WO2022156183A1 - 一种抑制后续换相失败的储能暂态功率协调控制方法 - Google Patents

一种抑制后续换相失败的储能暂态功率协调控制方法 Download PDF

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WO2022156183A1
WO2022156183A1 PCT/CN2021/109753 CN2021109753W WO2022156183A1 WO 2022156183 A1 WO2022156183 A1 WO 2022156183A1 CN 2021109753 W CN2021109753 W CN 2021109753W WO 2022156183 A1 WO2022156183 A1 WO 2022156183A1
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Prior art keywords
energy storage
command
threshold
arc
current
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English (en)
French (fr)
Inventor
李程昊
姚伟
刘明洋
周泓宇
崔惟
文劲宇
周宁
饶宇飞
高泽
肖寒
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Huazhong University of Science and Technology
Electric Power Research Institute of State Grid Henan Electric Power Co Ltd
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Huazhong University of Science and Technology
Electric Power Research Institute of State Grid Henan Electric Power Co Ltd
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Priority to AU2021282558A priority Critical patent/AU2021282558B2/en
Priority to US17/622,247 priority patent/US11888315B2/en
Publication of WO2022156183A1 publication Critical patent/WO2022156183A1/zh
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; 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
    • H02J3/001—Arrangements for handling faults or abnormalities, e.g. emergencies or contingencies
    • H02J3/0012—Arrangements for handling faults or abnormalities, e.g. emergencies or contingencies characterised by the contingency detection means in AC networks, e.g. using phasor measurement units [PMU], synchrophasors or contingency analysis
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; 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
    • H02J3/36—Arrangements for transfer of electric power between AC networks via high-voltage DC [HVDC] links; Arrangements for transfer of electric power between generators and networks via HVDC links
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; 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
    • H02J3/001—Arrangements for handling faults or abnormalities, e.g. emergencies or contingencies
    • H02J3/00125—Transmission line or load transient problems, e.g. overvoltage, resonance or self-excitation of inductive loads
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; 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
    • H02J3/12—Arrangements for adjusting voltage in AC networks by changing a characteristic of the network load
    • H02J3/16—Arrangements for adjusting voltage in AC networks by changing a characteristic of the network load by adjustment of reactive power
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; 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
    • H02J3/28—Arrangements for balancing of the load in networks by storage of energy
    • H02J3/32—Arrangements for balancing of the load in networks by storage of energy using batteries or super capacitors with converting means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; 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 feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; 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 feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel
    • H02J3/46—Controlling the sharing of generated power between the generators, sources or networks
    • H02J3/466—Scheduling or selectively controlling the operation of the generators or sources, e.g. connecting or disconnecting generators to meet a demand
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2101/00—Supply or distribution of decentralised, dispersed or local electric power generation
    • H02J2101/20—Dispersed power generation using renewable energy sources
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2101/00—Supply or distribution of decentralised, dispersed or local electric power generation
    • H02J2101/40—Hybrid power plants, i.e. a plurality of different generation technologies being operated at one power plant
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2103/00—Details of circuit arrangements for mains or AC distribution networks
    • H02J2103/30—Simulating, planning, modelling, reliability check or computer assisted design [CAD] of electric power networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2103/00—Details of circuit arrangements for mains or AC distribution networks
    • H02J2103/30—Simulating, planning, modelling, reliability check or computer assisted design [CAD] of electric power networks
    • H02J2103/35—Grid-level management of power transmission or distribution systems, e.g. load flow analysis or active network management
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Definitions

  • the invention belongs to the technical field of multi-feed ultra-high voltage AC/DC hybrid power grids, and more particularly, relates to an energy storage transient power coordinated control method for suppressing subsequent commutation failures.
  • Commutation failure is one of the most common faults in HVDC transmission systems based on grid commutation converters. After the commutation failure occurs, the DC voltage drops rapidly and the DC current increases sharply, which has a serious impact on the system and even leads to interruption of transmission power. With the successive investment of high-voltage direct current transmission projects, the characteristics of “strong direct current weak alternating current and multiple direct current direct current centralized feeding” have become increasingly prominent in my country’s power grid, the support capacity of the receiving end power grid has decreased, and the fault of the alternating current system may induce multiple commutation of a single converter station. If it fails, it even causes DC blocking, which seriously threatens the safety of AC-DC hybrid power grid in my country's new form.
  • the energy storage power station groups can play a role in scenarios such as peak regulation, frequency regulation, and stabilization of power fluctuations after new energy is connected to the grid.
  • electrochemical energy storage has the advantages of fast response speed, strong dynamic active and reactive power support capability, high environmental adaptability, short construction period, and decentralized configuration. It is a very high-quality power grid. Regulate resources.
  • the present invention provides an energy storage transient power coordinated control method that suppresses subsequent commutation failures.
  • Response and transient support capabilities provide transient power support for the AC system after a fault, reduce the number of subsequent commutation failures, and improve the recovery ability of the power grid after a fault.
  • a method for coordinating energy storage transient power for suppressing subsequent commutation failures including:
  • S2 Use the magnitude relationship between the DC current and the first current threshold and the second current threshold to determine the energy storage active power output time command, where the first current threshold is greater than the second current threshold;
  • the magnitude relationship between the arc angle and the first arc-extinguishing angle threshold and the second arc-extinguishing angle threshold determines the energy storage reactive power output time command, and the first arc-extinguishing angle threshold is smaller than the second arc-extinguishing angle threshold;
  • S3 Determine the energy storage active power output amplitude command by using the magnitude relationship between the AC bus voltage and the voltage threshold; determine the energy storage reactive power output amplitude command by using the total energy storage capacity constraint;
  • S4 Send an energy storage active command and a reactive power command with a target output range to the energy storage power station at the target output time; the output time command carries the target output time, and the output range command carries the target output range.
  • step S2 includes:
  • step S2 further includes:
  • the method further includes: setting the active time threshold to 8ms and the reactive time threshold to 5ms.
  • step S3 includes:
  • S302 Determine a reactive power output amplitude command according to the active power output amplitude command and the energy storage capacity constraint.
  • P dc is the rated DC transmission power of the HVDC transmission system
  • f is the rated frequency of the AC system
  • U N is the rms value of the rated voltage of the AC busbar on the inverter side
  • U f0.1 is the RMS value of the AC busbar on the inverter side 0.1s after the failure of the AC busbar on the inverter side. the AC bus voltage;
  • S BESS is the energy storage capacity.
  • the method further includes:
  • step S4 includes:
  • S401 Determine the target output time from the rising edge time or the falling edge time in the output time command; take the output value corresponding to the output range command as the target output range;
  • S402 Output the energy storage active command corresponding to the target output amplitude at the target output moment, where the value of the energy storage active command is the algebraic product of the value of the active output time command and the value of the active output amplitude command ; Output the energy storage reactive power command corresponding to the target output magnitude at the target output moment, and the value of the energy storage reactive power command is the value of the reactive power output time command and the value of the reactive power output amplitude command. algebraic product of .
  • the method further includes:
  • the energy storage power station When the DC current is less than or equal to the first current threshold, or the AC bus voltage is greater than or equal to the voltage threshold, controlling the energy storage power station to continue to maintain the value of the energy storage active command as 0; When the real-time arc-extinguishing angle is greater than or equal to the first arc-extinguishing angle threshold, the energy storage power station is controlled to continue to maintain the value of the energy storage reactive power command as 0.
  • the invention determines the active power output time command and reactive power output time command of the energy storage respectively by detecting the DC current and the arc extinguishing angle of the inverter side; determines the active power output amplitude command by detecting the AC bus voltage, and uses the total energy storage capacity constraint to determine the reactive power Output range command; thus, the energy storage active command and reactive power command of the target output range are sent to the energy storage power station at the target output time.
