Research On Substation Area Protection Based On The Principle Of Current Phase Comprison

As technology of smart grid grew, more widely used the smart substation. It has solved a number of flaws, such as long delay time of the traditional backup protection, setting with difficulty and easily cause interlocking tripping. On the research of the construction plan of smart substation and protection algorithm, Chinese scholars focus on the exploration of centralized protection, optimizing the substation protection by utilizing the advantage that all the information could be shared. Traditional phase differential high frequency protection could defend system oscillation, work properly during non-full-operation state, have simple structure and no need of voltage, it acted as the main protection for power transmission line all the time. So it is meaningful to apply the principle of the current phase comparison to the protection of substation and take advantage of the whole information in order to optimize the performance of the protection. Based on these reasons, this text do a research on realizing the substation area protection by utilizing the principle of phase comparison of phase to phase sudden change of current and sequence current.The text firstly sketched the history and development of smart grid and smart substation, after contrasted with each countries' development, found that although the different target, the goal of the smart grid are same, that is to build up the grid which is safe, environmental protection, efficient and economic. The text also introduced the research status of substation area protection, including centralized protection, distributed protection and the protection algorithm of substation area protection. Summarizing the status of engineering application: To the 220 kV and above, we just apply the IEC 61850 standard to the local control level and above and no reconstruction on process layer. Below the 220 kV, we apply the IEC 61850 standard to the process layer and above.After then, based on analyzing the defect of traditional phase differential high frequency protection, introducing the characteristic of digitized substation, studying the suitable network structure for smart substation, the text proposed the construction plan which is voltage level configuration protection, that is retain a set of traditional main protection and configuring double substation area protection. At the same time, towards different voltage classes the text designed the process layer network scheme.The text sketched the characteristic of traditional phase differential high frequency principle, then did a research on the feasibility that apply the phase comparison principle by phase to phase ?I, sequence current to the substation protection. Study a new way to realize the principle which only catch the starting point of the current waveform in order to make sure of the phase difference. It raised tripping strategy of the substation and solve the problems such as topology identification, magnetic saturation, magnetizing rush current, circuit breaker failure.At last, the text simulated the proposed project by using PSCAD/EMTDC by setting the Visual Studio as the application development platform, wrote C and Fortran code, and embed it in the PSCAD, in order to build up a similar environment as the physical truth. To certify the solution is good enough, we simulated single point of failure, fault circuit breaker failure and communication failure fault.