CN116432419A - New energy station equivalence method and system - Google Patents

New energy station equivalence method and system Download PDF

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Publication number
CN116432419A
CN116432419A CN202310263496.0A CN202310263496A CN116432419A CN 116432419 A CN116432419 A CN 116432419A CN 202310263496 A CN202310263496 A CN 202310263496A CN 116432419 A CN116432419 A CN 116432419A
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new energy
station
energy station
rotor
voltage
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孙华东
李佳豪
郭强
李文锋
王晖
艾东平
魏巍
贾媛
杨超
张健
马世俊
杨晓利
赵旭峰
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China Electric Power Research Institute Co Ltd CEPRI
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China Electric Power Research Institute Co Ltd CEPRI
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06Q—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
    • G06Q50/00—Systems or methods specially adapted for specific business sectors, e.g. utilities or tourism
    • G06Q50/06—Electricity, gas or water supply
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2113/00—Details relating to the application field
    • G06F2113/04—Power grid distribution networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy

Abstract

The invention discloses a new energy station equivalence method and a system with the new energy station equivalence method, wherein the new energy station equivalence method simultaneously constructs a new energy station equivalence model considering the size disturbance characteristic, can improve the power grid simulation efficiency, reflects the influence of the participation of the new energy station in the system frequency modulation and voltage regulation on the system characteristic, considers the size disturbance applicability of the model, and provides effective improvement for the stable operation of an electric power system.

Description

New energy station equivalence method and system
Technical Field
The invention relates to the field of power systems, in particular to a new energy station equivalence method and system.
Background
In recent years, photovoltaic wind power has been rapidly developed to construct a novel power system mainly composed of new energy. By the end of 2021, the installed ratio of new energy in China reaches 26.7%, part of provinces reaches 61.4%, and new energy power generation becomes a second most dominant power source next to thermal power. The new energy unit is heterogeneous with the traditional generator unit, the electric power system dominated by the traditional synchronous machine is gradually transited to the high-proportion new energy electric power system, and the system characteristics are greatly different from the dominant characteristics of the original synchronous machine. The method is characterized in that the system steady-state characteristic, the energy conversion characteristic, the control characteristic, the transient response characteristic and the like under fault disturbance are required to be subjected to relevant simulation and theoretical analysis, so that the safe and stable operation of the power system is ensured.
For a power system accessed by large-scale new energy, management should be performed by taking stations as units and an equivalent model should be built. Meanwhile, with the continuous improvement of new energy grid-connection standards, the new energy station has the frequency modulation and voltage regulation functions, and the basic requirement of providing auxiliary services for the power grid is becoming new energy grid-connection.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the invention provides a new energy station equivalent method with station-level control, which can improve the simulation efficiency of a power grid, reflect the influence of the participation of the new energy station in the frequency modulation and voltage regulation of the system on the system characteristics, and simultaneously give consideration to the size disturbance applicability of the model.
The invention also provides a B with the new energy station equivalent method with station level control.
According to a first aspect of the invention, the new energy station equivalence method is characterized by comprising the following steps:
based on the frequency modulation characteristics of the new energy station unit, calculating to obtain the relation of the frequency modulation quantity, the frequency modulation time and the real-time working condition;
performing voltage regulation margin calculation on a unit in the new energy station to obtain reactive power availability margin of the unit;
analyzing the internal running state of the new energy station, and analyzing the running state of the new energy station and the influence of the internal tide of the new energy station on the voltage of the grid-connected point of the new energy station;
analyzing the voltage regulation characteristic of the new energy station, monitoring the voltage of a new energy station bus in real time, and rapidly regulating the voltage through a controller;
an equivalence strategy of a new energy station equivalence model is constructed based on the influence of power distribution, and a station-level control strategy of the equivalence model is considered;
the station-level active controller is equivalent to the station-level reactive controller;
and constructing a new energy station equivalent model with station-level control.
The new energy station equivalence method provided by the embodiment of the invention has at least the following beneficial effects: the method simultaneously builds the new energy station equivalent model considering the size disturbance characteristic, can improve the power grid simulation efficiency, reflects the influence of the new energy station on the system characteristic caused by the participation of the system frequency modulation and voltage regulation, gives consideration to the size disturbance applicability of the model, and makes effective improvement for the stable operation of the power system.
