Ultracapacitors (UCs), with their features of high power density and high current charge-discharge, have become the best choice for dynamic power compensation to improve the stability of microgrids and are increasingly being applied in microgrids. This paper presents the control of an energy storage system (ESS) based on ultracapacitors in the context of grid-connected microgrids. The ESS is co...

The impact of wind energy generation connected to a weak grid is studied with SIMULINK as simulation platform. The wind energy conversion system is modelled by a squirrel cage asynchronous induction machine (ASM). The grid is modelled as an infinite bus. In the proposed system the ASM is connected to the grid through a DC-link with incorporated battery storage. An ultracapacitor (UCap) bank in ...

A three-phase four-leg inverter-based shunt active power filter (APF) is proposed to compensate three-phase unbalanced currents under unbalanced load conditions in grid-connected operation in this study. Since a DC-link capacitor is required on the DC side of the APF to release or absorb the instantaneous apparent power, the regulation control of the DC-link voltage of the APF is important espe...

-This paper describes an alternative STATic synchronous COMpensator (STATCOM), by connecting a number of Gate Turn Off (GTO) thyristor converters in series on the ac side of the system. Each GTO converter forms one ‘link’ of a 1-phase, full-bridge Voltage-Source-Converter (VSC) and is referred to as a ‘Chain Link Converter’ (CLC). Each GTO of a CLS, is switched ‘ON/OFF’ only once per cycle of t...

Recently, there has been a fast development and deployment of wind energy to meet the increasing electrical power demand and to limit the use of fossil fuels. More and more wind farms are planned far from shore because of good wind condition and less visual impact. This is so called offshore wind farm (OWF). In such a situation, high voltage direct current (HVDC) transmission is a favorable opt...

In this paper a compensation strategy based on a particular CUPS device, the Unified Power Quality Compensator (UPQC) has been proposed. A customized internal control scheme of the UPQC device was developed to regulate the voltage in the WF terminals, and to mitigate voltage fluctuations at grid side. The voltage regulation at WF terminal is conducted using the UPQC series converter, by voltage...

Thammasat International Journal of Science and Technology, Vol. 18, No. 2, April-June 2013 42 Abstract Mainly, a photovoltaic (PV) system is able to generate wide ranges of voltage and current at terminal output. However, a PV cell is required to functionally maintain a constant direct current (DC) voltage at a desired level during real-time variations of incident light illumination and ambient...

The low voltage ride-through (LVRT) capability of the doubly-fed induction generator (DFIG) significantly impacts upon the integration of wind power into the power grid. This paper develops a novel comprehensive control strategy to enhance the LVRT and reactive power support capacities of the DFIG by installing the energy storage system (ESS). The ESS is connected to the DC-link capacitor of th...