CN111082473A - Station level reactive power coordination control method and system - Google Patents
Station level reactive power coordination control method and system Download PDFInfo
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- H—ELECTRICITY
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- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
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- H—ELECTRICITY
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Abstract
The invention provides a station-level reactive power coordination control method. The method comprises the following steps: acquiring a grid-connected point voltage; judging whether the grid-connected point finishes low voltage ride through or not based on the grid-connected point voltage, and resetting parameters of a station level voltage regulator and a PI regulator if the grid-connected point finishes low voltage ride through; and obtaining reactive power required by the photovoltaic power generation system based on the grid-connected point voltage and the voltage control point reference voltage, and performing reactive compensation control on a reactive compensation device and each photovoltaic power generation unit according to the reactive power required by the photovoltaic power generation system. The technical scheme provided by the invention focuses on the system overvoltage, and makes a corresponding reactive power coordination control strategy for inhibiting the overvoltage after the photovoltaic power station fault, so that the reactive power coordination control strategy is used for the steady-state reactive power voltage regulation of the photovoltaic power station and simultaneously solves the short-time overvoltage problem after the transient fault of the photovoltaic power station.
Description
Technical Field
The invention relates to the technical field of power automation, in particular to a station-level reactive power coordination control method and system.
Background
With the continuous reduction of system cost and the continuous improvement of power generation efficiency, the construction of large-scale photovoltaic power stations is an effective way for utilizing solar energy on a large scale. Different from a small-capacity photovoltaic grid-connected power generation system, a plurality of large photovoltaic power stations are established in desert regions which are far away from a load center and rich in illumination resources, and regional power grids connected with the photovoltaic power stations are mostly located in remote regions, so that the load is relatively dispersed, the power transmission lines of the regional power grids are relatively long, and the power grids are relatively weak. The grid-connected voltage fluctuation and even out-of-limit can be caused by the illumination intensity, temperature change and the like of the photovoltaic power generation system, and a large photovoltaic power station needs to participate in voltage regulation control and provides emergency reactive support for a power grid when necessary. At present, the research on the reactive power and voltage control problem mainly focuses on the fields of distributed photovoltaic power generation and the like, and the research on the reactive power and voltage control problem of a large photovoltaic power station is very little. Therefore, the research on the reactive power and voltage control strategy applicable to the large photovoltaic power station has very important practical significance aiming at the current situation that the reactive power compensation device of the current large photovoltaic power station is constructed backward or does not have the reactive power compensation requirement.
Generally, when the system is in a steady state, voltage sag, power surge and current surge generated in the voltage fluctuation process do not seriously affect the direct current body and the receiving end alternating current power grid, and the system can bear the influence of a voltage fluctuation band through the reactive power regulation capacity of the system. After the system has a transient fault, if the system voltage is too low within a certain time and cannot be recovered by the reactive power regulation capability of the system, huge impact is caused on a receiving-end power grid. At present, the measure for dealing with the system voltage being too low is to deal with the system voltage through reactive compensation, but due to the characteristics of a reactive compensation device, the system voltage can be caused in the response process.
Disclosure of Invention
The invention provides a plant-level reactive power coordination control method, which aims to solve the steady-state reactive power voltage regulation of a photovoltaic power station and solve the problem of short-time overvoltage after transient faults of the photovoltaic power station.
The technical scheme provided by the invention is as follows:
a plant-level reactive power coordination control method comprises the following steps:
acquiring a grid-connected point voltage;
judging whether the grid-connected point finishes low voltage ride through or not based on the grid-connected point voltage, and resetting parameters of a station level voltage regulator and a PI regulator if the grid-connected point finishes low voltage ride through;
and obtaining reactive power required by the photovoltaic power generation system based on the grid-connected point voltage and the voltage control point reference voltage, and performing reactive compensation control on a reactive compensation device and each photovoltaic power generation unit according to the reactive power required by the photovoltaic power generation system.