  • the present invention is designed from the three dimensions of energy storage output time, output amplitude, and active and reactive power coordination, so as to make full use of the fast response and transient support capabilities of electrochemical energy storage on the grid side, so that the active and reactive power of energy storage can be coordinated.
  • the output is applied in the field of commutation failure suppression, which can effectively improve the transient control effect of the energy storage power station on the UHV AC-DC hybrid system, and can effectively prevent the DC voltage from falling rapidly and the DC current sharply increasing after the commutation failure occurs. Serious impact on the power grid system. It is also possible to suppress subsequent commutation failures after the first commutation failure after a DC fault.
  • FIG. 1 is a flowchart of a method for coordinating transient active and reactive power in an energy storage power station for suppressing subsequent commutation failures according to an embodiment of the present invention
  • step S2 is a flowchart of step S2 in a method for coordinating transient active and reactive power in an energy storage power station for suppressing subsequent commutation failures according to an embodiment of the present invention
  • FIG. 3 is a schematic diagram of an energy storage power station active time output command in an embodiment of the present invention.
  • FIG. 4 is a schematic diagram of an energy storage power station reactive time output command in an embodiment of the present invention.
  • step S3 is a flowchart of step S3 in a method for coordinating transient active and reactive power in an energy storage power station for suppressing subsequent commutation failures according to an embodiment of the present invention
  • step S4 is a flowchart of step S4 in a method for coordinating transient active and reactive power in an energy storage power station for suppressing subsequent commutation failures according to an embodiment of the present invention
  • FIG. 7 is a logic implementation block diagram of a method for coordinating transient active and reactive power in an energy storage power station for suppressing subsequent commutation failures provided by the present invention
  • FIG. 8 is a schematic diagram of a model of a multi-feed DC system in Henan provided by the present invention.
  • FIG. 9 is a schematic diagram of a lithium battery electrochemical energy storage power station model provided by the present invention.
  • FIG. 10 are schematic diagrams of the simulation results of the commutation failure suppression effect when the grounding inductance L is 0.002H, 0.02H, and 0.1H, respectively.
  • the present invention provides an energy storage transient power coordinated control method for suppressing subsequent commutation failure, including:
  • the real-time DC current I dci on the inverter side and the AC bus voltage U aci on the inverter side are continuously collected and detected, and the first current threshold I drefH is set to 1.2pu, the second current threshold I drefL is 0.88pu, and U acirefA is 0.95 pu, the first arc extinguishing angle threshold ⁇ l is 12°, and the second arc extinguishing angle threshold ⁇ h is 35°.
  • the method for coordinating transient active and reactive power in an energy storage power station for suppressing subsequent commutation failure further includes: when the real-time direct current I dci is less than or equal to the first current threshold I drefH , or, When the AC bus voltage is greater than or equal to the voltage threshold, the energy storage power station is controlled to continue to keep the energy storage active command at 0; when the real-time arc extinguishing angle ⁇ is greater than or equal to the first arc extinguishing angle threshold ⁇ l , the energy storage station is controlled to continue to maintain the specified value.
  • the value of the energy storage reactive power command is 0.
  • S2 Determine the output time command corresponding to the energy storage active power output by using the magnitude relationship between the real-time DC current I dci and the first current threshold I drefH and the second current threshold I drefL , where the first current threshold I drefH is greater than the second current threshold IDrefL .
  • the output time command corresponding to the energy storage reactive power output is determined, and the first arc-extinguishing angle
  • the threshold value ⁇ l is smaller than the second arc extinguishing angle threshold value ⁇ h ;
  • step S2 is to determine the output time command corresponding to the active power output moment of the energy storage according to the detected real-time DC current I dci , that is, when to release or absorb active power to the HVDC transmission system; determine the energy storage according to the detected real-time arc extinguishing angle
  • the output time command corresponding to the moment of reactive power output that is, when to release or absorb reactive power to the HVDC transmission system.
  • the process of determining the output time command is as follows: 1) When it is detected that the DC current I dci is greater than the threshold value I drefH , the controller sends a falling edge command P T to be -1 at this time, and controls the energy storage to absorb the reverse direction of the HVDC transmission system.
  • DC current I dci will first drop and be smaller than I drefH and I drefL under the constant current control of the system, and then continue to rise; when it is detected that the real-time arc extinguishing angle ⁇ is smaller than the first arc extinguishing
  • the angle threshold is ⁇ 1
  • the reactive power rising edge command Q T is 1
  • the energy storage is controlled to release reactive power to the inverter side of the HVDC transmission system
  • the control When it is detected that the DC current I dci rises to the threshold I drefL , the control When it is detected that the real-time arc-extinguishing angle ⁇ drops below the second arc-extinguishing angle threshold ⁇ h is greater than the first
  • the controller changes Q T to 0; 3) If the DC current I dci crosses the threshold I drefL and reaches the threshold I drefH again or when the
  • S3 Determine the output amplitude command by using the magnitude relationship between the AC bus voltage U aci and the voltage threshold U acirefA ; determine the output amplitude command corresponding to the energy storage reactive power output by using the total energy storage capacity constraint;
  • step S3 is to determine the output amplitude command corresponding to the energy storage active power output amplitude according to the magnitude relationship between the AC bus voltage U aci and the voltage threshold U acirefA , and determine the reactive power output amplitude according to the active power output command and the energy storage capacity constraint.
  • the output value of the first gear output Among them, P dc is the rated DC transmission power of the HVDC transmission system, f is the rated frequency of the AC system, U N is the rms value of the rated voltage of the AC bus on the inverter side, and U f0.1 is the AC bus 0.1s after the failure of the AC bus on the inverter side. bus voltage.
  • Reactive output amplitude command Among them, S BESS is the energy storage capacity.
  • control parameters (U acirefA , I drefL , I drefH , ⁇ l , ⁇ h ) selected in the present invention are artificially selected empirical values, and can be appropriately adjusted.
  • the selection principle of U acirefA is to determine that the AC-DC system is in a transient process with large disturbance; the selection principle of I drefL and I drefH is to determine that the DC is in the high-risk stage of subsequent commutation failure in the recovery process of commutation failure; ⁇ l , ⁇ The selection principle of h is to ensure that in the recovery stage of commutation failure, the real-time turn-off angle is within the range of current deviation control.
  • the energy storage active command and the energy storage reactive command of the target output range are sent to the energy storage power station.
  • the output time command carries the target output time
  • the output range command carries the target output range.
  • the target output time is determined according to the rising edge time or the falling edge time in the output time instruction.
  • the output value P 1 or P 2 corresponding to the command of the active power output amplitude is taken as the target active power output amplitude, and the energy storage active command of the target output amplitude is sent to the energy storage power station at the target output time, and the value of the energy storage active command P ref is the output time command.
  • step S2 includes: S201 : when it is detected that the DC current is greater than the first current threshold, send an active power falling edge command, and the value P T of the active power output time command is -1, the active power falling edge command is used to control the energy storage power station to absorb the active power on the inverter side of the HVDC transmission system; when it is detected that the arc extinguishing angle is smaller than the first arc extinguishing angle threshold, a reactive power rising edge is issued command, the value Q T of the reactive power output time command is 1, and the reactive power rising edge command is used to control the energy storage to release reactive power to the inverter side of the HVDC transmission system;
  • the controller when it is detected that the DC current I dci is greater than the threshold I drefH , the controller sends a falling edge command P T to be -1 at this time, and controls the energy storage to absorb the active power on the inverter side of the HVDC transmission system; the DC current I dci is in the system Under the action of its own constant current control, it will first drop and be smaller than I drefH and I drefL and then continue to rise; when it is detected that the real-time arc extinguishing angle ⁇ is less than the first arc extinguishing angle threshold ⁇ l , a reactive power rising edge is issued.
