CN106684841A - Method and device for DC short-circuit fault protection of flexible DC power grid system - Google Patents
Method and device for DC short-circuit fault protection of flexible DC power grid system Download PDFInfo
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- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
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Abstract
Description
技术领域technical field
本发明属于柔性直流输电系统继电保护技术领域，具体涉及柔性直流电网系统直流短路故障保护方法及装置。The invention belongs to the technical field of relay protection of a flexible direct current transmission system, and in particular relates to a method and a device for protecting a direct current short circuit fault of a flexible direct current power grid system.
背景技术Background technique
目前，采用模块化多电平换流器(MMC)的高压柔性直流输电是解决大规模新能源集中外送的重要途径。以我国的张北地区为例，要将张北和康保地区的风电通过柔性直流输电集中外送至北京和冀北的丰宁，需要建设四端柔性直流输电网。采用柔性直流电网进行远距离输电时，考虑到经济性，换流站之间不宜采用直流电缆，而应采用直流架空线路，但直流架空线路的应用增大了直流侧发生短路故障的概率。At present, high-voltage flexible direct current transmission using modular multilevel converters (MMCs) is an important way to solve large-scale centralized transmission of new energy. Taking the Zhangbei region of my country as an example, to transfer wind power from Zhangbei and Kangbao regions to Beijing and Fengning in northern Hebei through flexible DC transmission, it is necessary to build a four-terminal flexible DC transmission network. When the flexible DC grid is used for long-distance power transmission, considering the economy, DC cables should not be used between converter stations, but DC overhead lines should be used, but the application of DC overhead lines increases the probability of short-circuit faults on the DC side.
现有的柔性直流输电线路保护主要针对双端或多端系统，目前还没有可行的区别方法，将直流线路上断路器与电抗器之间的短路故障保护、和断路器与换流器之间的短路故障保护区别开来，现有技术中，当换流器和电抗器之间的线路上(包括断路器与电抗器之间、和断路器与换流器之间的线路)任意一处发生短路故障时，都会启动相应的保护动作，例如，如图2所示的直流线路上b点发生短路故障时，现有的保护不仅断开上述直流线路上的断路器，如断路器①，还会断开与换流器MMC相连的其他线路上的断路器，如断路器②，而实际上当b点发生短路故障时只需断开b点所在直流线路上的断路器，即隔离b点所在的直流线路，其他线路可继续正常运行。The existing flexible DC transmission line protection is mainly aimed at double-terminal or multi-terminal systems. At present, there is no feasible method to distinguish between the short-circuit fault protection between the circuit breaker and the reactor on the DC line, and the protection between the circuit breaker and the converter. In the prior art, when a fault occurs anywhere on the line between the converter and the reactor (including the line between the circuit breaker and the reactor, and the line between the circuit breaker and the converter) When a short-circuit fault occurs, corresponding protection actions will be activated. For example, when a short-circuit fault occurs at point b on the DC line as shown in Figure 2, the existing protection not only disconnects the circuit breaker on the above-mentioned DC line, such as circuit breaker ①, but also It will disconnect the circuit breaker on other lines connected to the converter MMC, such as circuit breaker ②, but in fact, when a short-circuit fault occurs at point b, it only needs to disconnect the circuit breaker on the DC line where point b is located, that is, to isolate the circuit breaker where point b is located the DC line, other lines can continue to operate normally.
发明内容Contents of the invention
本发明的目的是提供一种柔性直流电网系统直流短路故障保护方法及装置，用于解决现有技术中换流器和电抗器之间的短路故障保护切断无故障线路的问题。The purpose of the present invention is to provide a DC short-circuit fault protection method and device for a flexible DC power grid system, which is used to solve the problem in the prior art that the short-circuit fault protection between the converter and the reactor cuts off the non-faulty line.