Preferably, the determining whether the grid-connected point finishes low voltage ride through based on the grid-connected point voltage includes:
when the voltage of the high-voltage side of the grid-connected point voltage recovers to the set highest threshold value in the transient recovery process, the grid-connected point finishes low voltage ride through, otherwise, the grid-connected point is still in a low voltage ride through state.
Preferably, the resetting the plant-level voltage regulator and the PI regulator parameters includes:
setting the reactive limiting upper limit value of the station level voltage regulator to be zero;
and after delaying the preset time length, restoring the reactive limiting upper limit of the station level voltage regulator to an initial value, and setting the integral initial value of the PI regulator to be zero.
Preferably, the obtaining of the reactive power required by the photovoltaic power generation system based on the grid-connected point voltage and the voltage control point reference voltage includes:
and obtaining voltage deviation according to the grid-connected point voltage and the voltage control point reference voltage, and then obtaining the reactive power required by the photovoltaic power generation system through plant-level control calculation.
Preferably, the performing reactive compensation control on the reactive compensation device and each photovoltaic power generation unit according to the reactive power required by the photovoltaic power generation system includes:
the reactive power compensation device outputs reactive power according to the maximum reactive power requirement based on the reactive power required by the photovoltaic power generation system;
and judging whether the photovoltaic inverter of each photovoltaic power generation unit enters a low voltage ride through state, if so, responding to the low-voltage ride through strategy control of each photovoltaic power generation unit, otherwise, sharing the residual reactive power of the reactive power compensation device after the reactive power is output by the reactive power compensation device and when the reactive power required by the photovoltaic power generation system is not met by each photovoltaic power generation unit.
Further, the reactive power compensation device outputs reactive power with a maximum reactive power requirement based on the reactive power required by the photovoltaic power generation system, and comprises:
taking the reactive power required by the photovoltaic power generation system as a reactive power reference of the reactive power compensation device;
when the reactive power reference quantity of the reactive compensation device is smaller than the capacitive reactive capacity of the reactive compensation device and larger than the inductive reactive capacity, the reactive compensation device outputs reactive power by using the reactive power reference quantity of the reactive compensation device, otherwise, the reactive compensation device outputs reactive power by using the inductive reactive capacity or the capacitive reactive capacity of the reactive compensation device.
Further, the determining whether the photovoltaic inverter of each photovoltaic power generation unit enters the low voltage ride through state includes:
and when the voltage of the high-voltage side of the pre-collected grid-connected point voltage falls to a set lowest threshold value, the photovoltaic inverters of the photovoltaic power generation units enter a low-voltage ride-through state.
Further, each photovoltaic power generation unit shares the residual reactive power when the reactive power required by the photovoltaic power generation system is not met after the reactive power output by the reactive power compensation device is reactive, and the method comprises the following steps:
taking the residual reactive power as the reference total reactive power of each photovoltaic power generation unit, and respectively distributing the reference amount of reactive power to each photovoltaic power generation unit based on a preset distribution strategy;
and each photovoltaic power generation unit outputs reactive power based on the reactive power reference quantity.
Further, each photovoltaic power generation unit outputs reactive power based on the reference amount of reactive power, including:
when the reference amount of reactive power of each photovoltaic power generation unit is smaller than the capacitive reactive capacity of the photovoltaic power generation unit and larger than the inductive reactive capacity, the photovoltaic power generation unit outputs reactive power by using the reference amount of reactive power of the photovoltaic power generation unit, otherwise, the photovoltaic power generation unit outputs reactive power by using the inductive reactive capacity or the capacitive reactive capacity of the photovoltaic power generation unit.
Further, the setting of the time length includes:
simulating the duration of an overvoltage state in the voltage recovery process under multiple modes and multiple faults through a simulation experiment based on a power grid structure;
and setting the time period needing time delay based on the duration.
Further, the set maximum threshold value is 0.9 times of the rated voltage.
Further, the set minimum threshold is 0.2 times of the rated voltage.
