Method for calculating new energy low-voltage splitting protection constant value in regional power grid

Abstract

The invention relates to a method for calculating a new energy low-voltage splitting protection constant value in a regional power grid. The method comprises the following steps: step 1, calculating voltage values of a new energy power station under various faults by adopting PSD-BPA software; step 2, simulating a low-voltage splitting protection device principle to count new energy tripping conditions under different fixed values based on the new energy power station voltage values under various faults calculated in the step 1; and step 3, carrying out differential calculation on the tripping quantity to obtain a low-voltage splitting protection constant value. According to the method, the low-voltage constant value and the delay constant value of low-voltage splitting protection can be accurately calculated.

Description

Technical Field

[0001] The invention belongs to the technical field of relay protection, and relates to a method for calculating a fixed value of low-voltage disconnection protection, in particular to a method for calculating a fixed value of low-voltage disconnection protection for renewable energy in a regional power grid. Background Art

[0002] Relay protection setting refers to a technology that protects power equipment and circuits from damage caused by faults by calculating and setting relay protection parameters (such as action time, action current, etc.) according to system parameters and fault types in the power system.

[0003] Renewable energy power stations are equipped with low-voltage disconnection protection at the grid connection point. If the voltage setting value of the low-voltage disconnection protection is Uset and the delay setting value is Tset, when the protection device detects that the grid connection point voltage is lower than Uset and the duration reaches Tset, the new energy grid connection point switch will be tripped.

[0004] If the voltage setting of the disconnection protection is set too low or the delay is too long, it will cause the grid to fail. The new energy will continue to provide energy to the fault point, and the arc will not be easy to extinguish. If the voltage setting of the low voltage disconnection protection is set too low, or the delay is too short, it will cause the temporary drop of voltage after the grid disturbance to easily reach the voltage setting and delay setting. If there are multiple new energy power stations in the area, a single grid disturbance can cause the grid-connected switches of multiple new energy power stations to trip at the same time.

[0005] At present, there is no mature calculation basis for the low voltage setting and delay setting of the new energy disconnection protection. They are mostly determined by the experience of technicians, and the calculation results are inaccurate. If the disconnection setting is set too high, a large area of ​​new energy stations will be disconnected from the grid when a power grid failure occurs. If the disconnection setting is set too low, the new energy will not be disconnected from the grid in time, affecting the power grid to remove the fault.

[0006] After searching, no public documents of the prior art that are identical or similar to the present invention were found. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and to propose a method for calculating the constant value of low-voltage disconnection protection of renewable energy in a regional power grid, which can accurately calculate the low voltage constant value and delay constant value of the low voltage disconnection protection.

[0008] The present invention solves the practical problem by adopting the following technical solutions:

[0009] A method for calculating a fixed value of low-voltage disconnection protection of new energy in a regional power grid comprises the following steps:

[0010] Step 1: Use PSD-BPA software to calculate the voltage value of the new energy power station under various faults;

[0011] Step 2: Based on the voltage values ​​of the renewable energy power station under various faults calculated in step 1, the principle of the low voltage disconnection protection device is simulated to count the renewable energy tripping conditions under different set values;

[0012] Step 3: perform differential calculation on the number of trips to obtain the low voltage disconnect protection setting value;

[0013] Moreover, the specific steps of step 1 include:

[0014] 1.1 Set the fault point, set each bus in the regional power grid, and set a permanent three-phase short circuit fault at the beginning and end of each line; set the relay protection tripping situation to be the same as the actual situation; set the number of faults to Nf and the simulation calculation time for each fault to Ts;

[0015] 1.2 Calculate the voltage of the grid connection point of the renewable energy power station in the region under Nf faults as Uk, where k is the kth renewable energy power station; the total number of renewable energy power stations in the region is Ns; then the total voltage data of the calculated parameters is NA=Nf*Ns.

[0016] Moreover, the specific steps of step 2 include:

[0017] 2.1 Set the calculation step size to 0.01s, then each Uk contains N data points, where N = 100Ts;

[0018] 2.2 Set the low voltage setting value to Uset, the low voltage delay setting value to Tset, and set the data window length Nd = 100Tset;

[0019] 2.3 Starting from the first point of Uk, go to Nd consecutive data in Uk. If all the data in the data window are less than Uset, mark Uk as trip data;

[0020] 2.4 If the data in the data window does not meet 2.3, move the data window back one data point and repeat 2.3 and 2.4 until the remaining data in Uk is less than Nd. Then mark Uk as non-tripping data;

[0021] 2.5 Repeat the process from 2.1 to 2.4 until all NA Uk are calculated, and finally the number marked as tripped is NT;

[0022] 2.6 Repeat the above process with different Uset and Tset values.