  • the command Q T is 1, and the energy storage is controlled to release reactive power to the inverter side of the HVDC transmission system; when it is detected that the DC current I dci rises to the threshold I drefL , the controller sends a rising edge command P T to 0 to control the energy storage Stop absorbing active power to the inverter side of the HVDC transmission system; when it is detected that the real-time arc extinguishing angle ⁇ decreases to be smaller than the second arc extinguishing angle threshold ⁇ h and greater than the first arc extinguishing angle threshold ⁇ l , the controller changes Q T is 0; if the DC current I dci crosses the threshold I drefL and reaches the threshold I drefH again, the active falling edge command P T is -1; when the real-time arc-extinguishing angle ⁇ that falls again is smaller than the first arc-extinguishing angle threshold ⁇ l When the reactive power rising edge command is issued, Q T
  • step S2 further includes: S205: when the real-time DC current I dci exceeds the second current threshold I drefL for the first time during the recovery process after the first inverter-side commutation failure, Issue the active power rising edge command and make the value P T of the output time command 0 exceed the active power time threshold to avoid high-frequency oscillation of the real-time DC current near the second current threshold, resulting in short-term repeated triggering; when the real-time arc extinguishing angle is at When the second arc-extinguishing angle threshold is lower for the first time in the recovery process after each inverter-side commutation failure, a reactive power falling edge command is issued and the value Q T of the output time command is 0 for a duration exceeding the reactive power
  • the time threshold is used to avoid short-term repeated triggering due to high-frequency oscillation of the real-time arc-extinguishing angle near the second arc-extinguishing angle threshold.
  • the two time thresholds can be set according to requirements, and are generally set at the millisecond level.
  • the method for coordinating the transient active and reactive power of the energy storage power station to suppress subsequent commutation failures further includes: setting the active power time threshold to 8ms, and setting the reactive power time threshold to 5ms.
  • setting the controller The shortest time for the rising edge command P T to be 0 is 8ms.
  • step S3 includes: S301 : when the AC bus voltage is lower than the voltage threshold, the first amplitude AND gate P A1 outputs a high level. When the real-time DC current exceeds the preset range, it is determined that the energy storage power station is unstable, and the second amplitude AND gate P A2 outputs a high level. S302: When both the first amplitude AND gate P A1 and the second amplitude AND gate P A2 output a high level, select the output amplitude command output by the first gear, and record the output output value as P 1 . Otherwise, select the output amplitude command of the second gear output, and the output output value is recorded as P 2 . Wherein, P 1 >P 2 , the reactive power output amplitude command is determined according to the active power output command and the energy storage capacity constraint.
  • the transient active power control method of the energy storage power station further includes: setting the sampling and holding time of U f0.1 to 1 s by default.
  • the sampling and holding time of U f0.1 is set to 1s.
  • the sampling and the sampling size are determined according to whether the fault is removed or not and the degree of the fault.
  • the sampling time is 0.1s after the fault, and the sampling is maintained for 1s.
  • step S4 comprises: S401: determine the target output moment from the rising edge moment or the falling edge moment in the output time instruction; take the output magnitude command corresponding output value as the target output power magnitude.
  • S402 output the energy storage active command corresponding to the target output amplitude at the target output moment, and the value of the energy storage active command is the algebraic product of the value of the active output time command and the value of the active output amplitude command; output the target output at the target output moment
  • the energy storage reactive power command corresponding to the amplitude, the value of the energy storage reactive power command is the algebraic product of the value of the reactive power output time command and the value of the reactive power output amplitude command.
  • the energy storage active command value P ref and the reactive power command can be obtained according to I dci , U aci and ⁇ The whole process of the value Qref .
  • the energy storage power station is controlled to enter a transient state Control mode; use the magnitude relationship between the real-time DC current I dci and the first current threshold I drefH and the second current threshold I drefL to determine the output time command P T corresponding to the energy storage active output, and the first current threshold is greater than the second current Threshold; use the magnitude relationship between the AC bus voltage U aci and the voltage threshold U acirefA to determine the active power output amplitude command P A ; according to the output time command P T and the output amplitude command P A , at the target output moment, the energy storage power station sends the target output amplitude storage power station.
  • Active power command P ref determine the output time command corresponding to the energy storage reactive power output by using the magnitude relationship between the real-time inverter side arc-extinguishing angle ⁇ and the first arc-extinguishing angle threshold ⁇ l and the second arc-extinguishing angle threshold ⁇ h Q T , the first arc-extinguishing angle threshold is smaller than the second arc-extinguishing angle threshold; the output amplitude command Q A corresponding to the energy storage reactive power output is determined by using the total energy storage capacity constraint; according to the output time command Q T and the output amplitude command Q A At the target output moment, the energy storage reactive power command Q ref with the target output range is sent to the energy storage power station.
  • the purpose of delaying 30ms is to ensure that the controller maintains the original output mode when the DC current is smaller than the first current threshold and the second current threshold in turn; in the energy storage reactive output control, the delay is 10ms.
  • the purpose is to ensure that the controller maintains the original output mode when the arc-extinguishing angle jumps from less than the first arc-extinguishing angle threshold to greater than the second arc-extinguishing angle threshold.
  • a simulation experiment is carried out by taking the Henan multi-feed DC system as a case of a UHV AC-DC hybrid system.
  • the corresponding simulation model is built in PSCAD/EMTDC, as shown in Figure 8.
  • the Henan multi-feed DC system includes two UHV DC transmission lines, Qinghai-Henan DC and Tianzhong DC, with voltage levels of ⁇ 800kV and DC power transmission of 8000MW in steady state.
  • the parameters in Figure 8 are shown in Table 1.
  • Impedance number parameter value Impedance number parameter value Z5( ⁇ ) 0.5992+j6.8484 Z45( ⁇ ) 3.3994+j38.8554 Z4( ⁇ ) 0.7977+j9.1169 Z35( ⁇ ) 3.86436+j44.1699 Z3( ⁇ ) 0.5864+j0.02133 Z34( ⁇ ) 1.39404+j15.9340
  • a lithium battery electrochemical energy storage power station model was built in PSCAD/EMTDC, as shown in Figure 9.
  • the model is mainly composed of three parts: lithium battery array, Boost boost circuit and grid-connected inverter.
  • the energy storage power station adopts constant power control, and the power output of the energy storage power station can be flexibly changed by changing the active and reactive power commands P ref and Q ref .
  • a simulation example is used to verify the inhibitory effect of the proposed energy storage power station active power control strategy on the subsequent commutation failure of the multi-infeed DC system in Henan.
  • the three-phase grounding fault occurs on the AC busbar on the DC inverter side in Tianzhong at 0.5s, and the duration is 0.1s.
  • the energy storage power station with a capacity of 1200MVA is connected to the AC bus, and the active power control strategy of the energy storage power station adopts the active power control method proposed by the present invention.
  • working condition 1 no energy storage access
  • working condition 2 energy storage access and adopt the coordinated control strategy of transient active power and transient reactive power according to the present invention
  • working condition 3 energy storage access and only adopt storage Energy storage transient active power control strategy
  • Condition 4 Energy storage is connected and only the energy storage transient reactive power control strategy is adopted, and the output amplitude is 1200MVar.
  • the traversal simulation results are shown in Table 2. It can be seen that in most of the working conditions, the number of commutation failures after the DC fault can be effectively reduced after the energy storage is connected, which has a good control effect. Further, under certain working conditions, when the energy storage is connected and the transient active power and transient reactive power coordinated control mode is adopted, the number of DC commutation failures can be suppressed to the minimum, and the energy storage can achieve the best control effect. It can be seen from the ergodic simulation results that the proposed coordinated control strategy of transient active power and transient reactive power of the energy storage power station has good applicability to different operating conditions of the system.
