Recently，participation of distributed generators(DG)，such as wind turbines，co-generation system etc，is natural trend from ecological point of view and will increase more and more. However，since outputs of these DGs depend on not only changes of load demand but weather condition，power flow will be complex. As a consequence it will cause unexpected voltage deviation. The DGs has few ability to maintain system voltage，because its capacity against the system is very sma1l. Then SVRs （Step Voltage Regulators）would be applied to the distributed system. In this paper，the coordinated voltage control scheme of SVR tap changers in distributed system is proposed in order to maintain the system voltage against the changes of DGs' outputs. The proposed control scheme is based on the hierarchical structure of distributed system. The control action of a tap changer of each SVR is cooperatively decided in accordance with the behaviors of both upper and lower level SVRs through the communication channel. The effectiveness of the proposed scheme is confirmed by showing some numerical simulations under several conditions on voltage deviations.

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