Broadband Sub-synchronous Signal Extraction and Analysis of the Key Parameters

Recently, with the development of new energy power generation and power electronic technology, wind power are applied more and more widely, which has improved energy efficiency while bringing some influence on stability of the power grid. A large collection of Doubly-fed wind farms, together with series compensation on the line, will lead to resonance and produce sub-synchronous oscillation, which will harm the grid. Since the network structure of the actual wind power transmission system is complex, such sub-synchronous signal is broadband and time-varying, and its amplitude is small, leading to difficulties to be extracted. To address this issue, an effective sub-synchronous signal extraction method is proposed here, to apply to a parallel sub-synchronous resonance suppression device and its control strategy. Then the extraction method is compared with other methods to prove its superiority and implemented on hardware. The effectiveness of the sub-synchronous signal extraction method is also verified through a digital-hardware in-loop test. Moreover, the regulation of its valid key parameters is summarized through simulations on different working conditions.