A UPFC emergency coordinated control method and system for suppressing direct current continuous commutation failure and a storage medium

Abstract

The application discloses a UPFC emergency coordination control method and system for inhibiting continuous commutation failure of direct current and a storage medium. When commutation failure of direct current occurs, commutation failure information of direct current is acquired, and it is judged whether to start UPFC voltage emergency control according to the commutation failure information of direct current. If the UPFC voltage emergency control is started, a reactive power control instruction is sent to a UPFC execution substation based on UPFC operation information, and the UPFC execution substation sends reactive power according to the reactive power control instruction to inhibit continuous commutation failure of direct current. The application can effectively reduce the probability of continuous commutation failure of direct current of a multi-direct-current feeding receiving end power grid, prevent the direct current from being blocked due to multiple commutation failures, and be beneficial to preventing large-area power failure caused by multi-direct-current blocking.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power system and automation, and particularly relates to a UPFC emergency coordination control method for suppressing continuous commutation failure of DC, a system and a storage medium. BACKGROUND

[0002] With the rapid development of UHV DC, it plays an important role in realizing the large-scale optimal allocation of resources in China. Under the background of slow load growth, a large number of local units in the receiving end power grid of UHV DC are shut down, the dynamic reactive power reserve of the system is greatly reduced, and the conventional AC fault of the power grid often leads to simultaneous commutation failure of multiple DCs, and in serious cases, it may even cause simultaneous blocking of multiple DCs. These factors lead to the increasing trend of local load loss or large-area power outage accidents caused by voltage instability or voltage collapse.

[0003] In order to improve the dynamic reactive power reserve of the power grid and enhance the voltage stability characteristics of the power grid, prevent or avoid the occurrence of simultaneous commutation failure and blocking of multiple DCs, a large number of synchronous phase modulators and unified power flow controllers (UPFCs) are constructed in the receiving end power grid of UHV DC. The phase modulator adjusts its reactive power output according to the change of the terminal voltage during normal operation, which can effectively improve the dynamic reactive power reserve of the system. The UPFC can be regarded as the combination of Statcom and SSSC, which can not only be used as an active control measure but also can provide dynamic reactive power compensation capability. However, most UPFCs are currently used only as steady-state and transient-state power flow control means, and the reactive power control capability is not effectively utilized. A large number of simulation analyses show that the UPFC releases dynamic reactive power regulation capability, which can greatly reduce the probability of DC commutation failure in the receiving end power grid of multiple DCs, and the operation mode of UPFC participating in power grid control needs to be explored. SUMMARY

[0004] The purpose of the present application is to solve the problems in the background art, and to provide a UPFC emergency coordination control method for suppressing continuous commutation failure of DC, a system and a storage medium.

[0005] The technical scheme adopted by the present application is as follows: a UPFC emergency coordination control method for suppressing continuous commutation failure of DC, when DC commutation failure occurs, DC commutation failure information is obtained, and it is judged whether to start UPFC voltage emergency control according to the DC commutation failure information; if UPFC voltage emergency control is started, a reactive power control instruction is sent to the UPFC execution substation based on UPFC operation information, the UPFC execution substation sends reactive power according to the reactive power control instruction, and continuous commutation failure of DC is suppressed.

[0006] Further, the DC commutation failure information includes the number of DCs that have commutation failure, the operating power of the DCs that have commutation failure, and the bus voltage on the inverter side of the DC converter station.

[0007] Further, when the following conditions are met, it is judged to start the UPFC voltage emergency control:

[0008] P 总 ≥P set , wherein P 总 = P1+ P2+…P i , P 总 is the total active power of the commutation failure DC, P set is the set threshold value, and P i is the active power of the i-th commutation failure DC, and i is the number of commutation failure DCs.

[0009] Further, the determination process of the set threshold value P set is as follows: in different operation modes of the power grid, different power values are set through offline time-domain simulation calculation, and when a certain power value meets any one or more conditions that the power grid remains stable when any one or more DCs simultaneously and continuously commutate failure for more than three times, the power value is determined as the set threshold value P set .

[0010] Further, the process of sending the reactive power control instruction to the UPFC execution substation based on the UPFC operation information is as follows: for each commutation failure DC, the voltage sensitivity of the UPFC execution substation to the commutation failure DC commutation station is greater than or equal to the set sensitivity as the reference, the UPFC execution substation associated with the commutation failure DC is found, and the reactive power control instruction is sent to all found UPFC execution substations in order according to the order of the voltage sensitivity from large to small.

[0011] Further, when the reactive power control instruction is first sent to the UPFC execution substation, the size of the reactive power control instruction value is half of the controllable reactive power adjustment amount of the UPFC execution substation.

