A generic multi-period optimal power flow framework for combating operational constraints via residential flexibility resources

Abstract

In low voltage networks, the majority of distributed energy resources are customer owned. As such, it is harder for the distribution system operator to control its system and maintain acceptable operating conditions. Even if residential flexibility is available, it should be employed without significant disturbances to customer-driven device profile patterns. Here a generic tool is developed to assist the distribution system operator in making informed decisions regarding its best course of action to combat operational issues with a limited amount of customer-driven flexibility. The proposed tool relies on a novel and versatile multi-period optimal power flow model for centralised control of low voltage distribution systems. Various scenarios of flexibility resources controllability are examined, coupled with a number of novel modelling approaches and customer-driven restrictions for the distribution system operator. For most scenarios, the multi-period optimal power flow model is amenable to nonlinear programming (NLP) problems, though there are cases that end up as mixed-integer nonlinear programming (MINLP) problems. For the latter, a heuristic approach is employed to approximate the MINLP into a sequence of size-decreasing mixed-integer linear programming (MILP) and a final NLP problem. The proposed formulation and approximation are applied to two low voltage networks of 18 nodes and 308 nodes, respectively.