A reactive voltage control method for active supervision and detection of a new energy photovoltaic power station

Abstract

The application discloses a new energy photovoltaic power station active supervision and detection reactive voltage control method, comprising: initializing inverter group, setting data acquisition period and control period of AVC substation; collecting bus voltage, outgoing line active value and reactive value of grid-connected point, and voltage setting value issued by the main station, and calculating voltage difference; when the voltage difference is greater than the control dead zone, entering the correction control mode; when the voltage difference is in the balance dead zone, entering the optimization control mode; after issuing the reactive instruction, dynamically adjusting the inverter group according to the adjustment effect; after the fault blocking group equipment fault is removed, preferentially testing, and moving to the full optimization group after the test is qualified. Through dynamic adjustment and optimization of inverter reactive voltage, the method improves power quality and system stability, enhances the automation and response speed of the system, is suitable for photovoltaic power stations of different scales, and effectively guarantees efficient utilization of new energy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power grid automatic voltage control, and particularly relates to a reactive power voltage control method for active supervision and detection of a new energy photovoltaic power station. BACKGROUND

[0002] The photovoltaic power station refers to a photovoltaic power generation system connected to a power grid and delivering power to the power grid, which utilizes solar energy and adopts special materials such as a crystalline silicon panel and an inverter to form a power generation system.

[0003] In recent years, the installed capacity of new energy photovoltaic power stations in China has rapidly increased. Photovoltaic power generation has the characteristics of intermittency, volatility and seasonality, which brings great challenges to the voltage stability of the power grid. In order to solve the voltage stability problem caused by new energy photovoltaic power stations, AVC sub-stations need to be configured in new energy power stations in addition to installing phase modulators on the power grid side.

[0004] The AVC (Automatic Voltage Control) sub-station of the photovoltaic station is generally installed in the photovoltaic station, which receives the instructions issued by the AVC master station system of the power grid control center, and then controls the reactive power equipment (inverters and other reactive power equipment) in the station to make the grid-connected point voltage / reactive power meet the requirements of the power grid.

[0005] In the past, photovoltaic power stations mostly adopted the mode of rapid development. A power station may use inverters from many manufacturers. The reactive power voltage regulation performance of inverters from different manufacturers is quite different. With the passage of time, due to inverter failure maintenance and wear and tear, the reactive power voltage regulation performance of the inverters becomes more uneven. The traditional AVC sub-station mostly adopts the mode of average distribution or margin distribution for the control of the inverters, considering that the regulation performance of the inverters is consistent, which leads to unsatisfactory reactive power voltage regulation effect of the entire power station. Some AVC sub-stations have proposed control methods for sorting the reactive power voltage regulation performance of different inverters, but mostly use manual configuration or analyze the reactive power voltage regulation performance of different inverters according to historical data, which lacks active detection capability and is not flexible enough. SUMMARY

[0006] The present application aims to provide a reactive power voltage control method for active supervision and detection of a new energy photovoltaic power station. In the case of reasonable voltage and reactive power, the AVC sub-station actively detects the regulation performance of each inverter, dynamically changes the control group to which each inverter belongs according to the detection result, and maintains an optimal regulation group, so that the subsequent AVC sub-station regulation can achieve better regulation effect.

[0007] To achieve the above-mentioned purpose, the present application is implemented according to the following technical scheme:

[0008] The application comprises the following steps:

[0009] S1: initializing the inverters, divided into full-optimization group, fault-locking group and test group;

[0010] S2: setting the data acquisition period and control period of the AVC substation;

[0011] S3: acquiring the grid point information and the instruction information issued by the main station, and calculating the voltage difference;

[0012] S4: when the voltage difference is greater than the voltage control dead zone, entering the correction control mode, calculating the reactive power demand and adjusting the reactive power value of the inverter;

[0013] S5: when the voltage difference is within the voltage balance dead zone, entering the optimization control mode, optimizing the reactive power distribution and testing the inverters in the test group;

[0014] S6: monitoring the adjustment effect of the inverters, and dynamically adjusting the inverter groups according to the adjustment effect;

[0015] S7: preferentially testing the devices in the fault-locking group after the fault is removed or manually unlocked, and moving them to the full-optimization group after passing the test.