[0012] Further, the voltage sensitivity of the UPFC execution substation to the commutation failure DC commutation station is determined by the following formula:

[0013]

[0014] ΔV i = V i -V i0 ;

[0015] wherein η ij is the voltage sensitivity of the j-th UPFC execution substation connected to the UPFC voltage emergency control master station to the i-th commutation failure DC commutation station; ΔQ j is the reactive power amount increased by the j-th UPFC execution substation connected to the UPFC voltage emergency control master station, and ΔV iV is the voltage variation value of the i-th commutation failure DC converter station bus, V i V is the i-th commutation failure DC converter station bus voltage, V i0 V is the initial voltage of the i-th commutation failure DC converter station bus.

[0016] Further, after the UPFC execution substation first sends reactive power according to the reactive power control instruction, if continuous commutation failure occurs in a certain DC, the UPFC execution substation associated with the DC with continuous commutation failure is sent a continuous reactive power control instruction, and the value of the continuous reactive power control instruction is equal to the controllable reactive power adjustment amount of the UPFC execution substation.

[0017] A UPFC emergency coordination control system for suppressing continuous commutation failure of DC, comprising

[0018] A DC commutation failure information substation for receiving DC commutation failure information when DC commutation failure occurs and sending the DC commutation failure information to the UPFC voltage emergency control master station;

[0019] A UPFC voltage emergency control master station for judging whether to start UPFC voltage emergency control according to the DC commutation failure information, and if UPFC voltage emergency control is started, sending a reactive power control instruction to the UPFC execution substation based on UPFC operation information;

[0020] A UPFC execution substation for sending reactive power according to the reactive power control instruction.

[0021] A computer storage medium, the computer readable storage medium stores a computer program, the computer program is executed by a processor to realize the steps of the method.

[0022] The present application has the following advantages:

[0023] The present application takes DC commutation failure signal as the emergency control starting condition, takes the received DC operation power of DC commutation failure as the starting criterion, controls each DC with commutation failure independently, and issues an emergency reactive power control instruction to the UPFC execution substation that meets the requirements, so that the UPFC execution substation sends reactive power, thereby suppressing continuous commutation failure of DC. The present application utilizes UPFC to participate in emergency control of the power grid, which can effectively reduce the probability of continuous commutation failure of DC in the multi-DC feeding receiving end power grid, prevent DC from being blocked due to multiple commutation failures, and is beneficial to preventing large-area power failure caused by multiple DC blocking. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A flowchart of the control method of the present application.

[0025] Figure 2 A schematic diagram of the control system of the present application. DETAILED DESCRIPTION

[0026] The specific embodiments of the present application will be further described with reference to the drawings. It is to be noted that the descriptions of these embodiments are intended to assist in understanding the present application, and are in no way constituting limits to the present application. Furthermore, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0027] As shown in Figure 1 , the present application provides a UPFC emergency coordination control method for suppressing continuous commutation failure of direct current, comprising the following steps:

[0028] 1) Using a substation in the power grid control system as a direct current commutation failure information substation, receiving a direct current commutation failure signal sent by a direct current control protection system, when a direct current commutation failure occurs, sending the direct current commutation failure signal to a UPFC voltage emergency control master station by the direct current commutation failure information substation.

[0029] 2) After the UPFC voltage emergency control master station receives the direct current commutation failure signal, immediately obtaining the number of direct currents that have commutation failure, the operating power P i , the bus voltage V i of the direct current converter station before the direct current commutation failure, and the operating information of all UPFC execution substations connected to the UPFC voltage emergency control master station from the direct current commutation failure information substation.

[0030] 3) The UPFC voltage emergency control master station determines whether to start UPFC voltage emergency control according to the obtained power of the direct current that has commutation failure, if the starting condition is met, step 4) is entered, otherwise the process is ended or the detection of whether there is a direct current commutation failure signal is restarted.

[0031] 4) The UPFC voltage emergency control master station sends reactive power control instructions to the corresponding UPFC execution substations according to the monitored UPFC operating information and the control strategy.

[0032] 5) The UPFC execution substations generate reactive power according to the control instructions sent by the UPFC voltage emergency coordination control master station, until the UPFC voltage emergency control master station does not receive a direct current commutation failure signal after a certain time and exits the control.

[0033] As a preferred scheme, the UPFC operating information in step 2) includes the number of current UPFC execution substations and controllable reactive power adjustment amount Q j , where j is the number of UPFC execution substations in the power grid.