为解决上述技术问题，本发明提出一种柔性直流电网系统直流短路故障保护方法，对于一条直流线路，将其一侧换流器与近端线路电抗器之间的部分分为第一、第二两个保护区域，第一保护区域包括近端线路的电抗器与直流断路器之间的区域，第二保护区域包括直流断路器与换流器之间的区域；In order to solve the above technical problems, the present invention proposes a DC short-circuit fault protection method for a flexible DC grid system. For a DC line, the part between the converter on one side and the near-end line reactor is divided into first and second Two protection areas, the first protection area includes the area between the reactor of the near-end line and the DC circuit breaker, and the second protection area includes the area between the DC circuit breaker and the converter;
对于第一保护区域，以直流断路器电流和近端线路电抗器电流作为差动输入，执行差动保护，若第一保护区域内发生短路故障，则至少发出对应线路近端直流断路器跳闸指令；For the first protection area, the DC circuit breaker current and the near-end line reactor current are used as differential inputs to implement differential protection. If a short-circuit fault occurs in the first protection area, at least a trip command for the corresponding line near-end DC circuit breaker is issued. ;
对于第二保护区域，以换流阀出口直流母线电流、与换流器相连的所有线路的近端直流断路器电流为差动输入，执行差动保护，若第二保护区域内故障，则至少发出与换流器相连的所有线路近端断路器的跳闸指令。For the second protection area, the DC bus current at the outlet of the converter valve and the current of the near-end DC circuit breakers of all lines connected to the converter are used as differential inputs to implement differential protection. If there is a fault in the second protection area, at least Issue a trip command for all line-near circuit breakers connected to the inverter.
进一步，所述第一保护区域、第二保护区域的差动保护是以差动电流变化率为判据的差动保护。Further, the differential protection in the first protection area and the second protection area is a differential protection based on a differential current change rate criterion.
进一步，所述第一、第二保护区域内发生短路故障时，还向所述直流线路上对应的远端直流断路器发出跳闸指令。Further, when a short-circuit fault occurs in the first and second protection areas, a trip command is also sent to the corresponding remote DC circuit breaker on the DC line.
进一步，对于所述一条直流线路，还包括近端线路电抗器与远端线路电抗器之间的第三保护区域，对于第三保护区域，执行行波保护和电压突变量保护，若区域内发生短路故障，则发出对应线路两端直流断路器跳闸指令。Further, for the one DC line, a third protection area between the near-end line reactor and the far-end line reactor is also included, and for the third protection area, traveling wave protection and voltage mutation protection are implemented. If there is a short-circuit fault, a trip command will be issued for the DC circuit breakers at both ends of the corresponding line.
为解决上述技术问题，本发明提出一种柔性直流电网系统直流短路故障保护装置，包括以下单元：In order to solve the above technical problems, the present invention proposes a DC short-circuit fault protection device for a flexible DC grid system, which includes the following units:
用于对一条直流线路，将其一侧换流器与近端线路电抗器之间的部分分为第一、第二两个保护区域，第一保护区域包括近端线路的电抗器与直流断路器之间的区域，第二保护区域包括直流断路器与换流器之间的区域的单元；For a DC line, the part between the converter on one side and the near-end line reactor is divided into the first and second two protection areas, the first protection area includes the reactor of the near-end line and the DC circuit breaker The area between the breakers, the second protection area includes the units in the area between the DC circuit breaker and the converter;
用于对第一保护区域，以直流断路器电流和近端线路电抗器电流作为差动输入，执行差动保护，若第一保护区域内发生短路故障，则至少发出对应线路近端直流断路器跳闸指令的单元；For the first protection area, the current of the DC circuit breaker and the current of the near-end line reactor are used as differential inputs to perform differential protection. If a short-circuit fault occurs in the first protection area, at least the corresponding line near-end DC circuit breaker unit of trip command;
用于对第二保护区域，以换流阀出口直流母线电流、与换流器相连的所有线路的近端直流断路器电流为差动输入，执行差动保护，若第二保护区域内故障，则至少发出与换流器相连的所有线路近端断路器的跳闸指令的单元。For the second protection area, the DC bus current at the outlet of the converter valve and the near-end DC circuit breaker current of all lines connected to the converter are used as differential inputs to perform differential protection. If there is a fault in the second protection area, Then at least a unit that issues tripping commands for all line-near circuit breakers connected to the converter.
进一步，所述第一保护区域、第二保护区域的差动保护是以差动电流变化率为判据的差动保护。Further, the differential protection in the first protection area and the second protection area is a differential protection based on a differential current change rate criterion.
进一步，所述第一、第二保护区域内发生短路故障时，还包括用于向所述直流线路上对应的远端直流断路器发出跳闸指令的单元。Further, when a short-circuit fault occurs in the first and second protection areas, it further includes a unit for sending a trip command to a corresponding remote DC circuit breaker on the DC line.
进一步，对所述一条直流线路，还包括用于将近端线路电抗器与远端线路电抗器之间的部位定义为第三保护区域，对于第三保护区域，执行行波保护和电压突变量保护，若区域内发生短路故障，则发出对应线路两端直流断路器跳闸指令的单元。Further, for the one DC line, it also includes defining the part between the near-end line reactor and the far-end line reactor as the third protection area, and for the third protection area, implementing traveling wave protection and voltage mutation amount Protection, if a short-circuit fault occurs in the area, it will issue a unit that trips the DC circuit breaker at both ends of the corresponding line.