[0016] The application has the following beneficial effects:

[0017] The application is a reactive voltage control method for active supervision and detection of a new energy photovoltaic power station, and has the following technical effects compared with the prior art:

[0018] Active supervision and testing: through the adjustment mode of increasing and decreasing the reactive power of a group of inverters, the voltage and reactive power in the station are basically not affected, the power generation benefit of the station is not affected, and the active monitoring of the reactive voltage adjustment capability of the inverters is realized;

[0019] Improving power quality: through real-time acquisition of the voltage and reactive power information of the grid point and correction and optimization control, the reactive power can be effectively balanced, the power quality can be improved, and the influence of voltage fluctuation on the power grid can be reduced.

[0020] Improving system stability: when the inverter fails or abnormally, it is added to the fault-locking group in time to avoid affecting the normal operation of the system; after the fault is removed, it is preferentially tested and restored to normal operation to ensure the stability and reliability of the system.

[0021] Dynamic optimization of reactive power distribution: through the optimization control mode, the inverters in the test group can be tested for adjustment performance, the groups of the inverters can be dynamically adjusted, the reactive power distribution in the station can be optimized, and the overall operation efficiency of the system can be improved.

[0022] Automatic control: The AVC substation automatically performs data collection, analysis, and control instructions, achieving automatic adjustment and optimization of reactive power and voltage, reducing manual intervention, and improving operation efficiency and response speed.

[0023] Flexibility and adaptability: This method is suitable for photovoltaic power stations of different scales and types, and can flexibly adjust the reactive power output of inverters according to actual operation conditions to adapt to changes in grid demand.

[0024] This reactive voltage control method can significantly improve the operation efficiency and power quality of photovoltaic power stations, enhance the stability and reliability of the system, and provide a strong guarantee for the efficient use of new energy. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a flowchart of the method of the present application;

[0026] Figure 2 is an inverter control group conversion diagram. DETAILED DESCRIPTION

[0027] The present application will be further described below in conjunction with the drawings and specific embodiments, which are illustrative examples and explanations of the present application, but do not limit the present application.

[0028] As shown in Figure 1 and 2 : The present application comprises the following steps:

[0029] (1) Initialize the inverters participating in regulation, divided into full optimization group, fault locking group and test group. Among them, the inverters that have sent fault or abnormal signals are marked by the AVC substation as fault abnormal and added to the fault locking group. For inverters manually set to be locked, they are also included in the fault locking group; in addition, the remaining inverters are added to the full optimization group; the test group maintains a queue, and the queue queue is initialized as empty.

[0030] (2) Set the data collection period of the AVC substation as Tg, and the control period as T c , which is an integer multiple of Tg, and set the multiple as N c ; the AVC substation starts timing after issuing instructions to the inverters, and checks the regulation effect of the inverters after N test collection periods. Obviously N test <N c , and generally N c >=2×N test .

[0031] (3) Collect photovoltaic station grid-connected point information U real , P gate , Q gate and instruction information Uref . wherein U real represents the grid-connected point bus voltage value, P gate represents the grid-connected point outgoing line active value, Q gate represents the grid-connected point outgoing line reactive value, U ref represents the grid-connected point bus voltage set value issued by the main station. The voltage difference ΔU = U ref - U real is calculated. When |ΔU| >= U dead , the AVC substation enters into correction control, and the reactive demand ΔQ = ΔU / C dead is calculated. v q wherein C v q is the grid-connected point voltage reactive sensitivity. After further considering the voltage adjustment step size of each round and the reactive adjustment step size of each round, the corrected ΔQ is obtained. The AVC substation obtains the total adjustment reactive ΔQ gen of the inverters and the adjustment reactive ΔQ other of other devices according to the inverter priority or balanced proportion algorithm, and ΔQ = ΔQ gen + ΔQ other ; when |ΔU| < U bal , U bal is the voltage balance dead zone of the AVC substation, and U bal < U dead , the AVC substation enters into optimization control, and the reactive distribution in the station is optimized. In the control period, the inverters in the test group queue are tested.