According to some embodiments of the present invention, the step of calculating the relation between the frequency modulation amount, the frequency modulation time and the real-time working condition based on the frequency modulation characteristic of the new energy station unit includes two processes, which are respectively:
for rotor speed overspeed control and pitch angle control, when rotor speed overspeed and pitch angle control are adopted, the action time of the system frequency response characteristic is consistent, the adjustment quantity is consistent, the time of frequency reaching the lowest point is consistent, and the time of frequency recovery stabilization is consistent, namely under the control strategy, the total frequency modulation instructions provided by the new energy stations before and after equivalence are consistent, namely the frequency curve characteristics of the grid-connected points are consistent;
for rotor kinetic energy release, there are two processes, namely, rotor kinetic energy release provides energy and rotor rotational speed resumes energy absorption.
According to some embodiments of the invention, the rotor kinetic energy release provides energy and the rotor rotational speed resumes the energy absorbing process, in particular:
in the process of releasing the kinetic energy of the rotor: the fan rotation speed is different, the stored energy is different, and under the same frequency modulation quantity, the frequency modulation time is different, so that the difference of equivalent front and rear system frequency response characteristic curves is caused;
in the process of recovering and absorbing energy by the rotating speed of the rotor: due to the influence of power distribution, the time for the new energy units under different working conditions to enter the rotor speed recovery stage is different, the time for absorbing power from the system is different, and the supporting power provided by the new energy station is gradually reduced.
According to some embodiments of the invention, in the step of calculating the voltage regulating margin of the unit in the new energy station and obtaining the reactive power availability margin of the unit, the reactive power margin of the new energy station is constrained by the real-time active power of the new energy unit and the maximum output capacity of the stator-rotor side converter of the new energy unit; and for the voltage regulation of the new energy participation system, the available reactive margin of the new energy unit part of the whole new energy station needs to be evaluated.
According to some embodiments of the invention, the new energy unit is fed into the new energy station and is sent out after being connected with the grid through the current collecting circuit.
According to some embodiments of the invention, in the process of analyzing the voltage regulation characteristics of the new energy station, the voltage of the grid-connected point bus of the new energy station is monitored in real time, and when the voltage of the grid-connected point bus is suddenly changed or is beyond the limit, the new energy station-level reactive power controller is used for adjusting the output reactive power of the new energy unit or the coordination between the new energy unit and the output reactive power of the reactive power compensation device so as to realize the rapid regulation of the voltage/reactive power and ensure that the voltage deviation of the grid-connected point bus is within an allowable range.
According to a second aspect of the present invention, a new energy station equivalence system is provided, which is characterized by comprising: the frequency modulation characteristic analysis module can calculate and obtain the relation of the frequency modulation quantity, the frequency modulation time and the real-time working condition based on the frequency modulation characteristic of the new energy station unit;
the voltage regulating margin calculation module can calculate the voltage regulating margin of the unit in the new energy station to obtain the reactive margin of the unit;
the running state analysis module is capable of analyzing the running state of the inside of the new energy station and analyzing the influence of the current in the new energy station on the voltage of the grid-connected point of the new energy station;
the voltage regulation characteristic analysis module can analyze the voltage regulation characteristic of the new energy station, monitor the voltage of the new energy station bus in real time and rapidly regulate the voltage through the controller;
the equivalent strategy simulation module can integrate the equivalent strategy of the equivalent model of the new energy station, construct the equivalent model based on the influence of power distribution, and consider the station-level control strategy of the equivalent model;
the controller equivalent module can perform station-level active controller equivalent and station-level reactive controller equivalent;
the equivalent model construction module can be used for constructing the equivalent model of the new energy station with station-level control.
Further, the frequency modulation characteristic analysis module includes:
the overspeed control element is used for controlling the overspeed of the rotor speed and the pitch angle, when the overspeed of the rotor and the pitch angle are adopted, the action time of the system frequency response characteristic is consistent, the adjustment amount is consistent, the time of the frequency reaching the lowest point is consistent, and the time of the frequency recovery stability is consistent, namely under the control strategy, the total frequency modulation instructions provided by the new energy stations before and after the equivalent are consistent, so that the frequency curve characteristics of the grid-connected points are consistent;
the kinetic energy release control element has two processes for rotor kinetic energy release, namely, a process of providing energy for rotor kinetic energy release and a process of recovering and absorbing energy by rotor rotation speed.