本发明的有益效果是：将直流线路一侧换流器与近端线路电抗器之间的部分分为第一、第二保护区域，其中，近端线路的电抗器与直流断路器之间区域为第一保护区域，直流断路器与换流器之间为第二保护区域，并对第一、第二保护区域内的短路故障进行相应的保护。该方法能有效识别直流线路上断路器与电抗器之间(第一保护区域)的短路故障保护，以及断路器与换流器之间(第二保护区域)的短路故障保护，当任一保护区域发生短路故障，都不会影响另一保护区域的正常运行，保证了无故障线路不被错切的问题，实现直流线路上短路故障准确和快速隔离。The beneficial effect of the present invention is that the part between the converter on one side of the DC line and the near-end line reactor is divided into the first and second protection areas, wherein the area between the reactor of the near-end line and the DC circuit breaker It is the first protection area, and the second protection area is between the DC circuit breaker and the converter, and corresponding protection is carried out for short-circuit faults in the first and second protection areas. This method can effectively identify the short-circuit fault protection between the circuit breaker and the reactor (the first protection area) and the short-circuit fault protection between the circuit breaker and the converter (the second protection area) on the DC line. If a short-circuit fault occurs in one area, it will not affect the normal operation of another protection area, ensuring that the non-faulty line will not be miscut, and realizing accurate and rapid isolation of short-circuit faults on the DC line.
附图说明Description of drawings
图1是本发明柔性直流电网系统直流短路故障保护配置方案示意图；Fig. 1 is a schematic diagram of a DC short-circuit fault protection configuration scheme of a flexible DC power grid system according to the present invention;
图2是换流器直流侧短路故障分区示意图；Figure 2 is a schematic diagram of the DC side short-circuit fault zone of the converter;
图3是第一保护区域的短路故障隔离示意图；Fig. 3 is a schematic diagram of short-circuit fault isolation in the first protection zone;
图4是第二保护区域的短路故障隔离示意图；Fig. 4 is a schematic diagram of short-circuit fault isolation in the second protection zone;
图5是第三保护区域的短路故障隔离示意图；Fig. 5 is a schematic diagram of short-circuit fault isolation in the third protection zone;
图6是保护动作逻辑示意图。Fig. 6 is a schematic diagram of protection action logic.
具体实施方式detailed description
下面结合附图对本发明的具体实施方式作进一步的说明。The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.
本发明一种柔性直流电网系统直流短路故障保护方法的实施例：An embodiment of a DC short-circuit fault protection method for a flexible DC power grid system according to the present invention:
对于一条直流线路，将其一侧换流器与近端线路电抗器之间的部分分为第一、第二两个保护区域，第一保护区域包括近端线路的电抗器与直流断路器之间的区域，第二保护区域包括直流断路器与换流器之间的区域；将近端线路电抗器与远端线路电抗器之间的部位定义为第三保护区域。For a DC line, the part between the converter on one side and the near-end line reactor is divided into the first and second two protection areas. The first protection area includes the reactor between the near-end line and the DC circuit breaker. The area between the second protection area includes the area between the DC circuit breaker and the converter; the area between the near-end line reactor and the remote line reactor is defined as the third protection area.
对于第一保护区域，以直流断路器电流和近端线路电抗器电流作为差动输入，执行差动保护，若第一保护区域内发生短路故障，则至少发出对应线路近端直流断路器跳闸指令。对于第二保护区域，以换流阀出口直流母线电流、与换流器相连的所有线路的近端直流断路器电流为差动输入，执行差动保护，若第二保护区域内故障，则至少发出与换流器相连的所有线路近端断路器的跳闸指令。对于第三保护区域，执行行波保护和电压突变量保护，若区域内发生短路故障，则发出对应线路两端直流断路器跳闸指令。For the first protection area, the DC circuit breaker current and the near-end line reactor current are used as differential inputs to implement differential protection. If a short-circuit fault occurs in the first protection area, at least a trip command for the corresponding line near-end DC circuit breaker is issued. . For the second protection area, the DC bus current at the outlet of the converter valve and the current of the near-end DC circuit breakers of all lines connected to the converter are used as differential inputs to implement differential protection. If there is a fault in the second protection area, at least Issue a trip command for all line-near circuit breakers connected to the inverter. For the third protection area, the traveling wave protection and voltage mutation protection are implemented. If a short circuit fault occurs in the area, a trip command for the DC circuit breaker at both ends of the corresponding line will be issued.
