Review: Voltage Unbalance Control Techniques for Islanded Microgrid System (original) (raw)

Experimental evaluation of voltage unbalance compensation in an islanded microgrid

2011 IEEE International Symposium on Industrial Electronics, 2011

In this paper, a method for voltage unbalance compensation in an islanded microgrid based on the proper control of distributed generators (DGs) interface converter is proposed. In this method, active and reactive power control loops are considered to control the power sharing among the DGs. Also, a virtual impedance loop and voltage and current proportional-resonant controllers are included. Experimental results show the effectiveness of the proposed method for compensating voltage unbalance to an acceptable level.

IRJET- A Novel Control Strategy for Reduce Voltage Unbalance in an Islanded Microgrid

IRJET, 2021

Micro Grids (MG) provide advantages such as providing energy supply to areas far from the distribution grid, efficient use of resources by supporting demand management and having a more dynamic grid. However, if an advanced control system is not implemented in the islanded MG, problems of power quality may arise. One of these problems is the voltage unbalance. Increasing the number of single-phase roof-mounted PV plants and the number of electric vehicle charging stations in recent times may negatively affect voltage unbalance. One of the methods used to mitigate this problem is the Demand-Side Management (DSM). Here, a solution method based on DSM is presented for the voltage unbalance problem that may occur in an islanded MG. The proposed Direct power control algorithm reduces successfully both the voltage unbalance factor.

A direct voltage unbalance compensation strategy for islanded microgrids

2015 IEEE Applied Power Electronics Conference and Exposition (APEC), 2015

In this paper, a control strategy with low bandwidth communications for paralleled three-phase inverters is proposed to achieve satisfactory voltage unbalance compensation. The proposed control algorithm mainly consists of voltage/current inner loop controllers, a droop controller, a selective virtual impedance loop, and an unbalance compensator. The inner loop controllers are based on the stationary reference frame to better mitigate the voltage distortion under nonlinear loads. Droop control and selective virtual impedance loop achieve accurate current-sharing when supplying both linear and nonlinear loads. Moreover, by adjusting voltage references according to the amplitude of the negative sequence voltage, the unbalance factor, which is mainly caused by single phase generators/loads, can be mitigated to an extremely low value. Finally, an AC microgrid which includes three three-phase three-leg inverters was tested in order to validate the proposed control strategy.

Review: Unbalance Voltage Compensation in an Islanded Microgrid

2021

DGs have been a major component in addressing environmental, technological, and economic concerns throughout the history of power system development. The usage of DGs based on renewable energy supplies has decreased climate change worries substantially. Furthermore, the stability of DGs at consumption sites might provide some of the load from these resources, resulting in lower power transmission system loads and losses. The rising interest in pooling renewable energy resources in power microgrids poses a significant challenge in terms of power system reliability and control. In the recent decade, the subject of microgrid autonomous control has gotten a lot of attention. For islanded microgrids, a hierarchical control method can be used as the power system control architecture. Various approaches for hierarchical microgrid control have been explored thus far. The most up-to-date main control approaches for autonomous microgrid operation are described in this study. Index Terms – Vol...

Hierarchical control scheme for voltage unbalance compensation in islanded microgrids

IECON 2011 - 37th Annual Conference of the IEEE Industrial Electronics Society, 2011

The concept of microgrid hierarchical control is presented, recently. In this paper, a hierarchical scheme which includes primary and secondary control levels is proposed for islanded microgrids. The primary control level consists of DG local controllers. Local controller of each DG comprises active and reactive power controllers, virtual impedance loop and voltage and current controllers. The secondary level is designed to compensate the voltage unbalance at the load bus (LB) of the islanded microgrid. Also, restoration of LB voltage amplitude and microgrid frequency to the rated values is considered in the secondary level. These functions are achieved by proper control of distributed generators (DGs) interface converters. The presented simulation results show the effectiveness of the proposed control structure in compensating the voltage unbalance and restoring the voltage amplitude and system frequency.

Voltage Imbalance Compensation for Droop-Controlled Inverters in Islanded Microgrid

2017

In this paper, a new control strategy is proposed for implementation in low-voltage microgrids with balanced/ unbalanced load circumstances. The proposed scheme contains, the power droop controllers, inner voltage and current loops, the virtual impedance loop, the voltage imbalance compensation. The proposed strategy balances the voltage of the single-phase critical loads by compensating the imbalanced voltage drop on the feeders. In addition, this strategy has also shown to be capable of restoring critical loads' voltage to nominal values. This method also shares the real and reactive load accurately between DG units, based on their capacity. The simulation results in MATLAB /SIMULINK environment show the efficiency of the proposed approach in improving power sharing among DG units and decreasing voltage imbalance

Autonomous Voltage Unbalance Compensation in an Islanded Droop-Controlled Microgrid

IEEE Transactions on Industrial Electronics, 2000

Recently, there is an increasing interest in using distributed generators (DGs) not only to inject power into the grid, but also to enhance the power quality. In this paper, a stationary-frame control method for voltage unbalance compensation in an islanded microgrid is proposed. This method is based on the proper control of DGs interface converters. The DGs are controlled to compensate voltage unbalance autonomously while share the compensation effort and also active and reactive power, properly. The control system of the DGs mainly consists of active and reactive power droop controllers, virtual impedance loop, voltage and current controllers and unbalance compensator. The design approach of the control system is discussed in detail and simulation and experimental results are presented. The results demonstrate the effectiveness of the proposed method in compensation of voltage unbalance.

An overview of control approaches of inverter-based microgrids in islanding mode of operation

Renewable and Sustainable Energy Reviews, 2017

Increased penetration of distributed generation (DG) into the power systems has created fundamental challenges from the viewpoints of control and reliable operation of systems. Microgrids (an aggregation of DG units, loads, and storage elements) with proper control strategies can be a good solution for removing or facilitating these challenges. The introduction of inverter-based microgrid in a distribution network has facilitated the utilization of renewable energy resources, distributed generations, and storage resources; furthermore, it has improved power quality and reduced losses, thus improving the efficiency and the reliability of the system. As most DG units are connected via a power electronic interface to the grid, special control strategies have been developed for inverter interfaces of DG units in islanded microgrids. This paper presents an overview of advanced control methods for microgrids, especially the islanded and inverter-based. Moreover, various control methods are compared and categorized in terms of their respective features. It also summarizes microgrid control objectives with their most problematic solutions as well as their potential advantages and/or disadvantages. Finally, some suggestions are put forward for the future research.