Active power decoupling methods are developed to deal with the inherent ripple power at twice the grid frequency in single-phase systems generally by adding active switches and energy storage units. They have obtained a wide range of applications, such as photovoltaic (PV) systems, light-emitting diodes (LEDs) drivers, fuel cell (FC) power systems, and electric vehicle (EV) battery chargers, etc. This paper provides a comprehensive review of active power decoupling circuit topologies. They are categorized into two groups in terms of the structure characteristics: independent and dependent decoupling circuit topologies. The former operates independently with the original converter, and the latter, however, shares the power semiconductor devices with the original converter partially and even completely. The development laws for the active power decoupling topologies are revealed from the view of “duality principle,” “switches sharing,” and “differential connection.” In addition, the exceptions and special cases are also briefly introduced. This paper is targeted to help researchers, engineers, and designers to construct some new decoupling circuit topologies and properly select existing ones according to the specific application.

Review of Active Power Decoupling Topologies in Single-Phase Systems

Parameter extraction of solar photovoltaic models using an improved whale optimization algorithm

Comprehensive overview of meta-heuristic algorithm applications on PV cell parameter identification

This paper proposes a new converter for photovoltaic (PV) water pumping or treatment systems without the use of chemical storage elements, such as batteries. The converter is designed to drive a three-phase induction motor directly from PV energy. The use of a three-phase induction motor presents a better solution to the commercial dc motor water pumping system. The development is oriented to achieve a more efficient, reliable, maintenance-free, and cheaper solution than the standard ones that use dc motors or low-voltage synchronous motors. The developed system is based on a current-fed multiresonant converter also known as resonant two-inductor boost converter (TIBC) and a full-bridge three-phase voltage source inverter (VSI). The classic topology of the TIBC has features like high voltage gain and low input current ripple. In this paper, it is further improved with the use of a nonisolated recovery snubber along with a hysteresis controller and the use of a constant duty cycle control to improve its efficiency. Experimental results show a peak efficiency of 91% at a rated power of 210 W for the dc/dc converter plus the three-phase VSI and a peak efficiency of 93.64% just for the dc/dc converter. The system is expected to have a high lifetime due to the inexistence of electrolytic capacitors, and the total cost of the converter is below 0.43 U$/Wp. As a result, the system is a promising solution to be used in isolated locations and to deliver water to poor communities.

Implementation of a High-Efficiency, High-Lifetime, and Low-Cost Converter for an Autonomous Photovoltaic Water Pumping System

Power electronic converter (PEC)-interfaced renewable energy generators (REGs) are increasingly being integrated to the power grid. With the high renewable power penetration levels, one of the key power system parameters, namely reactive power, is affected, provoking steady-state voltage and dynamic/transient stability issues. Therefore, it is imperative to maintain and manage adequate reactive power reserve to ensure a stable and reliable power grid. This paper presents a comprehensive literature review on the reactive power management in renewable rich power grids. Reactive power requirements stipulated in different grid codes for REGs are summarized to assess their adequacy for future network requirements. The PEC-interfaced REGs are discussed with a special emphasis on their reactive power compensation capability and control schemes. Along with REGs, conventional reactive power support devices (e.g., capacitor banks) and PEC-interfaced reactive power support devices (e.g., static synchronous compensators) play an indispensable role in the reactive power management of renewable rich power grids, and thus their reactive power control capabilities and limitations are thoroughly reviewed in this paper. Then, various reactive power control strategies are reviewed with a special emphasis on their advantages/disadvantages. Reactive power coordination between support devices and their optimal capacity are vital for an efficient and stable management of the power grid. Accordingly, the prominent reactive power coordination and optimization algorithms are critically examined and discussed in this paper. Finally, the key issues pertinent to the reactive power management in renewable rich power grids are enlisted with some important technical recommendations for the power industry, policymakers, and academic researchers.

Reactive Power Management in Renewable Rich Power Grids: A Review of Grid-Codes, Renewable Generators, Support Devices, Control Strategies and Optimization Algorithms

This paper investigates power shunt filter topologies composed of three standard three-leg converters applied in either three or four-wire system. Compared with the usual three-phase shunt filter, the proposed ones allow us to reduce dc-link voltages, harmonic distortion or/and the semiconductor losses, and fault tolerant operation. Suitable control strategies to adjust filter and circulating currents, as well as the three dc-link voltages are presented. Two pulse-width modulation techniques are developed for the proposed topologies in order to achieve the best voltage-pulse pattern. Comparisons between these techniques are carried out in this paper. Simulation and experimental results are presented to validate the theoretical approach.

Y-Connected Three-Leg Converters Applied in Three or Four-Wire Shunt Compensator

In this work it is presented a technique to reduce DC link pulsation due to the pulsating single-phase energy flow in Voltage Source Converter (VSC) and Current Source Converter (CSC). The pulsation reduction is achieved by adding two power switches and a passive energy storage element to the converter. Both, rectifier and inverter operation are evaluated. Details about design and control strategies, which has demonstrated performance improvements, when compared with others solutions, are presented. Simulation and experimental results are provided to validate the theoretical approach.

Compensation of DC link pulsation in single-phase static converters

In this work it is presented a generalized converter configuration for a high-frequency pulsating DC-link inverter for three-phase applications The configuration consists of a DC/DC-pulsating converter cascaded with a DC-link capacitor-less three-phase inverter Due to the absence of a DC-link electrolytic capacitor, the presented inverter guarantees a long life-time and high power density The DC/DC-pulsating converter aims to generate the high-frequency pulsating DC-link waveform profile which has to be synchronized with the three-phase inverter PWM Comparing to the conventional PWM, the harmonic spectrum of voltages is the same, but the pulsating DC-link three-phase inverter presents reduced switching losses due to the fact that only one leg commutes during a switching period while the other two legs keep clamped in high or low Details of control strategy and modulation are presented Experimental results of a 16 kW prototype are presented to validate the effective operation of the proposed structure

High-frequency pulsating DC-link three-phase inverter without electrolytic capacitor

This paper aims to propose solutions for mitigating the adverse effects of starting torque transients, especially in low cost single-phase to three-phase drive systems. The first approach employed for reducing hard current transient and troublesome torque is based on Steinmetz connection; this minimizes the currents of negative sequence and uses the grid source in series with the converter. The second proposal uses the midpoint of dc-link capacitors. The motor starts in a configuration that allows three-phase control, an efficient soft start and the power factor control, as well. Several relevant characteristics of the proposed strategies are addressed. Simulated and experimental results are presented to validate the proposed approaches.

Soft-starting techniques for low cost single-phase to three-phase drive system configuration

An active control law for a current fed push-pull converter used in photovoltaic applications is discussed in this paper. The proposed control law aims at avoiding magnetic flux saturation and eliminating the magnetic flux imbalance observed at both windings of the converter transformer. The most prominent advantages of operating without flux saturation are: a more effective magnetic core design; power switches and converter live endurance; less voltage switching stress. Detailed analysis including simulation and experimental results are used to demonstrate the effectiveness of the proposed active control law.

Mauricio B. R. Correa

Papers

Y-Connected Three-Leg Converters Applied in Three or Four-Wire Shunt Compensator

Compensation of DC link pulsation in single-phase static converters

High-frequency pulsating DC-link three-phase inverter without electrolytic capacitor

Soft-starting techniques for low cost single-phase to three-phase drive system configuration

A simple and effective control strategy for improved operation of a current-fed push-pull converter