具体的，如图2所示的换流器，采用MMC拓扑结构，以直流断路器①所在的第一直流线路为例，将第一直流线路的近端线路上的电抗器与直流断路器①设为第一保护区域，将直流断路器①与换流器MMC之间的区域设为第二保护区域，将第一直流线路的近端线路上的电抗器与远端线路上的电抗器之间设为第三保护区域。采集第一保护区域两侧进出线的电流i2、i3，执行差动保护：当i2、i3的差动电流变化率的绝对值超过第一整定值时，判定第一保护区域发生短路故障(例如b点发生短路)，判定公式如下：Specifically, the converter shown in Figure 2 adopts the MMC topology. Taking the first DC line where the DC circuit breaker ① is located as an example, the reactor on the near-end line of the first DC line and the DC breaker Set the breaker ① as the first protection area, set the area between the DC circuit breaker ① and the converter MMC as the second protection area, and set the reactor on the near-end line of the first DC line and the reactor on the far-end line The third protection area is set between the reactors. Collect the currents i 2 and i 3 of the incoming and outgoing lines on both sides of the first protection area, and implement differential protection: when the absolute value of the differential current change rate of i 2 and i 3 exceeds the first setting value, it is determined that the first protection area has occurred Short-circuit fault (for example, a short-circuit occurs at point b), the judgment formula is as follows:
式中，dibset为第一整定值，识别第一保护区域发生短路故障后，触发第一直流线路近端线路上的直流断路器①，以及远端线路上的直流断路器，如图3所示，实现该短路故障快速隔离。In the formula, di bset is the first setting value, after identifying the short-circuit fault in the first protection area, trigger the DC circuit breaker ① on the near-end line of the first DC line, and the DC circuit breaker on the remote line, as shown in Figure 3 As shown, the short-circuit fault can be quickly isolated.
采集第一保护区域两侧进出线的电流i2、i3的同时，还需采集第二保护区域中换流器MMC出线侧电流i1，以及与换流器MMC相连的另一线路上直流断路器②进线端的电流i4，执行差动保护：当i1、i2、i4的差动电流变化率的绝对值超过第二整定值时，判定第二保护区域发生短路故障(例如a点发生短路)，判定公式如下：While collecting the current i 2 and i 3 of the incoming and outgoing lines on both sides of the first protection area, it is also necessary to collect the current i 1 on the outgoing line side of the converter MMC in the second protection area, and the DC disconnection on another line connected to the converter MMC The current i 4 at the input terminal of the device ② performs differential protection: when the absolute value of the differential current change rate of i 1 , i 2 , i 4 exceeds the second setting value, it is determined that a short-circuit fault has occurred in the second protection area (for example, a point short circuit), the judgment formula is as follows:
式中，diaset为第二整定值，识别第二保护区域发生短路故障后，触发第一直流线路近端线路上的直流断路器①、另一线路近端线路上的直流断路器②，以及第一直流线路和另一线路的远端线路上的直流断路器，如图4所示，实现快速隔离该短路故障。In the formula, di aset is the second setting value. After identifying the short-circuit fault in the second protection area, trigger the DC circuit breaker ① on the near-end line of the first DC line and the DC circuit breaker ② on the near-end line of the other line, And the DC circuit breaker on the remote line of the first DC line and the other line, as shown in FIG. 4 , realizes rapid isolation of the short-circuit fault.
对于第一直流线路上近端线路电抗器与远端线路电抗器之间的第三保护区域，执行行波保护和电压突变量保护，若区域内发生短路故障(例如c点短路)，则发出对应线路两端直流断路器跳闸指令，如图5所示。其中，行波保护原理为：For the third protection area between the near-end line reactor and the far-end line reactor on the first DC line, carry out traveling wave protection and voltage mutation protection, if a short-circuit fault occurs in the area (for example, point c short circuit), then Issue a trip command for the DC circuit breakers at both ends of the corresponding line, as shown in Figure 5. Among them, the principle of traveling wave protection is:
式中，Pdif为直流侧极模波；Gcom为直流侧地模波；Zdif为直流侧极模波阻抗；Zcom为直流侧地模波阻抗；Idif、Udif为系统差模分量；Icom、Ucom为系统共模分量；△1为极波变化率整定值；△2为极波整定值；△3为地模波整定值。In the formula, P dif is the DC side polar mode wave; G com is the DC side ground mode wave; Z dif is the DC side polar mode wave impedance; Z com is the DC side ground mode wave impedance; I dif and U dif are the system differential mode Component; I com , U com are system common mode components; △1 is the setting value of polar wave change rate; △2 is the setting value of polar wave; △3 is the setting value of ground mode wave.
