CN109713681B - Method for offline verifying control strategy of dynamic reactive power compensation device - Google Patents
Method for offline verifying control strategy of dynamic reactive power compensation device Download PDFInfo
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Abstract
The invention discloses a method for offline verifying a control strategy of a dynamic reactive power compensation device, which comprises the following steps: building a dynamic reactive power compensation control strategy verification system; (2): setting a control strategy of a dynamic reactive power compensation device; (3): according to different selected control strategies, correspondingly determining different control targets; (4): the control strategy verification system simulates the operation or fault states of various new energy power stations, so as to achieve the purpose of verifying the control strategy of the dynamic reactive power compensation device controller; according to the method, the dynamic reactive power compensation device control strategy verification system simulates various complicated power grid operation conditions, various control strategies of the dynamic reactive power compensation device can be verified, offline optimization is carried out on the control performance of the dynamic reactive power compensation device, the debugging and starting period before on-site operation is greatly shortened, and the problems that the operation performance of a part of new energy power stations which are put into operation of the dynamic reactive power compensation device is required to be optimized, but the on-site operation conditions limit that parameters cannot be optimized on line are solved.
Description
Technical Field
The invention belongs to the field of control, and provides a method for verifying the performance of a related control strategy of a dynamic reactive power compensation device in an off-line manner.
Background
The dynamic reactive power compensation device integrates reactive power compensation and power grid monitoring, plays roles in compensating reactive power loss in a power grid, improving power factor, reducing line loss, improving load capacity and power supply quality of the power grid, is commonly used in a power distribution system, and generally comprises dynamic reactive power compensation devices such as a static dynamic reactive power generator (SVG), a Thyristor Controlled Reactor (TCR), a magnetic valve type controllable reactor (MCR) and the like; the control strategy mainly comprises the following steps: the voltage control strategy, the reactive power control strategy, the reactive voltage comprehensive control strategy (power factor control), the fault ride-through control strategy and the abnormal condition locking control strategy have the advantages that the control strategy is correct, and the setting value of the control parameters reasonably plays a decisive role in the performance of the dynamic reactive power compensation device.
At present, most of control strategy verification adopts a simulation technology, a dynamic reactive compensation device control system model is established to verify the feasibility and correctness of the designed control strategy, and although a certain reference can be provided for the development of a control system, the controller cannot be verified, the actual working condition of the system cannot be reflected, and the test basis is lacked. There are also controllers and control strategies that use real-time digital simulation techniques to build a system model to verify the design, but real-time digital simulation devices are usually costly and interface circuits are complex, limiting the application of real-time digital simulation techniques in chained static synchronous compensators. In addition, the existing method for verifying the correctness of the control strategy has the following defects: 1. the method has the advantages that the number of the operation parts is large, the test conditions are complex, and the influence factors are large during the field test, so that the period for finding and solving the problems is long; 2. the test results of the dynamic reactive power compensation devices of the same model at different installation sites have larger difference; 3. different field technicians debug the same model dynamic reactive power compensation device, and the test results have larger difference possibly caused by the lack of a control strategy or the difference of parameter setting values, so that the problem reasons are often difficult to find; 4. the power factor control capability (namely voltage reactive comprehensive control) of the dynamic reactive power compensation device is limited by various factors such as the power grid environment, so that the test period is greatly prolonged or the field test cannot be performed.
From the network performance test situation of the developed dynamic reactive power compensation device, most dynamic reactive power compensation devices have imperfect/missing control strategies or the control effect corresponding to the actually set parameter setting value cannot reach the expected effect, and a quick, economical and effective method for verifying the correctness of the control strategies and the rationality of the parameter setting value is urgently needed.
Disclosure of Invention
In view of the above-mentioned challenges and difficulties, the present patent proposes a method for offline verifying a control strategy of a dynamic reactive compensation device, comprising the steps of:
(1): building a dynamic reactive power compensation control strategy verification system;
(2): setting a control strategy of a dynamic reactive power compensation device;
(3): according to different selected control strategies, correspondingly determining different control targets;
(4): the control strategy verification system simulates the operation or fault states of various new energy power stations, so as to achieve the purpose of verifying the control strategy of the dynamic reactive power compensation device;
(5): and recording the voltage and current of the grid-connected point of the dynamic reactive power compensation device, the voltage and current of the new energy power station or the grid-connected point of the dynamic reactive power compensation device and the response characteristic parameters of the controller under abnormal conditions, and calculating the voltage, reactive power, active power, power factor, reactive current response time and reactive current regulation proportionality coefficient to be used as the basis for judging the control performance of the dynamic reactive power compensation device.
