外文翻譯---一種針對多終端平行輸電線路新型故障定位算法的發(fā)展 英文

1、1516 IEEE Transactions on Power Delivery, Vol. 7 .No. 3, July 1992 DEVELOPMENT OF A NEW FAULT LOCATION ALGORITHM FOR MULTI-TERMINAL TWO PARALLEL TRANSMISSION LINES T.Nagasawa M.Abe N.0tsuzuki The Kansai Electric P

2、ower Co., Inc. Osaka, Japan ABSTRACT conventional fault location methods using one-terminal ac voltage and current are not applicable to multi-terminal systems. This paper describes a new fault location algorithm f

3、or multi-terminal two parallel transmission lines. This method uses the magnitude of the differential currents at each terminal and also uses an algorithm based on a 3-terminal fault location algorithm and

4、 an equivalent conversion from an n-terminal to a 3-terminal system. For a multi-fault occurring at the same place and same time on both lines as well as a single-fault this new algorithm is reasonably accurate.

5、 EMTP simulation results are shown. KEYWORDS Multi-terminal, TWO parallel transmission lines, Fault location, PT, CT, Equivalent conversion, 3-terminal algorithm. 1. INTRODUCTION - When a fault occurs on the

6、 t r a n s m i s : i o nlines of an electric power system, it is very important, especially in the case of unsuccessful reclosing, to find the fault location and make necessary repairs, in order to prevent

7、the fault from spreading. If there are no facilities to detect a fault location, it is necessary to search for the fault location by patrolling all of the transmission lines, and this would involve a treme

8、ndous amount of labor and expense. This is especially true on long lines, in rough terrain. Fault locators, that measure the distance to a fault point on a transmission line, conventionally use surge method or p

9、ulse method. In the former method, a surge voltage caused by a fault is detected at both terminals of the transmission line and the fault point is determined by the time difference of the surge detected at eac

10、h terminal. In the latter method, pulse signals are sent to the transmission line when a fault occurs and by measuring the pulse return time from the fault point, the fault point is determined. In these methods

11、, if the surge voltage or reflected pulse can be precisely detected the fault location is very accurate. These fault locators have made practical use in direct grounded systems. However, in resistance gr

12、ounded systems, when a fault, especially a common single phase-to-ground fault This paper w a spresented at the Transmission and Distribution Conference in Dallas, Texas from September 22-27, 1991 at the Dallas Con-

13、vention Center. Sponsored by the IEEE Power Engineering Society. T. Emura Y. Jikihara M. Takeuchi Nissin Electric Co., Ltd. Kyoto, Japan occurs, a large location error comes about because the surge voltage level

14、is essentially low and becomes lower by the influence of branch lines. Thus, the above methods have limited practical applications. In the meantime, distance relays for transmission-line protection have a funct

15、ion to measure an impedance to a fault point. Taking note of this function, researches have been done into using the relay method to determine fault point. Research efforts are expanding and emphasize development o

16、f fault locators based on a microprocessor. These locators make practical use in resistance grounded systems as well as direct grounded systems. Most of these locators use one- terminal ac voltage and current o

17、f PT and CT. A drawback of this method is that in application to multi-terminal transmission lines withbratichpoints, it is impossible to determine the fault point lying beyond the branchpoint. This paper prop

18、oses a new fault location algorithm for multi-terminal two parallel trans- mission lines. These transmission lines are expected to be increased in subtransmission systems. The method uses the same ac inputs as p

19、rotective relays, and uses only the magnitude of the differ- ential currents at each terminal. This method is based on a fault location algorithm for 3-terminal two parallel transmission lines, and an equivalent c

20、onversion from n-terminal two parallel transmission lines to 3-terminal two parallel transmission lines. - 2. THE PRINCIPLE OF THE 3-TERMINAL SYSTEM This section relates the principle of the fault lo

21、cation algorithm for 3-terminal two parallel transmission lines. First of all we will explain the fundamental equations for the differential currents. 2.1 Fundamental Equations for Differential Currents Fig. 1 sho

22、ws the general 3-terminal two parallel transmission lines. There are no limitations on the presence of a back power source or limitations on the grounding system (direct grounded, resistance grounded, ungrounded

23、) for the terminals T1, T2 and T3. Consider a fault occurring at a distance of x km away from the terminal T1. The fault types need not be restricted to a single- fault occurring at one place on one of the tr

24、ansmission lines, even a multi-fault occurring simultaneously at the same place on both transmission lines is allowed. There are also no limitations on the fault-point resistance. Fig. 2 shows the currents fl

25、owing from each terminal and from the fault points. In Fig. 2, the last suffix i of the currents becomes 0, 1 or 2 corresponding respectively to the zero sequence, positive sequeiice or negative sequence of the sy

26、mmetrical coinponents. In this figure the fault currents are shown as flowing from both lines but for instance if we set i2fi = 0 ( i = 0, 1, 2). this can be taken as a single-fadlt in line lL. Also we can conside

27、r f,,, = 0 and f,,, = 0 as a phase-to-phase fault or a three-phase fault (with or without ground). Accordingly, Fig. 2 represents all faults discussed in this paper. 1518 Table 1 shows the differential curren

28、t distribution of each terminal when the fault point is changed. From the table it can be seen that the differential currents of each terminal have the same angle. Using this we get the following equ

29、ation. Further, for example in case 1, we get the next equation. And then from the equations (14) and (15), we obtain the following equation. It is further shown that by computing the left hand side of t

30、he equation (16) the distance to the fault point can be found. The computation formula on the b DiEemntial c u r r e n tDZ€. c u r r e n to fterminal TI A I,i Diff. curmlt of terminal T2 A I ,D i f f .c m

31、 n t o fterminal T3 A f i left hand side of the equation (16) is regarded as a fault location computation formula using only the magnitude of the differential currents of each terminal. Table 2 shows the resu

32、lts computed from the three kinds of computation formulas I, I1 and 111 with respect to the fault point in cases 1, 2 and 3. From Table 2 the following can be derived: Apply formula I as a computing formula for the

33、 fault between terminal T1 and the branchpoint, and formulas I1 and I11 for terminals T2 and T3, respectively. At which time: If there is a fault point between a certain terminal and the branchpoint, the result

34、derived from the computation formula of that terminal is less than the distance to the branchpoint, or If there is no fault point between the terminal and the branchpoint, the result derived from the computation

35、formula of that terminal is greater than the distance to the branchpoint. From this we get the 3-terminal system fault location algorithm shown in Fig. 5. Table 1. Differential Current Distribution of Each Termi