Abstract
Crowbar protection and chopper protection (CCP) are commonly used hardware protection measures in the process of low voltage ride through (LVRT) of doubly-fed induction generator (DFIG). The protections operating states during fault have an important influence on the electromagnetic transient (EMT) process of DFIG. Therefore, different from only considering the influence of single protection, the coordinated control of crowbar protection and chopper protection are further considered in this paper, and a novel analysis method of CCP operation criterion is proposed by analyzing the relationship between rotor current, DC-link voltage and post-fault terminal voltage (PFTV) of DFIG. On this basis, the states of CCP under different voltage drop depths are analyzed. And an EMT analysis model of DFIG considering CCP is studied. The proposed method and EMT analysis model for DFIG are later validated through PSCAD/EMTDC-based simulation results. The results show that the method and model proposed in this paper have good accuracy and practicability, which provides more references for further study of the transient characteristics of DFIG.
Highlights
With the world's attention to renewable energy, wind power generation technology has become one of the largest scale and the best commercial momentum development of renewable energy power generation technologies [1],[2]
That is, when the short-circuit fault occurs and the post-fault terminal voltage (PFTV) sag degree is not deep, the more sensitive chopper protection will be put into operation firstly
For Doubly-fed induction generator (DFIG)-based wind turbines, different fault severities will lead to different protection operating states, and the corresponding DFIG transient process will be quite different
Summary
With the world's attention to renewable energy, wind power generation technology has become one of the largest scale and the best commercial momentum development of renewable energy power generation technologies [1],[2]. To improve the power support capability of DFIG under fault conditions, a coordinated LVRT control strategy with crowbar and chopper protection (CCP) is proposed in [7]. According to the characteristics of DFIG in the process of voltage change, a LVRT strategy for fast coordinated control of DFIG rotor side converter, chopper protection and grid side converter is developed in [16]. A design and analysis of a CCP control strategy with artificial intelligence for DFIG-based wind turbine system is studied in [17]. The previous studies mainly consider the influence of crowbar action or chopper protection on transient characteristics, individually. For the DFIG-based wind turbine system with CCP, the error of analysis results may be caused in studying DFIG transient process, if only a single protection is considered. According to the standard model of 1MW DFIGbased wind turbine system provided by PSCAD/EMTDC (Power Systems Computer Aided Design/ Electromagnetic Transients including DC), the accuracy of proposed DFIG transient equivalent model is verified
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