The control strategy verification system comprises: the system comprises a main circuit simulation module, a new energy power station and power grid simulation module, an optical fiber conversion interface, a level conversion interface and a man-machine interaction interface, wherein the main circuit simulation module performs signal interaction with a dynamic reactive power compensation device controller executing a dynamic reactive power compensation device control strategy through the optical fiber conversion interface; and the new energy power station and the power grid simulation module interact signals with the dynamic reactive power compensation device controller through the level conversion interface.
The dynamic reactive power compensation device control strategy is a voltage control strategy or a voltage reactive power comprehensive control strategy or a fault ride-through control strategy.
The control targets are as follows: the voltage or reactive power of the grid-connected point of the new energy power station is used as a control target or the voltage of the grid-connected point of the dynamic reactive power compensation device is used as a control target.
The operation or fault state of the new energy power station is one of the following working conditions:
1) Simulating active output change of the new energy power station to cause voltage fluctuation of grid-connected points;
2) Simulating external power grid changes by adjusting related grid-related parameters;
3) According to the related standard requirements, the dynamic reactive power compensation device is respectively simulated to run in a light load state and a full load state by setting the control parameters of the controller of the dynamic reactive power compensation device, and then the falling, rising or falling-first rising-then working conditions of different voltage grades of the power grid voltage are simulated;
4) Simulating abnormal bus voltage of the new energy power station, abnormal regulation instruction of the dynamic reactive power compensation device or abrupt interruption of communication;
5) And (3) adjusting the short-circuit capacity of the grid-connected point of the new energy power station to be 1.0, 0.5 and 1.5 respectively, and selecting the test working condition which needs to be repeated in 1) -4).
When the control strategy of the dynamic reactive power compensation device is a voltage control strategy, the verification steps are as follows:
(1) Setting a dynamic reactive power compensation device as a constant voltage control strategy, setting the grid-connected point short-circuit capacity of the dynamic reactive power compensation device as a reference short-circuit capacity, taking the grid-connected point voltage of the new energy power station as a control target, setting a control target voltage value Vg of the dynamic reactive power compensation device, simulating the fluctuation of the grid-connected point voltage of the new energy power station caused by the fluctuation of the grid-connected point active power output of the new energy power station, and recording the reactive power output value of the dynamic reactive power compensation device and the voltage value of the grid-connected point of the new energy power station under the fluctuation of the grid-connected point active power output of the new energy power station;
(2) Setting a control target voltage value which is different from a target voltage value Vg as Vt, and recording a grid-connected point voltage control dead zone and a reactive power output value and a reactive power output dead zone value of the dynamic reactive power compensation device under different voltage target values;
(3) Setting a control mode of the dynamic reactive power compensation device as voltage curve control, taking the voltage of a grid-connected point of a new energy power station as a control target, and setting a control interval as a steady-state voltage limit value interval [ V ] d- —V d+ ]Simulating the fluctuation of the grid-connected active output of the new energy power station to cause the fluctuation of the grid-connected voltage, and recording the reactive power output value and the grid-connected voltage value of the dynamic reactive power compensation device under the fluctuation of the grid-connected active output of the new energy power station;
(4) Maintaining the voltage target value Vg of the grid-connected point of the new energy power station, and giving the voltage value of the grid-connected point of the new energy power station to be respectively in [ V ] d- —V l ]And [ V d+ —V h ]In the interval, recording reactive power output values corresponding to the dynamic reactive power compensation device of the new energy power station under different grid-connected point voltage set values, calculating dynamic voltage regulation proportion coefficients of the dynamic reactive power compensation device, and drawing a characteristic curve;
(5) And (3) adjusting the short-circuit capacity of the grid-connected point of the new energy power station to be 0.5 times and 1.5 times of the reference capacity, and repeating the test steps (1) - (4).
When the control strategy of the dynamic reactive power compensation device is a voltage reactive power integrated control strategy (namely a power factor control strategy), the verification steps are as follows:
a) Setting different target power factor values through a man-machine interaction interface by taking a power factor of a new energy power station grid connection point or a power factor of a new energy power station main transformer low-voltage side as a control target, simulating active output fluctuation of the new energy power station, recording power factors of the new energy power station grid connection point, active power of the grid connection point, reactive power of the grid connection point and reactive power output values of a dynamic reactive compensation device under the fluctuation of the active power and the different power factor target values, and recording a dead zone of power factor control;
b) Setting a dynamic reactive power compensation device control target point as a new energy power station grid-connected point voltage in a steady-state voltage limit value interval V d- —V d+ ]And when the reactive power exchange between the new energy power station and the power grid is minimum in the range, simulating the fluctuation of the active output of the grid-connected point of the new energy power station, recording the reactive power of the grid-connected point of the new energy power station and the reactive power output value of the dynamic reactive power compensation device under the fluctuation of the active power, and verifying the power factor control capability of the dynamic reactive power compensation device.
