Voltage compensation in weak distribution networks using a D-STATCOM

Voltage regulation of long weak distribution lines is a challenging problem, particularly when it may not be economic to simply upgrade the network. D-STATCOMs offer an attractive alternative, with their potential to provide both steady state and transient voltage compensation for a limited capital investment. However, operation of these systems with weak networks needs careful attention to achieve a stable and fast response under all supply conditions. This paper proposes a new cascade loop control strategy to regulate and balance the voltage at a distribution bus using a D-STATCOM which, compared to other reported strategies, is more robust and works well under all system conditions. Simulation and experimental results are presented to verify the stability of this control strategy across a range of operating conditions.