Further, the process of recovering and absorbing energy by releasing the kinetic energy of the rotor and recovering the rotating speed of the rotor is specifically as follows:
in the process of releasing the kinetic energy of the rotor: the fan rotation speed is different, the stored energy is different, and under the same frequency modulation quantity, the frequency modulation time is different, so that the difference of equivalent front and rear system frequency response characteristic curves is caused;
in the process of recovering and absorbing energy by the rotating speed of the rotor: due to the influence of power distribution, the time for the new energy units under different working conditions to enter the rotor speed recovery stage is different, the time for absorbing power from the system is different, and the supporting power provided by the new energy station is gradually reduced.
Further, in the voltage regulating margin calculation module, the reactive margin of the new energy station is constrained by the real-time active power of the new energy unit and the maximum output capacity of the current transformer at the stator side and the rotor side of the new energy unit; and for the voltage regulation of the new energy participation system, the available reactive margin of the new energy unit part of the whole new energy station needs to be evaluated.
Further, the new energy unit is fed into the new energy station through the current collecting circuit and then sent out after being connected with the network.
Further, the voltage regulation characteristic analysis module monitors the voltage of the grid-connected point bus of the new energy station in real time, and when the voltage of the grid-connected point bus is suddenly changed or is beyond the limit, the new energy station reactive power controller adjusts the output reactive power of the new energy unit or the coordination between the new energy unit and the output reactive power of the reactive power compensation device so as to realize the rapid regulation of the voltage/reactive power, and ensure that the voltage deviation of the grid-connected point bus is within an allowable range.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic diagram of steps of a new energy station equivalence method according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a detailed model, an equivalent model, and a relationship between rotor speed and time modulation according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a typical wind farm topology provided by an embodiment of the present invention;
FIG. 4 is a station level active control block diagram provided by an embodiment of the present invention;
fig. 5 is a station-level reactive power control block diagram provided by an embodiment of the present invention;
FIG. 6 is a schematic diagram of an equivalent structure of a new energy station according to an embodiment of the present invention;
fig. 7 is a block diagram of a new energy station equivalence system according to an embodiment of the present invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.
For a power system accessed by large-scale new energy, management should be performed by taking stations as units and an equivalent model should be built. Meanwhile, with the continuous improvement of new energy grid-connection standards, the new energy station has the frequency modulation and voltage regulation functions, and the basic requirement of providing auxiliary services for the power grid is becoming new energy grid-connection.
In order to solve the defects of the prior art, the application aims to provide a new energy station equivalent strategy with station-level control and a new energy station equivalent model considering the size disturbance characteristics, which can improve the power grid simulation efficiency, reflect the influence of the participation of the new energy station in the system frequency modulation and voltage regulation on the system characteristics, and simultaneously give consideration to the size disturbance applicability of the model.
As shown in fig. 1, the present application provides a new energy station equivalence method, which includes the following steps:
and step S100, calculating the relation among the frequency modulation quantity, the frequency modulation time and the real-time working condition based on the frequency modulation characteristic of the new energy station unit.
And step 200, calculating the voltage regulating margin of the unit in the new energy station, and obtaining the reactive power availability margin of the unit.
And step S300, analyzing the internal operation state of the new energy station, and analyzing the operation state of the new energy station and the influence of the internal tide of the new energy station on the voltage of the grid-connected point of the new energy station.
And step 400, analyzing the voltage regulation characteristics of the new energy station, monitoring the voltage of the new energy station bus in real time, and rapidly regulating the voltage through a controller.
And S500, constructing an equivalent model based on the influence of power distribution by using an equivalent strategy of the equivalent model of the new energy station, and considering a station-level control strategy of the equivalent model.
Step S600, station-level active controller equivalent and station-level reactive controller equivalent.
And S700, constructing a new energy station equivalent model with station-level control.
For purposes of describing the teachings of the present application in more detail, the foregoing steps are now described in detail.
The application provides a new energy station equivalence method, which comprises the following steps:
and step S100, calculating the relation among the frequency modulation quantity, the frequency modulation time and the real-time working condition based on the frequency modulation characteristic of the new energy station unit.
Taking a doubly-fed fan as an example, analyzing the relation among the frequency modulation quantity, the frequency modulation time and the real-time working condition. The motion equation of the rotor of the fan is as follows:
Figure BDA0004132224500000061
where np is the pole pair number, wr is the rotor speed, J is the fan moment of inertia, TL is the fan mechanical torque, and Te is the fan electromagnetic torque.
