Evaluation method of inductive reactive power margin in provincial power grid

Abstract

The present invention discloses a method for evaluating the inductive reactive power margin of a provincial power grid. Based on actual power grid lines and substation equipment parameters, the present invention evaluates the inductive reactive power margin of each level of the provincial power grid 500kV~110kV, evaluates the inductive reactive power balance of the power supply area or a single substation containing several substations at each level by voltage level, calculates the inductive reactive power compensation shortfall corresponding to the power supply area or specific substation, determines the priority of the inductive reactive power compensation configuration requirements of substations at each voltage level, finds the weak points of inductive reactive power compensation in the whole network, and avoids the phenomenon of reactive power transmission across voltage levels of the provincial power grid in the valley mode. The method of the present invention can be used for substation planning and design and inductive reactive power margin analysis of actual substations in operation in the valley mode, to ensure the reactive power layering and partitioning balance of the power grid in the valley mode and improve the safety and stability level of the power grid.

Description

Technical Field

[0001] The invention relates to the field of reactive layered and zoned balance of provincial power grids, and in particular to a method for evaluating the inductive reactive power margin of provincial power grids. Background Art

[0002] The reactive power stratification and zoning balance of power grid is a key factor affecting the safe and economic operation of power grid. Under the background of rapid development of power grid, there are two main reasons for the insufficient compensation of inductive reactive power in provincial power grid: 1) With the enhancement of 220 kV voltage level grid, the charging power of 220 kV overhead lines has gradually reached a large scale, and the current planning and design of 220 kV substations have not yet considered the configuration of inductive reactive power corresponding to the charging power of 220 kV overhead lines; 2) The "overhead to cable" project of 110 kV and 10 kV power grids is actively promoted, and the number of incoming and outgoing cables of 110 kV substations in urban centers has increased. Its larger line charging power also affects the balance of inductive reactive power. The two main reasons together cause the phenomenon that during the low-load operation of provincial power grids, there is a phenomenon of high voltage, high power factor and even cross-region and cross-level transmission of inductive reactive power due to the charging power process, which ultimately affects the operation efficiency, power supply quality and user power safety of the power grid during low-load operation.

[0003] At present, there is no simple and easy-to-implement inductive reactive power margin assessment method for provincial power grids, which is used to guide the inductive reactive power balance of each voltage level power supply area or a single substation in the provincial power grid, so as to make up for the fact that the analysis of inductive reactive power balance was not fully considered in the previous substation planning and design stages, resulting in insufficient inductive reactive power compensation in the provincial power grid, and the voltage, power factor and reactive power balance are difficult to control during low load mode. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a provincial power grid inductive reactive power margin assessment method based on inductive reactive power compensation rate in response to the phenomenon that line charging power fails to be fully compensated during the development of the existing power grid, resulting in cross-regional and cross-level transmission of inductive reactive power during low load periods. The method is based on actual power grid data, evaluates the inductive reactive power compensation rate of power supply areas or single substations at each level containing several substations according to voltage levels, calculates the corresponding inductive reactive power compensation shortfall, evaluates the inductive reactive power balance level, and provides an inductive reactive power compensation configuration plan.

[0005] To this end, the technical solution adopted by the present invention is as follows: a provincial power grid inductive reactive power margin assessment method, which comprises the following steps:

[0006] The first step is to determine the basic ledger information and equipment parameters of 500 kV, 220 kV, and 110 kV substations;

[0007] The second step is to determine the information of the first and last substations, line types and length parameters of the transmission lines above 10 kV;

[0008] Step 3: Select the target voltage level, power supply area, reactive power balance or reactive power compensation rate requirement. If the data is complete and valid, go to step 4; otherwise, go to step 1.

[0009] The fourth step is to determine the parameters of the substations and the connected incoming lines of the voltage level above each substation of the target voltage level, and determine the parameters of all the subordinate substations and the connected outgoing lines of the voltage level below each substation of the target voltage level; calculate the type and length of the incoming and outgoing lines of each substation;

[0010] The fifth step is to consider the inductive reactive power compensation capacity that has been configured and needs to be configured in the power supply area containing several substations or a single substation, calculate the charging power of the lines connected to the substations in the power supply area, and calculate the inductive reactive power compensation rate of several substations or a single substation in the power supply area;

[0011] Step 6: Conduct target voltage level inductive reactive power margin analysis and set the target voltage level power supply area or single substation inductive reactive power compensation rate limit; if the substation inductive reactive power compensation rate is less than the set limit, go to step 7, otherwise go to step 8;

[0012] Step 7: Calculate the required capacity of inductive reactive power compensation of the substation according to the actual compensation rate of the power supply area or substation and the set limit value, form an inductive reactive power compensation configuration plan for several substations or a single substation in the power supply area, and go to step 5;

[0013] The eighth step is to output the target voltage level inductive reactive power balance analysis results and the corresponding inductive reactive power compensation configuration plan.

