技术领域technical field
本发明属于交流输电系统的继电保护技术领域，更具体地，涉及一种提高串补线路电流差动保护动作性能的方法。The invention belongs to the technical field of relay protection for AC power transmission systems, and more specifically relates to a method for improving the operating performance of series-compensated line current differential protection.
背景技术Background technique
输电线路加装串联电容补偿装置可提高超高压远距离输电线路的输电能力和系统稳定性，且对输电通道上的潮流分布具有一定的调节作用，因此得到了越来越广泛的应用。串联在输电线路中、以补偿线路感抗为目的、由电容器及其控制保护等设备组成的装置，称之为串联电容补偿装置，简称串补。串补线路即指装设了串联电容补偿装置的输电线路。随着近年来电网结构的不断加强，许多安装串补的线路出现了串补本身容抗大于串补安装点背后系统总等值电抗的状况，当串补线路靠近串补安装处发生短路故障时，特别是发生单相带大过渡电阻接地故障，线路两侧故障电流可能发生电流反向，即从母线流向故障点的电流超前系统等值电源电势(无串补时从母线流向故障点的电流滞后系统等值电源电势)。The installation of series capacitor compensation devices on transmission lines can improve the transmission capacity and system stability of ultra-high voltage long-distance transmission lines, and has a certain adjustment effect on the power flow distribution on transmission channels, so it has been more and more widely used. The device connected in series in the transmission line for the purpose of compensating the inductive reactance of the line, consisting of capacitors and their control and protection equipment, is called a series capacitance compensation device, or series compensation for short. The series compensation line refers to the transmission line equipped with a series capacitor compensation device. With the continuous strengthening of the power grid structure in recent years, many lines installed with series compensation have the situation that the capacitance reactance of the series compensation itself is greater than the total equivalent reactance of the system behind the installation point of the series compensation. , especially when a single-phase grounding fault with a large transition resistance occurs, the fault current on both sides of the line may be reversed, that is, the current flowing from the bus to the fault point is ahead of the equivalent power supply potential of the system (the current flowing from the bus to the fault point when there is no series compensation hysteresis system equivalent supply potential).
电流差动保护是电力系统中性能最为优越的一种保护，广泛应用于高压输电线路，其动作性能主要由其动作判据来决定。目前高压输电线路广泛使用的保护判据是基于故障后故障点两侧线路故障电流是由线路两端母线流向故障点的，因此串补导致电流反向的出现将严重影响分相电流差动保护的动作性能，甚至串补线路电流差动保护可能拒动。Current differential protection is a kind of protection with the most superior performance in the power system, which is widely used in high-voltage transmission lines, and its operating performance is mainly determined by its operating criteria. At present, the protection criterion widely used in high-voltage transmission lines is based on the fact that after a fault, the fault current on both sides of the fault point flows from the busbars at both ends of the line to the fault point. Therefore, the occurrence of current reversal caused by series compensation will seriously affect the phase-separated current differential protection. The operating performance of the series compensation line current differential protection may even refuse to operate.
发明内容Contents of the invention
针对现有技术的以上缺陷或改进需求，本发明提供了一种提高串补线路电流差动保护动作性能的方法，其目的在于解决现有技术存在的在串补线路应用时，发生内部故障时动作性能不佳甚至保护可能拒动的问题。In view of the above defects or improvement needs of the prior art, the present invention provides a method for improving the operating performance of the current differential protection of the series-compensated line. Poor action performance and even guards that may refuse to move.
本发明提供了一种提高串补线路电流差动保护动作性能的方法，包括下述步骤：The invention provides a method for improving the operating performance of the series-compensated line current differential protection, which includes the following steps:
S1：当串补线路发生故障且电流差动保护启动后，采集串补线路故障点两侧的第一故障电流和第二故障电流S1: When the series compensation line fails and the current differential protection starts, collect the first fault current on both sides of the fault point of the series compensation line and the second fault current
其中故障点两侧的电流是指输电线路两端的电流，可以通过获取串补线路两端的线路保护所在处的电流来获得。当输电线路发生内部故障，故障点两侧的线路电流不再一样，因此有故障线路两侧电流的说法。The current on both sides of the fault point refers to the current at both ends of the transmission line, which can be obtained by obtaining the current at the line protection at both ends of the series-compensated line. When an internal fault occurs on the transmission line, the line current on both sides of the fault point is no longer the same, so there is a saying of current on both sides of the fault line.
作为本发明的一个实施例，采集故障电流可以采用如下技术手段：通过电流互感器获得。电流互感器可以把数值较大的一次电流通过一定的变比转换为数值较小的二次电流，用来进行保护、测量等用途。如变比为400/5的电流互感器，可以把实际为400A的电流转变为5A的电流。As an embodiment of the present invention, the following technical means may be used to collect the fault current: obtain it through a current transformer. The current transformer can convert the primary current with a large value into a secondary current with a small value through a certain transformation ratio, which is used for protection, measurement and other purposes. For example, a current transformer with a transformation ratio of 400/5 can convert the actual 400A current into a 5A current.
