Investigation on a Hardware Simplified Static Synchronous Compensator

Inverter based flexible ac transmission system (FACTS) devices have been expected to play important roles in operating and controlling modern power systems, in which a number of potential concepts, e.g. distributed generation and micro-grid are implemented. FACTS devices can be divided into series-type and shunt-type controllers based on their connection means with the system. As one of the shunt-type FACTS devices, the static synchronous compensator (STATCOM) is the most versatile and powerful FACTS device that can provide effective means for controlling reactive power flow and improving the voltage stability of power networks. However, the STATCOM circuitry has complex and coupled system dynamics which require advanced controllers to achieve satisfactory performances. This paper presents the investigation of a hardware simplified STATCOM in providing satisfactory performances in performing various reactive power flow control functions during steady-state and dynamic operations of power systems. For comparative purposes, two topologies, i.e. 2-leg 4-switch (2L-4S) and 3-leg 6-switch (3L-6S) based STATCOM are investigated in this study. Mathematical models and simulation studies carried out in the Matlab/Simulink environment are firstly described. Typical results are then presented to verify the feasibility of the 2L-4S STATCOM and the effectiveness of the proposed controllers.