The relation between the rotating speed of the fan and the output power can be obtained after per unit:
Figure BDA0004132224500000062
wherein H is the inertial time constant of the fan rotor, pm is the mechanical power of the fan, and Pe is the electromagnetic power of the fan.
Further, with respect to rotor speed overspeed control, pitch angle control, it is possible to:
Figure BDA0004132224500000071
Figure BDA0004132224500000072
wherein Δpm is the fan mechanical power increment, Δpe is the fan electromagnetic power increment, Δpm is the wind farm total frequency modulation increment in detail, Δpm1, Δpm2, …, Δpmn is the wind farm internal fan frequency modulation increment, Δpmequi is the equivalent model frequency modulation increment.
When the rotor speed is overspeed and the pitch angle is adopted for control, the action time, the adjustment quantity and the frequency reaching the lowest point of the system frequency response characteristic are consistent, and the frequency recovery stabilization time is also consistent.
Further, for rotor kinetic energy release, there are two processes, namely, rotor kinetic energy release provides energy and rotor rotational speed resumes energy absorption. For the rotor kinetic energy release process:
Figure BDA0004132224500000073
P m *t+△P m1 *t 1 +△P m2 *t 2 +…△P mn *t n -(P e +△P e )*t＝∫2H*(w r dw r ) (5)
wherein t1, t2, t3, … and tn are frequency modulation time of fans inside the wind farm respectively.
Namely, the fan rotation speed is different, the reserved energy is different, and the frequency modulation time is different under the condition of the same frequency modulation quantity. Resulting in a difference in the frequency response curves of the system before and after the equivalence.
Referring to FIG. 2, the response of the concave function curve results in a rotor kinetic energy release process, with less energy provided by the equivalent model and more conservative results.
Recovering the energy absorption process for the rotor rotation speed:
the detailed model is influenced by power distribution, the time of the new energy units under different working conditions entering the rotor rotating speed recovery stage is different, the time of absorbing power from the system is different, and the supporting power provided by the new energy station is gradually reduced. For the equivalent model, the response characteristic of the convex function curve results in a rotor rotating speed recovery stage, the time for the equivalent model to enter the recovery stage is longer, the frequency response characteristic of the system is more optimistic, and the frequency response curve of the system is more relevant and practical as the number of units increases.
And step 200, calculating the voltage regulating margin of the unit in the new energy station, and obtaining the reactive power availability margin of the unit.
And taking the doubly-fed wind turbine as an example to analyze the reactive power availability margin of the wind turbine. For a doubly-fed wind turbine, the reactive power output by the stator side is limited by the stator side current, the rotor side current and the real-time output power of the doubly-fed wind turbine.
I.e. for doubly fed, the reactive margin available is:
Figure BDA0004132224500000081
Figure BDA0004132224500000082
in the method, in the process of the invention,
Figure BDA0004132224500000083
for the voltage of the stator side under the dq coordinate system of the doubly-fed fan, ismax is the maximum current value allowed by the stator side of the doubly-fed fan, irmax is the maximum current value allowed by the rotor side of the doubly-fed fan, pes is the power of the stator side, xm and Xss are distributed to be excitation reactance and stator reactance, and Qsmin and Qsmax are the minimum and maximum values of reactive power availability margin respectively.
The active margin of the new energy station is related to the real-time active power of each new energy unit. Reactive margin of the new energy station is constrained by real-time active power of the new energy unit and maximum output capacity of the current transformer on the stator side and the rotor side of the new energy unit. And for the voltage regulation of the new energy participation system, the available reactive margin of the new energy unit part of the whole new energy station needs to be evaluated.
And step S300, analyzing the internal operation state of the new energy station, and analyzing the operation state of the new energy station and the influence of the internal tide of the new energy station on the voltage of the grid-connected point of the new energy station.
For the new energy station, because the capacity of the internal unit of the new energy station is smaller, the new energy station generally consists of a plurality of new energy units, and the new energy units are fed into the new energy station through the current collecting circuit and are sent out after being connected in parallel. Taking a wind power plant as an example, analyzing the running state of the new energy station and the influence of the internal tide of the new energy station on the voltage of the grid-connected point of the new energy station.