[0032] (4) When |ΔU| >= U dead , the AVC substation performs correction control, and the reactive upward adjustment ability of other devices is Qupabl other , the reactive downward adjustment ability of other devices is Qdnabl other , the reactive upward adjustment ability of the devices in the full-optimization group of inverters is Qupper gen , the reactive downward adjustment ability is Qdnper gen , the reactive upward adjustment ability of the devices in the test group is Quptest gen , the reactive downward adjustment ability is Qdntest gen , and the reactive adjustable ability of the devices in the fault locking group is 0.

[0033] When the reactive adjustment amount ΔQ > 0, Qupabl other + Qupper gen >= ΔQ, at this time, only the devices in other devices and the full-optimization group of inverters need to be adjusted, when Qupabl other + Qupper genWhen <ΔQ, in addition to other equipment and the inverter's optimal group equipment participating in reactive power regulation, the equipment in the inverter test group also needs to participate in regulation, with an adjustment amount of ΔQ - (Qupabl) other +Qupper gen When the reactive power regulation ΔQ < 0, Qdnabl other +Qdnper gen When Qdnabl is greater than or equal to |ΔQ|, only other devices and the devices in the inverter's optimal group need to be adjusted. other +Qdnper gen When <|ΔQ|, in addition to other equipment and the inverter's optimal group equipment participating in reactive power regulation, the equipment in the inverter test group also needs to participate in regulation, with an adjustment amount of ΔQ + (Qupabl). other +Qupper gen For the inverters in the optimal group and test group, the reactive power setpoint of each inverter can be obtained using an algorithm that prioritizes proportional or margin-based calculations. For inverter Di, its reactive power setpoint is QSet. i .

[0034] (5) Let the control dead zone of the inverter be Qdead gen When the AVC substation issues a reactive power command QSet to the inverter Di i After that, N tes After one acquisition cycle, the current reactive power value of the inverter is collected as QReal. i When |QSet i -QREal i |<Qdead gen When the adjustment is deemed satisfactory, the continuous failure counter Nerr of Di is reset to zero. i That is, let Nerr i =0, otherwise Nerr i Add 1. When Nerr i The maximum number of nonconformities greater than Di, NMaxerr i At that time, the inverter Di is removed from the excellent group and added to the tail of the test group's queue.

[0035] (6) When |ΔU|<U bal At this time, the AVC substation enters optimization control. In optimization control, optimization control for inverter equipment only applies to devices in the full-optimization group. Devices in the test group only participate in testing, not optimization. Each optimization control cycle tests the inverters in the inverter test group queue. Let U... diff =U dead -|ΔU|, NAdj Max To determine the maximum number of inverters that can be tested in one direction, typically NADJMax far greater than 1, when NAdj Max is less than 1, then the test is abandoned. For the inverter Dt i , the upper limit of its reactive power regulation is QLimtup i , the lower limit is QLimtdn i , and the current reactive power value is QReal i , then the up-regulation ability of the reactive power of Dt i is Qupabl i = QLimtup i - QReal i , and the down-regulation ability of the reactive power of Dt i is Qdnabl i = QReal i - QLimtdn gen . When the queue is empty, then no test is needed, otherwise the test is performed.

[0036] For the inverter at the head of the test queue:

