CN110414759A - A Differential Calculation Method of Capacity-load Ratio - Google Patents

Abstract

The invention discloses a differentiated capacity-load ratio calculation method, which belongs to the field of grid planning. The present invention solves the problem of unbalanced development of power supply capacity of each power supply area caused by the limitation of a single capacity-load ratio control index in the power supply area. A new calculation method is proposed, that is, when calculating the capacity of the main transformer, the main transformer of the step-up station and the capacity of the main transformer for improving the reliability of power supply in the network area or for precise poverty alleviation are eliminated, and at the same time, the key factors affecting the capacity-load ratio are found out, and the linear The formula recalculates the capacity-to-load ratio. This calculation method has been actually used in the Guangxi region. After using the new method to calculate the capacity-load ratio index within a reasonable range, the power grid planning professionals should reasonably adjust the layout and capacity of the main transformers in each power supply area when planning the power grid to effectively solve the problem. Unbalanced development of power grids in various regions.

Description

A Differential Calculation Method of Capacity-load Ratio

technical field

The invention belongs to the field of grid planning, and in particular relates to a differentiated capacity-load ratio calculation method.

Background technique

The capacity-to-load ratio is the ratio of the maximum power load of the same voltage level to the capacity of the public main transformer in a relatively independent power supply area. At present, the main problems in power grid planning are: first, the problem of excessive capacity-load ratio is common; Counties are surplus, or the reliability of power supply in remote areas is not high. Therefore, on the one hand, the lack of new main transformer capacity causes power shortage, and on the other hand, the new main transformer capacity causes the capacity-load ratio to exceed the standard, which does not meet the planning requirements. The main contradictions encountered in the development of the two power grids have always plagued power grid planners. Obviously, the traditional rigid capacity-to-load ratio index control method can no longer meet the development needs of the current power grid. For grassroots power grid planning professionals, there has never been a guiding standard for whether, how, and when the main transformer can be installed, and there is no basis for the work to be carried out. Based on this, it is necessary to invent a differentiated capacity-load ratio calculation method to guide power grid planning. At present, this calculation method has been actually used in the Guangxi region. After calculating the capacity-load ratio index in a reasonable range by using the new method, the layout and capacity of the main transformers in each power supply area should be adjusted reasonably during the grid planning, which can effectively solve the problem of Unbalanced grid development.

Contents of the invention

The invention discloses a differentiated capacity-load ratio calculation method. The principle is mainly reflected in two points. One is to innovate the principle of calculating the capacity of the main transformer, and the other is to propose a new method for reasonably adjusting the capacity-load ratio calculation index, which effectively solves the current existing problems. Limited by the single capacity-load ratio control index of the power supply area, the uneven development of power supply capacity in each power supply area is caused.

To achieve the above object, the technical solution of the present invention is:

First, find out the load development level of each network area and the progress of power transmission and transformation projects (lag years), and establish a linear formula to correct the capacity-load ratio index. The formula for calculating the differential capacity-load ratio is obtained as follows:

Rc=γ·Rs where: γ=(1+X) ⁿ

In the formula, Rc is the corrected differential capacity-to-load ratio, γ is the correction coefficient of the capacity-to-load ratio, and Rs is the calculated capacity-to-load ratio without correction. x is the average growth rate of regional load in the past three years (excluding large users above this voltage level), and n is the average lag time of power transmission and transformation projects.

Grass-roots power grid planners can calculate the current capacity-load ratio by 1. Comparing with the current situation of the network area, using conventional methods. 2. Combined with the load development of the network area and the progress of power transmission and transformation projects, calculate the range of capacity-load ratio indicators. Judgment criteria: If the capacity-to-load ratio is within the target range, the main transformer capacity can be increased; if it exceeds the upper limit of the target range, the new main transformer capacity will not be considered for the time being. The new calculation method of the invention enables grid planners to have operable methods and measures when determining the main transformer capacity demand in relevant areas. In the same way, the capacity-load ratio selection strategy table for each voltage level of high, medium and low distribution networks can be established to provide technical support for technical personnel's decision-making.

This calculation method is simple and easy, considering the two factors of load growth rate and average lag time of power transmission and transformation projects, and the obtained capacity-load ratio is more objective and scientific. At present, it has been actually used in the 35-220 kV power transmission and transformation project invested by Guangxi Power Grid Corporation. The project approval time for a single main transformer capacity expansion project was reduced from 2 working days to write a demonstration statement to 2 hours to complete. Taking a power transmission and transformation project as an example, it turns out that each project needs to go through the demonstration and explanation of load forecasting, power supply planning, power surplus analysis, and project necessity demonstration. However, using this calculation method can make a preliminary assessment and auxiliary decision-making on the feasibility of the project in a relatively short period of time, which can save about 6.6 man-days. Calculated on the basis of 500 yuan per man-day per person, a single project can effectively save human resources The cost is 3300 yuan/item. According to the total of 80 projects per year, 264,000 yuan in labor costs can be saved. The calculation method is simple to operate, and can allow non-planning professionals to easily evaluate the main transformer capacity demand in the power supply area, effectively improve the quality and efficiency of power grid planning, and effectively save human resource costs.