A plant-level reactive power coordinated control system, the system comprising:
the judging module is used for acquiring the grid-connected point power and judging whether the grid-connected point finishes low voltage ride through or not according to the grid-connected point voltage;
and the control module is used for calculating the reactive power required by the photovoltaic power generation system according to the judgment result of the judgment module and carrying out reactive power regulation based on the reactive power required by the photovoltaic power generation system.
The judging module comprises: the device comprises a collecting unit and a first judging unit;
the acquisition unit is used for acquiring the voltage of the grid-connected point and sending the voltage to the first judgment unit;
and the first judging unit is used for judging whether the grid-connected point finishes low voltage ride through according to the grid-connected point voltage from the judging unit.
The control module includes: the device comprises a resetting unit, a calculating unit, a distributing unit and an adjusting unit;
the reset unit is used for resetting the parameters of the station level voltage regulator and the PI regulator when the grid-connected point finishes low voltage ride through;
the calculating unit is used for obtaining the reactive power required by the photovoltaic power generation system through plant-level control calculation according to the voltage deviation between the grid-connected point voltage and the voltage control point reference voltage;
the distribution unit is used for distributing reactive instructions to the reactive compensation device and each photovoltaic power generation unit based on the reactive power required by the photovoltaic power generation system and sending the reactive instructions to the adjusting unit;
and the adjusting unit is used for carrying out reactive power adjustment on the photovoltaic power station according to the reactive power instruction from the distribution unit.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a station-level reactive power coordination control method, which comprises the following steps: acquiring a grid-connected point voltage; judging whether the grid-connected point finishes low voltage ride through or not based on the grid-connected point voltage, and resetting parameters of a station level voltage regulator and a PI regulator if the grid-connected point finishes low voltage ride through; and obtaining reactive power required by the photovoltaic power generation system based on the grid-connected point voltage and the voltage control point reference voltage, and performing reactive compensation control on a reactive compensation device and each photovoltaic power generation unit according to the reactive power required by the photovoltaic power generation system. The technical scheme provided by the invention is used for steady-state reactive power voltage regulation of the photovoltaic power station, and simultaneously solves the problem of short-time overvoltage after transient fault of the photovoltaic power station.
The technical scheme provided by the invention focuses on the system overvoltage, and makes a corresponding reactive power coordination control strategy for inhibiting the overvoltage after the photovoltaic power station fails, so that the system voltage is stabilized, and the impact on a receiving-end power grid is reduced.
Drawings
FIG. 1 is a flow chart of an embodiment of a plant-level reactive power coordination control method according to the present invention;
FIG. 2 is a diagram of the low voltage ride through capability requirement of a photovoltaic power plant in an embodiment of the invention;
FIG. 3 is a diagram of a specific implementation manner of a plant-level reactive power and voltage coordination control strategy according to an embodiment of the present invention;
FIG. 4 is a flow chart of a plant level voltage regulator coordination control strategy in an embodiment of the present invention;
FIG. 5- (1) is a comparison graph of voltage simulation of grid-connected points of a hidden heliostat photovoltaic power station in an embodiment of the invention;
FIG. 5- (2) is a comparison graph of voltage simulation of grid-connected points of the Sakyamuni photovoltaic power plant in the embodiment of the present invention;
FIG. 5- (3) is a comparison graph of voltage simulation of grid-connected points of the Tibet Oncon photovoltaic power station in the embodiment of the present invention;
FIG. 5- (4) is a voltage simulation comparison diagram of grid-connected points of a Tibetan Lazi photovoltaic power station in the embodiment of the invention;
fig. 6 is a schematic structural diagram of a plant-level reactive power coordination control system according to the present invention.
