A Strategy to Parameterize Q(U) Control to Enhance Voltage Stability using a Centralized Based Method

Abstract:
Local voltage control schemes of distributed generation (DG) such as reactive power as a function of voltage, characterised as Q(U) control have the advantage of providing faster control response to the variability nature of DGs and loads. The challenge however with this control is the tuning of the control parameters. Subsequently, this paper proposes a centralised control scheme based on system optimization to tune Q(U) control parameters. The optimization determines the optimal settings of the on-load tap changer (OLTC) and voltage regulator (VR), the voltage sensitivity with respect to reactive power and the optimal voltage values for the buses where DGs are integrated on an hourly basis. These sensitivity values are then used to tune and adjust the Q(U) control to regulate the voltage within a 15 minute interval. Thus, a coordinative voltage control scheme is achieved based on different timescales. This scheme when implemented on the United Kingdom generic 16 bus medium voltage distribution grid improved the voltage stability index as compared to the scenario where the DG operated with fixed Q(U) control parameters. Also, the scheme improved the voltage profile at the point of common coupling where the DGs were connected.