The influence of load and PV generation on operating P and Q envelopes of distribution network buses

Abstract

The increase in consumer-owned small-scale Low Carbon Technologies (LCT), solar photovoltaic (PV) generation in particular, has led to the calculation of feasible operating envelopes, which allows distribution network operators (DNOs) to benefit from those PVs without compromising network operation. This paper calculates and analyses day-ahead feasible operating regions (envelopes) of buses in a distribution network with solar PVs, considering the impacts of controllable loads, load models, and PV sizes and locations. The envelopes were calculated considering network voltage and line loading constraints using Latin Hypercube Sampling (LHS)-based probabilistic load flow simulation and convex hull estimation in DIgSILENT and MATLAB environment. Morris screening sensitivity analysis was used to determine which buses’ envelopes were the most or least sensitive to changes in PV sizes at different locations. The findings revealed that a share of controllable loads could expand or shrink the envelopes depending on the time of the day, providing insight into load curtailment and payback periods. Different load models produced different envelopes, emphasising the significance of accurate load modelling. Moreover, the study demonstrated how changes in envelope sizes in one area affect those in another, highlighting the need for careful consideration prior to connecting/ increasing PV size in an area of the network in response to an increase in network load or LCT connections. The paper also highlighted the methodology’s flexibility in adapting to networks of various sizes, including unbalanced ones. Additionally, the paper introduced operating, risk based, zones within the envelopes to improve the approach’s effectiveness.