Detailed Description
For a better understanding of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings and examples. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1:
the plant-level reactive power coordination control method provided by the embodiment of the invention has the specific implementation process shown in fig. 1, and comprises the following steps:
s101: acquiring a grid-connected point voltage;
s102: judging whether the grid-connected point finishes low voltage ride through or not based on the grid-connected point voltage, and resetting parameters of a station level voltage regulator and a PI regulator if the grid-connected point finishes low voltage ride through;
s103: and obtaining reactive power required by the photovoltaic power generation system based on the grid-connected point voltage and the voltage control point reference voltage, and performing reactive compensation control on a reactive compensation device and each photovoltaic power generation unit according to the reactive power required by the photovoltaic power generation system.
Specifically, step S102 is to determine whether the grid-connected point finishes low voltage ride through based on the grid-connected point voltage, and if so, reset the plant-level voltage regulator and PI regulator parameters, and the specific implementation process includes:
step S102-1, judging whether the voltage of the high-voltage side of the pre-collected grid-connected point voltage is recovered to 0.9p.u. in the transient recovery process, if so, finishing low-voltage ride through of the grid-connected point, otherwise, still keeping the grid-connected point in a low-voltage ride through state.
Step S102-2, if the grid-connected point finishes low voltage ride through, resetting the station level voltage regulator reactive power amplitude limiting upper limit, the station level voltage regulator reactive power amplitude limiting upper limit after the time T of delay and the PI regulator integral initial value, wherein:
s102-2-1, modifying the reactive limiting upper limit Q of the station level voltage regulatormaxIs zero;
reactive limiting upper limit Q of voltage regulatormaxCan send out inductive reactive capacity for the system, make Q max0 is inductive reactive power which is generated by the system stopping;
s102-2-2, after the time T is delayed, the reactive power amplitude limiting upper limit of the station level voltage regulator recovers to an initial value, and meanwhile, the integral initial value of the PI regulator is reset to be zero;
the determination of the time delay T needs to be combined with a specific power grid structure, and the duration of the overvoltage problem in the voltage recovery process under multiple modes and multiple faults is simulated through a large number of simulation experiments; after T time, QmaxRestoring the initial value, namely the inductive reactive power which can be sent by the system and the reactive power which can be sent according to the requirement of the system;
proportional coefficient k of PI regulatoriIntegral coefficient kpThe voltage/reactive static linear differential regulation characteristic and large photovoltaic are combinedThe voltage of the power station access area is set according to the specific situation of idle work.
Specifically, step S103 obtains the reactive power required by the photovoltaic power generation system based on the grid-connected point voltage and the voltage control point reference voltage, and performs reactive compensation control on the reactive compensation device and each photovoltaic power generation unit according to the reactive power required by the photovoltaic power generation system, and the specific implementation process includes:
step S103-1, according to the voltage deviation between the grid-connected point voltage and the voltage control point reference voltage, the reactive power Q required by the photovoltaic power generation system is obtained through plant-level control calculationord；
Step S103-2, based on the needed reactive power Q of the photovoltaic power generation systemordThe photovoltaic power station sends a reactive power distribution instruction to a reactive power compensation device (SVC) and a photovoltaic inverter of each photovoltaic power generation unit;
step S103-3, the reactive compensation device (SVC) and the photovoltaic inverter of each photovoltaic power generation unit jointly respond to a reactive power distribution instruction, wherein:
step S103-3-1, a reactive power compensation device (SVC) outputs reactive power with maximum reactive power requirement based on the reactive power required by the photovoltaic power generation system, and the method comprises the following steps:
step S103-3-1-1: reactive power (SVC) required by photovoltaic power generation system as reactive power reference quantity Q of reactive power compensation devicesref，Qsmax、QsminThe inductive reactive capacity and the capacitive reactive capacity of the SVC unit are represented;
step S103-3-1-2: if Qsmax＜Qsref＜QsminThe SVC unit sends out QsrefIf Q is not satisfiedsmax＜Qsref＜QsminThen the SVC unit sends out QsmaxOr Qsmin；
And S103-3-2, judging whether the photovoltaic inverter of each photovoltaic power generation unit enters a low voltage ride through state, if so, responding to the low ride through strategy control of each photovoltaic power generation unit, and otherwise, executing the step S103-3-3.
