Adaptive Volt-Var Control Algorithm to Grid Strength and PV Inverter Characteristics

Abstract

The high-penetration of Distributed Energy Resources (DER) in low voltage distribution grids, mainly photovoltaics (PV), might lead to overvoltage in the point of common coupling, thus, limiting the entrance of renewable sources to fulfill the requirements from the network operator. Volt-var is a common control function for DER power converters that is used to enhance the stability and reliability of the voltage in the distribution system. In this study, a centralized algorithm provides local volt-var control parameters to each PV inverter, which are based on the electrical grid characteristics. Because accurate information of grid characteristics is typically not available, the parametrization of the electrical grid is done using a local power meter data and a voltage sensitivity matrix. The algorithm has different optimization modes that take into account the minimization of voltage deviation and line current. To validate the effectiveness of the algorithm and its deployment in a real infrastructure, the solution has been tested in an experimental setup with PV emulators under laboratory conditions. The volt-var control algorithm successfully adapted its parameters based on grid topology and PV inverter characteristics, achieving a voltage reduction of up to 25% of the allowed voltage deviation.

V-Iq Based Control Scheme for Mitigation of Transient Overvoltage in Distribution Feeders With High PV Penetration

“…To avoid the issues related to communication constraints, i.e., cost, reliability, and latency, decentralized reactive power control methods can be employed [15,[19][20][21]30]. In the decentralized approaches, the reactive power reference of each PV inverter is calculated based on its own local measurements in accordance to constant power factor, power factor-active power and voltage-reactive power (V-Q) characteristics [15,31]. In [21], for three states of operation of PV, including normal, fluctuation and contingency, a scheme has been introduced to address adverse impacts while exploiting the benefits related to high penetration of rooftop PV in various weather conditions.…”

Characterization of Voltage Stabilization Functions of Residential PV Inverters in a Power Hardware-in-the-Loop Environment

“…Lastly, of significant relevance to this work are a few reports where authors have employed HIL laboratories for testing specific grid-supporting functions of smart inverters. For example, Gubert et al developed a centralized algorithm for volt-var control on PV inverters that was tested in a HIL setup with a grid emulator, an emulated distribution line with variable impedance, a PV emulator, a SCADA system, and a Remote Terminal Unit (RTU) [22]. In another study, Singh and Prabakar tested volt-var, volt-watt, and frequency watt controls of a 3-phase 50 kW silicon carbide (SiC) based inverter using a Controller HIL (C-HIL) testbed [23].…”