[0023] Moreover, the values ​​of Uset and Tset in step 2.6 are:

[0024] Uset takes 0.2pu, 0.3pu, 0.4pu, 0.5pu, 0.6pu, 0.7pu; Tset takes 0.2s, 0.3s, 0.4s, 0.5s, 0.6s.

[0025] Moreover, the specific steps of step 3 include:

[0026] 3.1 According to the tripping conditions of renewable energy under different fixed values ​​obtained in step 2, the tripping quantity data is differentially calculated by column, and the column number of the first column whose change amplitude is less than the threshold value is obtained;

[0027] 3.2 According to the tripping conditions of renewable energy under different set values ​​obtained in step 2, the tripping quantity data is differentially calculated row by row, and a row number with a change range less than the threshold value is obtained;

[0028] 3.3. According to the difference calculation results of step 3.1 and step 3.2, calculate L = min{L1, L2, L3, L4, L5}, R = min{R1, R2, R3, R4, R5}

[0029] 3.4. The low voltage amplitude constant obtained for low voltage tripping protection is the column name value of the low L column in Table 2.6, and the delay constant is the row name value of the R column in Table 2.6.

[0030] Moreover, the specific steps of step 3.1 include:

[0031] 3.1.1 Subtract the data in the next column from the data in the previous column one by one;

[0032] 3.1.2 Set the differential threshold value to DNT, calculate the first data in each row that is less than DNT and record the column numbers as L1, L2, L3, L4, and L5.

[0033] Moreover, the specific steps of step 3.2 include:

[0034] 3.2.1 Subtract the data in the next row from the data in the previous row one by one.

[0035] 3.2.2 For the set differential threshold value DNT, calculate the first data in each column that is less than DNT and record it as R1, R2, R3, R4, R5.

[0036] Advantages and beneficial effects of the present invention:

[0037] 1. The present invention provides a method for calculating the setting value of the new energy disconnection protection by PSD-BPA calculation data. The tripping number of the power grid is calculated by simulating the disconnection protection, and the differential active disconnection setting value of the tripping number is performed by row and column. The present invention can accurately calculate the low voltage setting value and delay setting value of the low voltage disconnection protection.

[0038] 2. The present invention provides an effective technical method for the setting of the protection of the disconnection of new energy. The general application PSD-BPA software can fully understand the voltage reduction of the regional power grid under fault conditions and effectively support the setting of the disconnection setting. The present invention provides a quantitative relationship between the disconnection setting and the number of trips. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0040] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings:

[0041] A method for calculating the fixed value of low-voltage disconnection protection of renewable energy in a regional power grid, such as Figure 1 As shown, the following steps are included:

[0042] Step 1: Use PSD-BPA software to calculate the voltage value of the new energy power station under various faults;

[0043] The specific steps of step 1 include:

[0044] 1.1 Set the fault point, set each bus in the regional power grid, and set a permanent three-phase short circuit fault at the beginning and end of each line; set the relay protection tripping situation to be the same as the actual situation; set the number of faults to Nf and the simulation calculation time for each fault to Ts;

[0045] 1.2 Calculate the voltage of the grid connection point of the renewable energy power station in the region under Nf faults as Uk, where k is the kth renewable energy power station; the total number of renewable energy power stations in the region is Ns; then the total voltage data of the calculated parameters is NA=Nf*Ns.

[0046] Step 2: Based on the voltage values ​​of the renewable energy power station under various faults calculated in step 1, the principle of the low voltage disconnection protection device is simulated to count the renewable energy tripping conditions under different set values;

[0047] The specific steps of step 2 include:

[0048] 2.1 Set the calculation step size to 0.01s, then each Uk contains N data points, where N = 100Ts;

[0049] 2.2 Set the low voltage setting value to Uset, the low voltage delay setting value to Tset, and set the data window length Nd = 100Tset;

[0050] 2.3 Starting from the first point of Uk, go to Nd consecutive data in Uk. If all the data in the data window are less than Uset, mark Uk as trip data;

