P-Q Control Matrix Converter Based UPFC By Direct Power Control Method

In the recent years, due to economics and environment problems, build of new power planet and transmission line become more difficult. Hence it is advisable to enhance power transfer capability of the existing transmission lines up to thermal limit instead of constructing new one. For enhancing the power capability, FACTS controller like SSC, TCSC, SVC are developed. But these controllers cannot compensate the real and reactive power separately. For this a controller called, Unified Power Flow Controller (UPFC) is developed which uses both the series and shunt controller with a common DC capacitor link. This capacitor brings several disadvantages such as affecting the reliability, high cost etc. This paper proposes a new topology for UPFC based on the Matrix converter design. Matrix converters (MCs) allow the direct ac/ac power conversion without dc energy storage links; therefore, the MC-based UPFC (MC-UPFC) has reduced volume and cost, reduced capacitor power losses, together with higher reliability. Theoretical principles of direct power control (DPC) based on sliding mode control techniques are established for an MC-UPFC dynamic model including the input filter. As a result, line active and reactive power, together with ac supply reactive power, can be directly controlled by selecting an appropriate matrix converter switching state guaranteeing good steady-state and dynamic responses.