A Virtual-Impedance Droop Control for Accurate Active Power Control and Reactive Power Sharing Using Capacitive-Coupling Inverters

2020 ◽  
Vol 56 (6) ◽  
pp. 6722-6733
Author(s):  
Wenyang Deng ◽  
NingYi Dai ◽  
Keng-Weng Lao ◽  
Josep M. Guerrero
Author(s):  
Eder A. Molina-Viloria ◽  
John E. Candelo Becerra ◽  
Fredy E. Hoyos Velasco

The traditional droop control strategy has been applied previously in microgrids (MGs) to share accurately the active power. However, in some cases the result obtained when sharing reactive power is not the best, because of the parameters related to the distances from distributed generators (DGs) to the loads and the power variations. Therefore, this paper proposes a reactive power control strategy for a low voltage MG, where the unequal impedance related to the distances between generators and loads requires adjustments to work with the conventional frequency and voltage droop methods. Thus, an additional coefficient is calculated from parameters of the network that relate the location of elements. The test is perfomed by simulations in the MATLAB-Simulink software, considering a three-node MG with three DGs and a load that can change power at different periods of time. The results show that it is possible to improve reactive power sharing between the DGs located in the MG according to the load changes simulated and to improve voltages with this method.


2015 ◽  
Vol 18 (1) ◽  
pp. 16-28
Author(s):  
Phuong Minh Le ◽  
Dai Tan Le ◽  
Hoa Thi Xuan Pham

This paper presents a new method for controling parallel inverters to share active power and reactive power in the energy system with non-linear loads. In these systems, the virtual output impedance is usually added to the control loop of each inverter to improve the active power and reactive power sharing as well as the quality of the voltage system. Paper also proposes a kind of virtual impedance as a second-order general-integrator (SOGI) scheme. The simulation results in Matlab Simulink show the ability of the proposed controller to good share power P-Q, when connected with unbalanced and nonlinear loads. By using the proposed algorithm allows to reduce the voltage THD to 1.9% and 1.2% for unbalanced and nonlinear loads according by comparision with traditional control scheme.


Author(s):  
Ikhlaq Hussain

AbstractThis paper presents an active power control of SPV (Solar Photovoltaic) grid tied system with the DSTATCOM (Distribution Static Compensator) capabilities using recursive least square (RLS) control algorithm with IC (Incremental Conductance) maximum power point tracking. The system serves dual purpose of working as a SPV-DSTATCOM and DSTATCOM in presence and absence of solar power, respectively. The SPV-DSTACOM provides compensating currents along with active current component thus fulfilling active power demand of connected load and feeds active power to the grid along with improving the power quality. Moreover, when the solar power is not available during night or low solar irradiation conditions, the system works as a DSTATCOM providing compensating current which improves the power quality of the system during load unbalance, harmonics and reactive power. A RLS based adaptive algorithm is used to do these functions at good convergence than conventional LMS (Least Mean Square) algorithm. Thus, the proposed system is capable to meet peak power demand when the solar energy is available and it improves the system power quality during day and night. The system responses under varying conditions is demonstrated on s developed prototype.


2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Herong Gu ◽  
Deyu Wang ◽  
Hong Shen ◽  
Wei Zhao ◽  
Xiaoqiang Guo

Power flow control is one of the most important issues for operating the inverter-dominated autonomous microgrid. A technical challenge is how to achieve the accurate active/reactive power sharing of inverters.P-FandQ-Vdroop control schemes have been widely used for power sharing in the past decades. But they suffer from the poor power sharing in the presence of unequal line impedance. In order to solve the problem, a comprehensive analysis of the power droop control is presented, and a new droop control based on the impedance match concept is proposed in this paper. In addition, the design guidelines of control coefficients and virtual impedance are provided. Finally, the performance evaluation is carried out, and the evaluation results verify the effectiveness of the proposed method.


Open Physics ◽  
2017 ◽  
Vol 15 (1) ◽  
pp. 948-953
Author(s):  
Aimeng Wang ◽  
Jia Zhang

AbstractThis paper investigates the problem of reactive power sharing based on virtual flux droop method. Firstly, flux droop control method is derived, where complicated multiple feedback loops and parameter regulation are avoided. Then, the reasons for inaccurate reactive power sharing are theoretically analyzed. Further, a novel reactive power control scheme is proposed which consists of three parts: compensation control, voltage recovery control and flux droop control. Finally, the proposed reactive power control strategy is verified in a simplified microgrid model with two parallel DGs. The simulation results show that the proposed control scheme can achieve accurate reactive power sharing and zero deviation of voltage. Meanwhile, it has some advantages of simple control and excellent dynamic and static performance.


2016 ◽  
Vol 19 (4) ◽  
pp. 14-34
Author(s):  
Phuong Minh Le ◽  
Duy Vo Duc Hoang ◽  
Hoa Thi Xuan Pham ◽  
Huy Minh Nguyen ◽  
Dieu Ngoc Vo

This paper proposes a new control sharing method for parallel three-phase inverters in an islanded microgrid. The proposed technique uses adaptive PIDs combined with the communication among the parallel inverters to accurately share active power and reactive power among the inverters via adjusting the desired voltage if there is a distinct difference between line impedance and the load change in the microgrid. Moreover, the paper also presents the response ability of the inverters to maintain the error within the allowed limits as the transmission line is interrupted. The proposed technique has been verified in a microgrid with three parallel distributed generation-inverter units using Matlab/Simulink. In the simulation, as the droop control using the communication information among the inverters, the sharing errors for active power and reactive power are around 0.2% and 0.6%, respectively. As the connection between the microgrid and transmission line is interrupted, the sharing errors for active power and reactive power increase to 0.4% and 2%, respectively. The simulation results have indicated that the proposed technique is superior to the traditional droop control in terms of the accuracy and stability. Therefore, the new proposed technique can be a favor alternative model for active power and reactive power sharing control of parallel inverters in an islanded microgrid.


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