10. Voltage Control on Distribution Smart Grids

Primary cabin (PC) voltage control of a distribution grid that hosts the DG is analysed, assuming a control scheme that includes transformers (TR) with on-load tap changer (OLTC), but also generators and flexible AC transmission systems (FACTS), allowing their reactive power remote control. Therefore, more than one contemporary closed-loop control operates on the same variable (voltage) or on the strictly linked variable (reactive power). These combined efforts require proper coordination among operating control loops that generally have different dynamic performances. Promising proposals of alternative coordinated PC controls, including reactive power flow between HV and MV bus bar control, are presented. They are aimed to a great extent to achieve effective automatic regulation via simple and practical solutions.