Design And Research Of The Integrated Protection Of Marine High-voltage Electric Power System

With the continuous development of the electric automation, intelligence for the large marine ships, they need more and more electric power, which results in stricter requirements of the power system in terms of security, economy and environment protection. As the traditional low-voltage AC power system can not meet the stricter requirements, the level of the voltage must be increased to set down this problem. Compared with the low-voltage AC power system, referred to the level of insulation and the protection of delay, the high-voltage system should pay more attentions on these items, so researching the integrated protection for the high-voltage AC system is significant for its application on new-building marine ships.Based on the AC electric power system with voltage rating-6600V installed in Bohai Train Ferry, this paper researches and analyzes the principles of all kinds of protections and designs an integrated protection system for marine high-voltage AC system according to its special requirements made by classification societies. Firstly, this paper researches the grounding methods of marine high-voltage AC system, that is, the grounding methods of the generators, and illuminates the transient and steady process of different kinds of methods during one phase was grounding. Build the mathematical model of the high-voltage synchronous generator, utilize Matlab/Similink simulation tool to set up the model of one phase grounding fault to test the above theoretical analysis. Compare the simulation results of the grounding fault over-voltage and grounding current with that of the theoretical calculation results to get the suitable grounding method for marine high-voltage AC power system, that is, if the grounding current is lower than15A, it is advised to adopt the neutral grounding with high resistance; if the grounding current is more than15A, it is advised to adopt the neutral grounding with resonance winding.Then, this paper theoretically analyzes the delay protection principles of high-voltage generator, transformer and main bus, and proposes the corresponding protection measures based on different kinds of protections, like cooling water leakage protection, bus arc protection, etc. According to the special requirements of CCS to the high-voltage system, propose its corresponding short current calculation and the method to choose the type of the main air circuit breaker, by the way, put forwards some announcements of selecting the short circuit points.At the end of this paper, according to the above theoretical analysis, with the help of the configuration software-WinCC Flexible and the programming software-STEP7V5.4of SIMENS PLC, the HMI integrated protection system of the marine high-voltage AC system is designed. The designed system can realize the function of online simulation of the integrated protection system, that is, during normal operation case, the HMI system can indicate and simulate the working status, change the control positions and operation ways through clicking the mouse of the PC(worked as the upper machine); during trouble case, it can actuate the functions of alarming, indicating, recording and make the corresponding ACB open to realize the function of automatic protection.