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The microgrid concept has the potential to solve major problems arising from large penetration of distributed generation in distribution systems. A microgrid is not a robust system when compared to a power system. Therefore, proper control strategies should be implemented for a successful operation of a microgrid. This paper proposes the use of a coordinated control of reactive sources for the improvement...
Islanding detection is one of the most dominant challenges for distributed generation systems connected to the main power grid. Rudimentary islanding detection methods (frequency relays, voltage relays), have considerable non-detection zones (NDZ). Nod-detection zone which defines as the area that the method fails to detect the islanding, is the primary criterion to evaluate the detection method performance...
This paper proposes a hybrid system consisting of a photovoltaic (PV) array and rechargeable battery integrated to the distribution grid with the aim to perform load sharing with the distribution grid. The PV array and the battery are connected to the dc-side of the voltage source inverter (VSI) through a boost converter and buck-boost converter respectively. A power management control strategy is...
The installation of distributed generation (DG) introduces challenges to distribution systems operation. The distribution network operator needs to schedule DG outputs considering some constraints, such as DG characteristics, reactive power control mode of generators, automatic voltage regulation, compensator and power quality standard, etc. Based on an optimal power flow model, this paper proposes...
Microgrid technology, becoming the main application form of distributed generation with high permeability, can effectively alleviate the impacts on large power grid of distributed generation. Microgrid system, as the carrier of microgrid control strategy, can provide verification platform for the research of microgrid control strategy. In this paper, an integrated microgrid system with flexible structure...
The microgrid is an environment constructed with the aim of controlling local distributed resources. The most common power flow control technique utilised inside a power electronics dominated or standalone microgrid is- a technique known as power frequency droop. This paper develops a novel droop controller based on an arctan power profile that can provide natural limiting of frequency deviations...
This paper discusses studies funded by the National Renewable Energy Laboratory (NREL) via SunPower, Inc. and the California Energy Commission (CEC), performed by New Power Technologies and Optimal Technologies that showed that high-penetrations of distribution-connected storage devices or plug-in vehicles can have adverse grid impacts due to their charging loads. Randomly-located or unmanaged additions,...
Keeping voltage limits in electric networks is obligatory. Voltage constraints often cause additional costs for network reinforcement or more distance connection points when distributed generators are to be connected in medium- and low-voltage grids. In this paper, we present three different approaches for voltage control by aggregation of controllable distributed energy units. We also present the...
Most existing power flow calculation methods use a swing bus as a reference node for the whole system. Increasingly, new distributed generation resources (DGRs) are being added to the grid. Sometimes, local demand or failure of the grid can result in independent micro-grids forming, which are known as `islanding' systems. However, current DGRs are often limited such that there is no single DGR which...
Control of power quality is one of the biggest issues for a microgrid. Voltage sags, flickers, interruptions, etc. are more critical in a small system with few generators. Super Capacitor Energy Storage (SCES) system applied to microgrid in this paper has the advantage of quick response, high power output, high efficiency and the ability to output both active and reactive power. The main structure...
This paper discusses the application of a shunt active power filter with energy storage, for voltage and power improvements within a local power supply network (micro-grid) in presence of distributed generation. Theoretical analysis investigates the control the shunt active power filter in response to voltage sag. The shunt active filter operates over a short period of time, and is coordinated with...
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