When the control strategy of the dynamic reactive power compensation device is a fault ride-through control strategy, the verification steps are as follows:
(1) In the fault process of the power grid, the grid-connected point voltage of the dynamic reactive power compensation device is used as a control target, and the device before the power grid faults respectively operates under the conditions of 0.2p.u., 1.0p.u., and the two phases and three phases of the grid-connected point voltage of the dynamic reactive power compensation device fall and then rise by controlling the fault simulation device, wherein the amplitude is respectively 0.9p.u. -0.02p.u., 0.50 p.u.+ -. 0.02p.u., 0.20p.u.+ -. 0.02p., 1.10p.u.+0.02p.u., 1.20p.u.+ -. 0.02p.u., 1.30p.+ -. 0.02p.u.
(2) Drawing a relation curve of grid-connected point voltage and reactive current of the dynamic reactive compensation device, recording transient reactive current regulation proportionality coefficient and transient reactive current response time, and verifying fault ride-through capability in the process that the grid-connected point voltage of the dynamic reactive compensation device is firstly reduced and then increased.
The fault ride-through control strategy is exemplified by voltage drop and then rise, and other types of fault ride-through capability (such as low-voltage fault or high-voltage fault) verification methods are the same.
The invention has the technical effects that:
1. the dynamic reactive power compensation device control strategy verification system simulates various complicated power grid operation conditions, and can give feedback signals of a link system (namely a dynamic reactive power compensation device power module) according to requirements, so that wiring and debugging are simple and convenient;
2. the dynamic reactive power compensation device can verify various control strategies of the dynamic reactive power compensation device, including a voltage control strategy, a reactive power control strategy, a voltage reactive power comprehensive control strategy, a fault ride-through control strategy and an abnormal state locking control strategy, and has good expansibility;
3. the closed-loop simulation verification can be realized on the dynamic reactive power compensation device controller, the off-line optimization is carried out on the control performance (parameter setting value) of the dynamic reactive power compensation device, the debugging and starting period before on-site operation is greatly shortened, and the off-line verification and off-line parameter optimization of the control strategy of the dynamic reactive power compensation device are realized;
4. the method solves the problems that the running performance of the dynamic reactive power compensation device which is put into operation in part of new energy power stations needs to be optimized, but the parameters cannot be optimized offline due to the limitation of on-site running conditions.
Drawings
FIG. 1 is a schematic diagram of a dynamic reactive power compensation device control strategy verification system;
FIG. 2 is a schematic diagram of a dynamic reactive power compensation device control interval;
FIG. 3 is a schematic diagram of a grid connection point of the new energy power station and the dynamic reactive power compensation device thereof;
FIG. 4 is a voltage control strategy verification flow chart;
FIG. 5 reactive control strategy verification flow chart;
FIG. 6 is a flowchart of reactive voltage integrated control strategy (power factor control) verification;
FIG. 7 is a fault ride-through (first low pass then high pass) control strategy verification flowchart;
FIG. 8 is a flowchart of an abnormal lockout control strategy verification.
Detailed Description
The present invention is described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth in detail. The present invention will be fully understood by those skilled in the art without the details described herein. Well-known methods, procedures, flows, components and circuits have not been described in detail so as not to obscure the nature of the invention.
Moreover, those of ordinary skill in the art will appreciate that the drawings are provided herein for illustrative purposes and that the drawings are not necessarily drawn to scale.
Meanwhile, it should be understood that in the following description, "circuit" refers to a conductive loop constituted by at least one element or sub-circuit through electrical connection or electromagnetic connection. When an element or circuit is referred to as being "connected to" another element or being "connected between" two nodes, it can be directly coupled or connected to the other element or intervening elements may be present and the connection between the elements may be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled to" or "directly connected to" another element, it means that there are no intervening elements present between the two.
Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is, it is the meaning of "including but not limited to".
In the description of the present invention, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Furthermore, in the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.
