Voltage Control of Photovoltaic Generator in Combination With Series Reactor

Abstract—

This paper examines voltage control of photovoltaic (PV) generators. Small PV generators are generally connected to service lines whose impedances are mostly resistive. Accordingly, it is hard to cancel voltage rise due to PV generation by changing power factor. This paper first proposes to insert a series reactor in a service line. Its value and effect are considered. Second, a combination of constant voltage control with unity power factor control is proposed to reduce line loss. The unity power factor control usually operates, but if the voltage exceeds an operating range, the constant voltage control starts. Two control block diagrams are drawn and rules for switching controls are derived. Some experimental results are demonstrated and compared with simulation results to verify its effectiveness.

Grid Interconnection of Renewable Energy Sources at the Distribution Level With Power-Quality Improvement Features

Abstract—

Renewable energy resources (RES) are being increasingly connected in distribution systems utilizing power electronic converters. This paper presents a novel control strategy for achieving maximum benefits from these grid-interfacing inverters when 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 inject power generated from RES to the grid, and 2) shunt APF to compensate current unbalance, load current harmonics, load reactive power demand and load neutral current. All of these functions may be accomplished either individually or simultaneously. With such a control, the combination of grid-interfacing inverter and the 3-phase 4-wire linear/non-linear unbalanced load at point of common coupling appears as balanced linear load to the grid. This new control concept is demonstrated with extensive MATLAB/Simulink simulation studies and validated through digital signal processor-based laboratory experimental results.

A Soft-Switching DC/DC Converter With High Voltage Gain

Abstract—

A soft-switching dc/dc converter with high voltage gain is proposed in this paper. It provides a continuous input current and high voltage gain. Moreover, soft-switching characteristic of the proposed converter reduces switching loss of active power switches and raises the conversion efficiency. The reverse-recovery problem of output rectifiers is also alleviated by controlling the current changing rates of diodes with the use of the leakage inductance of a coupled inductor. Experimental results obtained on 200 W prototype are discussed.

A Novel Five-Level Three-Phase PWM Rectifier With Reduced Switch Count

Abstract—

This paper proposes a new circuit topology for a multilevel pulse width modulation (PWM) rectifier. The proposed method forms a new circuit by combining a diode clamp-type topology with a flying capacitor-type topology. The proposed circuit uses only 12 switches, despite the use of a five-level three-phase PWM rectifier. Further, the proposed circuit can obtain good performance, same as a conventional multilevel circuit. This paper describes about the features of the proposed topology; the control strategy and the loss analysis that is estimated by a circuit simulator. In addition, the basic operation of the proposed method is confirmed by simulation and experimental results. The proposed converter achieved total harmonic distortion of 3.4% for the input current and efficiency of 97.4% for a 1 kW class experimental setup.

A Modified SEPIC Converter for High-Power-Factor Rectifier and Universal Input Voltage Applications

Abstract—

A high-power-factor rectifier suitable for universal line base on a modified version of the single-ended primary inductance converter (SEPIC) is presented in this paper. The voltage multiplier technique is applied to the classical SEPIC circuit, obtaining new operation characteristics as low-switch-voltage operation and high static gain at low line voltage. The new configuration also allows the reduction of the losses associated to the diode reverse recovery current, and soft commutation is obtained with a simple regenerative snubber circuit. The operation analysis, design procedure, and experimental results obtained from a 650-W universal line power-factor-correction prototype of the proposed converter are presented. The theoretical analysis and experimental results obtained with the proposed structure are compared with the classical boost topology.