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This paper proposes a grid code for photovoltaic (PV) integration to mitigate overvoltage and voltage variation problems caused by a large amount of PV generation in distribution circuits. According to the simulation results, PV generation causes overvoltage and voltage variation problems in distribution circuits. To mitigate the overvoltage and voltage variation problems due to the high penetration...
A control strategy of three-level multi-functional grid-connected inverter for distributed grid is proposed. According to different conditions of distributed generation, the multi-functional inverter can realize the function of injecting power from the distributed generation and suppling power into the grid simultaneously or separately, and the function of shunt active power filters such as the harmonic...
The power fluctuation of distributed generation has a negative effect on the power quality, losses and operation safety, and a good solution is to mitigate the power fluctuation near the grid-connected point of this generation. A new method for mitigating grid-side power fluctuation by the grid-connected inverter itself is proposed in this paper. A certain capacity of Li-ion supercapacitor is used...
In this paper, reactive power variation based on positive feedback is proposed for improving islanding detection in the distributed generation. The proposed reactive power variation method consists of two parts, where the first part has a fundamental amplitude as +5%Pinv or −5%Pinv, and the second part has a positive feedback using a frequency deviation. Polarity and amplitude of RPV method are determined...
This paper presents a design approach to an embedded monitoring system found in distributed renewable energy power systems. The grid connected distributed power system, delivers energy to the consumers located on the micro-grid, operating at distribution voltage levels, and also delivering the remaining surplus energy to the main distribution grid. The aim of this paper is to present the development...
Electrical energy obtained from state-owned electricity company is often can not fulfill the electrical energy required by the industry during peak load. Another problem that industry faced is the availability of electrical energy supply is not continuous. Solution to this problem, the industry needs another source of electrical energy so the availability of electrical energy can be achieved. This...
The paper addresses the problem of fault detection in an unbalanced microgrid with distributed generators, using algorithms based on harmonic estimation: Wavelet Transform (WT), Fast Fourier Transform (FFT) and Reduced Fast Fourier Transform (RFFT). Simulations were carried out in the MATLAB/SimPowerSystems environment. Modified IEEE13 bus system with distributed generation was used. Experimental...
Installation and control of proposed and/or connected distributed generation is constrained technically by the relevant protection systems, network structure and by documentation that governs its operation. This documentation which refers openly to the regulatory framework, standards and specification both by a utility, municipality or government regulatory body guides the manner in which a distributed...
The authors solve the problem of effective use of renewable energy sources for autonomous electric consumers. A new device for coupling heterogeneous energy sources has been developed. The universal coupling device (UCD) allows to connect diverse AC and DC sources to a 220/380VAC consumer. A 30 kVA UCD prototype is created. The article gives a UCD brief description and presents the results of the...
The rapidly rising penetration level of distributed generators (DGs) increases the risk of unacceptable voltages in distribution systems. The conventional voltage regulation devices are limited by physical constraints in their ability to perform voltage/var control in response to photovoltaic (PV) output fluctuations. However, the reactive power capability of PV inverters alongside with conventional...
The proposition for this study is to assess how much simulation results can differ from real measurements on the implementation of a control strategy for a grid-connected PV inverter. The system is simulated in Matlab/Simulink and experimentally evaluated on a real low-voltage distribution grid. The PV inverter is implemented using a power-hardware-in-the-loop platform running the control algorithm...
This paper identifies stable resonance frequency range for grid-connected inverter with Grid-Voltage Feedforward Regulator (GVFR). Beginning with the current loop stability analysis without GVFR, system poles distribution is analytically studied in z-domain, the critical frequency is therefore calculated as well as the control gain limit. Then, this paper reveals the GVFR would change the system stability...
The aim of this paper is to explain a novel technique to improve voltage and frequency profiles on microgrids controlled using the droop control scheme. The method consists on retuning the controller according to the present load scenario by adjusting the droop coefficients in a way that is proportional to the load changes. The proposed technique is tested through numerical simulations and the results...
This paper proposes a seamless transfer control strategy for bi-modal grid-connected (GC) power conditioning system (PCS). The load can be supplied the power continuously, regardless of the grid states. The PCS should be operated in two modes. One is the GC mode and the other is stand-alone (SA) mode. A current control loop and a feed-forward voltage control loop are used to control the grid current...
In this paper, an enhanced control strategy of the smooth transition between the grid-tied and stand-alone operation modes of the distributed generation (DG) inverter is proposed. In the grid-connected mode, the DG inverter controls active and reactive powers flowing into the grid by regulating grid currents using typical proportional integral plus resonant (PI+R) controllers, while direct voltage...
This paper presents a design approach for renewable energy power systems operation in case of power outage or grid failure. The grid connected distributed power system delivers energy to the consumers located on the micro-grid, operating at distribution voltage level, and also delivering the remaining surplus energy to the main distribution grid. The optimal and permanent system operation is when...
Electrical power demand have grown rapidly over the years which results in power system congestion, depletion of fossil fuels and increased environmental hazards. Further existing power system generations are inadequate for the exponential demand growth. Environmental risks and depleting fossil fuels created a pocket for renewable energy based distributed generations that are cleaner, and renewable...
Islanding detection methods have been proposed for inverter based distributed generation (DG) with grid connected capability only. Micro-grids are composed of DGs that are capable of operating in two modes: grid connected and islanded. This paper introduces and proposes the concept of micro-grid transition detection where the status of the micro-grid is detected based on adaptively modifying the droop...
Grid connected operation of Distributed generation (DG) is yet another approach to provide reliable and secured power. The operational issues of grid connected DG is the focus of research at present to achieve adequacy and security. The islanding is the situation where DG continues to operate with the utility disconnected. It is customary to detect islanding when it occurs to ensure continued stable...
Day by day demand of Electricity is increasing so, in order to fulfill this demand we need to increase generation of power. Because of this increasing demand, non-renewable energy sources are on the verge of extinction so the solution is to use renewable energy sources. One such solution is to connect DG having renewable energy sources in power system. But the insertion of DG has some impact on a...
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