximum allowable short-circuit current of the converter-type power supply and the rated current of the system,

Indicates the reference value of the output active power of the converter-type power supply,

is the output current phase angle of the converter-type power supply provided by the low-voltage ride-through control, k _v represents the reactive power support coefficient of the low-voltage ride-through control, and P _c is the actual output active power of the converter-type power supply. 3. The short-circuit calculation method of the converter-type power supply power system according to claim 1, characterized in that, in step S2, the fault network model containing the converter-type power supply power system is specifically:

in,

as well as

Respectively represent the synchronous motor node voltage phasor column vector, the system PCC point voltage phasor column vector and the load node voltage phasor column vector,

with

are the output current phasor column vector of the converter-type power supply and the transient current phasor column vector of the synchronous motor node, Z _s and K _s are the equivalent synchronous impedance matrix and the equivalent synchronous coefficient matrix respectively, Y _p and K _p represents the PCC point equivalent admittance matrix and PCC point equivalent coefficient matrix respectively, Y _ab represents the corresponding block matrix in the system admittance matrix, a, b=1, 2, 3. 4. the converter type power supply power system short-circuit calculation method according to claim 2, is characterized in that, the definition of each parameter in the fault network equation is as follows:

5. The short-circuit calculation method of the converter-type power supply power system according to claim 1, characterized in that, in step S3, the short-circuit calculation result of the converter-type power supply power system is as follows:

in,

is the PCC point voltage vector, V _p ∠θ _c is the output short-circuit current vector of the converter power supply, Y _p and K _p are the PCC point equivalent admittance matrix and PCC point equivalent coefficient matrix, respectively,

is the column vector of the synchronous motor node transient current phasor. 6. The converter type power supply power system short circuit calculation method according to claim 5, characterized in that the PCC point current vector

for:

Among them, I _ck is the short-circuit current output by the k-th converter-type power supply, θ _c is the short-circuit current phase angle vector provided by the phase-locked loop control, and θ _ck is the k-th converter-type power supply controlled by the phase-locked loop Provided the short-circuit current phase angle,

is the short-circuit current phase angle provided by the low-voltage ride-through control of the k-th converter-type power supply, the subscript k indicates the total number of converter-type power supplies included in the power system, j indicates the imaginary number unit, and T is the matrix transposition symbol. 7. The short-circuit calculation method of the converter-type power supply power system according to claim 5, wherein the converter-type power supply output short-circuit voltage _{vector Vp∠θc} is:

Among them, θ _c represents the short-circuit current phase angle vector provided by the phase-locked loop control, c represents the PCC point voltage phase angle vector provided by the phase-locked loop control, V _pk is the PCC point voltage amplitude of the k-th converter-type power supply value,

is the exponential expression form of the PCC point voltage phase angle of the k-th converter-type power supply, the subscript k indicates the total number of converter-type power supplies included in the power system, j indicates the imaginary number unit, and T is the matrix transposition symbol . 8. A short-circuit calculation system for a converter-type power supply system, characterized in that it includes: Constraint module, establish the control model of the converter-type power supply, obtain the converter-type power supply does not provide reactive power support, the converter-type power supply provides reactive power support for the system on the premise of not triggering the current limit control. The q-axis component of the output current of the converter-type power supply follows the reference value, the d-axis component of the output current of the converter-type power supply is smaller than the reference value, and the converter-type power supply provides reactive power support for the system with the maximum allowable current. converter-type power constraints; The modeling module is used to establish the fault network model of the power system with converter type power supply; The calculation module, based on the fault network model obtained by the modeling module and the constraints of the converter-type power supply under different control modes obtained by the constraint module, realizes the short-circuit calculation applicable to the power system containing the converter-type power supply. 9. A computer-readable storage medium storing one or more programs, wherein the one or more programs comprise instructions which, when executed by a computing device, cause the computing device to perform the Any one of the methods described in 1 to 7. 10. A computing device, comprising: one or more processors, memory, and one or more programs, wherein one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs include using Instructions for performing any one of the methods according to claims 1-7.

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