As shown in figure 1, the new energy power station mainly connects the output electric energy of the wind power or photovoltaic grid-connected inverter with a power grid through a main transformer of the new energy power station, and an additionally installed dynamic reactive power compensation device is connected to the low-voltage side of the main transformer of the new energy power station through a grid-connected point of the dynamic reactive power compensation device. The dynamic reactive power compensation device of the new energy power station generally comprises a static dynamic reactive power generator (SVG), a Thyristor Controlled Reactor (TCR), a magnetic valve type controllable reactor (MCR), a static reactive power compensator (SVC) and other dynamic reactive power compensation devices; the dynamic reactive power compensation control strategy realized by the specific control strategy of the dynamic reactive power compensation device controller is mainly as follows: voltage control strategy, reactive voltage integrated control strategy (power factor control), fault ride-through control strategy and abnormal condition lockout control strategy. The validity of these control strategies and the rationality of the parameter settings need to be verified by a control strategy verification system.
The structural schematic diagram of the dynamic reactive power compensation device control strategy verification system is further provided by fig. 1, and the dynamic reactive power compensation device control strategy verification system comprises: the system comprises a main circuit simulation module, a new energy power station and power grid simulation module, an optical fiber conversion interface, a level conversion interface and a man-machine interaction interface. The main circuit simulation module is used for simulating the running state of each power module in the dynamic reactive power compensation device after receiving the pulse control signal, and simultaneously simulating the dynamic reactive power compensation device to feed back the state signals of each power module to the dynamic reactive power compensation device controller, wherein the dynamic reactive power compensation device controller comprises a dynamic reactive power compensation device main controller and a device pulse controller. The new energy power station and the power grid simulation module correspondingly output the three-phase voltage, the three-phase current and the running state of the grid-connected switch of the dynamic reactive compensation device of the simulation control point according to the related parameters set by the main circuit simulation module;
the optical fiber conversion interface is used for receiving PWM pulse control signals (A0-An … …, cn) sent by the reactive power compensation device controller and feeding back a dynamic reactive power compensation device power module state signal given by the main circuit simulation module to the dynamic reactive power compensation device pulse controller; the level conversion interface module is used for converting the analog control point voltage, current, new energy power station grid-connected point voltage, the grid-connected switching state (switching value) of the dynamic reactive power compensation device and the grid-connected tripping and switching instruction signal into relevant analog quantity or switching value which can be identified by the dynamic reactive power compensation device main controller, and sending the relevant instruction to the dynamic reactive power compensation device main controller; the man-machine interaction interface is used for an operator to issue instructions such as control point voltage, current and grid-connected point voltage and relevant parameters, and information such as pulse instructions issued by the dynamic reactive power compensation device, grid-connected jump-in instructions and real-time simulation operation parameters of the dynamic reactive power compensation device is displayed.
In order to meet the control strategy verification requirement of the dynamic reactive power compensation device, the control strategy verification system should meet the following conditions: 1. the main circuit simulation module adopts a fixed-step simulation model, and the simulation step is not more than 5us; 2. the new energy power station and the power grid simulation module adopt a fixed-step simulation model, and the simulation step is not more than 10ms; 3. the optical fiber conversion interface and the level conversion interface meet the signal transmission requirement between the dynamic reactive power compensation device controller and the control strategy verification system; the accuracy of the analog output signal is better than 0.5%; the time error of the input and output signals of the switching value is less than 1ms; the pulse time error of the chain link modulation is less than 1us; the output precision of the chain link state feedback signal is better than 0.5%.
Firstly, an output unit of a device pulse controller in a dynamic reactive power compensation device controller is connected with an optical fiber conversion interface in a control strategy verification system, and is used for receiving a pulse control signal sent by the dynamic reactive power compensation device controller by the control strategy verification system; secondly, a chain link (dynamic reactive power compensation device power module) state feedback signal output by the simulation module is connected into the device pulse controller and is used for feeding back the simulated chain link running state to the dynamic reactive power compensation device pulse controller; thirdly, the analog output signals (control point voltage, current and grid-connected point voltage) and the switching value output signals in the new energy power station and the power grid simulation module are connected into a dynamic reactive power compensation device main controller through a level conversion interface, so that the running state of the power grid is simulated; finally, a switching value input signal (grid-connected tripping and closing instruction) sent by a main controller of the dynamic reactive power compensation device is connected to a control strategy verification system and is used for sending a tripping state signal of the dynamic reactive power compensation device to a new energy power station and a power grid simulation module; therefore, the dynamic reactive power compensation device control strategy verification system is built, and the off-line control strategy verification can be carried out on reactive power compensation device controllers of different models and different manufacturers.