[0037] Dt1 checks its up-regulation and down-regulation abilities. If Qupabl1> 2 x Qdead gen , then Dt1 has up-regulation test ability, and if Qdnabl1> 2 x Qdead i , then Dt1 has down-regulation test ability. Generally, since QLimtup i - QLimtdn gen is far greater than Qdead i , when the inverter Dt gen has no up-regulation test ability, it must have down-regulation test ability. When Dt1 has both up-regulation test ability and down-regulation test ability, then the up-regulation test ability and down-regulation test ability of the second inverter in the queue are checked. If Dt2 has only up-regulation test ability, then during the test, the reactive power command value of Dt1 is set to QReal1- 2 x Qdead gen , and the reactive power command value of Dt2 is set to QReal2+ 2 x Qdead gen , otherwise the reactive power command value of Dt1 is set to QReal1+ 2 x Qdead gen , and the reactive power command value of Dt2 is set to QReal2- 2 x Qdead j ; when Dt1 has only up-regulation test ability, then the inverter Dt gen with down-regulation ability is searched from the second inverter in the queue, and it is moved to the second position in the queue. During the test, the reactive power command value of Dt1 is set to QReal1+ 2 x Qdead genIf not found, only test Dt1 alone, set the reactive command value of Dt1 as QReal1+2×Qdead gen When Dt1 has only down-regulation test capability, then find the device Dt with up-regulation capability from the second inverter in the queue j , and move it to the second position in the queue, then set the reactive command value of Dt1 as QReal1-2×Qdead gen , and set the reactive command value of Dt2 as QReal2+2×Qdead gen If not found, only test Dt1 alone, set the reactive command value of Dt1 as QReal1-2×Qdead gen .

[0038] When the test command is issued to two or one tested inverters, N test acquisition cycles later, the current reactive value of the inverter is QReal i When |QSet i -QReal i |<Qdead gen , it is considered that the regulation is qualified, the tested device Dt i is moved to the full-optimization group, otherwise, Dt i is moved to the tail of the queue for subsequent testing.

[0039] For the device Dt i moved to the full-optimization group, the reactive command value QRealold i is issued to it again, QRealold i is the reactive value before testing of Dt i , and the regulation is recalled.

[0040] (7) For the device in the fault lockout group, when the fault signal collected by the AVC substation disappears or is manually unlocked, the device is first added to the head of the test group queue queue, and is tested preferentially, and is only moved to the full-optimization group to participate in full-optimization regulation after the test is qualified.

[0041] Specific implementation case:

[0042] A photovoltaic power station is provided, the high-voltage side bus voltage level is 220 kV, there are 200 inverters, each inverter has a capacity of 0.5 MW, the upper limit of reactive regulation is 0.12 Mvar, the lower limit of reactive regulation is -0.12 Mvar, the reactive control dead zone is 0.005 Mvar. The voltage control dead zone is 0.5 kV, and the voltage control balance dead zone is 0.3 kV. The acquisition period of the AVC substation is 5 s, the control period is 30 s, and the inverter test detection period is 15 s. The grid-connected point voltage and reactive sensitivity Cv q 0.12.

[0043] The groups of inverters are initialized, the #19 and #29 inverters are added to the fault lock group due to faults, the #109 and #159 inverters are also added to the fault lock group due to manual lock; and the other inverters are added to the full optimization group.

[0044] At this time, the voltage of the power station 220kV is 227.5kV, and the voltage setting value 228.5kV is issued by the dispatching master station. The absolute value of the voltage difference is greater than the voltage control dead zone, and the correction control mode is entered, and the reactive power demand ΔQ = (228.5-227.5) / 0.12 = 8.33Mvar is calculated. The reactive power of each inverter in the optimization group is about 0.05Mvar, and the AVC substation adopts the strategy of inverter priority regulation, so the inverter up-regulation capability of the optimization group is calculated as (0.12-0.05)*196 = 13.72Mvar, and only the inverters in the optimization group are needed to participate in the adjustment. According to the equal proportion strategy, the instruction of each inverter is calculated as QSet = (0.05*196+8.33) / (0.12*196)*0.12 = 0.0925Mvar. After the AVC substation issues the instruction to the inverter, the adjustment of each inverter is detected after 15s, most of the inverters can respond normally, and the reactive power is adjusted to about 0.092Mvar, among which #3, #23, #123, #153, #183 and #193 cannot respond normally, and the reactive power is still at 0.05Mvar. The unqualified counter of these four inverters is increased by 1, and the unqualified counter is currently 1. In subsequent adjustment, #3 inverter can respond normally, and its unqualified counter is set to 0, while #23, #123, #153, #183, #193 cannot respond normally for many times, and their unqualified counter reaches 11, which exceeds the maximum unqualified counter limit value. These inverters are moved from the full optimization group to the test queue of the test group in the order of #23, #123, #153, #183 and #193.

