Decentralised control of voltage in distribution systems by distributed generators

Recently, renewable energy such as wind turbine generators and photovoltaic systems are introduced as distributed generators (DGs). Connection of a large amount of DG causes voltage deviation beyond the statutory range in distribution systems. Reactive power control of inverters interfaced with DGs is one of the solutions against this problem. Additionally, reactive power control has a possibility to contribute to the reduction of distribution loss. In this study, the authors propose a voltage control method in distribution systems by reactive power control of inverters interfaced with DGs. The proposed method has been developed in order to reduce distribution loss and voltage regulation into statutory range without any telecommunication. In the proposed method, each interfaced inverter controls reactive power based on voltage control reference, which is calculated from self-information. The calculation rule of control reference has been developed using optimal data which consist of relations between randomly given inputs and corresponding optimal outputs, which are calculated by an optimisation technique. Simulations are conducted to show the effectiveness of the proposed method.