  • the transient power coordination support of energy storage power station is an effective control method to restrain the subsequent commutation failure after the UHVDC system fails.
  • the invention provides a coordinated control strategy for transient active power and transient reactive power of an energy storage power station suitable for ultra-high voltage direct current.
  • the control strategy is designed from three dimensions of energy storage output time, output amplitude, and active and reactive power coordination. Therefore, it is possible to take into account the favorable output timing and output size of energy storage, so that the energy storage power station can better restrain the commutation failure of the UHV AC-DC hybrid system.
  • embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.
  • computer-usable storage media including, but not limited to, disk storage, CD-ROM, optical storage, etc.
  • each flow and/or block in the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams can be implemented by computer program instructions.
  • These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in a flow or flow of a flowchart and/or a block or blocks of a block diagram.

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Abstract

本发明公开了一种抑制后续换相失败的储能暂态功率协调控制方法，属于多馈入特高压的交直流混联电网技术领域，方法包括：检测逆变侧的直流电流、交流母线电压以及熄弧角；当直流电流大于第一电流阈值或交流母线电压小于电压阈值或熄弧角小于第一熄弧角阈值时，控制储能电站进入暂态控制模式。通过检测逆变侧的直流电流以及熄弧角，分别确定储能有功出力时间指令、无功出力时间指令；通过检测交流母线电压确定有功出力幅度指令，利用储能总容量约束确定无功出力幅度指令；从而在目标出力时刻向储能电站发出目标出力幅度的储能有功指令与无功指令。如此，本发明能够有效抑制交直流混联系统故障后的后续换相失败，促进故障后电压恢复。

Description

一种抑制后续换相失败的储能暂态功率协调控制方法 技术领域
本发明属于多馈入特高压的交直流混联电网技术领域，更具体地，涉及一种抑制后续换相失败的储能暂态功率协调控制方法。
背景技术
换相失败是基于电网换相换流器的高压直流输电系统最为常见故障之一。换相失败发生后，直流电压迅速跌落、直流电流剧烈增加，对系统造成严重冲击，甚至会导致传输功率中断。随着高压直流输电工程的相继投入，我国电网“强直弱交、多回直流集中馈入”的特征日渐突出，受端电网支撑能力下降，交流系统故障可能诱发单个换流站的多次换相失败，甚至造成直流闭锁，严重威胁我国新形态下交直流混联电网安全。
随着电网侧规模化储能电站及百兆瓦级储能电站群的建设，储能电站群除了能够在调峰、调频、平抑新能源并网后功率波动等场景发挥作用外，还可针对电网故障提供暂态有功、无功紧急支撑。与其它储能形式相比，电化学储能具有响应速度快、动态有功无功支撑能力强、环境适应度高、建设周期短、可分散配置等优势，对于电网而言是一种非常优质的调节资源。
当直流系统发生首次换相失败之后，对于如何采用合适的控制策略以充分利用电网侧电化学储能的快速响应和暂态支撑能力，为故障后的交流系统提供暂态功率支撑，减少后续换相失败次数，提高故障后电网的恢复能力，具有重要的理论和实际意义。
发明内容
针对现有技术的缺陷和改进需求，本发明提供了一种抑制后续换相失败的储能暂态功率协调控制方法，其目的在于采用合适的控制策略以充分利用电网侧电化学储能的快速响应和暂态支撑能力，为故障后的交流系统提供暂态功率支撑，减少后续换相失败次数，提高故障后电网的恢复能力。
为实现上述目的，按照本发明的一个方面，提供了一种抑制后续换相失败的储能暂态功率协调控制方法，包括：
S1：检测逆变侧的直流电流、交流母线电压以及熄弧角；当所述直流电流大于第一电流阈值，或所述交流母线电压小于电压阈值，或所述熄弧角小于第一熄弧角阈值时，控制储能电站进入暂态控制模式；
S2：利用所述直流电流与所述第一电流阈值及第二电流阈值之间的大小关系确定储能有功出力时间指令，所述第一电流阈值大于所述第二电流 阈值；利用所述熄弧角与所述第一熄弧角阈值及第二熄弧角阈值之间的大小关系确定储能无功出力时间指令，所述第一熄弧角阈值小于所述第二熄弧角阈值；
S3：利用所述交流母线电压与所述电压阈值的大小关系确定储能有功出力幅度指令；利用储能总容量约束确定储能无功出力幅度指令；
S4：在目标出力时刻向所述储能电站发出目标出力幅度的储能有功指令与无功指令；所述出力时间指令携带所述目标出力时刻，所述出力幅度指令携带所述目标出力幅度。
进一步地，所述步骤S2包括：
S201：当检测到所述直流电流大于所述第一电流阈值时，发出有功下降沿指令，有功出力时间指令的值P T为-1，所述有功下降沿指令用于控制储能电站吸收高压直流输电系统逆变侧有功功率；当检测到所述熄弧角小于所述第一熄弧角阈值时，发出无功上升沿指令，无功出力时间指令的值Q T为1，所述无功上升沿指令用于控制储能向高压直流输电系统逆变侧释放无功功率；
S202：当检测到所述直流电流下降并先后低于所述第一电流阈值、第二阈值的过程中，维持P T为-1；当检测到所述熄弧角增大并先后大于所述第一熄弧角阈值、第二熄弧角阈值的过程中，维持Q T为1；
S203：当检测到所述直流电流上升到超过所述第二电流阈值时，改变P T为0；当检测到所述熄弧角减小到小于第二熄弧角阈值并大于第一熄弧角阈值时，改变Q T为0；
S204：当检测到所述直流电流上升到超过所述第一电流阈值时，或所述实时熄弧角减小到小于所述第一熄弧角阈值时，执行步骤S201。
进一步地，所述步骤S203之后，所述步骤S2还包括：
S205：当所述直流电流在每一次逆变侧换相失败后的恢复过程中首次超过所述第二电流阈值时，发出有功上升沿指令并使有功出力时间指令的值P T为0的时长超过有功时间阈值，以避免所述直流电流在所述第二电流阈值附近发生高频振荡导致短时重复触发；当所述熄弧角在每一次逆变侧换相失败后的恢复过程中首次小于所述第二熄弧角阈值时，发出无功下降沿指令并使无功出力时间指令的值Q T为0的时长超过无功时间阈值，以避免所述熄弧角在所述第二熄弧角阈值附近发生高频振荡导致短时重复触发。
进一步地，所述步骤S205之前，所述方法还包括：将所述有功时间阈值设置为8ms，所述无功时间阈值设为5ms。
进一步地，所述步骤S3包括：