[0045] In the subsequent regulation process, the power station 220kV voltage is 228.0kV, and the voltage setting value 228.1kV is issued by the dispatching master station. The voltage difference absolute value is less than the voltage control balance dead zone, and enters the optimization control mode. At this time, the maximum single-direction test inverter number is calculated as (0.5-(228.1-228)) / (0.12*2*0.005) = 333, which is far greater than 1, and the inverters in the test group can be actively tested. Select the inverter #23 at the head of the test group queue, and its current reactive power value is 0.05Mvar, its reactive power up-regulation capability is 0.12-0.05 = 0.07Mvar, and its reactive power down-regulation capability is 0.05-(-0.12) = 0.17Mvar, so it has both up-regulation test capability and down-regulation test capability, and the second inverter #123 in the queue is selected, and its current reactive power is 0.055Mvar, which also has both up-regulation test capability and down-regulation test capability. The reactive power command value of the inverter #23 is set to 0.05+2*0.005 = 0.06Mvar, and the reactive power command value of the inverter #123 is set to 0.055-2*0.005 = 0.045Mvar. After 15s of instruction issuance, detection is started, and the reactive power of the inverter #23 is adjusted to 0.059Mvar, while the reactive power of the inverter #123 is still 0.055Mvar, at this time, the #23 is moved to the full optimization group, and the reactive power instruction 0.05Mvar is issued, and the inverter #123 is moved to the tail of the test queue, behind the #193, and waits for subsequent testing.

[0046] In the subsequent regulation process, the power station personnel released the inverter #109 lock, at this time, the inverter #109 is added to the head of the test group queue, i.e. in front of the inverter #153, and is preferentially tested, at this time, the order of the inverters in the test queue is #109, #153, #183, #193, #123.

[0047] The technical scheme of the present application is not limited to the above specific embodiments, and any technical modification made according to the technical scheme of the present application falls within the protection scope of the present application.

Claims

1. A reactive power and voltage control method for active monitoring and detection in a new energy photovoltaic power station, characterized in that, Includes the following steps: S1: Initialize the inverter, which is divided into the optimal group, the fault lockout group, and the test group; S2: Set the data acquisition cycle and control cycle of the AVC substation; S3: Collect grid connection point information and command information issued by the master station, and calculate the voltage difference; S4: When the voltage difference is greater than the voltage control dead zone, enter the correction control mode, calculate the reactive power demand and adjust the reactive power value of the inverter. S5: When the voltage difference is within the voltage balance dead zone, enter the optimized control mode to optimize the reactive power distribution and test the inverters in the test group. S6: Monitor the inverter regulation effect and dynamically adjust the inverter group according to the regulation effect; S7: Equipment in the fault interlocking group shall be given priority testing after the fault is cleared or the interlock is manually released. After passing the test, it shall be moved to the excellent group.

2. The reactive power and voltage control method for active monitoring and detection of new energy photovoltaic power plants according to claim 1, characterized in that: In step S1, when initializing the inverter group, the inverters that send fault or abnormal signals and the inverters that are manually locked are added to the fault lockout group, and the remaining inverters are added to the full-excellence group. The test group is initialized as an empty queue.

3. The reactive power and voltage control method for active monitoring and detection of new energy photovoltaic power plants according to claim 2, characterized in that: Step S2 specifically involves: Let the data acquisition period of the AVC substation be Tg, and the control period be T... c T c It is an integer multiple of Tg, let this multiple be N. c After the AVC substation sends a command to the inverter, it starts timing, N test After one data acquisition cycle, check the inverter's adjustment effect. test <N c And N c >= 2×N tset .

