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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...
Services provided by distributed generation (DG) to power generation and transmission systems have become an urgent necessity due to increase in load demand in recent years. These services include bridging the lack of central generation, increase the reliability of the network, reduce the inactive power in the system, and improve the margin of voltage for the network. On the other hand, the use of...
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...
The stability problems of power electronics interfaced distributed generators with low inertia and damping can be well solved by the virtual synchronous generator technologies. However, when the grid voltages become unbalanced, oscillations in both the real and reactive power will arise with unbalanced voltages and currents of VSG being noticed. This paper proposed a flexible power control method...
The paper proposes a novel voltage event-triggered P-U control strategy for improving related active power sharing accuracy in low-voltage microgrid (MG). Active power sharing inaccuracy is associated with voltages difference of distributed generation units (DGs) that is basically attributed to mismatched lines impedance. So the inaccuracy is inevitable. The proposed voltage control strategy contains...
Hybrid Microgrids are currently of great interest and are considered the distribution and transmission systems of the future, because they enable the coexistence of the AC microgrids and DC microgrids. This paper deals with the implementation of a new power management algorithm of the power converters that form part of the hybrid microgrid of Distributed Generation. The hybrid microgrid consists of...
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 increasing share of renewables is creating new challenges for distribution grids and operators have to adopt more and more advanced tools for the evaluation of network investments, especially for scenarios in which distributed generation is expected to drastically grow. In particular, the maximum connectable power (Hosting Capacity) as well as the benefits that Smart Grid technology can bring...
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...
In this paper, a modular multilevel converter (MMC) integrated ultracapacitors energy storage system (UCESS) and the control strategy are proposed for Power Router. Half bridges integrated with UC modules are utilized as the sub-module (SM) of the converter. Due to the integration of UCESS, the input power and output power can be decoupled, which means that the power relationship of the Power Router...
Renewable energy sources (RESs), distributed energy sources (DERs), and energy storage systems (ESSs) grid integration resulted in forming microgrid (MG) concept. Recently, DC microgrids (DC-MGs) have gained intensive attention compared to AC microgrids due to their high reliability and efficiency, easy interface with RESs and ESSs, and simple control. Proper power sharing is one of the most important...
This paper attempts to thoroughly evaluate the long-term performance of the most well-established voltage control strategies applied in active medium-voltage (MV) networks. This is attained by performing an exhaustive probabilistic analysis to consider and assess the impact of generation and demand uncertainties on the network operation. More specifically, Monte Carlo-based time-series simulations...
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...
The rise in penetration levels of distributed generation (DG) poses some challenges to distribution networks. This paper presents the results of an investigation into the effect of high DG penetration levels on thermal limits of distribution lines, and voltage rise at the point of common coupling. The study system used was the 16-bus UK distribution test system. The results obtained indicate voltage...
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...
Reactive power regulation of distributed generation sources in the low voltage network is by many professionals still considered as unnecessary, especially in the cable type networks. In this paper we show, that this is not true. We present optimized reactive power regulation characteristics of the distributed sources for the low voltage network. Characteristic is active power as well as voltage dependent...
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