The value of conservation voltage reduction to electricity security of supply

In the specific event that there is not enough electricity being produced in the power market of Great Britain to meet demand, the system operator can use a set of mitigation tools to manage these supply shortfalls that are outside of normal operation of the market and that are used ahead of any controlled customer disconnections. Demand control is an emergency mitigation tool used by the system operator that instructs distribution network operators to implement voltage reduction across the electricity distribution system with the intent of achieving a reduction in customer's demand. The introduction of new low carbon generation and demand technologies in the electricity distribution networks, with fundamentally different technical and operating characteristics from the incumbent technologies, is likely to drive a dissimilar impact on the level of demand reduction that can be achieved through voltage reduction compared to those previously expected. Thus, there is a need to comprehensively understand the effectiveness of the voltage reduction in electricity distribution networks that can be realised through demand control events. The delivery of demand control can be achieved through conservation voltage reduction (CVR) techniques based on the principle of lowering the supply voltage to end-use consumers of electricity in order to reduce the energy consumption of some types of loads while maintaining customer service voltage within statutory limits. This paper presents a methodology to quantify and assess the value of CVR to security of supply of electricity systems. Specifically, it estimates the response of electricity demand to demand control events in the electricity distribution system to reduce customer's demand during periods of significantly low supply-demand margins. The methodology is applied to a network structure representative of the electricity distribution network of Great Britain and the value of CVR is estimated for individual distribution network feeders and for the distribution system over an annual load cycle. The analysis demonstrates that the response of demand to voltage reduction is relatively different from substation to substation, feeder to feeder and especially load to load. The CVR factor for the Great Britain electricity distribution network is assessed to vary on average from 0.81 in the summer season to 1.13 in the winter season. The CVR factors for the electricity distribution network of Great Britain are expressed in the form of a look up table to provide a simple framework for network operators to estimate the response of demand to voltage reduction/demand control events.