The Relay Protection Research On Permanent Magnet Direct-drive Wind Power Generator

With the wind power generation technology has become increasingly mature, the study of the direct-drive permanent magnet synchronous generator technology also entered the hot stage, the direct-permanent magnet generators with 6MW, 10 MW are being developed,but the protection of the corresponding has been lagging behind,so with the increase of permanent magnet generator unit capacity, the corresponding Research on relay protection should also keep up with, otherwise, the unit once fault occurs,it can cause serious consequences.So the research on the protection of permanent magnet synchronous generator should be imperative.In this paper, based on the MATLAB software, the relay protection of the direct drive permanent magnet generator carry out the research in the following aspects.First of all, this paper discusses the research significance and present situation of direct drive permanent magnet generator relay protection. Outlines the basic structure of direct drive permanent magnet synchronous wind generator and its basic principle, and the establishment of a permanent magnetic generator dynamic mathematical model and simulation model of three-phase static coordinate system. The establishment of mathematical model and dynamic simulation model of wind turbine.Second, analysis the current asymmetric operation fault and typical wind turbine fault of the PMSG.Analyzed the working principle of permanent magnet generator stator wingding inter turn short circuit. Put forward different protection strategies used in relay protection of the PMSG and the method matched with each other,and then put forward the logic design of the comprehensive protection strategy.Third, to the problem of wind farm 35 kV American box changed phase deficient operation, present to equip it with a defect protection and protection at h-side and gives the fuse type two class fuses several alternative. According to the current wind electric field high voltage across the formation mechanism,summarizes two kinds of ways of wind power unit high voltage ride through.Fourth, based on the MATLAB software to build: the 1.5MW permanent-magnet wind power system simulation model of the normal working situation. Permanent magnet generator fault simulation model under the given wind speed.PMSG stator winding inter turn short circuit fault simulation model. Fault simulation model of 1.6MVA/35 kV box transformer substation. Based on the above simulation model, obtained the fault feature of their respective corresponding model, and the characteristic quantity are analyzed and compared, thus obtains: PMSG outlet three-phase short circuit fault occurs in generator effect are serious than that in converter outlet. Box transformer short-circuit impact current produces three-phase short circuit occurred on both sides of the line should be more than other type of faults generated, which led to the line voltage drop than other fault generated significant Single-phase grounding fault,on both sides of the box changes produce line effects than other fault types produce little effect. Box transformer short-circuit fault occurs on the low pressure side of the line of the system the high side current is large,and its impact on system voltage is high pressure side of the small.Fifth, based on simulated data to further strengthen the permanent magnet generator system protection configuration, this paper made the following improvements and Perfection:1、In order to prevent the stator lead line fault when the fault current to the winding burn, equipped with differential protection.2、In order to prevent the stator winding inter turn short circuit, to its with the machine in high sensitivity transverse differential and the outgoing line of the incomplete longitudinal differential protection combined.3、In order to prevent the American box transformer substation low voltage circuits fault too large short circuit current burned box changed, to the low-pressure line is equipped with short delay current quick break protection.And through the MATLAB software, it verifies its feasibility.4、In order to prevent the box transformer high-voltage side lines on over-current circuit breaker tripping or malfunction, to its equipped with the combination of the over-current protection and voltage protection protection.5 、 In order to prevent the PMSG startup process for the startup current caused by the misoperation, to ensure the normal operation of a generator with high sensitive coefficient, to its equipped with improved current quick break protection. Based on the experimental data, it is recommended that: existing overcurrent protection setting value is increased accordingly and the existing protection action time was extended accordingly, and the improved scheme is verified by simulation. The simulation results show that: the improved scheme can correct action and has maneuverability.