电压突变量保护原理为：The principle of voltage mutation protection is as follows:
式中，duset为电压变化率整定值；Uset为直流电压整定值；diset为直流电流变化率整定值。In the formula, du set is the setting value of voltage change rate; U set is the setting value of DC voltage; dis set is the setting value of DC current rate of change.
本发明直流断路器的快速触发方案如下：当第二保护区域故障时，需要同时断开与故障换流站相连的所有直流线路两端的直流断路器才能够实现故障线路的准确隔离，如图4所示；当第一保护区域、直流线路上近端线路电抗器与远端线路电抗器之间的区域发生故障时，仅需要断开故障点所在直流线路两端的直流断路器，即可准确隔离故障线路，如图3所示；当第一保护区域、第二保护区域故障时，远端换流站将检测不到故障，但又必须触发直流断路器断开，因此就必须接受近端故障的检测与定位结果并触发断路器动作。The quick triggering scheme of the DC circuit breaker of the present invention is as follows: when the second protection area fails, it is necessary to disconnect the DC circuit breakers at both ends of all DC lines connected to the faulty converter station at the same time to achieve accurate isolation of the faulty line, as shown in Figure 4 As shown; when a fault occurs in the first protection area, the area between the near-end line reactor and the far-end line reactor on the DC line, it is only necessary to disconnect the DC circuit breakers at both ends of the DC line where the fault point is located to accurately isolate The fault line is shown in Figure 3; when the first protection area and the second protection area fail, the remote converter station will not detect the fault, but must trigger the DC circuit breaker to disconnect, so the near-end fault must be accepted The detection and location results and trigger the circuit breaker action.
由此可知，直流断路器的开断动作受四个指令控制，近端线路故障检测结果、近端直流断路器与线路电抗之间故障检测结果、近端直流断路器阀侧短路故障检测结果，以及远端直流断路器动作指令。It can be seen that the breaking action of the DC circuit breaker is controlled by four instructions, the detection result of the near-end line fault, the detection result of the fault between the near-end DC circuit breaker and the line reactance, the detection result of the short-circuit fault on the valve side of the near-end DC circuit breaker, And remote DC circuit breaker action command.
(1)近端线路故障检测结果：当近端直流线路故障检测装置检测到第三保护区域内发生短路故障时，指示该故障并触发近端直流断路器断开，同时远端故障检测装置检测到线路故障并触发远端直流断路器断开，实现故障线路的隔离。(1) Near-end line fault detection results: When the near-end DC line fault detection device detects a short-circuit fault in the third protection area, it indicates the fault and triggers the near-end DC circuit breaker to disconnect, and the remote fault detection device detects It detects the line fault and triggers the disconnection of the remote DC circuit breaker to realize the isolation of the faulty line.
(2)近端直流断路器与线路电抗之间故障检测结果：当检测装置检测到第一保护区域内发生短路故障时，指示该位置发生故障，并触发近端直流断路器断开，但此时远端故障检测装置无法检测到该故障，无法触发远端直流断路器断开，因此需要将近端故障检测结果传输至远端来触发远端直流断路器断开，实现故障线路的隔离。(2) Fault detection results between the near-end DC circuit breaker and the line reactance: When the detection device detects a short-circuit fault in the first protection area, it indicates that a fault occurs in this location and triggers the near-end DC circuit breaker to disconnect, but this At this time, the remote fault detection device cannot detect the fault and cannot trigger the disconnection of the remote DC circuit breaker. Therefore, it is necessary to transmit the detection result of the local fault to the remote end to trigger the disconnection of the remote DC circuit breaker to realize the isolation of the faulty line.