The topology of a typical wind power plant is shown in fig. 3, wherein the wind power plant comprises m feeder lines, and n rows of wind turbines are connected in series on each feeder line. Each wind turbine generator is boosted by a 0.69/35kV box-type transformer and then connected with a collector bus, the collector bus is collected to a grid-connected point of a wind farm, and the wind turbine generator is boosted by a 35/220kV boosting transformerAnd conveying the pressed product to a system. Wherein Wt is ij Wind turbine generator system of jth column on ith feeder line, T ij Box-type transformer Z corresponding to wind turbine generator set in jth column on ith feeder line ij And the current collecting line impedance between the wind turbine generator in the j th row and the wind turbine generator in the j+1 th row on the i th feeder line is represented.
Taking the grid voltage U as a reference, the wind farm grid-connected point voltage can be expressed as:
wherein U is PCC For wind farm grid-connected point voltage, P ij Active power Q for the j-th wind turbine generator system on the i-th feeder line ij And (5) reactive power generated by the j-th wind turbine generator on the i-th feeder line. R is R L 、X L The resistance and the reactance of the line between the power grid and the new energy station grid connection point are respectively. Δp and Δq are total losses inside the wind farm.
And step 400, analyzing the voltage regulation characteristics of the new energy station, monitoring the voltage of the new energy station bus in real time, and rapidly regulating the voltage through a controller.
For participation of the new energy station in voltage regulation, the voltage of the grid-connected point bus of the new energy station is monitored in real time, and when the voltage of the grid-connected point bus is suddenly changed or is beyond limit, the new energy station-level reactive power controller is used for adjusting the output reactive power of the new energy unit or the coordination between the new energy unit and the output reactive power of the reactive power compensation device so as to realize the rapid regulation of the voltage/reactive power and ensure that the voltage deviation of the grid-connected point bus is within an allowable range. The voltage change amplitude of the grid-connected point of the new energy station is closely related to the output reactive power and the short-circuit capacity of the system.
Wherein S is c Short circuit capacity for the system.
For a new energy station, the following relationship exists between the short-circuit ratio and the short-circuit capacity of the system:
Figure BDA0004132224500000093
wherein S is e And X is the per unit value of the system impedance for the rated capacity of the new energy station.
For the rapid voltage control of the new energy station, when the busbar voltage of the grid-connected point is suddenly changed or out of limit, the method can be as follows:
Figure BDA0004132224500000094
therefore, the reactive value to be compensated is:
Figure BDA0004132224500000101
the method is available, and for the rapid voltage control of the new energy station, when the total reactive power output by the new energy station is consistent, the voltage adjustment capability of the new energy station to the grid connection point is consistent. The equivalent impedance of the system is consistent before and after the equivalent of the new energy station, and the reactive power total instruction output during the rapid voltage control is consistent. For the rapid voltage control, the equivalent impedance of the system before and after the equivalent of the new energy station is consistent with the total reactive power instruction output by the system, so that the voltage characteristics of the system before and after the equivalent are consistent with the response characteristics of the grid-connected point.
And S500, constructing an equivalent model based on the influence of power distribution by using an equivalent strategy of the equivalent model of the new energy station, and considering a station-level control strategy of the equivalent model.
For the internal frequency modulation characteristic of the new energy station, the frequency response characteristic of the grid-connected point of the new energy station is different according to the difference of the frequency modulation energy provided by the new energy unit. For rotor overspeed control and pitch angle control, the starting response time is consistent with the frequency modulation time, namely the total frequency modulation instruction is consistent before and after the equivalence, so that the frequency response characteristics are consistent before and after the equivalence; for rotor kinetic energy release control release, the rotor rotating speed recovery stage takes the dominant role of the frequency response characteristic of the system, in the frequency modulation process, due to the difference of working conditions of wind turbine generators, different units exit from frequency modulation, namely, the power absorption time from the system is different, and due to the convex function characteristic of the rotor rotating speed recovery stage curve, after equivalence is caused, the system equivalent frequency modulation output is larger than the system actual frequency modulation output, so that the frequency response characteristic curve of an equivalent model grid-connected point is higher than the lowest point of the actual frequency modulation response characteristic curve, and meanwhile, the transient stability evaluation result of the system is optimistic. That is, for the station-level active control, in order to reduce the difference in frequency response characteristics of the grid-tie points, a multi-machine model that takes into consideration the power distribution may be employed.