[0014] Based on actual power grid data, the present invention evaluates the inductive reactive power balance of power supply areas or single substations at each level containing several substations according to voltage levels, finds the weak points of inductive reactive power compensation in provincial power grids, and improves the reactive power stratification and partitioning balance level of power grids.

[0015] Furthermore, in the fifth step, the charging power generated by the line is obtained by multiplying the length by the charging power generated by the line per unit length; the charging power generated by the line per unit length is calculated based on the line type and length, or the typical value of the charging power generated by the line per unit length at each voltage level in the power grid design and planning manual is used;

[0016] Q B =U 2 B=U 2 ×2πfc0L0=q B L0,

[0017] Where: Q Bis the charging power generated by the line, U is the line voltage; f is the grid frequency; B is the line susceptance; c0 is the charging capacitance of the line to the ground; L0 is the line length; q B is the charging power generated per unit length of line.

[0018] Furthermore, in the fifth step, considering that the power grid with a voltage level of 220 kV or above is a ring network structure, the charging power generated by the transmission line of the target voltage level is compensated by the inductive reactive power compensation devices in the substations at both ends of the transmission line in accordance with the principle of local balance, and the charging power of the incoming lines of each substation with a voltage level of 220 kV or above is considered to be half of the total; considering that the power grid below 110 kV is a radial structure, the charging power generated by the transmission line of the target voltage level is completely compensated by the inductive reactive power compensation device in the 110 kV substation connected to the transmission line, so as to avoid the reverse transmission of inductive reactive power to the 220 kV level; among them, due to the limited site factors of the 10 kV switchgear, the configuration of inductive reactive power compensation device is not considered.

[0019] Furthermore, in the fifth step, the inductive reactive balance analysis within the 500 kV provincial power grid supply area considers the inductive reactive balance of the charging power generated by all 110 kV and 220 kV substations under the jurisdiction of the joint supply area composed of multiple 500 kV substations or the independent supply area of ​​a single 500 kV substation, and the inductive reactive compensation devices in the compensation supply area compensate for the inductive reactive balance of the charging power generated by all 110 kV and 220 kV transmission lines under the jurisdiction of the supply area.

[0020] Furthermore, in the fifth step, the charging power of the 110 kV transmission line is converted from the 110 kV substation in-station compensation to the 220 kV substation in-station compensation according to the site factors, actual operation and management of the power grid in different provinces. The inductive reactive power balance in the 500 kV supply area is not affected before and after the conversion.

[0021] Furthermore, in the sixth step, if the inductive reactive power compensation rate of the target voltage level power supply area or a single substation is greater than the set limit, it is considered that the inductive reactive power compensation is sufficient; otherwise, it is considered that there is a shortage of inductive reactive power compensation in the target voltage level power supply area or site, and additional inductive reactive power compensation equipment needs to be configured.

[0022] Furthermore, in the seventh step, the difference between the actual compensation rate of the target voltage level power supply area or a single substation and the compensation rate setting limit is multiplied by the charging power generated by the target voltage level line that the target voltage level power supply area or substation should compensate, thereby obtaining the substation's inductive reactive power compensation demand capacity.

[0023] Furthermore, in the sixth step, the charging power of the transmission lines with a voltage level of 330 kV and above is compensated by parallel reactors, and the compensation rate must be greater than or equal to 100%; the charging power of the transmission lines with a voltage level of less than 220 kV corresponds to the reactor compensation rate according to the situation, and the priority of the coordination of the inductive reactive power compensation device is determined according to the corresponding compensation rate of each substation.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. The process is simple and the calculation is fast. The proposed analysis method can be used to evaluate the inductive reactive power margin of all voltage levels in the province. The required data is simple and can effectively guide the site selection and capacity determination of inductive reactive power compensation devices in actual power grids.

