Sensitivity and Robustness Issues of Operating Envelopes in Unbalanced Distribution Networks

Abstract

The fast-growing uptake of distributed energy resources (DER), such as home photovoltaic (PV) and battery systems and electric vehicles, has introduced new challenges in the operation of lowvoltage distribution networks (LVDNs). High levels of DER can produce large swings in power flow from the day (low-demand, high PV exports) to the night (high-demand) that can push the LVDN network to its operational limits. Network operating envelopes aim to maximise network capacity utilisation through the implementation of dynamic customer capacity limits, where DER exports or imports are constrained at times of network congestion and otherwise relaxed to potentially higher levels than those realisable through traditional static customer capacity limits. A common assumption underlying the implementation of operating envelopes is that operational constraint violations will be avoided if the realised demands of customers under dynamic connections all fall within their capacity envelopes. However, this assumption needs more careful consideration in the light of strong unbalance and mutual phase couplings common in LVDNs. This paper analyses phase voltage level sensitivities to customer demand levels and demonstrates that voltage violations can still occur when all customers are within their limits. These results, illustrated by experimental studies based on a two-bus example and a real representative Australian LVDN, underline the importance of incorporating uncertainty in the calculation of operating envelopes.INDEX TERMS DER architecture, distribution network, hosting capacity, operating envelopes, unbalanced three-phase power flow, voltage violations

Recent developments of demand‐side management towards flexible DER‐rich power systems: A systematic review

“…Therefore, it can be used for long‐term planning and specifying the available hosting capacity (HC) at each time interval on the MPSs, as shown, for example, in Figure 5b. Various articles applied the NOE concept to assess the PSF during integrating DERs in unbalanced distribution networks [58, 59], and others studied the DER services in energy markets [60, 61].…”