CAJ | 학술논문

针对双馈风电机组低电压穿越问题，国内外研究成果主要分为两类：电网电压小值跌落时，通过优化控制策略提高机组低电压运行能力，保证机组不间断运行；电网电压大值跌落时，通过转子并联撬棒(Crowbar)旁路转子变流器，保证机组不脱网，同时，网侧变流器可注入一定无功电流。对于电网电压大值跌落问题，目前采取的穿越技术较为被动，Crowbar投入后，双馈发电机以感应电机/发电机方式运行，需要吸收一定无功，不利于电网电压恢复。针对此问题，提出一种基于定子串联阻抗的低电压主动穿越方案，不仅能保证故障期间双馈风电机组的不间断运行，而且能够通过转子变流器向电网注入接近额定的无功电流，支撑电网电压；通过优化定子串联阻抗值和控制器参数，机组故障运行能力得到大幅提升。
침대쌍궤풍전궤조저전압천월문제，국내외연구성과주요분위량류：전망전압소치질락시，통과우화공제책략제고궤조저전압운행능력，보증궤조불간단운행；전망전압대치질락시，통과전자병련효봉(Crowbar)방로전자변류기，보증궤조불탈망，동시，망측변류기가주입일정무공전류。대우전망전압대치질락문제，목전채취적천월기술교위피동，Crowbar투입후，쌍궤발전궤이감응전궤/발전궤방식운행，수요흡수일정무공，불리우전망전압회복。침대차문제，제출일충기우정자천련조항적저전압주동천월방안，불부능보증고장기간쌍궤풍전궤조적불간단운행，이차능구통과전자변류기향전망주입접근액정적무공전류，지탱전망전압；통과우화정자천련조항치화공제기삼수，궤조고장운행능력득도대폭제승。
For double-fed induction generators (DFIGs) low voltage ride through (LVRT) issues, research achievements are mainly divided into two categories: when suffering from small values of the grid voltage drop, the low voltage operation capability can be strengthened through optimized control strategies to ensure uninterrupted operation of DFIG; when grid voltage drop value is large, the rotor converter should be bypassed by rotor crowbar, the tripping action can be avoided and DFIG stay connected during grid faults, in the mean while the grid-side converter operates in the STATCOM mode for grid voltage support. As for large value grid voltage drop, LVRT with the rotor crowbar are considered to be a passive measurement, DFIG behaves like an induction machine or a generator depends on its slip and absorbs certain reactive power during grid faults, which is not conducive to grid voltage recovery. To overcome this drawback, a stator series impedance based active LVRT strategy was proposed, uninterrupted operation of DFIG during grid faults is achieved, and a nearly rated reactive current can be injected into grids through the rotor-side converter, which is conducive to grid voltage recovery. Besides, a robust fault operation capability of DFIG is obtained through optimizing the value of the series impedance and controller parameters.