[0051] 2.4 If the data in the data window does not meet 2.3, move the data window back one data point and repeat 2.3 and 2.4 until the remaining data in Uk is less than Nd. Then mark Uk as non-tripping data;

[0052] 2.5 Repeat the process from 2.1 to 2.4 until all NA Uk are calculated, and finally the number marked as tripped is NT;

[0053] 2.6 Repeat the above process with different Uset and Tset values;

[0054] The values ​​of Uset and Tset in step 2.6 are:

[0055] Uset takes 0.2pu, 0.3pu, 0.4pu, 0.5pu, 0.6pu, 0.7pu; Tset takes 0.2s, 0.3s, 0.4s, 0.5s, 0.6s.

[0056] In this embodiment, the following data table is obtained:

[0057] 0.2pu 0.3pu 0.4pu 0.5pu 0.6pu 0.7pu 0.2s NT11 NT12 NT13 NT14 NT15 NT16 0.3s NT21 NT22 NT23 NT24 NT25 NT26 0.4s NT31 NT32 NT33 NT34 NT35 NT36 0.5s NT41 NT42 NT43 NT44 NT45 NT46 0.6s NT51 NT52 NT53 NT54 NT55 NT56

[0058] Step 3: perform differential calculation on the number of trips to obtain the low voltage disconnect protection setting value;

[0059] The specific steps of step 3 include:

[0060] 3.1 According to the tripping conditions of renewable energy under different fixed values ​​obtained in step 2, the tripping quantity data is differentially calculated by column, and the column number of the first column whose change amplitude is less than the threshold value is obtained;

[0061] In this embodiment, the trip quantity data of 2.6 is differentially calculated by column;

[0062] 0.2s NT11-NT21 NT12-NT22 NT13-NT23 NT15-NT25 NT16-NT26 0.3s NT21-NT31 NT22-NT32 NT23-NT33 NT25-NT35 NT26-NT36 0.4s NT31-NT41 NT32-NT42 NT33-NT43 NT35-NT45 NT36-NT46 0.5s NT41-NT51 NT42-NT52 NT43-NT53 NT45-NT55 NT46-NT56

[0063] The specific steps of step 3.1 include:

[0064] 3.1.1 As shown in the table above, subtract the data in the next column from the data in the previous column. 3.1.2 Set the difference threshold value to DNT, calculate the first data in each row that is less than DNT and record the column numbers as L1, L2, L3, L4, L5;

[0065] 3.2 According to the tripping conditions of renewable energy under different set values ​​obtained in step 2, the tripping quantity data is differentially calculated row by row, and a row number with a change range less than the threshold value is obtained;

[0066] In this embodiment, the trip quantity data of 2.6 is differentially calculated row by row.

[0067] 0.2s NT11-NT12 NT12-NT13 NT13-NT14 NT15-NT16 0.3s NT21-NT22 NT22-NT23 NT23-NT24 NT25-NT26 0.4s NT31-NT32 NT32-NT33 NT33-NT34 NT35-NT36 0.5s NT41-NT42 NT42-NT43 NT43-NT44 NT45-NT46 0.6s NT51-NT52 NT22-NT53 NT23-NT54 NT15-NT56

[0068] The specific steps of step 3.2 include:

[0069] 3.2.1 As shown in the table above, subtract the data in the next row from the data in the previous row one by one.

[0070] 3.2.2 For the set differential threshold value DNT, calculate the first data in each column that is less than DNT and record it as R1, R2, R3, R4, R5;

[0071] Step 3.3: According to the difference calculation results of step 3.1 and step 3.2, calculate L = min{L1, L2, L3, L4, L5}, R = min{R1, R2, R3, R4, R5}

[0072] Step 3.4, the low voltage amplitude constant of the low voltage decoupling protection is the column name value of the low L column in Table 2.6, and the delay constant is the row name value of the R column in Table 2.6.

[0073] The working principle of the present invention is:

[0074] The PSD-BPA software was introduced by the China Electric Power Research Institute. Through secondary development, it has become a software that meets the simulation calculation requirements of my country's large-scale power systems. The software can perform transient stability calculations or power flow and short-circuit calculations for large-scale AC and DC systems. The calculation data of PSD-BPA is stored through a data card. The PSD-BPA software can be used to calculate the voltage data of the new energy grid connection point when any point in the regional power grid fails. The present invention provides a method for calculating the new energy decoupling protection constant value through PSD-BPA calculation data, which can accurately calculate the low voltage constant value and delay constant value of the low voltage decoupling protection.