[0034] As a preferred scheme, when the following conditions are met in step 3), it is determined to start UPFC voltage emergency control:

[0035] P 总 ≥P set , wherein, P 总 = P1+ P2+…P i , P 总 is the total active power of the commutation failure DC power, P set is the set threshold value, P i is the active power of the i-th commutation failure DC, and i is the number of commutation failure DC.

[0036] The determination process of the set threshold value P set is as follows: in different operation modes of the power grid, different power values are set through offline time domain simulation calculation, and when a power value meets the condition that the power grid remains stable and has no transient stability problem when any one or more DCs simultaneously and continuously commutate failure for more than three times, the power value is determined as the set threshold value P set . The threshold value determined by this method greatly reduces the risk of frequent start of the device. Taking four DCs as an example, any one or more DCs simultaneously and continuously commutating failure for more than three times includes: one DC continuously commutating failure for more than three times, any two DCs continuously commutating failure for more than three times, any three DCs continuously commutating failure for more than three times, and four DCs continuously commutating failure for more than three times.

[0037] As a preferred scheme, the matching control strategy in step 4) is: for each commutation failure DC, the voltage sensitivity of the UPFC execution substation to the commutation failure DC commutation station is greater than or equal to the set sensitivity (i.e. η ij ≥η0) as the benchmark, the UPFC execution substation associated with the commutation failure DC is found, and the reactive power control instruction is sent to all found UPFC execution substations in order according to the order of voltage sensitivity from large to small. When the reactive power control instruction is sent to the UPFC execution substation for the first time, the size of the reactive power control instruction value is half of the controllable reactive power adjustment amount of the UPFC execution substation, i.e. Q j / 2, to reduce the frequent action of the UPFC substation with low sensitivity.

[0038] The voltage sensitivity of the UPFC execution substation to the commutation failure DC commutation station is determined by the following formula:

[0039]

[0040] ΔV i = V i -V i0 ;

[0041] wherein, η ij is the voltage sensitivity of the j-th UPFC execution substation connected to the UPFC voltage emergency control master station to the i-th commutation failure DC commutation station, and ΔQj the reactive power amount of the jth UPFC accessed by the UPFC voltage emergency control master station for substation overissue i the voltage change value of the ith commutation failure DC converter station bus, V i the voltage of the ith commutation failure DC converter station bus, V i0 the initial voltage of the ith commutation failure DC converter station bus.

[0042] As a preferred scheme, after the UPFC executing substation in step 5) first sends reactive power according to the reactive power control instruction, if continuous commutation failure occurs in a certain DC within a set time (which is generally very short), the UPFC executing substation associated with the DC continuously experiencing commutation failure is sent a continuous reactive power control instruction (i.e., the reactive power control instruction is sent again), and the size of the continuous reactive power control instruction value is equal to the controllable reactive power adjustment amount of the UPFC executing substation, i.e., Q j , until the UPFC voltage emergency control master station does not receive a DC continuous commutation failure signal within a set time to exit control.

[0043] The present application takes the DC commutation failure signal as the emergency control starting condition, takes the total power of the DC experiencing commutation failure as the starting criterion, independently controls each DC experiencing commutation failure, and issues an emergency reactive power control instruction to the executing substation whose voltage sensitivity to the DC converter station meets η ij ≥η0, and the control instruction value is half of the controllable capacity of the UPFC substation, i.e., Q j / 2. If continuous commutation failure is found in a certain DC, the controllable UPFC substation corresponding to the DC is further sent a reactive power control instruction, until the capacity is exhausted or no commutation failure signal is found. The present application utilizes UPFC to participate in emergency control of the power grid, which can effectively reduce the probability of continuous commutation failure of the multi-DC feeding receiving end power grid, prevent DC from being blocked due to multiple commutation failures, and is conducive to preventing large-area power outages caused by multiple DC blockages.

[0044] To realize the above-mentioned UPFC emergency coordination control method for suppressing continuous DC commutation failure, the present application further provides a UPFC emergency coordination control system for suppressing continuous DC commutation failure, as shown in Figure 2 , comprising

[0045] a DC commutation failure information substation for receiving DC commutation failure information when the DC experiences commutation failure and sending the DC commutation failure information to the UPFC voltage emergency control master station;

[0046] a UPFC voltage emergency control master station for judging whether to start UPFC voltage emergency control according to the DC commutation failure information, and sending a reactive power control instruction to the UPFC executing substation based on UPFC operation information if the UPFC voltage emergency control is started;

[0047] The UPFC executes a substation to send reactive power according to a reactive control instruction.

[0048] The application further provides a computer readable storage medium storing a computer program, the computer program being executed by a processor to implement the UPFC emergency coordination control method and the embodiments; or the computer program being executed by the processor to implement the functions of the modules / units in the UPFC emergency coordination system.