S301：当所述交流母线电压低于所述电压阈值时，且所述直流电流超出预设范围时，输出有功出力幅值指令值P A记为P 1；否则，输出有功出力幅值指令值P A记为P 2；其中，P 1＞P 2；
S302：根据所述有功出力幅度指令与储能自身容量约束确定无功出力幅值指令。
进一步地，
Figure PCTCN2021109753-appb-000001
其中，P dc为高压直流输电系统额定直流传输功率，f交流系统额定频率，U N为逆变侧交流母线额定电压有效值，U f0.1为逆变侧交流母线故障发生后0.1s时所述交流母线电压；
P 2＝7.5％P dc。
进一步地，储能无功幅值出力值
Figure PCTCN2021109753-appb-000002
其中，S BESS为储能容量。
进一步地，所述步骤S302之前，所述方法还包括：
将U f0.1的采样保持时间设置为1s。
进一步地，所述步骤S4包括：
S401：从所述出力时间指令中的上升沿时刻或下降沿时刻确定出所述目标出力时刻；将所述出力幅度指令对应出力值作为所述目标出力幅度；
S402：在所述目标出力时刻输出所述目标出力幅度对应的所述储能有功指令，所述储能有功指令的值为所述有功出力时间指令的值与有功出力幅度指令的值的代数乘积；在所述目标出力时刻输出所述目标出力幅度对应的所述储能无功指令，所述储能无功指令的值为所述无功出力时间指令的值与无功出力幅度指令的值的代数乘积。
进一步地，所述步骤S2之前，所述方法还包括：
当所述直流电流小于或等于所述第一电流阈值，或，所述交流母线电压大于或等于所述电压阈值时，控制所述储能电站继续保持所述储能有功指令的值为0；所述实时熄弧角大于或等于所述第一熄弧角阈值，控制所述储能电站继续保持所述储能无功指令的值为0。
总体而言，通过本发明所构思的以上技术方案与现有技术相比，能够取得有益效果包括：
本发明通过检测逆变侧的直流电流以及熄弧角，分别确定储能有功出力时间指令、无功出力时间指令；通过检测交流母线电压确定有功出力幅度指令，利用储能总容量约束确定无功出力幅度指令；从而在目标出力时刻向储能电站发出目标出力幅度的储能有功指令与无功指令。如此，本发明从储能出力时间、出力幅值、有功无功配合三个维度进行设计，以充分利用电网侧电化学储能的快速响应和暂态支撑能力，使储能有功与无功协调出力在换相失败抑制领域得到应用，可有效改善储能电站对特高压交直流混联系统的暂态控制效果，能够有效防止由于换相失败发生后直流电压迅速跌落、直流电流剧烈增加，对电网系统造成严重冲击。还能够抑制直流故障后首次换相失败后的后续换相失败。
附图说明
图1为本发明一实施例中抑制后续换相失败的储能电站暂态有功和无功协调控制方法的流程图；
图2为本发明一实施例中抑制后续换相失败的储能电站暂态有功和无功协调控制方法中步骤S2的流程图；
图3为本发明一实施例中储能电站有功时间出力指令示意图；
图4为本发明一实施例中储能电站无功时间出力指令示意图；
图5为本发明一实施例中抑制后续换相失败的储能电站暂态有功和无功协调控制方法中步骤S3的流程图；
图6为本发明一实施例中抑制后续换相失败的储能电站暂态有功和无功协调控制方法中步骤S4的流程图；
图7为本发明提供的抑制后续换相失败的储能电站暂态有功和无功协调控制方法的逻辑实现框图；
图8为本发明所提供的河南多馈入直流系统模型示意图；
图9本发明所提供的锂电池电化学储能电站模型示意图；
图10中(a)、(b)、(c)分别为本发明在接地电感L为0.002H、0.02H、0.1H时，对换相失败抑制效果仿真结果示意图。
具体实施方式
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。此外，下面所描述的本发明各个实施方式中所涉及到的技术特征只要彼此之间未构成冲突就可以相互组合。
参阅图1，结合图2至图7，本发明提供了一种抑制后续换相失败的储能暂态功率协调控制方法，包括：
S1：持续检测逆变侧的实时直流电流I dci及逆变侧的交流母线电压U aci以及熄弧角γ。当实时直流电流I dci大于第一电流阈值I drefH或交流母线电压U aci小于电压阈值U acirefA或所述实时熄弧角γ小于第一熄弧角阈值γ l时，控制储能电站进入暂态控制模式。
具体的，持续采集并检测逆变侧实时直流电流I dci及逆变侧交流母线电压U aci，设置第一电流阈值I drefH为1.2pu，第二电流阈值I drefL为0.88pu，U acirefA为0.95pu，第一熄弧角阈值γ l为12°，第二熄弧角阈值γ h为35°。若I dci幅值大于阈值I drefH或U aci幅值小于电压阈值U acirefA或γ幅值小于阈值γ l，则判定储能电站进入暂态控制模式。在其中一个实施例中，步骤S2之前，抑制后续换相失败的储能电站暂态有功和无功协调控制方法还包括：当实时直流电流I dci小于或等于第一电流阈值I drefH，或，交流母线电压大于或等于电压阈值时，控制储能电站继续保持储能有功指令为0；当实时熄弧角γ 大于或等于第一熄弧角阈值γ l，控制所述储能电站继续保持所述储能无功指令的值为0。
S2：利用实时直流电流I dci与第一电流阈值I drefH及第二电流阈值I drefL之间的大小关系确定出储能有功出力对应的出力时间指令，第一电流阈值I drefH大于第二电流阈值I drefL。利用实时逆变侧熄弧角γ与第一熄弧角阈值γ l及第二熄弧角阈值γ h之间的大小关系确定出储能无功出力对应的出力时间指令，第一熄弧角阈值γ l小于第二熄弧角阈值γ h；
具体的，步骤S2是根据检测到实时直流电流I dci确定储能有功出力时刻对应的出力时间指令，即何时向高压直流输电系统释放或吸收有功功率；根据检测到实时熄弧角确定储能无功出力时刻对应的出力时间指令，即何时向高压直流输电系统释放或吸收无功功率。举例来说，确定出力时间指令的过程如下：1)当检测到直流电流I dci大于阈值I drefH时，此时控制器发出下降沿指令P T为-1，控制储能吸收高压直流输电系统逆变侧有功功率；直流电流I dci在系统本身定电流控制的作用下，会先下降并小于I drefH、I drefL而后继续上升；当检测到所述实时熄弧角γ小于所述第一熄弧角阈值γ l时，发出无功上升沿指令Q T为1，控制储能向高压直流输电系统逆变侧释放无功功率；2)当检测到直流电流I dci上升到阈值I drefL时，控制器发出上升沿指令P T为0，控制储能停止向高压直流输电系统逆变侧吸收有功功率；当检测到所述实时熄弧角γ下降低于第二熄弧角阈值γ h大于第一熄弧角阈值γ l时，控制器改变Q T为0；3)若直流电流I dci越过阈值I drefL并再次达到阈值I drefH时或当再次下降的实时熄弧角γ小于第一熄弧角阈值γ l时，继续转至步骤1)；否则维持储能电站的储能有功指令、无功指令均为0。
S3：利用交流母线电压U aci与电压阈值U acirefA的大小关系确定出力幅度指令；利用储能总容量约束确定出储能无功出力对应的出力幅度指令；
具体的，步骤S3是根据交流母线电压U aci与电压阈值U acirefA的大小关系确定储能有功出力幅值对应的出力幅值指令，根据有功出力指令与储能自身容量约束确定无功出力幅值指令，具体过程如下：1)在有功控制时，电压U aci跌落超过阈值U acirefA时，向幅值选择部分的与门P A1输出高电平；当电流I dci在一定时间内不再发生大的波动，即判断为系统稳定，系统不稳定时向选择部分与门P A2输出高电平；2)当储能有功幅值选择部分同时收到来自P A1、P A2传来的高电平时，选择器切换到最佳出力幅值确定模块P 1，否则处于储能基础出力P 2档位，最终输出为P A，即P A＝P 1或者P A＝P 1；3)根据有功出力指令与储能自身容量约束确定无功出力幅值指令Q A。在其中一个实施例中，第一档位输出的出力值
Figure PCTCN2021109753-appb-000003
其中，P dc为高压直流输电系统额定直流传输功率，f交流系统额定频率，U N为逆变侧交流母线额定电压有效值，U f0.1为逆变侧交流母线故障发生后0.1s时交流母线电压。第二档位输出的出力值P 2＝7.5％P dc。无功出力幅值指令
Figure PCTCN2021109753-appb-000004
其中，S BESS为储能容量。