The criterion whether the photovoltaic power generation unit of the photovoltaic unit enters the low voltage ride through is shown in fig. 2: when the grid-connected point voltage is in the gray part area in fig. 2, the photovoltaic power station must ensure uninterrupted grid-connected operation. The minimum voltage limit for normal operation in fig. 2 is 0.9 times the rated voltage, and the lower voltage limit that needs to be tolerated is 0.2 times the rated voltage. The photovoltaic power station needs to have low-voltage ride through capability within 0-2s after the fault occurs, and even if the voltage of a photovoltaic grid-connected point falls to 0, the photovoltaic power station needs to be operated for 0.15s in a grid-connected mode;
step S103-3-3, each photovoltaic power generation unit shares the reactive power Q required by the photovoltaic power generation system and does not meet the reactive power Q required by the reactive power compensation device after the reactive power is outputordThe remaining reactive power of the time, including:
step S103-3-3-1: taking the residual reactive power as the reference total reactive power of each photovoltaic power generation unit, and distributing the reference quantity Q of the reactive power to each photovoltaic power generation unit based on a preset distribution strategyiref，Qimax、QimiRespectively representing the inductive reactive capacity and the capacitive reactive capacity of the photovoltaic power generation unit i;
step S103-3-3-2: for any photovoltaic power generation unit, if Qimax＜Qiref＜QiminThe photovoltaic power generation unit generates QirefIf Q is not satisfiedimax＜Qiref＜QiminThen the photovoltaic power generation unit generates QimaxOr Qimin。
Example 2:
as shown in fig. 3 and 4, the embodiment provides a plant-level reactive power coordination control strategy, and the specific method is as follows:
the method comprises the steps of collecting voltage of a grid-connected point of a large photovoltaic power station, calculating reactive power regulation requirements of the photovoltaic power station after coordinated control of a station-level voltage regulator, and then sending a reactive power distribution instruction to a reactive power compensation device (SVC) and a photovoltaic inverter in the power station for regulation. In the transient process, the photovoltaic inverter enters low voltage ride through control and does not respond to the station level reactive voltage regulation instruction, after the photovoltaic unit is detected to output a low voltage ride through control signal, the upper limit of reactive power amplitude limiting of the station level voltage regulator is modified to be zero, the initial value is recovered after the time delay T is 0.3s, and meanwhile, the integral value of the PI regulator is reset.
As shown in fig. 5- (1) to 5- (4), for the N-2 fault of the tibetan power grid linmai forest under the summer square formula, the plant-level reactive power coordination control strategy for inhibiting the overvoltage after the fault of the photovoltaic power station is adopted and the plant-level reactive power coordination control strategy is not adopted by comparing simulation (relevant parameters are shown in table 1), and the voltage of the grid-connected points of the tibetan solar power station, sakyamu, kanran and cumin photovoltaic power station can be monitored by: although both modes can be used for reactive voltage regulation, the problem of short-time overvoltage after transient fault can be obviously solved without adopting the reactive coordination control strategy. It can therefore be concluded that: the strategy can be used for steady-state reactive power voltage regulation of the photovoltaic power station, and meanwhile, the short-time overvoltage problem occurring after transient faults of the photovoltaic power station is solved.
TABLE 1
Example 3:
based on the same inventive concept, the present invention further provides a plant-level reactive power coordination control system, as shown in fig. 6, the system includes:
the judging module is used for acquiring the grid-connected point power and judging whether the grid-connected point finishes low voltage ride through or not according to the grid-connected point voltage;
and the control module is used for calculating the reactive power required by the photovoltaic power generation system according to the judgment result of the judgment module and carrying out reactive power regulation based on the reactive power required by the photovoltaic power generation system.