[0026] 2. Discover the weak points of inductive reactive power compensation at each voltage level in the provincial power grid, and implement the compensation scheme derived from the evaluation and analysis to effectively improve the inductive reactive power compensation rate in weak areas or sites, avoid cross-regional and cross-level long-distance transmission of inductive reactive power under low load, and ensure local balance of inductive reactive power and safe and efficient operation of the power grid.

[0027] 3. To solve the problem that the current planning and design of 220 kV substations in provincial power grids have not yet considered compensation for the charging power of 220 kV overhead lines, and the increase in charging power due to the increase in 110 kV and below voltage level cable lines, which ultimately makes it difficult to balance the inductive reactive power on-site during low load periods, and to provide the provincial power grid with corresponding evaluation and analysis methods and compensation measures for this problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of the method for evaluating the inductive reactive power margin of each voltage level of a provincial power grid according to the present invention. DETAILED DESCRIPTION

[0029] With the accumulation of 220 kV transmission lines and the increase of 110 kV and below cable lines in the distribution network, the relatively large charging power of the cable lines will cause voltage increase, network loss increase, and difficulty in balancing inductive reactive power on-site during low load periods, ultimately affecting the power supply quality of the provincial power grid, user power safety and efficient operation of the power grid.

[0030] Based on the above reasons, the present invention provides a method for evaluating the inductive reactive power margin of each voltage level of a provincial power grid based on the inductive reactive power compensation rate. The overall flow chart is as follows: Figure 1 The specific implementation of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] The first step is to determine the power supply area of ​​500 kV, 220 kV, and 110 kV voltage level substations, the substations of the previous voltage level, and other basic ledger information and equipment parameters such as the main transformer, low-voltage reactor, and dynamic reactive equipment in the station;

[0032] The second step is to determine the line name of the transmission line above 10 kV, the information of the first and last substations, the information system of the 500 kV power supply area to which the line belongs, the line type and length parameters;

[0033] Step 3: Select the target voltage level, power supply area, reactive power balance or reactive power compensation rate requirements and other prerequisites. The reactive power compensation rate requirements refer to "DL / T 5014-2010 Technical Regulations for the Design of Reactive Power Compensation Devices for 330kV-750kV Substations", "DL / T 5242-2010 Technical Regulations for the Design of Reactive Power Compensation Devices for 35kV-220kV Substations", and "DL / T 1773-2017 Technical Guidelines for Voltage and Reactive Power in Power Systems". If the data is complete and valid, go to step 4, otherwise go to step 1.

[0034] The fourth step is to determine the parameters of the substations and the connected incoming lines of the voltage level above each substation of the target voltage level, and determine the parameters of all the subordinate substations and the connected outgoing lines of the voltage level below each substation of the target voltage level; calculate the type and length of the incoming and outgoing lines of each substation;

[0035] The fifth step is to consider the inductive reactive power compensation capacity that has been configured and needs to be configured in the power supply area containing several substations or a single substation, calculate the charging power of the lines connected to the power supply area or a single substation, and calculate the inductive reactive power compensation rate of several substations or a single substation in the power supply area.

[0036] For 500 kV voltage level substation, the inductive reactive power compensation device in the station is used to balance and compensate the charging power generated by the nearby 500 kV power grid transmission line; the inductive reactive power compensation degree of 500 kV substation is k 500bus as follows:

[0037]

[0038] Where: Q B-500line The charging power generated by the incoming line of the 500 kV substation is taken into account. Considering the ring network structure, the charging power of a single station is half of the total length of the incoming line to consider the inductive reactive balance; Q R-500bus It is the inductive reactive power compensation capacity in 500 kV substation. The "DL / T 1773-2017 Technical Guidelines for Voltage and Reactive Power in Power Systems" requires that the charging power of 330 kV and above voltage level lines should be basically compensated.

[0039] For the 500 kV power supply area, the inductive reactive power compensation device in the 220 kV and 110 kV substations in the area is used to balance and compensate the charging power generated by the 220 kV and 110 kV transmission lines in the supply area; the inductive reactive power compensation degree k in the 500 kV power supply area 500area And the corresponding compensation degree k of each voltage level in the supply area 220area , k 110area as follows:

[0040]

[0041]

[0042]

[0043] Where: Q B-220line , Q B-110line Q is the charging power generated by all 220 kV and 110 kV transmission lines in the power supply area. R-220bus , Q R-110bus It is the inductive reactive power compensation capacity of 220 kV and 110 kV substations in the supply area.