This calculation method can be applied to the calculation of the capacity-load ratio of the whole district, each network area, and each urban area, and can be popularized and applied at all voltage levels (10-500kV). The calculation process is simple and the results are accurate, effectively avoiding multi-link demonstration work and greatly improving work efficiency. The tool has the characteristics of flexibility and strong practicability, and can combine the load development characteristics of each network area, power transmission and transformation obstructions and other indicators as input quantities, and has a high degree of agreement with the actual power supply capacity of the power grid.

Description of drawings

Figure 1 is a logic diagram of a differentiated capacity-to-load ratio calculation method.

Detailed ways

The specific implementation steps are as follows:

S1: Carry out load forecasting based on factors such as the current load conditions in the power supply area, the presence of large users, and changes in population density.

S2: Comparing the load forecast results with the previous year, get the growth rate of electricity load. If the load increases, go to step 3. If there is no load increase, go to step 4, and use the conventional capacity-load ratio to check whether the capacity of the main transformer in this area meets the requirements.

S3: Sort out the lagging progress of the power transmission and transformation project construction in the power supply area. If there is a delay in the construction progress of the power transmission and transformation project, go to step 5. If there is no delay in the construction progress of power transmission and transformation projects, go to step 4 and use the conventional capacity-load ratio to check whether the capacity of the main transformer in this area meets the requirements.

S4: Check whether the main transformer capacity in the area meets the requirements according to the conventional capacity-to-load ratio. The control index of 500kV conventional capacity-to-load ratio is 1.4-1.6, the control index of 220kV conventional capacity-to-load ratio is 1.6-1.9, and the control index of 110kV and 35kV conventional capacity-to-load ratio is 1.8-2.2.

S5: Calculate the capacity-to-load ratio using differentiation, and determine the main transformer capacity that needs to be increased in combination with the calculation results.

S6: Establish a new project in the power grid planning, build a new power transmission and transformation project or increase the capacity of the main transformer in the area by increasing the capacity of the main transformer.

Taking the 220kV voltage level of a certain power supply area as an example, the calculation results of the differentiated capacity-load ratio considering the delay period of the power transmission and transformation project and the load growth rate are shown in the table below:

load growth rate 1 year behind 2 years behind 3 years behind 4 years behind 5 years behind 0% 1.6～1.9 1.6～1.9 1.6～1.9 1.6～1.9 1.6～1.9 1% 1.62～1.92 1.63～1.94 1.65～1.96 1.66～1.98 1.68～2.0 2% 1.63～1.94 1.66～1.98 1.7～2.02 1.73～2.06 1.77～2.1 3% 1.65～1.96 1.7～2.02 1.75～2.08 1.8～2.14 1.85～2.20 4% 1.66～1.98 1.73～2.06 1.8～2.14 1.87～2.22 1.95～2.31 5% 1.68～2.0 1.76～2.09 1.85～2.20 1.94～2.31 2.04～2.42 6% 1.7～2.014 1.8～2.13 1.91～2.26 2.02～2.40 2.14～2.54 7% 1.71～2.03 1.83～2.18 1.96～2.33 2.1～2.49 2.24～2.66 8% 1.73～2.05 1.87～2.22 2.02～2.39 2.18～2.58 2.35～2.79 9% 1.74～2.07 1.9～2.26 2.07～2.46 2.26～2.68 2.46～2.92 10% 1.76～2.09 1.94～2.30 2.13～2.53 2.34～2.78 2.58～3.06

For example, the lagging period of a power transmission and transformation project in a network area is 1 year, and the average annual power growth rate is 3%. At this time, through calculation and table lookup, the adjusted index of capacity-load ratio is 1.65-1.96, and so on. Comparing the index value calculated by the differential capacity-load ratio with the current capacity-load ratio, the new scale of the main transformer capacity in this area can be obtained. The revised capacity-load ratio objectively reflects the real demand of the main transformer capacity in the power supply area, and gets rid of the restriction of the conventional capacity-load ratio on the newly-added main transformer capacity. Unbalanced development of power grids in various regions.

Claims (1)

1. A differentiated capacity-to-load ratio calculation method, characterized in that: find out the key factors, establish a new linear formula to modify the capacity-to-load ratio index calculation method, first find out the load growth of the corresponding power supply area, and the power transmission and transformation There are two key factors of project construction lag, and a linear formula is established to correct the capacity-load ratio index, and the differential capacity-load ratio calculation formula is obtained as follows: Rc=γ·Rs where: γ=(1+x) ⁿ In the formula, Rc is the corrected differentiated capacity-to-load ratio, γ is the correction factor of the capacity-to-load ratio, Rs is the uncorrected calculated capacity-to-load ratio, and x is the average power growth in the region excluding large users above this voltage level in the past three years rate, n is the average lag time of power transmission and transformation projects.