Voltage regulation in LV grids by coordinated volt-var control strategies

Abstract

The increasing penetration level of photovoltaic (PV) power generation in low voltage (LV) networks results in voltage rise issues, particularly at the end of the feeders. In order to mitigate this problem, several strategies, such as grid reinforcement, transformer tap change, demand-side management, active power curtailment, and reactive power optimization methods, show their contribution to voltage support, yet still limited. This paper proposes a coordinated volt-var control architecture between the LV distribution transformer and solar inverters to optimize the PV power penetration level in a representative LV network in Bornholm Island using a multi-objective genetic algorithm. The approach is to increase the reactive power contribution of the inverters closest to the transformer during overvoltage conditions. Two standard reactive power control concepts, cosu(P) and Q(U), are simulated and compared in terms of network power losses and voltage level along the feeder. As a practical implementation, a reconfigurable hardware is used for developing a testing platform based on real-time measurements to regulate the reactive power level. The proposed testing platform has been developed within PVNET.dk project, which targets to study the approaches for large PV power integration into the network, without the need of reinforcement.

Coordinated reactive power strategy using static synchronous compensator for photovoltaic inverters

“…Four different reactive power control methods have been suggested according to Ref. : fixed power factor, constant reactive power, power factor control dependent on the active power injection cos ′ ( P ), and local reactive power control dependent on voltage Q(U). The last technique is of interest for this study as the Q(U) method directly uses the local voltage information to stabilize the weak bus voltage.…”

Review of Voltage and Reactive Power Control Algorithms in Electrical Distribution Networks

“…Normally, uncoordinated local Q controllers provoke uncontrolled flows of reactive power in superordinate networks [31,45]. This shortfall is widely known; thus, in many cases, utility companies use conventional Volt/var control technologies for step-setting of the distribution transformer (DTR) and coordinate reactive power devices [31,46]. The implementation of such coordination at low voltage levels requires large-scale data exchange among consumers and DSOs, ensuring stringent data privacy requirements [31].…”

Information-Quality Based LV-Grid-Monitoring Framework and Its Application to Power-Quality Control

“…When more distributed power sources penetrate into the LV grid, voltage control becomes more challenging. In particular, the voltage rise is the major issue in LV grids with high share of PVs due to active power injection and small X/R ratios [5]. The purpose of our reference controller is to keep the voltage levels within defined range by regulating grid-interfaced PV inverters upon over-voltage occurrence.…”