強(qiáng)致穩(wěn)性風(fēng)機(jī)

袁小明 胡家兵

摘 要：傳統(tǒng)電力系統(tǒng)的同步穩(wěn)定主要取決于常規(guī)同步電源提供的整步和阻尼轉(zhuǎn)矩的作用，整步轉(zhuǎn)矩不足將導(dǎo)致轉(zhuǎn)子角的滑移不穩(wěn)定，阻尼轉(zhuǎn)矩不足將導(dǎo)致轉(zhuǎn)子角的周期不穩(wěn)定。并且，常規(guī)同步電源所表現(xiàn)的慣性響應(yīng)特性對(duì)系統(tǒng)短期頻率穩(wěn)定起重要作用。因此，常規(guī)同步電源對(duì)電網(wǎng)具有較強(qiáng)的“致穩(wěn)”作用。然而，現(xiàn)有主流風(fēng)機(jī)（雙饋型風(fēng)力發(fā)電機(jī)、全功率型風(fēng)力發(fā)電機(jī)）通常采用基于鎖相同步的電流矢量控制，鎖相環(huán)用于快速跟蹤電網(wǎng)頻率、相位變化，為控制系統(tǒng)提供頻率及相位基準(zhǔn)。對(duì)于電網(wǎng)機(jī)電時(shí)間尺度的擾動(dòng)，鎖相環(huán)快速的響應(yīng)特性導(dǎo)致風(fēng)機(jī)無法提供整步轉(zhuǎn)矩及慣性響應(yīng)特性。隨著大規(guī)模風(fēng)電并入電網(wǎng)，逐步取代電網(wǎng)中部分常規(guī)同步電源，導(dǎo)致電網(wǎng)慣性減小，甚至整步轉(zhuǎn)矩不足等問題，對(duì)電網(wǎng)“致穩(wěn)”作用較弱，這種現(xiàn)象在多風(fēng)電、少同步電源的弱電網(wǎng)情況下（酒泉風(fēng)電基地）將更為嚴(yán)重。因此，風(fēng)機(jī)機(jī)電時(shí)間尺度的擾動(dòng)響應(yīng)特性亟需優(yōu)化，以增強(qiáng)其對(duì)電網(wǎng)尤其是弱電網(wǎng)的“致穩(wěn)”作用。該文將依據(jù)同步發(fā)電機(jī)內(nèi)同步機(jī)理，對(duì)現(xiàn)有風(fēng)機(jī)控制系統(tǒng)進(jìn)行優(yōu)化，針對(duì)雙饋風(fēng)機(jī)提出強(qiáng)致穩(wěn)性控制，改善其對(duì)電網(wǎng)機(jī)電時(shí)間尺度的擾動(dòng)響應(yīng)特性，即提供整步轉(zhuǎn)矩及慣性響應(yīng)特性，以增強(qiáng)其對(duì)電網(wǎng)尤其是弱電網(wǎng)的致穩(wěn)作用。

關(guān)鍵詞：整步轉(zhuǎn)矩 慣性響應(yīng) 同步穩(wěn)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

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