4. The reactive power and voltage control method for active monitoring and detection of new energy photovoltaic power plants according to claim 3, characterized in that: Step S3 specifically involves: collecting photovoltaic station grid connection point information U real P gate Q gate And the instruction information U issued by the main station ref ;where U real P represents the bus voltage at the grid connection point. gate Q represents the active power output from the grid connection point. gate U represents the reactive power value of the outgoing line from the grid connection point. ref This indicates the setpoint voltage for the grid connection point bus issued by the master station; Calculate the voltage difference ΔU = U ref -U real When |ΔU|>=U dead U dead This is the voltage control dead zone of the AVC substation. During this time, the AVC substation enters correction control and calculates reactive power demand. in To determine the reactive power sensitivity at the grid connection point, the AVC substation calculates the total regulated reactive power ΔQ of the inverter based on an inverter priority or balancing ratio algorithm. gen Adjustment of reactive power ΔQ with other equipment other And ΔQ = ΔQ gen +ΔQ other When |ΔU| < U bal At that time, U bal For the voltage balance dead zone of the AVC substation, and U bal <U dead At this point, the AVC substation enters optimization control to optimize the reactive power distribution within the station. During this control cycle, the inverter devices in the test group queue are tested.

5. The reactive power and voltage control method for active monitoring and detection of new energy photovoltaic power plants according to claim 4, characterized in that: Specifically, step S4 is: when |ΔU|>=U dead When the AVC substation performs calibration control, the reactive power up-adjustment capability of other devices is set to Qupabl. other The reactive power reduction capability of other devices is Qdnabl other The reactive power upscaling capacity of the inverter's optimal group is Qupper. gen The capability has been reduced to Qdnper. gen The reactive power upscaling capability of the equipment in the test group is Quptest. gen The capability has been reduced to Qdntest. gen The reactive power adjustable capacity of the equipment in the fault interlocking group is 0; when the reactive power adjustment ΔQ>0, Qupabl other +Qupper gen When ΔQ >=, adjust other devices and devices in the inverter's optimal group, when Qupabl other +Qupper gen When <ΔQ, in addition to other equipment and the inverter's optimal group equipment participating in reactive power regulation, the equipment in the inverter test group also needs to participate in regulation, with an adjustment amount of ΔQ - (Qupabl) other +Qupper gen When the reactive power regulation ΔQ < 0, Qdnabl other +Qdnper gen When Qdnabl is greater than or equal to |ΔQ|, adjust other devices and devices in the inverter's optimal group. other +Qdnper gen When <|ΔQ|, in addition to other equipment and the inverter's optimal group equipment participating in reactive power regulation, the equipment in the inverter test group also needs to participate in regulation, with an adjustment amount of ΔQ + (Qupabl) other +Qupper gen For the inverters in the optimal group and test group, the reactive power setpoint of each inverter is obtained according to the algorithm of equal proportion or margin priority. For inverter Di, its reactive power setpoint is QSet. i .

6. The reactive power and voltage control method for active monitoring and detection of new energy photovoltaic power plants according to claim 5, characterized in that: Step S5 specifically involves: setting the control dead zone of the inverter to Qdead. gen When the AVC substation issues a reactive power command QSet to the inverter Di i After that, N test After one acquisition cycle, the current reactive power value of the inverter is collected as QReal. i When |QSet i -QReal i |<Qdead gen When the adjustment is deemed satisfactory, the inverter's continuous failure counter Nerr (Di) is reset. i That is, let Nerr i =0, otherwise Nerr i Add 1; when Nerr i The maximum non-conforming count NMaxerr is greater than the inverter Di. i At that time, the inverter Di is removed from the excellent group and added to the tail of the test group's queue.

7. The reactive power and voltage control method for active monitoring and detection of new energy photovoltaic power plants according to claim 6, characterized in that: Specifically, step S6 is: when |ΔU|<U bal At this time, the AVC substation enters optimization control, and in each optimization control cycle, it tests the inverters in the inverter test group queue; U diff =U dead -|ΔU|, Round down to get NADJ Max NAdj Max For the maximum number of inverters that can be tested in one direction, NADJ Max Greater than 1, when NADJ Max If the value is less than 1, the test is abandoned; for the inverter Dt in the queue i The upper limit for reactive power adjustment is QLimtup i The lower bound is QLimtdn i The current reactive power value is QReal i Then Dt i reactive power upscaling capability Qupabl i =QLimtup i -QReal i Reduce capabilities Qdnabl i =QReal i -QLimtdn i If the queue is empty, no test is needed; otherwise, test is performed.

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