S2：判断所述第一故障电流和第二故障电流是否满足保护判据若是，则电流差动保护动作，断路器跳闸；若否，则电流差动保护不动作。S2: Judge the first fault current and the second fault current Whether the protection criterion is met If yes, the current differential protection operates and the circuit breaker trips; if not, the current differential protection does not operate.
本发明采用保护判据在系统正常运行或区外故障时，线路两侧电流幅值接近，该部分动作增量接近于零，不会增加误动风险；在区内故障时，由于串补线路发生电流反向的故障均为故障点接近串补安装处的故障，因此两侧故障电流幅值相差较大，因此该部分动作增量能有效增加动作量，提高了保护的动作灵敏度，有效降低了拒动风险，从而大大提高了保护的可靠性；且本发明提出的保护判据原理简单明确，仅在原有保护判据的基础上修改即可，易于对现有的微机保护改进。The present invention adopts protection criterion When the system is running normally or there is a fault outside the zone, the current amplitude on both sides of the line is close, and the action increment of this part is close to zero, which will not increase the risk of misoperation; Both are faults where the fault point is close to the installation of the series compensation, so the fault current amplitude difference on both sides is relatively large, so the action increment of this part can effectively increase the action amount, improve the action sensitivity of the protection, and effectively reduce the risk of refusal to operate, thereby The reliability of the protection is greatly improved; and the principle of the protection criterion proposed by the invention is simple and clear, and only needs to be modified on the basis of the original protection criterion, which is easy to improve the existing microcomputer protection.
附图说明Description of drawings
图1为本发明实施例提供的一种提高串补线路电流差动保护动作性能的方法的实现流程图。Fig. 1 is a flow chart of an implementation of a method for improving the operating performance of a series-compensated line current differential protection provided by an embodiment of the present invention.
图2为含串补线路系统等效示意图。Figure 2 is an equivalent schematic diagram of a line system with series compensation.
具体实施方式detailed description
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。In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.
本发明提供了一种提高串补线路电流差动保护动作性能的方法；该方法改进了现有的电流差动保护判据，增加了保护的动作灵敏度，有效的降低了保护拒动风险，提高了保护的可靠性。The invention provides a method for improving the operating performance of the current differential protection of the series-compensated line; the method improves the existing current differential protection criterion, increases the action sensitivity of the protection, effectively reduces the risk of protection rejection, and improves protection reliability.
如图1所示，本发明一种提高串补线路电流差动保护动作性能的方法包括以下步骤：As shown in Figure 1, a method for improving the operating performance of series-compensated line current differential protection in the present invention includes the following steps:
(1)串补线路发生故障，电流差动保护启动元件动作；(1) A fault occurs in the series compensation line, and the starting element of the current differential protection operates;
(2)采集故障线路两侧的电流计算其中为保护装置启动后一周波的电流；(2) Collect the current on both sides of the fault line calculate in It is the current of one cycle after the protection device is activated;
(3)采用如下保护判据：(3) Adopt the following protection criteria:
其中KD为动作系数，一般取1即可，KZ为制动系数，Iop0为电流门槛定值。KZ、Iop0均由生产厂家在装置内部整定。KZ的值小于1，典型值如0.6、0.8，Iop0一般较小，典型值如0。为的幅值。Among them, KD is the action coefficient, generally 1 is sufficient, KZ is the braking coefficient, and Iop0 is the fixed value of the current threshold. KZ and Iop0 are all set by the manufacturer inside the device. The value of KZ is less than 1, with a typical value such as 0.6, 0.8, and Iop0 is generally small, with a typical value such as 0. for the magnitude of .
(4)若满足保护判据，则电流差动保护动作，若不满足，则电流差动保护不动作。(4) If the protection criterion is met, the current differential protection operates; if not, the current differential protection does not operate.