需要说明的是，该方法在储能电站暂态控制的每个控制周期(取决于控制系统的精度)内都会循环执行一次。另外，在本发明中所选取的控制参数(U acirefA、I drefL、I drefH、γ l、γ h)是人为选定的经验值，可以进行适当调整。U acirefA的选取原则为判定交直流系统处于较大扰动的暂态过程；I drefL、I drefH的选取原则是判定直流处于换相失败恢复过程中的后续换相失败高风险阶段；γ l、γ h的选择原则为确保在换相失败恢复阶段，实时关断角处于电流偏差控制的范围。
S4：在目标出力时刻向储能电站发出目标出力幅度的储能有功指令与储能无功指令，出力时间指令携带目标出力时刻，出力幅度指令携带目标出力幅度。具体的，根据出力时间指令中的上升沿时刻或下降沿时刻确定出目标出力时刻。将有功出力幅度指令对应出力值P 1或者P 2作为目标有功出力幅度，在目标出力时刻向储能电站发出目标出力幅度的储能有功指令，储能有功指令的值P ref为出力时间指令的值P T与出力幅度指令的值P A的代数乘积，即P ref＝P T*P A；在目标出力时刻向储能电站发出目标出力幅度的储能无功指令，储能无功指令的值Q ref为出力时间指令的值Q T与出力幅度指令的值Q A的代数乘积，即Q ref＝Q T*Q A。
在其中一个实施例中，如图2所示，步骤S2包括：S201：当检测到所述直流电流大于所述第一电流阈值时，发出有功下降沿指令，有功出力时间指令的值P T为-1，所述有功下降沿指令用于控制储能电站吸收高压直流输电系统逆变侧有功功率；当检测到所述熄弧角小于所述第一熄弧角阈值时，发出无功上升沿指令，无功出力时间指令的值Q T为1，所述无功上升沿指令用于控制储能向高压直流输电系统逆变侧释放无功功率；
S202：当检测到所述直流电流下降并先后低于所述第一电流阈值、第二阈值的过程中，维持P T为-1；当检测到所述熄弧角增大并先后大于所述第一熄弧角阈值、第二熄弧角阈值的过程中，维持Q T为1；
S203：当检测到所述直流电流上升到超过所述第二电流阈值时，改变P T为0；当检测到所述熄弧角减小到小于第二熄弧角阈值时，改变Q T为0；
S204：当检测到所述直流电流上升到超过所述第一电流阈值时，或所述实时熄弧角减小到小于所述第一熄弧角阈值时，执行步骤S201。
具体的，当检测到直流电流I dci大于阈值I drefH时，此时控制器发出下降沿指令P T为-1，控制储能吸收高压直流输电系统逆变侧有功功率；直流电流I dci在系统本身定电流控制的作用下，会先下降并小于I drefH、I drefL而后继续上升；当检测到所述实时熄弧角γ小于所述第一熄弧角阈值γ l时，发出无功上升沿指令Q T为1，控制储能向高压直流输电系统逆变侧释放无功功率；当检测到直流电流I dci上升到阈值I drefL时，控制器发出上升沿指令P T为0，控制储能停止向高压直流输电系统逆变侧吸收有功功率；当检测到所述实时熄弧角γ减小到小于第二熄弧角阈值γ h大于第一熄弧角阈值γ l时， 控制器改变Q T为0；若直流电流I dci越过阈值I drefL并再次达到阈值I drefH时，发出有功下降沿指令P T为-1；当再次下降的实时熄弧角γ小于第一熄弧角阈值γ l时，发出无功上升沿指令Q T为1；否则维持储能电站的储能有功指令、无功指令均为0，储能电站处于等待出力状态。
在其中一个实施例中，在步骤S203之后，步骤S2还包括：S205：当实时直流电流I dci在第一次逆变侧换相失败后的恢复过程中首次超过第二电流阈值I drefL时，发出有功上升沿指令并使出力时间指令的值P T为0的时长超过有功时间阈值，以避免实时直流电流在第二电流阈值附近发生高频振荡导致短时重复触发；当实时熄弧角在每一次逆变侧换相失败后的恢复过程中首次低于所述第二熄弧角阈值时，发出无功下降沿指令并使所述出力时间指令的值Q T为0的时长超过无功时间阈值，以避免所述实时熄弧角在所述第二熄弧角阈值附近发生高频振荡导致短时重复触发。两时间阈值可以根据需求进行设置，一般设置在毫秒级。在其中一个实施例中，步骤S205之前，抑制后续换相失败的储能电站暂态有功和无功协调控制方法还包括：将有功时间阈值设置为8ms，将无功时间阈值设置为5ms。在该步骤中，为避免I dci上升到阈值I drefL附近发生高频振荡导致短时重复触发，当I dci在第一次换相失败后的恢复过程中首次超过阈值I drefL时，设置控制器发出上升沿指令P T为0的时间最短为8ms，为避免γ下降到阈值γ h附近发生高频振荡导致短时重复触发，当γ在第一次换相失败后的恢复过程中首次小于阈值γ h时，设置控制器发出上升沿指令Q T为0的时间最短为5ms。需要说明的是，首次换相失败后，由于直流系统本身具有调节控制作用，会使系统换相条件改善，如直流电流、交流电压恢复，此为第一次换相失败恢复过程。若恢复过渡将引发第二次或后续换相失败。储能无功时间出力指令示意图与储能有功时间出力指令示意图分别如图3、图4所示。
在其中一个实施例中，如图5所示，步骤S3包括：S301：当交流母线电压低于电压阈值时，第一幅值与门P A1输出高电平。当实时直流电流超出预设范围内，判定储能电站不稳定，并使第二幅值与门P A2输出高电平。S302：当第一幅值与门P A1和第二幅值与门P A2均输出高电平时，选择第一档位输出的出力幅度指令，输出出力值记为P 1。否则，选择第二档位输出的出力幅度指令，输出出力值记为P 2。其中，P 1＞P 2，根据有功出力指令与储能自身容量约束确定无功出力幅值指令。
在其中一个实施例中，步骤S302之前，储能电站的暂态有功控制方法还包括：将U f0.1的采样保持时间默认设置为1s。为使P 1能随直流系统故障恢复程度而动态变化，设置U f0.1的采样保持时间为1s，采样保持结束后，根据故障是否切除以及故障程度决定是否采样及采样大小。交流母线电压低于电压阈值时，即判断故障发生。采样时刻均在故障后0.1s，并采样保持1s。
在其中一个实施例中，如图6所示，步骤S4包括：S401：从出力时间 指令中的上升沿时刻或下降沿时刻确定出目标出力时刻；将出力幅度指令对应出力值作为目标出力幅度。S402：在目标出力时刻输出目标出力幅度对应的储能有功指令，储能有功指令的值为所述有功出力时间指令的值与有功出力幅度指令的值的代数乘积；在目标出力时刻输出目标出力幅度对应的储能无功指令，储能无功指令的值为无功出力时间指令的值与无功出力幅度指令的值的代数乘积。
如图7所示，检测实时直流电流I dci、逆变侧的交流母线电压U aci以及熄弧角γ之后，可根据I dci、U aci以及γ获取储能有功指令值P ref和无功指令值Q ref的全过程。具体的，当实时直流电流I dci大于第一电流阈值I drefH或交流母线电压U aci小于电压阈值U acirefA时或熄弧角γ小于第一熄弧角γ l阈值，控制储能电站进入暂态控制模式；利用实时直流电流I dci与第一电流阈值I drefH及第二电流阈值I drefL之间的大小关系确定出储能有功出力对应的出力时间指令P T，第一电流阈值大于第二电流阈值；利用交流母线电压U aci与电压阈值U acirefA的大小关系确定有功出力幅度指令P A；根据出力时间指令P T和出力幅度指令P A在目标出力时刻向储能电站发出目标出力幅度的储能有功指令P ref；利用实时逆变侧熄弧角γ与第一熄弧角阈值γ l及第二熄弧角阈值γ h之间的大小关系确定出储能无功出力对应的出力时间指令Q T，第一熄弧角阈值小于第二熄弧角阈值；利用储能总容量约束确定出储能无功出力对应的出力幅度指令Q A；根据出力时间指令Q T和出力幅度指令Q A在目标出力时刻向储能电站发出目标出力幅度的储能无功指令Q ref。在储能有功出力时间控制中，延时30ms目的为确保控制器在直流电流在依次小于第一电流阈值及第二电流阈值期间保持原出力方式；在储能无功出力控制中，延时10ms目的为确保控制器在熄弧角从小于第一熄弧角阈值跳跃到大于第二熄弧角阈值时保持原出力方式。
为了验证本发明提供控制方法的技术效果，以河南多馈入直流系统作为特高压交直流混联系统案例进行仿真实验。在PSCAD/EMTDC中搭建了相应仿真模型，如图8所示。河南多馈入直流系统包括青海-河南直流、天中直流两条特高压直流输电线路，其电压等级均为±800kV，稳态时传输的直流功率均为8000MW。图8中各参数如表1所示。
