Distributed Electric Spring Based Smart Thermal Loads for Overvoltage Prevention in LV Distributed Network Using Dynamic Consensus Approach

Overvoltage arising from reverse power flow in low-voltage (LV) distribution network caused by surplus roof-top photovoltaic (PV) energy generation is a major challenge in the emerging smart grid. This paper reports a study on the use of distributed thermal Smart Loads (SLs) for overvoltage prevention along a LV feeder. The basic principle involves the combined use of electric springs (ESs) and storage-type electric water heaters (EWHs) as distributed smart loads. Through distributed control, these smart loads play the important roles of mitigating reverse power flow problems and maintaining local mains voltage within the specified tolerance. Detailed modeling of the combined ES and EWH including their practical electrical and thermal capacities and constraints is adopted and optional distributed energy storage system (ESS) is also considered in the evaluation. Based on the Sha Lo Bay residential LV network in Lantau Island, Hong Kong, these case studies confirm the feasibility of the proposed approach for overvoltage prevention. The proposed distributed SLs-plus-ESS method is proved to be a cost-effective and environmental friendly way for overvoltage prevention in LV distributed network with high PV penetration.