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

In this work it is proposed a multilevel NPC configuration for a high-frequency pulsating DC-link inverter for three-phase applications. The configuration consists of two DC/DC-pulsating converters cascaded with a DC-link capacitorless three-phase three-level NPC inverter. Due to the absence of DC-link electrolytic capacitors, the proposed inverter guarantees a long lifetime and high power density. The DC/DC-pulsating converters aim to generate the high-frequency pulsating DC-link waveform profiles which have to be synchronized with the three-phase inverter PWM. Comparing to the conventional PWM, the three-phase multilevel NPC inverter presents reduced switching losses due to the fact only one leg commutes during a switching period while the other two legs keep clamped in high or low impedance. Details of control strategy and modulation are explained. Experimental results for a 2kW setup are presented to validate the theoretical approach.

High-Frequency Pulsating DC-Link Three-Phase Multilevel NPC Inverter Without Electrolytic Capacitor

This work introduces a family of Current Source Converters (CSCs) that allows to control single-phase AC converters with two outputs independently sharing the same DC-bus. It is presented four different topologies which have their own advantages and disadvantages compared to each other. The comparison criterias are the total number of switches, the number of conducting switches per switching cycle, quadrant operations and DC-bus current. One of the topologies needs to always have four conducting switches with full-quadrant operation (named Fq4c), while another topology (Lq2c) needs only two, however with limited-quadrant operation. The last two presented topologies have three conducting switches in a switching period, one with full-quadrant operation (Fq3c) and another with limited-quadrant operation (Lq3c). Also it is presented the Scalar Pulse Width Modulations (SPWMs) to control each converter with switching optimization. Details of the topologies, operation and modulation logic are presented. Simulations and experimental results are provided to validate the theoretical approach.

A family of single-phase Current Source Converters with double outputs

In this paper two two-phase current source open-end asymmetric rectifiers are proposed. These new rectifiers are derived from an improved multi-phase crossed switches current source converter, named X-type CSC. The X-type CSC presents independent full quadrant operation, lower DC-bus current value, high magnetic power density, higher efficiency (when compared to similar ones), and high AC output voltage waveform quality. Being used exclusively as a rectifier, the X-type CSC can be even further improved. One can replace the series switch-diode configurations by only diodes, resulting in an asymmetric converter with only four active switches. With this modification, the efficiency can be increased and the cost reduced. The two-phase asymmetric X-type current source rectifiers are presented with their respective pulse-width modulation technique and also proper control technique. Simulation and experimental results are presented in order to validate the theoretical approach. At last, a comparison of the studied topologies is made and the best converter is selected.

Two-phase X-type current source rectifier with reduced active switch count for open-end permanent-magnet synchronous generator

This paper investigates a power shunt filter composed by three standard three-leg converters, acting in three or four-wire system. Compared with the usual three-phase shunt filter, the proposed converter permits reducing the dc-link voltages, the harmonic distortion or/and the switching losses and being fault tolerant. Suitable control strategies to adjust the filter and circulating currents as well as the three dc-link voltages are presented. The PWM strategy is designed to command the converter according to the reference voltage solicited by the controllers. Simulation and experimental results are presented.

Y-connected three-leg converters applied in three or four-wire shunt compensator

This paper proposes a method of extracting the intrinsic parameters of a Photovoltaic (PV) generator by using Shuffled Complex Evolution (SCE) technique for a single-diode PV model. The characteristic equation of a single-diode PV generator presents a nonlinear behavior, which its solution to obtain the intrinsic parameters from an I × V experimental curve requires to use nonlinear optimization methods. To evaluate the effectiveness of the usage of SCE in extracting the intrinsic parameters of a PV generator, it is presented a comparison with Genetic Algorithms (GA) nonlinear optimization method. This evaluation uses statistic analysis as comparison criteria for an unknown PV module and relative error for each parameter in a known PV cell. The proposed SCE and AG are consider evolutionary optimization methods, so this paper shows that SCE needs less iterations/generations to converge than the other. Results show that the proposed method is feasible, faster and presents better results than the conventional technique.

Mauricio B. R. Correa

Papers

High-Frequency Pulsating DC-Link Three-Phase Multilevel NPC Inverter Without Electrolytic Capacitor

A family of single-phase Current Source Converters with double outputs

Two-phase X-type current source rectifier with reduced active switch count for open-end permanent-magnet synchronous generator

Y-connected three-leg converters applied in three or four-wire shunt compensator

Photovoltaic parameter extraction using Shuffled Complex Evolution