本发明提供的提高继电保护整定计算效率的方法具有以下优点：The method for improving the calculation efficiency of relay protection setting provided by the present invention has the following advantages:
(1)本发明提出的保护判据中，增加了动作增量在系统正常运行或区外故障时，线路两侧电流幅值接近，该部分动作增量接近于零，不会增加误动风险；在区内故障时，由于串补线路发生电流反向的故障均为故障点接近串补安装处的故障，因此两侧故障电流值相差较大，因此该部分动作增量能有效增加动作量，提高了保护的动作灵敏度，有效降低了拒动风险，从而大大提高了保护的可靠性；(1) In the protection criterion proposed by the present invention, an action increment is added When the system is running normally or there is a fault outside the zone, the current amplitude on both sides of the line is close, and the action increment of this part is close to zero, which will not increase the risk of misoperation; Both are faults where the fault point is close to the installation of the series compensation, so the fault current values on both sides differ greatly, so the action increment of this part can effectively increase the action amount, improve the action sensitivity of the protection, and effectively reduce the risk of refusal to operate, thus greatly Improved reliability of protection;
(2)本发明提出的保护判据原理简单明确，仅在原有保护判据的基础上修改即可，易于对现有的微机保护改进；(2) The principle of the protection criterion proposed by the present invention is simple and clear, and only needs to be modified on the basis of the original protection criterion, which is easy to improve the existing microcomputer protection;
下面结合具体实施例进一步说明本发明实施例提供的一种提高串补线路电流差动保护动作性能的方法；详述如下：A method for improving the operating performance of the series-compensated line current differential protection provided by the embodiment of the present invention is further described below in conjunction with specific embodiments; the details are as follows:
采用本发明方法对华北电网装设有串补的万顺一串、万顺二串进行了仿真研究，该系统等效系统示意图如图2所示。串补安装在万全站内，系统运行方式为大方式，考虑系统电阻，不考虑串补MOV保护。在万顺一串设置故障，故障类型为单相带过渡电阻接地故障，过渡电阻设为100欧，结果如表1所示。表1中故障位置是指故障点距离万全站的线路长度占线路全长的百分比。电流值为采用标幺值表示，系统基准容量为1000MVA，基准电压为525kV。Using the method of the present invention, a simulation study has been carried out on the first series of Wanshun and the second series of Wanshun equipped with series compensation in the North China power grid. The equivalent system diagram of the system is shown in Figure 2. The series compensation is installed in the Wanquan station, and the system operates in the large mode, considering the system resistance and not considering the series compensation MOV protection. Set the fault in Wanshun series, the fault type is single-phase ground fault with transition resistance, and the transition resistance is set to 100 ohms, the results are shown in Table 1. The fault location in Table 1 refers to the percentage of the line length from the fault point to the Wanquan station to the total line length. The current value is represented by per unit value, the system reference capacity is 1000MVA, and the reference voltage is 525kV.
由表1可见，在故障点接近串补侧母线时，故障后线路两侧电流相角接近180度，发生了电流反向。输电线路电流差动保护判据为其中为线路两侧电流相量和的模值，为线路两侧电流相量差的模值，KZ为制动系数，取值小于1，Iop0为电流门槛定值。KZ、Iop0均由生产厂家在装置内部整定。当保护判据满足时，保护动作。这里取典型值Iop0＝0，KZ＝0.6，即保护判据为It can be seen from Table 1 that when the fault point is close to the bus on the series compensation side, the current phase angle on both sides of the line after the fault is close to 180 degrees, and the current reverse occurs. The criterion for current differential protection of transmission line is in is the modulus of the sum of the current phasors on both sides of the line, is the modulus value of the current phasor difference on both sides of the line, KZ is the braking coefficient, and the value is less than 1, and Iop0 is the fixed value of the current threshold. KZ and Iop0 are all set by the manufacturer inside the device. When the protection criterion is satisfied, the protection action. Here take the typical value Iop0 =0, KZ =0.6, that is, the protection criterion is
以故障点位置为1％处为例，对应于保护判据，则因此动作量小于制动量对于传统保护来说，即使采取降低制动系数的方法，但由于考虑到误动风险，制动系数一般不会太小，对于本例中取0.6，保护判据仍然不满足，因此存在拒动风险。Taking the fault point at 1% as an example, corresponding to the protection criterion, but Therefore the amount of action less than braking For traditional protection, even if the method of reducing the braking coefficient is adopted, the braking coefficient is generally not too small due to the risk of misoperation. For this example, the protection criterion is still not satisfied when 0.6 is taken, so there is a refusal to operate risk.
采用本发明提出的电流差动保护判据，可取KD＝1，Iop0＝0，KZ＝0.6，则动作量大于制动量保护判据满足，保护可以正确动作，不存在拒动风险。Using the current differential protection criterion proposed by the present invention, KD = 1, Iop0 = 0, KZ = 0.6, then amount of movement greater than the amount of braking The protection criterion is satisfied, the protection can operate correctly, and there is no risk of refusal to operate.
本发明提出了一种适用于串补线路电流差动保护的新判据，原理简单明确，仅在原有保护判据的基础上修改即可，易于对现有的微机保护改进，在不增加误动风险的基础上提高了保护的动作灵敏度，有效降低了拒动风险，从而大大提高了保护的可靠性。The present invention proposes a new criterion suitable for the current differential protection of series-compensated lines. The principle is simple and clear, and only the original protection criterion can be modified. On the basis of reducing the risk of movement, the action sensitivity of the protection is improved, and the risk of refusal to operate is effectively reduced, thereby greatly improving the reliability of the protection.
表1万顺一串单相接地故障仿真结果Table 1 Simulation results of a series of single-phase ground faults in Wanshun
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。It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.
| Application Number | Priority Date | Filing Date | Title |
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| CN201410050950.5ACN103779845B (en) | 2014-02-14 | 2014-02-14 | A kind of method improving serial supplementary line current differential protection performance |
| Application Number | Priority Date | Filing Date | Title |
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| CN201410050950.5ACN103779845B (en) | 2014-02-14 | 2014-02-14 | A kind of method improving serial supplementary line current differential protection performance |
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| CN103779845A CN103779845A (en) | 2014-05-07 |
| CN103779845Btrue CN103779845B (en) | 2017-03-08 |
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| CN201410050950.5AActiveCN103779845B (en) | 2014-02-14 | 2014-02-14 | A kind of method improving serial supplementary line current differential protection performance |
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