順滑模態觀測速度控制應用於無轉速感測之直驅式可變速風力發電機

Abstract

風力發電系統中可變速型發電機比定速型可獲取較多風能，其特色為發電機的轉速需要控制以隨風速變化。大型風力發電機與小型風力發電機比較起來造價高昂且需要維護，因此大型風力發電機轉速控制常安裝轉速感測器偵測發電機轉速與轉子位置。然而對於小型風力發電機而言其成本受市場效益因素而受限且必需保證長時間免維護，因此常採用無轉速感測轉速控制策略取代安裝轉速感測器所帶來的成本與可靠度問題。本文以順滑模態觀測器估測發電機轉速與轉子位置，其優點為對發電機參數變化敏感度低具強健性，此外運算程序簡易，可由數位訊號處理器或微處理器實現其控制法則。本研究使用永磁同步發電機搭配實作的周邊迴授電路、驅動電路與控制器軟硬體實現順滑模態觀測器於永磁同步發電機的轉速估測與控制，從模擬與實驗上探討順滑模態觀測器應用在風力發電系統無轉速感測轉速控制的可行性與強健性，最後搭配實驗數據與市面上風力發電機規格分析其應用範圍。

Variable speed wind turbines can obtain more wind energy than fixed speed wind turbines in wind energy conversion system (WECS). To obtain maximum power from wind, variable speed wind turbines need be controlled by rotor speed controller as wind speed varied. Compare with large scale variable wind turbines with small scale variable wind turbines, the former are expensive and need maintenance, therefore, they usually install rotor speed sensor for speed control application. However, the latter are restricted to low cost due to market consideration and guarantee maintenance free for long time. Therefore, they preferred to adopt sensorless control strategy. In this thesis, rotor position and speed estimation is established via sliding mode observer (SMO). It is good at its robustness against parameter variation and it can be implemented in microprocessors or digital signal processors (DSP). Permanent magnet synchronous generator (PMSG) with peripheral circuits, gate driver and DSP are used for PMSG sensorless speed controller implementation in this thesis. Feasibility of SMO in WECS application is discussed by simulation and experimental results. Finally, Applicable range of SMO is analyzed by experimental data and wind turbine specification from market.