表1河南多馈入直流受端交流系统等值模型阻抗参数
阻抗编号 参数值 阻抗编号 参数值
Z5(Ω) 0.5992+j6.8484 Z45(Ω) 3.3994+j38.8554
Z4(Ω) 0.7977+j9.1169 Z35(Ω) 3.86436+j44.1699
Z3(Ω) 0.5864+j0.02133 Z34(Ω) 1.39404+j15.9340
此外，在PSCAD/EMTDC中搭建了锂电池电化学储能电站模型，如图9所示。模型主要由三个部分组成：锂电池阵列、Boost升压电路以及并网逆变器。储能电站采用定功率控制，通过改变有功、无功指令P ref与Q ref能 够灵活改变储能电站的功率输出。通过仿真算例验证所提储能电站有功控制策略对于河南多馈入直流系统后续换相失败的抑制效果。设置图8所示天中直流逆变侧交流母线在0.5s时通过一定大小的接地电感发生三相接地故障，持续时间为0.1s。容量为1200MVA的储能电站接至交流母线上，储能电站的有功控制策略采用本发明所提的有功控制方法。
当接地电感L分别为0.002H、0.02H、0.1H时，仿真结果如图10所示。普遍认为关断角小于7°即发生换相失败。可以看到，当采用本发明对储能功率出力进行协调控制时，在不同故障程度下，均能对换相失败起到抑制作用。
需要补充的是，如图8所示，设置直流逆变侧交流母线通过一定大小的接地电感发生三相接地故障，持续时间为0.1s，储能容量为1200MVA。通过改变故障时刻和接地电感大小设置了多组工况进行了遍历仿真，并对比了不同工况下储能的换相失败抑制效果。其中，工况1：无储能接入；工况2：储能接入且采取本发明所述暂态有功与暂态无功协调控制策略；工况3：储能接入并仅采取储能暂态有功控制策略；工况4：储能接入并仅采取储能暂态无功控制策略，出力幅值为1200MVar。
遍历仿真结果如表2所示，可以看到，在绝大部分工况下，储能接入之后均能有效减少直流故障后换相失败次数，起到良好的控制效果。进一步地，在某些工况下，储能接入且采取暂态有功与暂态无功协调控制方式时，能够将直流换相失败次数抑制到最少，储能能够实现最佳的控制效果。由遍历仿真结果可知所提储能电站暂态有功与暂态无功协调控制策略对系统不同运行工况具有良好的适用性。
综上，储能电站暂态功率协调支撑是抑制特高压直流系统故障后后续换相失败的有效控制手段。
表2遍历仿真结果
Figure PCTCN2021109753-appb-000005
Figure PCTCN2021109753-appb-000006
本发明提供了一种适用于特高压直流的储能电站暂态有功与暂态无功协调控制策略，该控制策略从储能出力时间、出力幅值、有功无功配合三个维度进行设计，从而能够兼顾储能有利的出力时机与出力大小，使得储能电站对特高压交直流混联系统换相失败起到较好抑制作用。
本领域内的技术人员应明白，本发明的实施例可提供为方法、系统、或计算机程序产品。因此，本发明可采用完全硬件实施例、完全软件实施例、或结合软件和硬件方面的实施例的形式。而且，本发明可采用在一个或多个其中包含有计算机可用程序代码的计算机可用存储介质(包括但不限于磁盘存储器、CD-ROM、光学存储器等)上实施的计算机程序产品的形式。
本发明应理解可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器，使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。
本领域的技术人员容易理解，以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种抑制后续换相失败的储能暂态功率协调控制方法，其特征在于，包括以下步骤：
    S1：检测逆变侧的直流电流、交流母线电压以及熄弧角；当所述直流电流大于第一电流阈值，或所述交流母线电压小于电压阈值，或所述熄弧角小于第一熄弧角阈值时，控制储能电站进入暂态控制模式；
    S2：利用所述直流电流与所述第一电流阈值及第二电流阈值之间的大小关系确定储能有功出力时间指令，所述第一电流阈值大于所述第二电流阈值；利用所述熄弧角与所述第一熄弧角阈值及第二熄弧角阈值之间的大小关系确定储能无功出力时间指令，所述第一熄弧角阈值小于所述第二熄弧角阈值；
    S3：利用所述交流母线电压与所述电压阈值的大小关系确定储能有功出力幅度指令；利用储能总容量约束确定储能无功出力幅度指令；
    S4：在目标出力时刻向所述储能电站发出目标出力幅度的储能有功指令与无功指令；所述出力时间指令携带所述目标出力时刻，所述出力幅度指令携带所述目标出力幅度。
  2. 如权利要求1所述的抑制后续换相失败的储能暂态功率协调控制方法，其特征在于，所述步骤S2包括：
    S201：当检测到所述直流电流大于所述第一电流阈值时，发出有功下降沿指令，有功出力时间指令的值P T为-1，所述有功下降沿指令用于控制储能电站吸收高压直流输电系统逆变侧有功功率；当检测到所述熄弧角小于所述第一熄弧角阈值时，发出无功上升沿指令，无功出力时间指令的值Q T为1，所述无功上升沿指令用于控制储能向高压直流输电系统逆变侧释放无功功率；
    S202：当检测到所述直流电流下降并先后低于所述第一电流阈值、第二阈值的过程中，维持P T为-1；当检测到所述熄弧角增大并先后大于所述第一熄弧角阈值、第二熄弧角阈值的过程中，维持Q T为1；
    S203：当检测到所述直流电流上升到超过所述第二电流阈值时，改变P T为0；当检测到所述熄弧角减小到小于第二熄弧角阈值并大于第一熄弧角阈值时，改变Q T为0；
    S204：当检测到所述直流电流上升到超过所述第一电流阈值时，或所述实时熄弧角减小到小于所述第一熄弧角阈值时，执行步骤S201。
  3. 如权利要求2所述的抑制后续换相失败的储能暂态功率协调控制方法，其特征在于，所述步骤S203之后，所述步骤S2还包括：
    S205：当所述直流电流在每一次逆变侧换相失败后的恢复过程中首次超过所述第二电流阈值时，发出有功上升沿指令并使有功出力时间指令的值P T为0的时长超过有功时间阈值，以避免所述直流电流在所述第二电流 阈值附近发生高频振荡导致短时重复触发；当所述熄弧角在每一次逆变侧换相失败后的恢复过程中首次小于所述第二熄弧角阈值时，发出无功下降沿指令并使无功出力时间指令的值Q T为0的时长超过无功时间阈值，以避免所述熄弧角在所述第二熄弧角阈值附近发生高频振荡导致短时重复触发。
  4. 如权利要求3所述的抑制后续换相失败的储能暂态功率协调控制方法，其特征在于，所述步骤S205之前，所述方法还包括：将所述有功时间阈值设置为8ms，所述无功时间阈值设为5ms。
  5. 如权利要求1所述的抑制后续换相失败的储能暂态功率协调控制方法，其特征在于，所述步骤S3包括：
    S301：当所述交流母线电压低于所述电压阈值时，且所述直流电流超出预设范围时，输出有功出力幅值指令值P A记为P 1；否则，输出有功出力幅值指令值P A记为P 2；其中，P 1＞P 2；
    S302：根据所述有功出力幅度指令与储能自身容量约束确定无功出力幅值指令。
  6. 如权利要求5所述的抑制后续换相失败的储能暂态功率协调控制方法，其特征在于，
    Figure PCTCN2021109753-appb-100001
    其中，P dc为高压直流输电系统额定直流传输功率，f交流系统额定频率，U N为逆变侧交流母线额定电压有效值，U f0.1为逆变侧交流母线故障发生后0.1s时所述交流母线电压；
    P 2＝7.5％P dc。
  7. 如权利要求6所述的抑制后续换相失败的储能暂态功率协调控制方法，其特征在于，
    储能无功幅值出力值
    Figure PCTCN2021109753-appb-100002
    其中，S BESS为储能容量。
  8. 如权利要求7所述的抑制后续换相失败的储能暂态功率协调控制方法，其特征在于，所述步骤S302之前，所述方法还包括：
    将U f0.1的采样保持时间设置为1s。
