Hardware-in-the-Loop Experimental Validation of a Reliability–Resilience Co-Optimization Framework for Solar-Integrated Active Distribution Networks: A Case Study of a Nigerian 33 kV Urban Feeder.
Keywords:
Active distribution network, hardware-in-the-loop, Nigerian 33kv feeder, reliability-resilience co-optimization, solar photovoltaic integrationAbstract
The rapid integration of rooftop photovoltaics (PV) and battery energy storage systems (BESS) into weak distribution networks in Sub-Saharan Africa raises operational questions that simulation-only studies have so far left unresolved. In particular, planning frameworks that optimize long-run reliability while neglecting short-horizon resilience to extreme events can produce designs that perform well on average yet fail catastrophically under contingencies. This paper reports what is, to the authors' knowledge, the first hardware-in-the-loop (HIL) experimental validation of a reliability–resilience co-optimization framework applied to an actual Nigerian 33 kV urban feeder: the Yenagoa–Ogbia feeder in Bayelsa State. Field data obtained from the local distribution company and the injection substation were used to build an electromagnetic-transient model of the feeder on a real-time digital simulator (RTDS). Two commercial inverters 5 kVA PV inverter and a 3 kVA BESS inverter—were coupled to the simulated network through a 15 kVA linear power amplifier, closing a power hardware-in-the-loop (PHIL) interface with a measured round-trip delay below 120 µs. A composite reliability–resilience index (RRI) was formulated and embedded in a multi-objective (NSGA-II) design loop whose candidate control settings were verified experimentally under chronic faults, N-1 and N-2 contingencies, and a full grid-collapse event. Experimental results show that the co-optimized Volt-VAR and intentional-islanding controller reduced SAIDI from 38.4 to 12.9 h/yr and SAIFI from 27.6 to 9.8 interruptions/yr, raised the fraction of critical load served during grid collapse from 41% to 84%, and improved the RRI from 0.52 to 0.87, with HIL-to-offline model deviations remaining below 4.2% across all measured channels. The findings provide an implementable evidence base for Nigerian regulators and distribution companies drafting interconnection and islanding codes for active distribution networks.
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