[0044] For 220 kV voltage level substation, considering that only a very small number of 110 kV substations put into operation in the provincial power grid at this stage are equipped with inductive reactive power compensation devices, and at the same time, the 220 kV power grid is a ring network structure and the 110 kV power grid is a radiation structure, the present invention combines the actual consideration of the inductive reactive power compensation device in the 220 kV substation to simultaneously compensate for half of the charging power generated by the total length of the 220 kV transmission line incoming line and the charging power generated by the 110 kV transmission line connected to the downstream to evaluate the inductive reactive power balance of the 220 kV substation; the inductive reactive power compensation degree k of the 220 kV substation 220bus as follows:

[0045]

[0046] Where: Q B-220line The charging power generated by the incoming line of the 220 kV substation; Q B-220line The power generated by the 110 kV transmission line connected to the substation; Q R-220bus It is the inductive reactive power compensation capacity within the 220 kV substation.

[0047] For 110 kV voltage level substation, the present invention sets the average load rate of 110 kV main transformer and the average load power factor of the low voltage side of the main transformer according to the actual operation data of the power grid, analyzes the inductive reactive power balance of the 110 kV substation, and proposes the inductive reactive power compensation demand Q in the station. com :

[0048]

[0049]

[0050] In the formula, Q D is the reactive power on the load side; Q B-10line is the charging power generated by the 10 kV line connected to the downstream; Q R-110bus The capacity of the configured or newly configured inductive reactive power compensation device; is the average power factor of the load on the low voltage side of the main transformer, where is the vector angle between the apparent power and the active power on the load side; the power factor on the high voltage side of the main transformer of the substation during low load is not higher than requirements, including The vector angle between the apparent power and active power on the high-voltage side of the main transformer (for example, in the State Grid Enterprise Standard "Technical Guidelines for Reactive Power Compensation Configuration in Power Systems Q / GDW 1212-2015", Article 6.3.1 stipulates that under the condition of off-peak load, the power factor on the high-voltage side of the main transformer of the 35-220 kV substation should meet the requirement of less than or equal to 0.95, that is, is 0.95); α T The average active load rate of the main transformer; P T The active power of the main transformer; S N Main variable capacity.

[0051] Step 6: Conduct inductive reactive power margin analysis and set the target voltage level power supply area or single substation inductive reactive power compensation rate limit k S ; If the substation compensation rate k is less than the set limit k S , then go to step 7, otherwise go to step 8;

[0052] According to the inductive reactive power compensation degree of 500 kV substation, the compensation situation of different 500 kV substations in provincial power grid or municipal power grid can be found, and if under-compensated sites are found, compensation devices will be added preferentially.

[0053] According to the inductive reactive power compensation degree of the 500 kV power supply area, the inductive reactive power compensation situation in each power supply area of ​​the provincial power grid or the municipal power grid can be discovered, the imbalance of compensation rate between under-compensated power supply areas and different voltage levels in the power supply areas can be discovered, and the priority of adding compensation devices between different power supply areas and different voltage levels within the same power supply area can be guided.

[0054] According to the inductive reactive power compensation degree of 220 kV substation, the inductive reactive power compensation situation of each 220 kV substation in the provincial power grid or municipal power grid can be found. The ranking results according to the compensation rate can provide a reference basis for the additional site, additional priority order and additional capacity in the inductive reactive power compensation plan of 220 kV substation.

[0055] According to the analysis of inductive reactive balance of 110 kV substation, the charging power of 10 kV lines connected to the inductive reactive balance of each 110 kV substation in the municipal power grid can be found. According to the shortage of inductive reactive compensation, a reference can be provided for the site selection and capacity of the 110 kV inductive reactive compensation device.

[0056] Step 7: According to the actual compensation rate k of the power supply area or substation and the set limit k S , calculate the additional capacity Q required for inductive reactive power compensation of the substation 增 , form an inductive reactive power compensation configuration plan for several substations or a single substation in the power supply area, and go to step 5;

[0057] Q 增 =(k s -k)*Q 需 ,k s >k

[0058] Q 增 =0,k s ≤k

[0059] In the formula, Q 需 The charging power of the incoming and outgoing lines obtained in step 5 is the inductive reactive capacity that the substation needs to balance and compensate. Step 8: Output the target voltage level inductive reactive balance analysis results and the corresponding inductive reactive compensation configuration plan.

