Adaptive Reactive-Power-Priority Fuzzy Q + P Voltage Control in PV-Rich Low-Voltage Distribution Networks: A Multi-Criteria Scenario-Based Comparison with Q(U) Control

Smart-inverter Volt–Var and Volt–Watt control is established practice, but the relative merits of local controller architectures depend on network conditions and inverter capability. This simulation-based study evaluates a reactive-power-priority adaptive Fuzzy Q + P controller against fixed Q(U), conventional Q(U) + P(U), and Q(U) with the same selective P(U) decision mechanism, together with the Fuzzy Q-only and uncontrolled cases. All six cases were assessed under 400 matched 48 h scenarios using a balanced three-phase quasi-steady-state equivalent. Relative to Q(U), Fuzzy Q + P reduced exposure above 1.11 p.u. by 2.20% and modelled voltage-protection trips by 3.98%, with 48.33% greater reactive-power effort and 0.23% less generated PV energy. Against conventional Q(U) + P(U), the critical-overvoltage duration was 1.17% shorter, but trips were 1.59% more frequent, generated PV energy was 0.57% lower, and reactive-power effort was 46.89% higher. Direct P(U) curtailment occurred in 113 of the 400 scenarios. An uncalibrated equivalent feeder-voltage calculation was separately assessed against 81,951 synchronized real-site samples (RMSE 0.001038 p.u.); this does not experimentally validate the controllers. The time-step convergence assessment did not meet its predefined acceptance criteria; therefore, protection-related results should be interpreted as numerical indicators within the implemented model. The findings therefore indicate a scenario-dependent voltage-security–energy–reactive-effort trade-off, not universal superiority over established combined control.