For the reactive power control mode of the new energy station level, the reactive power control mode can be mainly divided into a fixed power control mode and a fixed voltage control mode. For a fixed power control mode, the analysis can be used for ensuring that the total power instruction of the station-level reactive power control is consistent by evaluating the total reactive power availability margin of the system, namely, the voltage response characteristics of the grid-connected points are consistent; for constant voltage control, the system short-circuit ratio is consistent, namely the voltage response characteristics of grid-connected points can be consistent. For the station equivalent model, the station reactive power control strategy can be determined according to the grouping of the station active power control strategy, and the reactive power instruction before and after the station reactive power control equivalent is ensured to be consistent with the system short-circuit ratio.
For voltage disturbance, the new energy station level control only responds to small voltage disturbance, the new energy station level control does not act during large voltage disturbance, and the new energy unit responds to fault characteristics according to self-high and low-pass characteristics; for frequency disturbance, the new energy station level control has an effect on the frequency disturbance. To sum up, in order to ensure the consistency of the equivalent model to the frequency size disturbance and the voltage size disturbance, the equivalent model is constructed by only considering the influence of the power distribution, and the station-level control strategy of the equivalent model is considered.
Step S600, station-level active controller equivalent and station-level reactive controller equivalent.
Typical active control strategies at the new energy station level can be divided into the following, namely, active control, open loop frequency control and closed loop frequency control, as shown in fig. 4:
Figure BDA0004132224500000111
Figure BDA0004132224500000112
wherein P is ord Active command value, P of new energy station ord_eqi Is the equivalent machine active instruction value, P plant For the active power output of the new energy station, f req For the frequency of grid-connected points of new energy stations, f req_ref For controlling frequency reference value at station level, P plant_ref And k is an active frequency droop coefficient, and is an active output reference value of the new energy station.
Typical reactive power control strategies at the new energy station level can be divided into the following types, namely, fixed reactive power control, fixed power factor control, fixed voltage control and reactive voltage sag control, as shown in fig. 5:
Figure BDA0004132224500000121
Figure BDA0004132224500000122
wherein Q is ord Reactive power instruction value, Q of new energy station ord_eqi Is equivalent to the reactive power instruction value of the machine, V reg Voltage of grid-connected point of new energy station, Q plant Reactive power output for new energy station, PF poi_ref Giving power factors to new energy stations, Q plant_ref Reactive power output is given to a new energy station, V reg_ref And the voltage reference value is the voltage reference value of the grid-connected point of the new energy station.
And S700, constructing a new energy station equivalent model with station-level control.
The new energy station level model comprises equivalent new energy units and auxiliary equipment such as SVG/SVC, series compensation capacitors and the like for the new energy station configuration. For the new energy station equivalent model, a 1-2 machine equivalent model is constructed by considering the influence of power distribution, and the station level control part is perfected, and the model structure is shown in figure 6.
Yet another embodiment of the present application provides a new energy station equivalence system, as shown in fig. 7, the apparatus 70 includes: the system comprises a frequency modulation characteristic analysis module 701, a voltage regulation margin calculation module 702, an operation state analysis module 703, a voltage regulation characteristic analysis module 704, an equivalent strategy simulation module 705, a controller equivalent module 706 and an equivalent model construction module 707.
The frequency modulation characteristic analysis module 701 can calculate and obtain the relation of the frequency modulation quantity, the frequency modulation time and the real-time working condition based on the frequency modulation characteristic of the new energy station unit;
the voltage regulating margin calculation module 702 can calculate the voltage regulating margin of the unit in the new energy station to obtain the reactive power availability margin of the unit;
the running state analysis module 703 is capable of analyzing the running state of the new energy station and the influence of the internal tide of the new energy station on the voltage of the grid-connected point of the new energy station;
the voltage regulation characteristic analysis module 704 is capable of analyzing the voltage regulation characteristic of the new energy station, monitoring the voltage of the new energy station bus in real time and rapidly regulating the voltage through the controller;
the equivalent strategy simulation module 705 can integrate the equivalent strategy of the equivalent model of the new energy station, construct the equivalent model based on the influence of power distribution, and consider the station-level control strategy of the equivalent model;
the controller equivalent module 706 is capable of performing station-level active controller equivalent and station-level reactive controller equivalent;
the equivalent model construction module 707 can perform new energy station equivalent model construction with station level control.
The embodiment of the application provides a new energy station equivalent system which has station-level control characteristics, improves the simulation efficiency of a power grid, gives consideration to the size disturbance applicability of a model, and brings effective improvement to the stable operation of a power system.