[0075] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0076] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0077] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0078] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

Claims

1. A method for calculating the fixed value of low-voltage disconnection protection of renewable energy in a regional power grid, characterized by: The following steps are involved: Step 1: Use PSD-BPA software to calculate the voltage value of the new energy power station under various faults; Step 2: Based on the voltage values ​​of the renewable energy power station under various faults calculated in step 1, the principle of the low voltage disconnection protection device is simulated to count the renewable energy tripping conditions under different set values; Step 3: Perform differential calculation on the number of trips to obtain the low-voltage trip protection setting.

2. According to claim 1, a method for calculating the fixed value of low-voltage disconnection protection of renewable energy in a regional power grid is characterized by: The specific steps of step 1 include: 1.1 Set the fault point, set each bus in the regional power grid, and set a permanent three-phase short circuit fault at the beginning and end of each line; set the relay protection tripping situation to be the same as the actual situation; set the number of faults to Nf and the simulation calculation time for each fault to Ts; 1.2 Calculate the voltage of the grid connection point of the renewable energy power station in the region under Nf faults as Uk, where k is the kth renewable energy power station; the total number of renewable energy power stations in the region is Ns; then the total voltage data of the calculated parameters is NA=Nf*Ns.

3. According to claim 1, a method for calculating the fixed value of low-voltage disconnection protection of renewable energy in a regional power grid is characterized by: The specific steps of step 2 include: 2.1 Set the calculation step size to 0.01s, then each Uk contains N data points, where N = 100Ts; 2.2 Set the low voltage setting value to Uset, the low voltage delay setting value to Tset, and set the data window length Nd = 100Tset; 2.3 Starting from the first point of Uk, go to Nd consecutive data in Uk. If all the data in the data window are less than Uset, mark Uk as trip data; 2.4 If the data in the data window does not meet 2.3, move the data window back one data point and repeat 2.3 and 2.4 until the remaining data in Uk is less than Nd; then mark Uk as non-tripping data; 2.5 Repeat the process from 2.1 to 2.4 until all NA Uk are calculated, and finally the number marked as tripped is NT; 2.6 Repeat the above process with different Uset and Tset values.

4. The method for calculating the fixed value of low-voltage disconnection protection of renewable energy in a regional power grid according to claim 3 is characterized in that: The values ​​of Uset and Tset in step 2.6 are: Uset takes 0.2pu, 0.3pu, 0.4pu, 0.5pu, 0.6pu, 0.7pu; Tset takes 0.2s, 0.3s, 0.4s, 0.5s, 0.6s.

5. The method for calculating the fixed value of low-voltage disconnection protection of renewable energy in a regional power grid according to claim 1 is characterized in that: The specific steps of step 3 include: 3.1 According to the tripping conditions of renewable energy under different fixed values ​​obtained in step 2, the tripping quantity data is differentially calculated by column, and the column number of the first column whose change amplitude is less than the threshold value is obtained; 3.2 According to the tripping conditions of renewable energy under different set values ​​obtained in step 2, the tripping quantity data is differentially calculated row by row, and a row number with a change range less than the threshold value is obtained; 3.

3. According to the difference calculation results of step 3.1 and step 3.2, calculate L = min{L1, L2, L3, L4, L5}, R = min{R1, R2, R3, R4, R5} 3.

4. The low voltage amplitude constant obtained for low voltage tripping protection is the column name value of the low L column in Table 2.6, and the delay constant is the row name value of the R column in Table 2.

6.

6. A method for calculating the fixed value of low-voltage disconnection protection of renewable energy in a regional power grid according to claim 5, characterized in that: The specific steps of step 3.1 include: 3.1.1 Subtract the data in the next column from the data in the previous column one by one; 3.1.2 Set the differential threshold value to DNT, calculate the first data in each row that is less than DNT and record the column numbers as L1, L2, L3, L4, and L5.

7. The method for calculating the fixed value of low-voltage disconnection protection of renewable energy in a regional power grid according to claim 5 is characterized in that: The specific steps of step 3.2 include: 3.2.1 Subtract the data in the next row from the data in the previous row one by one; 3.2.2 For the set differential threshold value DNT, calculate the first data in each column that is less than DNT and record it as R1, R2, R3, R4, R5.

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