強致穩性風機

袁小明 胡家兵

摘 要：傳統電力系統的同步穩定主要取決于常規同步電源提供的整步和阻尼轉矩的作用，整步轉矩不足將導致轉子角的滑移不穩定，阻尼轉矩不足將導致轉子角的周期不穩定。并且，常規同步電源所表現的慣性響應特性對系統短期頻率穩定起重要作用。因此，常規同步電源對電網具有較強的“致穩”作用。然而，現有主流風機（雙饋型風力發電機、全功率型風力發電機）通常采用基于鎖相同步的電流矢量控制，鎖相環用于快速跟蹤電網頻率、相位變化，為控制系統提供頻率及相位基準。對于電網機電時間尺度的擾動，鎖相環快速的響應特性導致風機無法提供整步轉矩及慣性響應特性。隨著大規模風電并入電網，逐步取代電網中部分常規同步電源，導致電網慣性減小，甚至整步轉矩不足等問題，對電網“致穩”作用較弱，這種現象在多風電、少同步電源的弱電網情況下（酒泉風電基地）將更為嚴重。因此，風機機電時間尺度的擾動響應特性亟需優化，以增強其對電網尤其是弱電網的“致穩”作用。該文將依據同步發電機內同步機理，對現有風機控制系統進行優化，針對雙饋風機提出強致穩性控制，改善其對電網機電時間尺度的擾動響應特性，即提供整步轉矩及慣性響應特性，以增強其對電網尤其是弱電網的致穩作用。

關鍵詞：整步轉矩 慣性響應 同步穩定

Abstract：The synchronism stability of conventional power system is mainly determined by synchronizing and damping torques provided by synchronous generators （SGs） in grid. In addition， the rotational inertia of grid-connected SGs plays an important role in the short-term stabilization of grid frequency. It can be seen that SGs have strong ability to stabilize the power grid. However， the installed wind turbines （WTs） including DFIG-based WTs and full-power WTs can hardly provide either synchronizing torque or inertial response. In other words， the contribution WTs can make to stabilizing the power grid is quite small. This is because the present WTs synchronize with the power grid relying on phase-locked loop （PLL） technique， which is generally used to quickly capture the grid phase angle and frequency as control reference. When disturbance on electromechanical time scale， i.e.， high-power motor start-up， occurs in power grid， the rapid and precise response of PLL almost makes WTs immune to this disturbance. As a consequence， WTs almost have no response， and SGs are forced to be the only contributors in power grid. It is worth noting that this phenomenon will get worsen in weak grid with high penetration of wind power and lack of SGs like Jiuquan wind power base in China. Therefore， good response characteristics of WTs to disturbances need to be available to ensure the safety and reliable operation of grid. This paper proposes two novel control methodologies for DFIG-based WTs with reference to the intra-synchronization mechanism contained in SGs. This can make DFIG-based WTs naturally provide synchronizing torque and inertial response characteristics for disturbances on electromechanical time scale in power grid， and be the positive contributors to stabilize the power grid as SG does.

Key Words：Synchronizing torque；Inertial response；Synchronism stability

閱讀全文鏈接（需實名注冊）：http：//www.nstrs.cn/xiangxiBG.aspx？id=49182&flag=1