Reducing the Unfairness of Coordinated Inverter Dispatch in PV-Rich Distribution Networks

Abstract

The integration of a high share of solar photovoltaics (PV) in distribution networks requires advanced voltage control technologies or network augmentation, both associated with significant investment costs. An alternative is to prevent new customers from installing solar PV systems, but this is against the common goal of increasing renewable energy generation. This paper demonstrates that solar PV curtailment in low voltage areas can be reduced and fairly distributed among PV owners by centrally coordinating the operation of PV inverters. The optimal inverter active and reactive power operation points are computed by solving a multi-objective optimization problem with a fairness objective. The main results show that fair optimal inverter dispatch (FOID) results in less power curtailment than passive voltage regulation based on Volt/VAr droop control, especially at high solar PV to load ratios. The effectiveness of the model is demonstrated on a residential low voltage network.

Review on the PV Hosting Capacity in Distribution Networks

“…However, the curtailment alone results in energy losses that can be avoided by the storage in conjunction with small curtailment and reactive power support as an economical solution. Similarly, a Fair Optimal Inverter Dispatch method has been verified for the even curtailment across the tested LV residential network of 12 houses resulting in 13% higher PV HC in [32]. A small PV power curtailment enabled double PV penetration into the LV network with HC value of 88% (142 kWp) of transformer rating by opting for a probabilistic approach in [89].…”

“…Reactive power control is very efficient in high voltage grids having a high X/R ratio as compared to low voltage grids. The Active Power Curtailment (APC) for maintaining the network stability under high PV penetration has been discussed in some studies [32,89] but the authors of [45] prioritized RPC in terms of voltage compensation as compared to APC. The system works at a unity PF during the normal operation with the network voltages within acceptable limits.…”

“…APC as an important aspect for HC increase is discussed by authors of [1,32,52,81,89]. A curtailment up to PV HC of 30% and 50% is more profitable as compared to RPC and Storage as discussed in [81].…”

“…PV inverters and battery storages are good alternatives to voltage regulators due to the slow response time of the latter. The OLTC operation integrated with capacitors can increase hosting capacity with only minor operational changes and without prominent additional grid investment costs [32]. The main motivation for using OLTC in [28] is the voltage violation as the limiting factor for the rural and suburban networks thus making OLTC the appropriate option.…”

Interaction Between Coordinated and Droop Control PV Inverters

“…Autonomous inverters are network-agnostic, which makes them simple and easy to deploy, but it also means that they provide only suboptimal operations of the network [6], particularly in the areas with a large number of customers per distribution transformer [24]. While passive inverter control can reduce the number of customers experiencing overvoltages [19], the limitations of such control approach become particularly obvious when operating in a network with high PV penetration [23].…”