[0049] Those skilled in the art will further appreciate that the various illustrative logical blocks, modules, and steps described in connection with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans can implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present embodiments.

[0050] The various illustrative logical blocks, or steps, described in connection with the embodiments disclosed herein can be implemented or performed by a general purpose processor, a digital signal processor, an application specific integrated circuit (ASIC), a field programmable gate array or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor can be a microprocessor, but in the alternative, the general purpose processor can be any conventional processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, e.g., a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration.

[0051] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. The contents not described in detail in the specification belong to the prior art known by the person skilled in the art.

Claims

1. A UPFC emergency coordinated control method for suppressing direct current continuous commutation failure, characterized in that: When the DC commutation failure occurs, the DC commutation failure information is acquired, and it is determined whether to start the UPFC voltage emergency control according to the DC commutation failure information; if the UPFC voltage emergency control is started, the reactive power control instruction is sent to the UPFC execution substation based on the UPFC operation information, and the UPFC execution substation sends the reactive power according to the reactive power control instruction to suppress the continuous DC commutation failure; When the following conditions are met, it is determined to start the UPFC voltage emergency control: P 总 ≥P set , where P 总 = P1+ P2+ … Pi+ … P i , P 总 is the total active power of the DC power with commutation failure, P set is the set threshold value, P i is the active power of the i-th DC with commutation failure, and i is the number of DC with commutation failure. The set threshold value P set The determination process is as follows: in different operation modes of the power grid, different power values are set through offline time-domain simulation calculation, when a power value meets one or more than one simultaneous continuous commutation failure of the DC for more than three times, the power grid remains stable, and it is determined that the power value is the set threshold value P set .

2. The UPFC emergency co-ordinated control method for suppressing DC continuous current commutation failure according to claim 1, characterized in that: The DC commutation failure information includes the number of DCs with commutation failure, the operation power of the DC with commutation failure, and the DC converter station bus voltage.

3. The UPFC emergency co-ordinated control method for suppressing DC continuous current commutation failure according to claim 1, characterized in that: The process of sending the reactive power control instruction to the UPFC execution substation based on the UPFC operation information is as follows: for each commutation failure DC, the voltage sensitivity of the UPFC execution substation to the commutation failure DC is greater than or equal to the set sensitivity, and the UPFC execution substation associated with the commutation failure DC is searched, and the reactive power control instruction is sent to all searched UPFC execution substations in order according to the voltage sensitivity from large to small.

4. The UPFC emergency co-ordinated control method of claim 3, wherein: When the reactive power control instruction is sent to the UPFC execution substation for the first time, the value of the reactive power control instruction is half of the controllable reactive power adjustment amount of the UPFC execution substation.

5. The UPFC emergency co-ordinated control method of claim 3, wherein: The voltage sensitivity of the UPFC execution substation to the commutation failure DC is determined by the following formula: ΔV i = V i - V i0 ; wherein, η ij is the voltage sensitivity of the jth UPFC executing substation connected under the UPFC voltage emergency control master station to the ith commutation failure DC converter station; ΔQ j is the reactive power increased by the jth UPFC executing substation connected under the UPFC voltage emergency control master station, ΔV i is the voltage change value of the bus of the ith commutation failure DC converter station, V i is the bus voltage of the ith commutation failure DC converter station, V i0 is the initial voltage of the bus of the ith commutation failure DC converter station.

6. The UPFC emergency co-ordinated control method for suppressing DC continuous current commutation failure according to claim 1, characterized in that: After the UPFC execution substation sends the reactive power according to the reactive power control instruction for the first time, if a DC continuously commutates failure within a set time, the continuous reactive power control instruction is sent to the UPFC execution substation associated with the continuously commutating failure DC, and the value of the continuous reactive power control instruction is equal to the controllable reactive power adjustment amount of the UPFC execution substation.

7. A system for implementing the UPFC emergency coordinated control method for suppressing DC continuous commutation failure as claimed in claim 1, characterized in that: The DC commutation failure information substation is configured to receive the DC commutation failure information when the DC commutation failure occurs, and send the DC commutation failure information to the UPFC voltage emergency control master station. The UPFC voltage emergency control master station is configured to determine whether to start the UPFC voltage emergency control according to the DC commutation failure information, and send the reactive power control instruction to the UPFC execution substation based on the UPFC operation information if the UPFC voltage emergency control is started. The UPFC execution substation is configured to send the reactive power according to the reactive power control instruction. The computer program is executed by the processor to realize the steps of the method of any one of claims 1 to 6.

8. A computer storage medium, the computer readable storage medium having stored thereon a computer program, characterized in that: ​

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