Research On Fault Simulation And Location Using Two-terminal Data For HVDC Transmission Lines

With the rapid development of modern power transmission technology, HVDC (high voltage direct current) plays an increasingly important role in the long distance and high power transmission. It has many advantages, such as lower cost, easier connection, good control performance and so on. The developed countries in the world regard it as the main means of large capacity, long distance transmission and asynchronous networking. Due to the complex geographical environment and long transmission lines in practical engineering, it is difficult to find the transmission line fault point when the fault occurs. Therefore, the study of HVDC transmission line fault location is full of important significance.In this paper, a ±500kV HVDC transmission system simulation model was established by the electromagnetic transient simulation software PSCAD/EMTDC. PSCAD/EMTDC gives us a convenient platform to simulate the entire HVDC transmission system with the CIGRE HVDC benchmark model. The operation results show that the model can accurately simulate the normal operation and line fault of a ±500kV HVDC transmission system.In this paper, the Bergeron distributed parameter line model and fault location algorithm considering two-terminal synchronous data for HVDC transmission line are described in detail. Considering from the actual situation, this paper presents a novel fault location algorithm for HVDC transmission line based on two-terminal asynchronous data. The algorithm is performed in time domain and based on the Bergeron distributed parameter transmission line model. The asynchronous time error function, which is established by the detection of voltage waveform mutation, has been taken into account before the voltage distributions are calculated by the voltage and current measured in each terminal. The fault can be located according to the principle that the calculated voltage distributions of the fault point are equal at all times.In order to improve the accuracy of fault location at a low sampling frequency, the influence of different interpolation methods on sample data is studied, we could find that the piecewise linear interpolation can be used to improve the accuracy of fault location results. In order to locate the fault point quickly, this paper adopts the variable step algorithm which can reduce the operation time and ensure the accuracy of location. The simulation results in PSCAD show that any fault of the HVDC transmission line can be located fastly and accurately under the circumstance of two-terminal asynchronous data.