[0060] Application effect verification: In order to test the effectiveness of the method described in the present invention, the present invention is used to analyze and verify the current status of the inductive reactive power balance of the power grid in Jiaxing, Zhejiang Province, and the corresponding results are shown in Tables 1 to 4.

[0061] Table 1 Inductive reactive power compensation of Jiaxing 500 kV substation Unit: km, 10,000 kW, 10,000 kWvar

[0062]

[0063] Table 2 Inductive reactive power compensation in each power supply area in Jiaxing Unit: km, 10,000 kW, 10,000 kW

[0064]

[0065] Table 3 Inductive reactive power compensation of 220 kV substations in Jiaxing Unit: km, 10,000 kW, 10,000 kW

[0066]

[0067]

[0068] Table 4 Inductive reactive power balance of Jiaxing 110 kV substation

[0069]

[0070] According to the analysis and evaluation results in Tables 1 to 4, we can see that:

[0071] 1) Jiaxing power grid 500 kV level compensation The inductive reactive power compensation degree of 500 kV lines is about 99.4%, and the compensation rate is above 90%, which generally meets the requirements of "DL / T 1773-2017 Technical Guidelines for Voltage and Reactive Power of Power Systems" that the charging power of lines with voltage levels of 330 kV and above should be basically compensated.

[0072] 2) Compensation for low-voltage reactors at 220 kV and 110 kV stations in each supply area of ​​Jiaxing power grid There is a certain imbalance in the compensation rate of charging power of 220 kV and 110 kV transmission lines in the supply area, among which the compensation rates of A / B and E supply areas are lower than 90%, which are 55.1% and 28.5% respectively. The total low-voltage reactors configured in 220 kV and 110 kV stations in Jiaxing area are 354,000 kvar, and the total charging power of 220 kV and 110 kV lines is 566,000, with a compensation degree of 62.6%. .

[0073] 3) Jiaxing power grid has 220 kV substations equipped with low-voltage reactors totaling 345,000 kVar, with the charging power of the 220 kV incoming line at the station being about 240,000 kVar, and the charging power of the downstream 110 kV being about 220,000 kVar, with an overall reactive power compensation rate of 74.8%. The evaluation and analysis results show that it is necessary to add inductive reactive power compensation devices to the 220 kV substations where the inductive reactive power compensation is weak and the line charging power is large.

[0074] 4) There is basically no inductive reactive power compensation device in the 110 kV substation of Jiaxing Power Grid. In the 110 kV substation with a long 10 kV cable line, it is easy for the main transformer to send reactive power back to the main grid during low load. According to the evaluation and analysis results, it is necessary to install inductive reactive power compensation devices in the 110 kV substation with a long 10 kV cable line to prevent the problem of reactive power crossing across levels caused by the long cable line.

[0075] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above specific embodiments. The above specific embodiments and the description in the specification are only for further illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of the present invention to be protected is defined by the claims and their equivalents.

Claims

1. A method for assessing the inductive reactive power margin of a provincial power grid, characterized in that: The steps include: The first step is to determine the basic account information and equipment parameters of 500 kV, 220 kV and 110 kV substations; The second step is to determine the information of the first and last substations, line types and length parameters of the transmission lines above 10 kV; Step 3: Select the target voltage level, power supply area, reactive power balance or reactive power compensation rate requirement. If the data is complete and valid, go to step 4; otherwise, go to step 1. The fourth step is to determine the parameters of the substations and the connected incoming lines of the voltage level above each substation of the target voltage level, and determine the parameters of all the subordinate substations and the connected outgoing lines of the voltage level below each substation of the target voltage level; calculate the type and length of the incoming and outgoing lines of each substation; The fifth step is to consider the inductive reactive power compensation capacity that has been configured and needs to be configured in the power supply area or a single substation containing several substations, calculate the charging power of the lines connected to several substations or a single substation in the power supply area, and calculate the inductive reactive power compensation rate of several substations or a single substation in the power supply area; Step 6: Perform target voltage level inductive reactive power margin analysis and set the inductive reactive power compensation rate limit of several substations or a single substation in the target voltage level power supply area; if the inductive reactive power compensation rate of the substation is less than the set limit, go to step 7, otherwise go to step 8; Step 7: Calculate the required capacity of inductive reactive power compensation of the substation according to the actual compensation rate and set limit of several substations or substations in the power supply area, form the inductive reactive power compensation configuration plan of several substations or a single substation in the power supply area, and go to step 5; The eighth step is to output the target voltage level inductive reactive power balance analysis results and the corresponding inductive reactive power compensation configuration plan.