The dynamic reactive power compensation device has various control strategies, and when the dynamic reactive power compensation device is verified through the control strategy verification system, the verification method and the verification steps are similar, and the specific verification steps are as follows.
(1) Setting a control mode of the dynamic reactive power compensation device. Such as a voltage control mode, a reactive power control mode, a power factor control mode, etc.;
(2) And correspondingly determining different control target points according to different selected control modes and different control targets. If the voltage or reactive power of the new energy power station grid-connected point is used as a control target, or the voltage of the dynamic reactive power compensation device grid-connected point is used as a control target;
(3) The control strategy verification system simulates the operation/fault states of various new energy power stations, achieves the aim of verifying the control strategy of the dynamic reactive compensation device controller, and has the following main working conditions to be verified:
a. simulating active output change of the new energy power station to cause voltage fluctuation of grid-connected points;
b. simulating external power grid changes by adjusting related grid-related parameters;
c. according to the related standard requirements, the dynamic reactive power compensation device is respectively operated in a light load state and a full load state, and the conditions that the grid voltage drops, rises or drops first and then rises are simulated (for example, the grid voltage drops to 0.2p.u., the duration is 625ms, and then the grid voltage rises to 1.3p.u., the duration is 500 ms);
d. simulating abnormal states such as abnormal bus voltage of the new energy power station, abnormal regulation instruction of the dynamic reactive power compensation device, abrupt communication interruption and the like;
e. the short-circuit capacity of the grid-connected point of the new energy power station is adjusted to be 1.0, 0.5 and 1.5 respectively, and the test working conditions required to be repeated in a-d are selected according to the related standard requirements;
(4) And recording voltage and current of the grid-connected point of the dynamic reactive power compensation device, voltage and current of the grid-connected point of the new energy power station/dynamic reactive power compensation device and response characteristic parameters (if the controller is blocked) of the controller in an abnormal state, and calculating relevant data such as voltage, reactive power, active power, power factor, reactive current response time, reactive current regulation proportion coefficient and the like of the controller to be used as a basis for judging the control performance of the controller of the dynamic reactive power compensation device.
(5) The test content mentioned above is only a general working condition, and the control strategy verification system can increase other working conditions according to standard requirements or actual working requirements, so that the purpose of verifying other new control strategies in the future is realized.
The following describes the implementation steps in detail, taking verification of a voltage control strategy, a reactive control strategy, a voltage reactive comprehensive control strategy (power factor), a fault ride-through control strategy and an abnormal locking control strategy of the dynamic reactive compensation device controller as examples.
(1) Voltage control strategy verification step:
a) Setting the dynamic reactive power compensation device as a constant voltage control strategy, and setting the grid-connected point short-circuit capacity of the dynamic reactive power compensation device as a reference short-circuit capacity. Setting a target voltage value V by taking the voltage of a grid-connected point of a new energy power station as a control target g The method comprises the steps that (given by a new energy power station and a power grid simulation module), fluctuation of the voltage of the grid-connected point of the new energy power station caused by fluctuation of the active power output of the grid-connected point of the new energy power station is simulated, and reactive power output value of a dynamic reactive power compensation device and voltage value of the grid-connected point of the new energy power station under fluctuation of the active power output of the grid-connected point of the new energy power station are recorded;
b) Setting a dynamic reactive power compensation device as a constant voltage control strategy, setting different control target voltage values V by taking the grid-connected point voltage of a new energy power station as a control target t Recording a grid-connected point voltage control dead zone and a reactive power output dead zone value of a dynamic reactive power compensation device under different voltage target values;
c) Setting a control mode of the dynamic reactive power compensation device as voltage curve control, taking the voltage of a grid-connected point of a new energy power station as a control target, and setting a control interval as a steady-state voltage limit value interval [ V ] d- ～V d+ ]Simulating the fluctuation of the grid-connected active output of the new energy power station to cause the fluctuation of the grid-connected voltage, and recording the reactive power output value and the grid-connected voltage value of the dynamic reactive power compensation device under the fluctuation of the grid-connected active output of the new energy power station;
d) Maintaining voltage target value V of grid-connected point of new energy power station g The voltage values of grid-connected points of a given new energy power station are respectively in [ V ] d- ～V l ]
And [ V d+ ～V h ]In the interval, recording the corresponding nothing of the dynamic reactive power compensation device of the new energy power station under different grid-connected point voltage set valuesCalculating a dynamic voltage regulation proportionality coefficient of the dynamic reactive power compensation device according to the power output value, and drawing a characteristic curve;
e) And (3) adjusting the short-circuit capacity of the grid-connected point of the new energy power station to be 0.5 times and 1.5 times of the reference capacity, and repeating the test steps of a) to d). The voltage/reactive power control interval of the dynamic reactive power compensation device is schematically shown in fig. 2, and the verification flow of the voltage control strategy is schematically shown in fig. 4.
