Research On Wide Area Fault Location Algorithm For Transmission Lines Based On Limited Number Of PMUs

Fast and accurate fault location for transmission lines is of great significance for promptly eliminating the fault and restoring power supply. For the last few years, phasor measurement units(PMUs) have been developed rapidly and applied in power system gradually. it provides the basis for the application of synchronized phasor measurement technology in fault location. At the same time, due to economic, technical and other constraints, it's impossible for installing PMU at the whole network. Moreover, taking into account equipment failure, communication failure, etc., it has important theoretical and practical significance to study on wide area fault location algorithm for transmission lines with finite PMU configuration.An optimal PMU placement method based on fault-location observability was proposed. Since fault location algorithm based on fault-location observability have certain requirements for PMU configuration, the optimal PMU placement model for transmission network fault-location observability considering zero-injection node and more practical constraints was established. The “virtual PMU node” processing approach was proposed to effectively take into account the impact of zero-injection node so that it could be applied in large-scale power grid. Biogeography based optimization algorithm was studied to solve the complex 0-1 integer programming problem. Simulation results of IEEE standard test system have shown the effectiveness of the proposed method. Compared with the existing methods, the proposed method can effectively reduce the number of installed PMU. Even though with the same number of PMU configuration, the proposed method has higher redundancy. The proposed method provides the PMU configuration strategy for wide area fault location algorithm.An adaptive wide area fault location algorithm for transmission lines based on fault-location zone was presented. The concept of fault-location zone was put forward, and it can be divided according to the grid topology and PMU installed nodes. When the grid topology changes, the fault-location zone was also updated correspondingly with partial modification. After the line failure, the two-step strategy was proposed to fast locate the fault point. Firstly, adaptive search strategy was implemented to determine the fault-location zone that the fault line belongs to. Then, the fault point was located accurately in the related fault-location zone. The proposed method does not require line fault information so that the ability to adapt to the information loss is enhanced. Besides, it has a certain adaptive capacity to accommodate changes in the network topology. Extensive simulation results have shown that the proposed fault location algorithm has strong adaptability and high accuracy and is suitable to grid topology changes as well as various fault types, fault positions and fault resistances. The proposed method provides a referenced fault location scheme under the incomplete information condition in power system.An adaptive fault location algorithm for series compensated transmission lines was proposed based on PMU. Based on two groups of the monitored synchronized voltage phasor and current phasor on both sides, the on-line parameters of series compensated transmission lines required for fault location algorithm were obtained utilizing the least square estimation method. After a line failure, distributed line parameter model and phase characteristics of fault point voltage and fault path current were utilized to form fault location function. Therefore, no model of series compensated device is needed. Theoretical analysis and simulation results show that the fault location function is monotonic and changes linear approximately in the possible fault sections. As a result, the roots can be extracted in the root sections efficiently and precisely by method of bisection or secant. Extensive simulation results have shown that the fault location results are stable. The proposed method does not need series compensation device model and is implemented simply, fast and accurately. Besides, the algorithm is suitable to various fault types, fault positions and fault resistances.