Further, the frequency modulation characteristic analysis module 701 includes:
the overspeed control element is used for controlling the overspeed of the rotor speed and the pitch angle, when the overspeed of the rotor and the pitch angle are adopted, the action time of the system frequency response characteristic is consistent, the adjustment amount is consistent, the time of the frequency reaching the lowest point is consistent, and the time of the frequency recovery stability is consistent, namely under the control strategy, the total frequency modulation instructions provided by the new energy stations before and after the equivalent are consistent, so that the frequency curve characteristics of the grid-connected points are consistent;
the kinetic energy release control element has two processes for rotor kinetic energy release, namely, a process of providing energy for rotor kinetic energy release and a process of recovering and absorbing energy by rotor rotation speed.
Further, the process of recovering and absorbing energy by releasing the kinetic energy of the rotor and recovering the rotating speed of the rotor is specifically as follows:
in the process of releasing the kinetic energy of the rotor: the fan rotation speed is different, the stored energy is different, and under the same frequency modulation quantity, the frequency modulation time is different, so that the difference of equivalent front and rear system frequency response characteristic curves is caused;
in the process of recovering and absorbing energy by the rotating speed of the rotor: due to the influence of power distribution, the time for the new energy units under different working conditions to enter the rotor speed recovery stage is different, the time for absorbing power from the system is different, and the supporting power provided by the new energy station is gradually reduced.
Further, in the voltage regulating margin calculating module 702, the reactive margin of the new energy station is constrained by the real-time active power of the new energy unit and the maximum output capacity of the current transformer on the stator side and the rotor side of the new energy unit; and for the voltage regulation of the new energy participation system, the available reactive margin of the new energy unit part of the whole new energy station needs to be evaluated.
Further, the new energy unit is fed into the new energy station through the current collecting circuit and then sent out after being connected with the network.
Further, the voltage regulation characteristic analysis module 704 monitors the voltage of the grid-connected point bus of the new energy station in real time, and when the voltage of the grid-connected point bus is suddenly changed or is beyond the limit, the new energy station reactive power controller adjusts the output reactive power of the new energy unit or the coordination between the new energy unit and the output reactive power of the reactive power compensation device so as to realize the rapid regulation of the voltage/reactive power, and ensure that the voltage deviation of the grid-connected point bus is within an allowable range.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of one of ordinary skill in the art without departing from the spirit of the present invention.

Claims (10)

1. The new energy station equivalence method is characterized by comprising the following steps:
based on the frequency modulation characteristics of the new energy station unit, calculating to obtain the relation of the frequency modulation quantity, the frequency modulation time and the real-time working condition;
performing voltage regulation margin calculation on a unit in the new energy station to obtain reactive power availability margin of the unit;
analyzing the internal running state of the new energy station, and analyzing the running state of the new energy station and the influence of the internal tide of the new energy station on the voltage of the grid-connected point of the new energy station;
analyzing the voltage regulation characteristic of the new energy station, monitoring the voltage of a new energy station bus in real time, and rapidly regulating the voltage through a controller;
an equivalence strategy of a new energy station equivalence model is constructed based on the influence of power distribution, and a station-level control strategy of the equivalence model is considered;
the station-level active controller is equivalent to the station-level reactive controller;
and constructing a new energy station equivalent model with station-level control.
2. The method of claim 1, wherein the step of calculating the relationship between the frequency modulation amount, the frequency modulation time and the real-time working condition based on the frequency modulation characteristic of the new energy station unit comprises two processes, namely:
for rotor speed overspeed control and pitch angle control, when rotor speed overspeed and pitch angle control are adopted, the action time of the system frequency response characteristic is consistent, the adjustment quantity is consistent, the time of frequency reaching the lowest point is consistent, and the time of frequency recovery stabilization is consistent, namely under the control strategy, the total frequency modulation instructions provided by the new energy stations before and after equivalence are consistent, namely the frequency curve characteristics of the grid-connected points are consistent;
for rotor kinetic energy release, there are two processes, namely, rotor kinetic energy release provides energy and rotor rotational speed resumes energy absorption.