(2) The reactive power control strategy verification method comprises the following steps:
a) Taking the reactive power of the grid-connected point as a control target, and gradually increasing (or decreasing) the target reactive power according to a preset step length until the reactive current output by the dynamic reactive compensation device reaches the capacitive (or inductive) rated value;
b) Keeping a reactive power target value of a grid-connected point of the device, and recording a reactive power dead zone of the dynamic reactive power compensation device and a grid-connected point active and reactive power curve when the active power of the wind power plant fluctuates;
c) Taking the reactive power of the connecting point as a control target, gradually increasing (or reducing) the target reactive power according to a preset step length until the reactive current output by the dynamic reactive compensation device reaches the capacitive (or inductive) rated value, and recording the reactive power control dead zone delta Q and the voltage of the connecting point;
d) The grid connection point of the new energy power station and the grid connection point position of the dynamic reactive power compensation device are shown in fig. 3, and the reactive power control strategy verification flow is shown in fig. 5.
(3) The voltage reactive comprehensive control strategy verification method comprises the following steps:
a) Setting different target power factor values by taking the power factor of the grid-connected point of the new energy power station as a control target, simulating the active output fluctuation of the new energy power station, recording the power factor of the grid-connected point, the active power of the grid-connected point, the reactive power of the grid-connected point and the reactive power output value of the dynamic reactive compensation device of the new energy power station under the active power fluctuation when different power factor target values are recorded, and recording a constant power factor control dead zone;
b) Setting dynamic reactive power compensation device as grid-connected point voltage of new energy power station, in figure 2 [ V ] d- ～V d+ ]When the range is in the range, the minimum reactive exchange between the new energy power station and the power grid is controlThe method comprises the steps of simulating active output fluctuation of a new energy power station, and recording reactive power and reactive compensation dynamic reactive power output values of grid-connected points of the new energy power station under the active power fluctuation;
c) The voltage/reactive power control interval of the dynamic reactive power compensation device is shown in fig. 2, the grid-connected point of the new energy power station and the grid-connected point position of the dynamic reactive power compensation device are shown in fig. 3, and the verification flow of the voltage reactive power comprehensive control strategy is shown in fig. 6.
(4) Fault ride through control strategy verification method (taking voltage drop followed by rise as an example):
a) In the process of power grid faults, the grid-connected point voltage of the reactive power compensation device is controlled to rise in a two-phase and three-phase manner by taking the grid-connected point voltage of the dynamic reactive power compensation device as a control target, and the grid-connected point voltage of the dynamic reactive power compensation device and three-phase fall are respectively controlled to have the amplitude of 0.9p.u. -0.02p.u., 0.50 p.u.+ -. 0.02p.u., 0.20 p.u.+ -. 0.02p.u., 1.10p.u.+0.02 p.u.+ -. 1.20 p.u.+ -. 0.02 p.u.+ -. 0.02p.u., 1.20 p.u.+ -. 0.02 p.u.+ -. 0.30 p.u.+ -. 0.02p.u.+ -. And the reactive power response time of the reactive power compensation device before the power grid faults occur, and the transient state current response curves and the reactive state current response time of the reactive power compensation device are drawn. The voltage drop and rise indicators are shown in table 1.
b) The grid connection point of the new energy power station and the grid connection point position of the dynamic reactive power compensation device are shown in fig. 3, and the verification flow of the voltage reactive power comprehensive control strategy is shown in fig. 7.
TABLE 1 Voltage sag and rise
(5) The abnormal locking strategy verification method comprises the following steps:
simulating conditions such as abnormal bus voltage of a new energy power station, abnormal device regulation instruction, communication interruption and the like, and recording response characteristics of a dynamic reactive power compensation device controller when the abnormality occurs. The abnormal latching control strategy verification flow is shown in fig. 8.
