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The demand of the electrical power is increasing per day which is supplied by fossil fuels resulting into huge carbon emissions in the atmosphere, which leads the electrical engineers to generate the power by using the renewable energy sources. This paper is aimed at simulation and development of Solar PV system which is able to fulfil the power demand in the isolated locations or in standalone condition...
This paper proposes a novel autonomous control scheme for equal load current distribution between n parallel-connected, LCL-based, three phase UPS units. The control is based on varying the capacitor reference voltage of each inverter as a function of its own output current, without exchanging information between the inverters. The load voltage is maintained fixed at the specified reference value...
Single phase rectifiers and inverters are inherently subject to double-line frequency ripple power, at both the ac and dc sides, which has adverse effects on the overall system performance. Normally a bulky capacitor is placed at the dc side of the circuit to prevent this ripple power ripple from reaching the dc source. This approach results in low power density and reliability issues. As a result,...
To date, a family of series-connected boost converter (SCBC) with enhanced efficiency has been presented as the front-end dc/dc stage of distributed photovoltaic (PV) inverter, which suffers the severe PV voltage/power oscillation when operated under unbalanced grid voltage condition. This paper proposes an operational scheme to enhance the performance of one type SCBC, namely the dual-input central...
In this paper, two different Reactive Power Injection (RPI) methods for a fully distributed PV inverter architecture are investigated. RPI methods are parts of ancillary service requirements for modern PV systems to play a more active role in grid regulation and control in future high penetrated PV generation networks. The main objective of this paper is to demonstrate and test RPI methods on a panel-level...
DC voltage control is crucial for the multi-stage converter, because it contributes to reduce the DC capacitance and improve the reliability of the whole system. A combined control scheme, induding two parts, is proposed in this paper for controlling the two DC bus voltages respectively in the Energy Router. Firstly, the energy feed-forward control scheme is used to control the low voltage DC bus,...
Power density and efficiency are important metrics for power converters in many applications including renewable energy interface. Combined with the desire to replace the bulky, unreliable electrolytic dc link capacitors with film or ceramic capacitors due to reliability concerns, this has led to the trend of allowing increasingly higher double line frequency dc link voltage ripple. This paper discusses...
Pulse width modulated voltage source inverters (PWM-VSI) have many advantages over the traditional bridge inverters; yet there are some challenges encountered by PWM inverters. As power and voltage rating increases; device constraint as well ashigh switching loss creates serious problems. Various pulse width modulated strategies like sinusoidal; 3rd harmonic injection and space vector PWM (SVPWM)...
In this paper, the topology and the control scheme of the photovoltaic three-phase grid connected inverter based on voltage-oriented control (VOC) is analyzed. In VOC, a current control loop is used. The currents are controlled in a synchronous rotating dq-frame using a decoupled feedback control. The reference current of d-axis controller is extracted from instruction which comes from the former...
A control strategy for PWM inverters used in double conversion UPS systems is proposed. The objectives of this control strategy are to control the inverter output voltage to comply with performance specification given by standards, and control the inductor current to achieve short-circuit and overload protection. The control strategy is composed by two feedback loops, where the inner current loop...
Renewable energy sources are highly intermittent in nature and also has different power characteristics. It is difficult to integrate more than one renewable energy sources using a monolithic dual-input DC/DC converter circuit topology with a proper controller. A fuzzy control scheme is designed for the integration of two different nonlinear characteristic sources (like solar PV, wind) using a DC/DC...
This paper proposes a scheme for changing the operation modes of bidirectional interleaved DC/DC converter used in battery powered electric vehicles (EVs). The proposed pattern changes the converter operation from boost to buck according to the DC-link voltage value. This strategy is suggested to save power and increase efficiency of the EV energy storage system (ESS). A buck-boost DC/DC converter...
This paper presents integration of solar-wind hybrid fed DC-grid to distributed AC grid. Generally, the renewable hybrid energy systems use two or more energy sources to supply power to the dc grid. In case of insufficient power generation or excessive load demand, in order to supply power to DC loads, it must integrate with AC grid. As dc loads increase in number, complexity increases and tighter...
The present work deals with a nonlinear control strategy for the purpose of photovoltaic (PV) systems integration into the power system through cascaded Z-source H-bridge inverters. The topology of the proposed system which is able to obtain a 5-level voltage is discussed. To facilitate a systematic voltage control, an exact nonlinear model of the proposed system is presented. A nonlinear voltage...
A novel power decoupling circuit using a flying capacitor topology is proposed in this paper. The inverters, which are connected to a single-phase grid, have single-phase power fluctuation at the twice the grid frequency. Thus, bulky electrolytic capacitor is generally used as DC link capacitor. In the proposed circuit, the power fluctuation is compensated by the flying capacitor in the flying capacitor...
One important type of power conditioning systems in photovoltaic (PV) application is the string inverter which requires small input voltage and current ripple. In addition, high-efficiency and high-power density are also the critical requirements for string inverter system. So the input voltage and current ripple cannot be easily rejected by paralleling large conventional electrolytic capacitors in...
This paper presents a three-phase transformerless uninterruptible power supply (UPS) with sinusoidal pulse width modulation (SPWM) based division-summation (D-Σ) digital control. A transformerless UPS controls the power flow between dc link and utility grid, as well as tracks the ac reference voltage. The proposed control law derived with D-Σ digital approach takes into account the effects of dc-link...
Recent advances in solid-state semiconductors have led to the development of medium-voltage power converters which could obviate the need for the step-up transformers of renewable power generation systems. The modular multilevel cascaded converters have been deemed as strong contenders for the development of medium-voltage converters, but it requires multiple isolated and balanced dc supplies. In...
The objective of this study was to develop a microinverter for solar power conversion systems for converting dc voltage generated by solar cells at varying voltage levels into single-phase ac power with constant voltage and constant frequency. This study proposes coupled inductors and double-boost topology architecture for maintaining a stable voltage on the output side and reducing the size and cost...
Since parabolic current control has fast transient response and high control precision with constant switching frequency, it is an attractive current control strategy for voltage source inverters. The employment of parabolic current control delivers great performance on current waveform control or voltage waveform control. The implementation of parabolic current control usually requires high speed...
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