(3)近端直流断路器阀侧短路故障检测结果：当检测装置检测到第二保护区域内发生短路故障时，指示该区域发生故障，并触发所有与故障换流站相连的直流线路近端直流断路器断开，但此时其它远端故障检测装置无法检测到该故障，无法触发远端直流断路器断开，因此需要将近端故障检测结果传输至远端来触发远端直流断路器断开，实现故障线路的隔离。(3) Detection results of short-circuit faults on the valve side of the near-end DC circuit breaker: When the detection device detects a short-circuit fault in the second protection area, it indicates that a fault has occurred in this area, and triggers all near-end DC lines connected to the faulty converter station The DC circuit breaker is disconnected, but at this time other remote fault detection devices cannot detect the fault and cannot trigger the disconnection of the remote DC circuit breaker. Therefore, it is necessary to transmit the detection results of the local fault to the remote end to trigger the remote DC circuit breaker Disconnect to isolate the faulty line.
(4)远端直流断路器动作指令：与上述(2)、(3)的分析类似，当远端直流断路器与线路电抗之间线路或远端直流母线发生故障时，近端保护装置检测不到故障，需要将远端的直流断路器动作指令传输至近端，触发近端断路器断开实现故障线路的隔离。(4) Remote DC circuit breaker action command: Similar to the analysis of (2) and (3) above, when the line between the remote DC circuit breaker and the line reactance or the remote DC bus fails, the near-end protection device detects If there is no fault, it is necessary to transmit the action command of the remote DC circuit breaker to the near end to trigger the disconnection of the near end circuit breaker to isolate the faulty line.
上述四种情况均应触发直流断路器动作开断，因此直流断路器开断指令由四者共同发出，当至少一个检测结果有效时，直流断路器即动作开断，如图6所示。The above four situations should trigger the DC circuit breaker to open, so the DC circuit breaker opening command is issued by the four together. When at least one detection result is valid, the DC circuit breaker will immediately open, as shown in Figure 6.
本发明基于行波保护原理与突变量保护原理，通过对电流变化率、电压变化率和变化量，以及差动电流变化率，并根据故障位置的不同，将故障分为三个区域的故障：直流电抗线路侧故障、直流断路器与直流电抗器之间的故障和近端直流断路器阀侧的故障。Based on the principle of traveling wave protection and sudden change protection, the present invention divides the faults into three fault areas by analyzing the rate of change of current, the rate of change of voltage and the amount of change, and the rate of change of differential current, and according to the different fault locations: Faults on the DC reactor line side, faults between the DC circuit breaker and the DC reactor, and faults on the valve side of the near-end DC circuit breaker.
当直流电抗器线路侧故障(指直流线路上两个直流电抗器之间所发生的故障)时，线路两端所配置的行波保护、电压突变量保护策略均能够检测到故障，并触发断路器动作。When there is a fault on the line side of the DC reactor (referring to the fault that occurs between two DC reactors on the DC line), the traveling wave protection and voltage mutation protection strategies configured at both ends of the line can detect the fault and trigger the circuit breaker device action.
当直流断路器与直流电抗器之间部分直流线路发生故障时，远端所配置保护策略无法检测到故障，而近端通过检测直流电抗线路侧、直流断路器线路侧的两个测点的差动电流变化率实现故障检测与定位，进而触发直流断路器动作，并将断路器动作信号传输至远端直流断路器。When a fault occurs on a part of the DC line between the DC circuit breaker and the DC reactor, the protection strategy configured at the far end cannot detect the fault, and the near end detects the difference between the two measuring points on the DC reactance line side and the DC circuit breaker line side. The rate of change of dynamic current realizes fault detection and location, and then triggers the action of the DC circuit breaker, and transmits the action signal of the circuit breaker to the remote DC circuit breaker.
当近端直流断路器阀侧故障(指直流断路器与换流器之间直流线路的故障)时，远端所配置保护策略同样无法检测到故障，而近端通过检测换流阀出口直流母线电流，与换流器相连的所有线路的近端直流断路器电流的变化率实现故障检测与定位，进而触发直流断路器动作，并将断路器动作信号传输至远端直流断路器。When the valve side of the near-end DC circuit breaker fails (referring to the fault of the DC line between the DC circuit breaker and the converter), the protection strategy configured at the far end cannot detect the fault, and the near-end detects the DC bus outlet of the converter valve. Current, the rate of change of the near-end DC circuit breaker current of all lines connected to the converter realizes fault detection and location, and then triggers the DC circuit breaker action, and transmits the circuit breaker action signal to the remote DC circuit breaker.
综上所述，本发明提出的短路故障保护方法针对柔性直流电网系统，在直流线路的任意处发生短路故障时，都能实现故障的快速检测与定位。To sum up, the short-circuit fault protection method proposed by the present invention is aimed at the flexible DC power grid system, and can quickly detect and locate the fault when a short-circuit fault occurs anywhere on the DC line.
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