After the control strategy is verified, whether the dynamic reactive power compensation device controller meets the requirements or not can be evaluated by referring to the following indexes:
a. within the steady-state voltage limit interval, the voltage control deviation should be less than + -0.1%;
b. reactive power control strategy: the overshoot rate is less than 2% during step output, and the steady-state control deviation is better than 1%;
c. voltage reactive comprehensive control strategy: under the condition of qualified voltage, the power factor meets the requirements of a local dispatching mechanism;
d. failure traditional control strategy: the reactive current regulation coefficient of the fault phase is greater than 1.5;
e. abnormal locking: when the strategy electric quantity is abnormal, reactive locking is output and alarming is carried out; when the adjusting instruction or the step size is over the limit, the method is not executed; and locking reactive power output and alarming when communication is abnormal.
By the control strategy verification system provided by the invention, the voltage control strategy, reactive power voltage comprehensive control strategy, fault ride-through control strategy and abnormal locking strategy of the dynamic reactive power compensation device required by relevant standards are verified or optimized, so that economic and time cost caused by on-site test delay/delay or technical transformation due to the loss of the control strategy of the dynamic reactive power compensation device is reduced; the difference of the setting values of the parameters of the controller of the dynamic reactive compensation device caused by different technical capacities of field debugging personnel and other factors is eliminated, and the dynamic reactive compensation device is not limited by field conditions; only the controller of the dynamic reactive power compensation device is required to be sent to a laboratory for verification/optimization, and the field test is not required, so that a large amount of manpower and material resources are saved; by using the control strategy verification system, not only the performance of the dynamic reactive power compensation device controller can be verified, but also the parameter optimization can be performed on the dynamic reactive power compensation device controller, and the optimal control parameter setting is finally realized through test-optimization-test-optimization … …; the control strategy verification method of the dynamic reactive power compensation device is simple and feasible, is convenient to operate, and can comprehensively verify the effectiveness of different control strategies of the dynamic reactive power compensation device; the dynamic reactive power compensation device control strategy verification system has good expansion characteristics, and can meet the requirements of verification/parameter optimization of various other new control strategies of the dynamic reactive power compensation device in the future.
Only the preferred embodiments of the present invention have been described herein, but it is not intended to limit the scope, applicability, and configuration of the invention. Rather, the detailed description of the embodiments will enable those skilled in the art to practice the embodiments. It will be understood that various changes and modifications may be made in the details without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (5)
1. A method for verifying a control strategy of a dynamic reactive power compensation device in an off-line manner comprises the following steps:
(1): building a dynamic reactive power compensation control strategy verification system;
(2): setting a control strategy of a dynamic reactive power compensation device;
(3): according to different selected control strategies, correspondingly determining different control targets;
(4): the control strategy verification system simulates the operation or fault states of various new energy power stations, so as to achieve the purpose of verifying the control strategy of the dynamic reactive power compensation device;
(5): recording voltage and current of a grid-connected point of the dynamic reactive power compensation device, voltage and current of a new energy power station or the grid-connected point of the dynamic reactive power compensation device and response characteristic parameters of a controller in an abnormal state, and calculating voltage, reactive power, active power, power factor, reactive current response time and reactive current regulation proportionality coefficient to be used as a basis for judging the control performance of the dynamic reactive power compensation device;
the dynamic reactive power compensation device control strategy is a voltage control strategy or a voltage reactive power comprehensive control strategy or a fault ride-through control strategy;
when the control strategy of the dynamic reactive power compensation device is a voltage control strategy, the verification steps are as follows:
(1) Setting a dynamic reactive power compensation device as a constant voltage control strategy, setting the grid-connected point short-circuit capacity of the dynamic reactive power compensation device as a reference short-circuit capacity, taking the grid-connected point voltage of the new energy power station as a control target, setting a control target voltage value Vg of the dynamic reactive power compensation device, simulating the fluctuation of the grid-connected point voltage of the new energy power station caused by the fluctuation of the grid-connected point active power output of the new energy power station, and recording the reactive power output value of the dynamic reactive power compensation device and the voltage value of the grid-connected point of the new energy power station under the fluctuation of the grid-connected point active power output of the new energy power station;
(2) Setting and target voltage value V g The different control target voltage value is V t Recording a grid-connected point voltage control dead zone and a reactive power output dead zone value of a dynamic reactive power compensation device under different voltage target values;