Wherein, the judging module includes: the device comprises a collecting unit and a first judging unit;
the acquisition unit is used for acquiring the voltage of the grid-connected point and sending the voltage to the first judgment unit;
and the first judging unit is used for judging whether the grid-connected point finishes low voltage ride through according to the grid-connected point voltage from the judging unit.
Wherein, the control module includes: the device comprises a resetting unit, a calculating unit, a distributing unit and an adjusting unit;
the reset unit is used for resetting the parameters of the station level voltage regulator and the PI regulator when the grid-connected point finishes low voltage ride through;
the calculating unit is used for obtaining the reactive power required by the photovoltaic power generation system through plant-level control calculation according to the voltage deviation between the grid-connected point voltage and the voltage control point reference voltage;
the distribution unit is used for distributing reactive instructions to the reactive compensation device and each photovoltaic power generation unit based on the reactive power required by the photovoltaic power generation system and sending the reactive instructions to the adjusting unit;
and the adjusting unit is used for carrying out reactive power adjustment on the photovoltaic power station according to the reactive power instruction from the distribution unit.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention which are filed as the application.
Claims (15)
1. A plant-level reactive power coordination control method is characterized by comprising the following steps:
acquiring a grid-connected point voltage;
judging whether the grid-connected point finishes low voltage ride through or not based on the grid-connected point voltage, and resetting parameters of a station level voltage regulator and a PI regulator if the grid-connected point finishes low voltage ride through;
and obtaining reactive power required by the photovoltaic power generation system based on the grid-connected point voltage and the voltage control point reference voltage, and performing reactive compensation control on a reactive compensation device and each photovoltaic power generation unit according to the reactive power required by the photovoltaic power generation system.
2. The plant-level reactive power coordination control method according to claim 1, wherein the determining whether the grid-connected point finishes low voltage ride through based on the grid-connected point voltage comprises:
when the voltage of the high-voltage side of the grid-connected point voltage recovers to the set highest threshold value in the transient recovery process, the grid-connected point finishes low voltage ride through, otherwise, the grid-connected point is still in a low voltage ride through state.
3. The plant-level reactive power coordinated control method according to claim 1, wherein the resetting plant-level voltage regulator and PI regulator parameters comprises:
setting the reactive limiting upper limit value of the station level voltage regulator to be zero;
and after delaying the preset time length, restoring the reactive limiting upper limit of the station level voltage regulator to an initial value, and setting the integral initial value of the PI regulator to be zero.
4. The plant-level reactive power coordination control method according to claim 1, wherein obtaining the reactive power required by the photovoltaic power generation system based on the grid-connected point voltage and the voltage control point reference voltage comprises:
and obtaining voltage deviation according to the grid-connected point voltage and the voltage control point reference voltage, and then obtaining the reactive power required by the photovoltaic power generation system through plant-level control calculation.
5. The plant-level reactive power coordination control method according to claim 1, wherein the reactive power compensation control of the reactive power compensation device and each photovoltaic power generation unit according to the reactive power required by the photovoltaic power generation system comprises:
the reactive power compensation device outputs reactive power according to the maximum reactive power requirement based on the reactive power required by the photovoltaic power generation system;
and judging whether the photovoltaic inverter of each photovoltaic power generation unit enters a low voltage ride through state, if so, responding to the low-voltage ride through strategy control of each photovoltaic power generation unit, otherwise, sharing the residual reactive power of the reactive power compensation device after the reactive power is output by the reactive power compensation device and when the reactive power required by the photovoltaic power generation system is not met by each photovoltaic power generation unit.
6. The plant-level reactive power coordination control method according to claim 5, wherein the reactive power compensation device outputs reactive power with a maximum reactive power requirement based on the reactive power required by the photovoltaic power generation system, and the method comprises the following steps:
taking the reactive power required by the photovoltaic power generation system as a reactive power reference of the reactive power compensation device;
when the reactive power reference quantity of the reactive compensation device is smaller than the capacitive reactive capacity of the reactive compensation device and larger than the inductive reactive capacity, the reactive compensation device outputs reactive power by using the reactive power reference quantity of the reactive compensation device, otherwise, the reactive compensation device outputs reactive power by using the inductive reactive capacity or the capacitive reactive capacity of the reactive compensation device.
