On mitigating voltage rise in distribution networks with high solar PV penetration

摘要

Voltage rise (VR) is the resulting issue of reverse power flow from solar PVs, owing to their highpenetration in the distribution network (DN). The main purpose of this thesis is to mitigate VR in suchsituation. Mitigation methods found in literature are evaluated in chapter 1 from PV-inverter andDistribution Network Operator (DNO)-side.By accurate assessment of the impact of high PV penetration in distribution networks, a risk-free level ofPV penetration can be estimated for each customer, to prevent the VR. Accordingly, a comprehensiveIndex-Based Assessment (IBA) methodology to investigate the impact of high PV penetration in DNs isdeveloped in Chapter 2 which suggests such safe margin and compares it to the Basic Active PowerCurtailment (BAPC) method in a modified IEEE 13-bus network.According to the literature review, diverse criteria are considered by hypothetical decision makers, such ascost, required data infrastructure, control complexity and energy losses. A Priority-Based Decision-MakingMethodology (PBDMM) is developed to consider these criteria in evaluating state-of-the-art of VR mitigationmethods. PBDMM is based on an Analytical Hierarchy Process (AHP), utilizing pair-wise comparisonstechnique. Consequently, reactive power control (RPC) methods are more robust than other VR mitigatingmethods. Accordingly, in Chapter 4, major reactive power control methods are elaborated and the resultsare compared to a base case with no applied VR control strategy and PVs operate at unity power-factor.Finally in chapter 5 a novel index-based single-point-reactive-power-control (SPRPC) methodology isintroduced for VR mitigation by absorbing adequate reactive power in a central fashion. The proposedindex uses short circuit impedance analysis for best point assessment. SPRPC benefits from "Networkeffect" and is supported by DNOs, technically and financially, which makes it simple and efficient for VRmitigation. With SPRPC, existing PV inverters do not need to be upgraded and can retain their unity powerfactor, to avoid conflicting with the grid codes. Comprehensive 24-hour simulation is done on a modifiedIEEE 69-bus network, emulating a traditional residential grid with high $r/x$ ratio. SPRPC is compared todroop control in terms of efficiency and effectiveness to evaluate its advantages.