(3) Setting a control mode of the dynamic reactive power compensation device as voltage curve control, taking the voltage of a grid-connected point of a new energy power station as a control target, and setting a control interval as a steady-state voltage limit value interval [ V ] d- —V d+ ]Simulating the fluctuation of the grid-connected active output of the new energy power station to cause the fluctuation of the grid-connected voltage, and recording the reactive power output value and the grid-connected voltage value of the dynamic reactive power compensation device under the fluctuation of the grid-connected active output of the new energy power station;
(4) Maintaining voltage target value V of grid-connected point of new energy power station g The voltage values of grid-connected points of a given new energy power station are respectively in [ V ] d- —V l ]And [ V d+ —V h ]In the interval, recording reactive power output values corresponding to the dynamic reactive power compensation device of the new energy power station under different grid-connected point voltage set values, calculating dynamic voltage regulation proportion coefficients of the dynamic reactive power compensation device, and drawing a characteristic curve;
(5) Adjusting the short-circuit capacity of the grid-connected point of the new energy power station to be 0.5 times and 1.5 times of the reference capacity, and repeating the test steps (1) - (4);
when the control strategy of the dynamic reactive power compensation device is a voltage reactive power integrated control strategy, the verification steps are as follows:
a) Setting different target power factor values through a man-machine interaction interface by taking a power factor of a new energy power station grid connection point or a power factor of a new energy power station main transformer low-voltage side as a control target, simulating active output fluctuation of the new energy power station, recording power factors of the new energy power station grid connection point, active power of the grid connection point, reactive power of the grid connection point and reactive power output values of a dynamic reactive compensation device under the fluctuation of the active power and the different power factor target values, and recording a dead zone of power factor control;
b) Setting a dynamic reactive power compensation device control target point as the voltage of a new energy power station grid-connected point, and setting a steady-state voltage limit value interval [ V d- —V d+ ]When the reactive power exchange between the new energy power station and the power grid is minimum in the range, simulating the active output fluctuation of the new energy power station, and recording the reactive power of the grid-connected point of the new energy power station and the dynamic reactive power output value of the dynamic reactive power compensation device under the active power fluctuation; verifying power factor control capability;
when the control strategy of the dynamic reactive power compensation device is a fault ride-through control strategy, the verification steps are as follows:
(1) In the process of power grid faults, the grid-connected point voltage of the dynamic reactive power compensation device is used as a control target, and the device before the power grid faults respectively operates under the conditions of 0.2p.u. of inductive low-power output, 1.0p.u. of inductive high-power output, 0.2p.u. of capacitive low-power output and 1.0p.u. of capacitive high-power output, and the two-phase and three-phase drop of the grid-connected point voltage of the dynamic reactive power compensation device are successively increased through the control of the fault simulation device;
(2) Drawing a relation curve of grid-connected point voltage and reactive current of the dynamic reactive compensation device, recording transient reactive current regulation proportionality coefficient and transient reactive current response time, and verifying fault ride-through capability of the device in the process that voltage is firstly reduced and then increased.
2. The method of claim 1, the control strategy verification system comprising: the system comprises a main circuit simulation module, a new energy power station and power grid simulation module, an optical fiber conversion interface, a level conversion interface and a man-machine interaction interface, wherein the main circuit simulation module performs signal interaction with a dynamic reactive power compensation device controller executing a dynamic reactive power compensation device control strategy through the optical fiber conversion interface; and the new energy power station and the power grid simulation module interact signals with the dynamic reactive power compensation device controller through the level conversion interface.
3. The method of claim 1, the control objective being: the voltage or reactive power of the grid-connected point of the new energy power station is used as a control target or the voltage of the grid-connected point of the dynamic reactive power compensation device is used as a control target.
4. The method of claim 1, wherein the new energy power station operation or fault condition is one of the following conditions:
1) Simulating active output change of the new energy power station to cause voltage fluctuation of grid-connected points;
2) Simulating external power grid changes by adjusting related grid-related parameters;
3) According to the related standard requirements, the dynamic reactive power compensation device is respectively operated in a light load state and a full load state, and the conditions of falling, rising or falling before rising of different voltage grades of the power grid voltage are simulated;
4) Simulating abnormal bus voltage of the new energy power station, abnormal regulation instruction of the dynamic reactive power compensation device or abrupt interruption of communication;
5) And (3) adjusting the short-circuit capacity of the grid-connected point of the new energy power station to be 1.0 times, 0.5 times and 1.5 times of the reference capacity respectively, and selecting the test working condition which needs to be repeated in 1) -4).
5. The method of claim 1, wherein the dynamic reactive compensation device grid-tie point voltage is raised by a magnitude of 0.9p.u.+ -. 0.02p.u.+ -. 0.20 p.u.+ -. 0.02p.u., 1.10p.u.+0.02p.u., 1.20p.u.+ -. 0.02p.u.+ -. 1.30p.u.+ -. 0.02p.u.+ -. 0.30 p.u.+ -. 0.02 p.u..c.) respectively.
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