  9. 如权利要求1所述的抑制后续换相失败的储能暂态功率协调控制方法，其特征在于，所述步骤S4包括：
    S401：从所述出力时间指令中的上升沿时刻或下降沿时刻确定出所述目标出力时刻；将所述出力幅度指令对应出力值作为所述目标出力幅度；
    S402：在所述目标出力时刻输出所述目标出力幅度对应的所述储能有功指令，所述储能有功指令的值为所述有功出力时间指令的值与有功出力幅度指令的值的代数乘积；在所述目标出力时刻输出所述目标出力幅度对应的所述储能无功指令，所述储能无功指令的值为所述无功出力时间指令的值与无功出力幅度指令的值的代数乘积。
  10. 如权利要求1-9任一项所述的抑制后续换相失败的储能暂态功率协调控制方法，其特征在于，所述步骤S2之前，所述方法还包括：
    当所述直流电流小于或等于所述第一电流阈值，或，所述交流母线电压大于或等于所述电压阈值时，控制所述储能电站继续保持所述储能有功指令的值为0；所述实时熄弧角大于或等于所述第一熄弧角阈值，控制所述储能电站继续保持所述储能无功指令的值为0。
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115776132A (zh) * 2023-02-10 2023-03-10 四川大学 高压直流系统的控制方法、装置和电子设备
CN115800345A (zh) * 2022-12-05 2023-03-14 西南大学 应对多直流换相失败功率冲击的电网侧储能紧急控制方法
CN115882493A (zh) * 2022-11-25 2023-03-31 东北电力大学 抑制控制器交互不当引发换相失败的电流偏差控制方法
CN119109055A (zh) * 2024-07-25 2024-12-10 中国电力科学研究院有限公司 暂态电压稳定的功率-电流增强控制方法及终端
CN119134455A (zh) * 2024-07-23 2024-12-13 国家电网有限公司华中分部 一种直流同时换相失败后的协同恢复控制方法及系统

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112865165B (zh) * 2021-01-25 2024-03-19 华中科技大学 一种抑制后续换相失败的储能暂态功率协调控制方法
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CN118971009B (zh) * 2024-07-31 2026-01-16 湖北省电力规划设计研究院有限公司 一种抑制直流连续换相失败的upfc紧急协调控制方法、系统及存储介质
CN119518996B (zh) * 2024-10-29 2025-09-23 中国电力科学研究院有限公司 用于电化学储能机电暂态模型的故障穿越控制方法及系统
CN119674986B (zh) * 2025-02-20 2025-09-05 深圳市三和电力科技有限公司 构网型变流器协同控制方法及系统

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20140036797A (ko) * 2012-09-18 2014-03-26 한국전력공사 Ｈｖｄｃ 시스템의 정류실패 방지를 위한 소호각 제어 장치
CN105958504A (zh) * 2016-05-04 2016-09-21 国网江苏省电力公司电力科学研究院 一种减少换相失败的统一潮流控制器无功补偿方法
CN108701998A (zh) * 2016-06-08 2018-10-23 Abb瑞士股份有限公司 线路换相换流器控制系统和方法
CN109347133A (zh) * 2018-10-18 2019-02-15 国家电网公司华中分部 一种基于特高压直流输电工程的逆变侧控制方法与系统
CN109861267A (zh) * 2019-03-14 2019-06-07 南京师范大学 基于熄弧角判据的高压直流输电连续换相失败预测及无功紧急控制方法
CN110212565A (zh) * 2019-06-19 2019-09-06 东南大学 一种抑制连续换相失败的直流功率控制策略
CN111864781A (zh) * 2020-08-31 2020-10-30 华中科技大学 一种储能电站的暂态有功控制方法
CN111900747A (zh) * 2020-08-25 2020-11-06 华中科技大学 用于多馈入直流系统的储能电站暂态无功控制方法和系统
CN112865165A (zh) * 2021-01-25 2021-05-28 华中科技大学 一种抑制后续换相失败的储能暂态功率协调控制方法

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11223229B2 (en) * 2017-02-28 2022-01-11 Lsis Co., Ltd. Uninterruptible power supply system comprising energy storage system

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20140036797A (ko) * 2012-09-18 2014-03-26 한국전력공사 Ｈｖｄｃ 시스템의 정류실패 방지를 위한 소호각 제어 장치
CN105958504A (zh) * 2016-05-04 2016-09-21 国网江苏省电力公司电力科学研究院 一种减少换相失败的统一潮流控制器无功补偿方法
CN108701998A (zh) * 2016-06-08 2018-10-23 Abb瑞士股份有限公司 线路换相换流器控制系统和方法
CN109347133A (zh) * 2018-10-18 2019-02-15 国家电网公司华中分部 一种基于特高压直流输电工程的逆变侧控制方法与系统
CN109861267A (zh) * 2019-03-14 2019-06-07 南京师范大学 基于熄弧角判据的高压直流输电连续换相失败预测及无功紧急控制方法
CN110212565A (zh) * 2019-06-19 2019-09-06 东南大学 一种抑制连续换相失败的直流功率控制策略
CN111900747A (zh) * 2020-08-25 2020-11-06 华中科技大学 用于多馈入直流系统的储能电站暂态无功控制方法和系统
CN111864781A (zh) * 2020-08-31 2020-10-30 华中科技大学 一种储能电站的暂态有功控制方法
CN112865165A (zh) * 2021-01-25 2021-05-28 华中科技大学 一种抑制后续换相失败的储能暂态功率协调控制方法

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115882493A (zh) * 2022-11-25 2023-03-31 东北电力大学 抑制控制器交互不当引发换相失败的电流偏差控制方法
CN115800345A (zh) * 2022-12-05 2023-03-14 西南大学 应对多直流换相失败功率冲击的电网侧储能紧急控制方法
CN115776132A (zh) * 2023-02-10 2023-03-10 四川大学 高压直流系统的控制方法、装置和电子设备
CN115776132B (zh) * 2023-02-10 2023-05-23 四川大学 高压直流系统的控制方法、装置和电子设备
CN119134455A (zh) * 2024-07-23 2024-12-13 国家电网有限公司华中分部 一种直流同时换相失败后的协同恢复控制方法及系统
CN119109055A (zh) * 2024-07-25 2024-12-10 中国电力科学研究院有限公司 暂态电压稳定的功率-电流增强控制方法及终端

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