Papers by Keyword: Grid-Connected Inverter

Abstract: Control strategy under unbalanced grid voltage conditions is one of the most important issues for grid-connected inverter. Under unbalanced grid voltage conditions, the 2^nd active and reactive power ripples generate, they pollute the grid. To meet the demands of IEEE Std.929-2000, this paper proposed a modified power compensation control strategy; the proposed solution is based on direct power control. To provide accurate compensating power, the power model of three-phase inverter under unbalanced grid voltage conditions is given, using the positive sequence current component and the negative sequence voltage component, the compensating powers are calculated in details. Theoretical analysis and comparative simulation verification are presented to demonstrate the effectiveness of the proposed control strategy.

Abstract: The effective control of a grid-connected inverter (GCI) under unbalanced grid voltages condition is able to enhance the grid-connected operation ability of the inverter. This paper studies the control scheme of a three-phase GCI with proportional plus resonant (PR) regulators in the stationary αβ frame to remove the power ripples caused by the unbalanced condition and the currents of positive and negative components can be controlled directly without any decomposition. A precise and fast phase locked loop is also introduced in this paper. Three control targets are achieved on a 2KVA experimental platform of a GCI and the experimental results agree well with the theoretical analysis.

Abstract: The limitations of both grid-connection control and var optimization for improving the voltage of the distribution network with DGs are pointed out in this paper. Thus, it is proposed that the integration of grid-connection control and var optimization for complementary advantages becomes necessary. A model of var optimization based on genetic algorithm is designed, and analysis of examples is carried out by use of MATLAB. Meanwhile, control models of grid-connected inverters based on P-f droop control and P-δ droop control are designed, whose characteristics are compared by simulations done on MATLAB/Simulink. Results show the validity of the supposed var optimization technique and grid-connection control technique.

Abstract: Due to the perturbation between multiple PV Grid-connected power system can’t be synchronized easily, the islanding detection often lose efficacy when multiple PV Grid-connected inverters are running simultaneously. The paper show the in-depth analysis of the principle and the advantages and disadvantages of the detection method of AFDPF and SMS, a composition controller is designed aim at the non-detection zone in multiple PV Grid-connected system in the practical application. Through the software simulation, it shows that the method mentioned in the paper practically improves the effect of the islanding detection.

Abstract: Based on the basic principles of anti-islanding detection, this paper puts forward an anti-islanding (AI) detection method which combined/q-axis voltage decoupling and positive feedback with Euler-Lagrange (EL) model .The proposed method is classified as an passive islanding detection method and it is based on the voltage change at the point of common coupling (PCC) that occurs in islanding .In the method, Add the d-axis decoupling voltage of PCC to the d-axis reference current of the EL model. A simulation study shows that the method is simple and feasible.

Abstract: This paper studied the control strategy of single-phase two-stage grid-connected photovoltaic generation system. The two-stage topology includes the boost converter and single phase inverter. The function of maximum power point tracking (MPPT) is achieved in the boost circuit by IC (Increment Conductance) method. The inverter circuit adopted the double-closed loop control, a DC voltage outer loop control for power balance with PI correction and an AC current inner loop control for feedback designed to ensure the current quality and stabilize the DC voltage. The inner loop used the novel quasi-Proportional-Resonant (PR) controller, which has a better steady tracking characteristics and stronger anti-interference ability to the disturbance. Finally, a simulation system is built with Matlab/Simulink in this paper to verify the validity of the MPPT algorithm and the quasi-PR control strategy.Keywords：Photovoltaic Generation System;Maximum Power Point Tracking; Grid-connected Inverter; quasi-Proportional-Resonant (PR) controller

Abstract: This study proposes an active islanding detection method for use of grid-connected inverter of renewable energy generation system (REGS). With a digital signal processor (DSP) integrated, the proposed method is capable of detecting the islanding fault of grid-connected inverters of REGS during the variable load conditions. To verify the effectiveness of the proposed method, the method was tested on a practical inverter of REGS, the field practical operations of the proposed method were studied in accordance with the conditions for the different loads and fault types. Test results are presented which show that the new proposed method is reliable, economical and easy for implementation.

Abstract: It is necessary that the grid-connected inverter was set up in wind power, in order to convey energy generated in wind power to the grid. There are many sorts of inverters, but only two sorts of inverters suit wind power system, which are current-source inverter and voltage-source inverter, and only the later is being widely used. Their configuration, principle, control and characteristic were analyzed in this paper. Results have shown that, voltage-source grid-connected inverter has been the core of the commutation control configuration of direct-driven wind power, which is decided by the peculiarity of itself.

Abstract: It is necessary that the grid-connected inverter was set up in wind generation system (WGS), in order to convey energy generated in WGS to the electrical grid. There are many sorts of inverters, but only two sorts of inverters suit wind generation system, which are current-source and voltage-source inverter, and only the latter is being widely used. The configuration, principle, control and characteristic of the two inverters were analyzed. Results have shown that, voltage-source grid-connected inverter has been the core of the commutation control configuration of direct-driven WGS, which is decided by the peculiarity of itself.

Abstract: Renewable energy resources (RES) are being increasingly connected in distribution systems by utilizing power electronic converters. However, the extensive use of power electronics has resulted in a rise in power quality (PQ) concerns faced by the utility. A novel control strategy implementing reference compensation current was proposed in this paper. So that these grid-connected inverters can achieve maximum benefits when they installed in 3-phase 4-wire distribution systems. The inverter is controlled to perform as a multi-function device by incorporating active power filter functionality. The inverter can thus be utilized as: 1) power converter to transfer active power from RES to the grid, and 2) load reactive power demand support; 3) current harmonics compensation at PCC; and 4) current unbalance and neutral current compensation in case of 3-phase 4-wire system. Moreover, with adequate control of grid-interfacing inverter, all the four objectives can be accomplished either individually or simultaneously. Simulation results show the validity and capability of the novel proposed control strategy.