Study of fuzzy modulation control of UPFC

Abstract

FACTS (flexible AC transmission systems) technology offers an alternative way in damping low frequency powersystem oscillations. Oriented to the modulation control of UPFC (unified power flow controller), this paper constructs afuzzy modulation controller (FMC) with fuzzy logic incorporated, so as to damp the power oscillations of tie-lines andimprove the dynamic stability of the whole system. The structure of FMC is given in detail, and the key parameters are tunedby gradient descent training method. Furthermore, taking the feature of the shunt--series structure of UPFC intoconsideration, the concept of combined modulation is proposed to get better damping performance than the single--elementmodulation. The digital simulation conducted on a multi--machine interconnected power system shows that the designed FMCis efficient in damping power oscillations, and has better performance than the linear counterpart when operating pointchanges. The simulation results also show that the combined modulation is better than shunt or series modulation.This project is jointly supported by National Scaling Project--B and PGC Foundation of Hong Kong SAR.

以統一潮流控制器 ( UPFC)為研究對象 ,針對其調制控制 ,引入模糊技術 ,設計了模糊調制控制器 ,以抑制互聯電力系統聯絡線功率振蕩 ,改善系統的動態穩定性。給出了模糊調制控制器的結構 ,運用梯度下降法對模糊控制器的關鍵參數進行了優化。結合 UPFC具有串、并聯元件的特點 ,提出了模糊聯合調制控制器 ,相對于單一元件調制控制 ,可更有效地阻尼功率振蕩。多機系統仿真結果表明模糊調制控制器能有效地抑制振蕩 ,并且在運行工況改變時性能優于線性調制控制器 ,而聯合調制又優于單一元件調制