7. The plant-level reactive power coordination control method according to claim 5, wherein the step of judging whether the photovoltaic inverter of each photovoltaic power generation unit enters a low voltage ride through state comprises the steps of:
and when the voltage of the high-voltage side of the pre-collected grid-connected point voltage falls to a set lowest threshold value, the photovoltaic inverters of the photovoltaic power generation units enter a low-voltage ride-through state.
8. The plant-level reactive power coordination control method according to claim 5, wherein the step of sharing the residual reactive power of the reactive power compensation device after the reactive power output by the photovoltaic power generation unit does not satisfy the reactive power required by the photovoltaic power generation system comprises:
taking the residual reactive power as the reference total reactive power of each photovoltaic power generation unit, and respectively distributing the reference amount of reactive power to each photovoltaic power generation unit based on a preset distribution strategy;
and each photovoltaic power generation unit outputs reactive power based on the reactive power reference quantity.
9. The plant-level reactive power coordination control method according to claim 8, wherein each photovoltaic power generation unit outputs reactive power based on the reference amount of reactive power, and the method comprises the following steps:
when the reference amount of reactive power of each photovoltaic power generation unit is smaller than the capacitive reactive capacity of the photovoltaic power generation unit and larger than the inductive reactive capacity, the photovoltaic power generation unit outputs reactive power by using the reference amount of reactive power of the photovoltaic power generation unit, otherwise, the photovoltaic power generation unit outputs reactive power by using the inductive reactive capacity or the capacitive reactive capacity of the photovoltaic power generation unit.
10. The plant-level reactive power coordination control method according to claim 3, wherein the setting of the time length comprises:
simulating the duration of an overvoltage state in the voltage recovery process under multiple modes and multiple faults through a simulation experiment based on a power grid structure;
and setting the time period needing time delay based on the duration.
11. The plant-level reactive power coordinated control method according to claim 2, wherein the set maximum threshold value is 0.9 times of rated voltage.
12. The plant-level reactive power coordinated control method according to claim 7, wherein the set minimum threshold value is 0.2 times of rated voltage.
13. A plant-level reactive power coordinated control system is characterized by comprising:
the judging module is used for acquiring the grid-connected point power and judging whether the grid-connected point finishes low voltage ride through or not according to the grid-connected point voltage;
and the control module is used for calculating the reactive power required by the photovoltaic power generation system according to the judgment result of the judgment module and carrying out reactive power regulation based on the reactive power required by the photovoltaic power generation system.
14. The plant-level reactive power coordinated control system of claim 13, wherein the determining module comprises: the device comprises a collecting unit and a first judging unit;
the acquisition unit is used for acquiring the voltage of the grid-connected point and sending the voltage to the first judgment unit;
and the first judging unit is used for judging whether the grid-connected point finishes low voltage ride through according to the grid-connected point voltage from the judging unit.
15. The plant-level reactive power coordinated control system of claim 13, wherein the control module comprises: the device comprises a resetting unit, a calculating unit, a distributing unit and an adjusting unit;
the reset unit is used for resetting the parameters of the station level voltage regulator and the PI regulator when the grid-connected point finishes low voltage ride through;
the calculating unit is used for obtaining the reactive power required by the photovoltaic power generation system through plant-level control calculation according to the voltage deviation between the grid-connected point voltage and the voltage control point reference voltage;
the distribution unit is used for distributing reactive instructions to the reactive compensation device and each photovoltaic power generation unit based on the reactive power required by the photovoltaic power generation system and sending the reactive instructions to the adjusting unit;
and the adjusting unit is used for carrying out reactive power adjustment on the photovoltaic power station according to the reactive power instruction from the distribution unit.
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