3. The method according to claim 2, characterized in that the rotor kinetic energy release provides energy and rotor speed resumes the energy absorption process, in particular:
in the process of releasing the kinetic energy of the rotor: the fan rotation speed is different, the stored energy is different, and under the same frequency modulation quantity, the frequency modulation time is different, so that the difference of equivalent front and rear system frequency response characteristic curves is caused;
in the process of recovering and absorbing energy by the rotating speed of the rotor: due to the influence of power distribution, the time for the new energy units under different working conditions to enter the rotor speed recovery stage is different, the time for absorbing power from the system is different, and the supporting power provided by the new energy station is gradually reduced.
4. The method according to claim 1, wherein in the step of calculating a voltage regulating margin for a unit in the new energy station and obtaining a reactive power availability margin for the unit, the reactive power margin for the new energy station is constrained by real-time active power of the new energy unit and maximum output capacity of a stator-rotor side converter of the new energy unit; and for the voltage regulation of the new energy participation system, the available reactive margin of the new energy unit part of the whole new energy station needs to be evaluated.
5. The method of claim 1, wherein the new energy unit is fed into the new energy station grid-connected point via a collector line and then sent out.
6. The method according to claim 1, wherein in the process of analyzing the voltage regulation characteristics of the new energy station, the voltage/reactive power is quickly regulated by monitoring the voltage of the grid-connected point bus of the new energy station in real time, and when the voltage of the grid-connected point bus is suddenly changed or is out of limit, the voltage deviation of the grid-connected point bus is ensured to be within an allowable range by regulating the output reactive power of the new energy unit or the coordination of the output reactive power of the reactive power compensation device through the new energy station reactive power controller.
7. A new energy station equivalence system, comprising:
the frequency modulation characteristic analysis module can calculate and obtain the relation of the frequency modulation quantity, the frequency modulation time and the real-time working condition based on the frequency modulation characteristic of the new energy station unit;
the voltage regulating margin calculation module can calculate the voltage regulating margin of the unit in the new energy station to obtain the reactive margin of the unit;
the running state analysis module is capable of analyzing the running state of the inside of the new energy station and analyzing the influence of the current in the new energy station on the voltage of the grid-connected point of the new energy station;
the voltage regulation characteristic analysis module can analyze the voltage regulation characteristic of the new energy station, monitor the voltage of the new energy station bus in real time and rapidly regulate the voltage through the controller;
the equivalent strategy simulation module can integrate the equivalent strategy of the equivalent model of the new energy station, construct the equivalent model based on the influence of power distribution, and consider the station-level control strategy of the equivalent model;
the controller equivalent module can perform station-level active controller equivalent and station-level reactive controller equivalent;
the equivalent model construction module can be used for constructing the equivalent model of the new energy station with station-level control.
8. The system of claim 7, wherein the frequency modulation characteristic analysis module comprises:
the overspeed control element is used for controlling the overspeed of the rotor speed and the pitch angle, when the overspeed of the rotor and the pitch angle are adopted, the action time of the system frequency response characteristic is consistent, the adjustment amount is consistent, the time of the frequency reaching the lowest point is consistent, and the time of the frequency recovery stability is consistent, namely under the control strategy, the total frequency modulation instructions provided by the new energy stations before and after the equivalent are consistent, so that the frequency curve characteristics of the grid-connected points are consistent;
the kinetic energy release control element has two processes for rotor kinetic energy release, namely, a process of providing energy for rotor kinetic energy release and a process of recovering and absorbing energy by rotor rotation speed.
9. The system according to claim 8, wherein the rotor kinetic energy release provides energy and rotor speed resumes the energy absorbing process, in particular:
in the process of releasing the kinetic energy of the rotor: the fan rotation speed is different, the stored energy is different, and under the same frequency modulation quantity, the frequency modulation time is different, so that the difference of equivalent front and rear system frequency response characteristic curves is caused;
in the process of recovering and absorbing energy by the rotating speed of the rotor: due to the influence of power distribution, the time for the new energy units under different working conditions to enter the rotor speed recovery stage is different, the time for absorbing power from the system is different, and the supporting power provided by the new energy station is gradually reduced.
10. The system according to claim 7, wherein the voltage regulation margin calculation module, the reactive margin of the new energy station is constrained by the real-time active power of the new energy unit, and the maximum output capacity of the current transformer on the stator and rotor sides of the new energy unit; and for the voltage regulation of the new energy participation system, the available reactive margin of the new energy unit part of the whole new energy station needs to be evaluated.
CN202310263496.0A 2023-03-10 2023-03-10 New energy station equivalence method and system Pending CN116432419A (en)

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