2. The method for evaluating the inductive reactive power margin of a provincial power grid according to claim 1, characterized in that: In the fifth step, the charging power generated by the line is obtained by multiplying the length by the charging power generated by the unit length of the line; The charging power per unit length of the line is calculated based on the line type and length, or the typical value of the charging power per unit length of each voltage level in the power grid design and planning manual is used; Q B =U 2 B=U 2 ×2πfc0L0=q B L0, Where: Q B is the charging power generated by the line, U is the line voltage; f is the grid frequency; B is the line susceptance; c0 is the charging capacitance of the line to the ground; L0 is the line length; q B is the charging power generated per unit length of line.

3. The method for evaluating the inductive reactive power margin of a provincial power grid according to claim 1, characterized in that: In the fifth step, the power grid with a voltage level of 220 kV or above is considered to be a ring network structure. The charging power generated by the transmission line of the target voltage level is compensated by the inductive reactive power compensation devices in the substations at both ends of the transmission line in accordance with the principle of local balance. The charging power of the incoming lines of each substation with a voltage level of 220 kV or above is considered to be half of the total. Considering that the power grid below 110 kV is a radial structure, the charging power generated by the transmission line of the target voltage level is completely compensated by the inductive reactive power compensation devices in the 110 kV substation connected to the transmission line, so as to avoid the reverse transmission of inductive reactive power to the 220 kV level. Among them, due to the limited site factors of the 10 kV switchgear, the configuration of inductive reactive power compensation devices is not considered.

4. The method for evaluating the inductive reactive power margin of a provincial power grid according to claim 1, characterized in that: In the fifth step, the inductive reactive balance analysis within the 500 kV provincial power grid supply area takes into account the inductive reactive balance of the charging power generated by all 110 kV and 220 kV substations under the jurisdiction of the joint supply area composed of multiple 500 kV substations or the independent supply area of ​​a single 500 kV substation. The inductive reactive compensation devices in all 110 kV and 220 kV substations under the jurisdiction of the supply area compensate for the inductive reactive balance of the charging power generated by all 110 kV and 220 kV transmission lines under the jurisdiction of the supply area.

5. The method for evaluating the inductive reactive power margin of a provincial power grid according to claim 1, characterized in that: In the fifth step, the charging power of the 110 kV transmission line is converted from 110 kV substation in-station compensation to 220 kV substation in-station compensation based on site factors in different provinces and the actual operation and management of the power grid. The conversion does not affect the inductive reactive power balance in the 500 kV supply area.

6. The method for evaluating the inductive reactive power margin of a provincial power grid according to claim 1, characterized in that: In the sixth step, if the inductive reactive power compensation rate of the target voltage level power supply area or a single substation is greater than the set limit, it is considered that the inductive reactive power compensation is sufficient; otherwise, it is considered that there is a shortage of inductive reactive power compensation in the target voltage level power supply area or site, and additional inductive reactive power compensation devices need to be configured.

7. The method for evaluating the inductive reactive power margin of a provincial power grid according to claim 1, characterized in that: In the seventh step, the difference between the actual compensation rate of the target voltage level power supply area or a single substation and the compensation rate setting limit is multiplied by the charging power generated by the target voltage level line that the target voltage level power supply area or substation should compensate, thereby obtaining the required capacity of inductive reactive power compensation of the substation.

8. The method for evaluating the inductive reactive power margin of a provincial power grid according to claim 1, characterized in that: In the sixth step, the charging power of transmission lines with voltage levels above 330 kV is compensated by shunt reactors, and the compensation rate must be greater than or equal to 100%; the charging power of transmission lines with voltage levels below 220 kV corresponds to the reactor compensation rate according to the situation, and the priority of the coordination of inductive reactive power compensation devices is determined according to the corresponding compensation rate of each substation.

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