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The paper presents an overview about operation and control of the inverter-interface generation units (IGUs) when connected to a microgrid either alone or together with other generation units. The following key connection paradigms are considered: i) one IGU and a grid, ii) one IGU and one machine-interface generation unit, iii) a single IGU, and iv) two IGUs. After illustrating how the IGUs operate...
A crude oil production and shipping terminal was built and expanded over time such that the facility was powered by three isolated power systems. These separate plants have since been interconnected to permit the sharing of generation reserves. Initially, the interconnected system was supervised by a power management system (PMS) that relied on isochronous operation of one power plant for frequency...
This paper presents a method to shed off the least important loads in a microgrid operated at constant frequency under the contingency of inadequate power generation. Different from conventional frequency deviation based load shedding, this paper discusses in detail how to shed off load based on the voltage deviation. The key issue is to differentiate whether the voltage deviation is due to sudden...
In Constant speed constant frequency (CSCF) AC power supply system, generator output constant frequency and constant voltage AC power by connecting engine with constant speed transmission device (CSD). However, CSCF has many disadvantages, such as complex structure, heavy weight, high cost and low energy conversion efficiency. By eliminating CSD in CSCF and taking output voltage and output frequency...
With the development of microgrid technologies, more and more distributed renewable sources have been connected into microgrids to provide power for loads. The coming problem is how to manage the distributed generations (DGs) that are not within the planning of a microgrid, one feasible solution is to realize the plug-and-play function of DGs. Focusing on this problem, this paper proposes a control...
Lately, new solutions have been added to the control of autonomous grids, which improve the way the power grids operate. These changes may affect the reliability and safety of power distribution grids, the dynamic stability being a real concern. This issue is more prominent in autonomous microgrids (MGs) with high penetration of renewable energy sources. On this topic, this paper aims to study how...
Traditional droop-controlled systems assume that the generators are able to provide sufficient power as required. This is however not always true, especially in renewable systems, where the energy sources (e.g., photovoltaic source) may not be able to provide enough power (or even loss of power generation) due to the intermittency. In that case, unbalance in active power generation may occur among...
As Internet-of-Things (IoT) systems proliferate, there is a greater demand for small and efficient power management units. Fully integrated switched-capacitor (SC) DC-DC converters are promising candidates due to their small form factor and low quiescent power, aided by dynamic activity scaling [1–3]. However, they offer a limited number of conversion ratios, making them challenging to use in actual...
This paper presents a self-sustained GEDPGS (Green Energy Driven Power Generating Station) to feed telecommunication tower. The proposed power plant employs a SCIG (Squirrel Cage Induction Generator) coupled with wind turbine to cater the needs of electricity at remote telecommunication tower. A VFC (Voltage and Frequency Controller) is used for GEDPGS to regulate voltage and frequency of generated...
This paper deals with control of hybrid standalone power generation using micro-hydro power turbine (MHP) coupled with a squirrel cage induction generator (SCIG) and a solar photovoltaic panel (PV), which is connected to the common DC bus of three-phase voltage source converter (VSC). The AC terminals of VSC are connected to point of common coupling (PCC) through interface inductors. A battery energy...
The hierarchical control structure of a microgrid can be described as consisting of four levels: processing, sensing and adjusting, monitoring and supervising, and maintenance and optimizing. This paper focuses on the secondary control level, which can be classified as centralized or decentralized control. A comprehensive investigation of both centralized and decentralized control is presented in...
The comparison of the power stage dynamics between a conventional LLC converter and a three-level LLC converter is presented in this paper. The frequency response was similar in continuous current mode, but different in discontinuous current mode. Moreover, how the variation of circuit parameters affects the transfer function of the three-level LLC converter is studied. The experimental verification...
Droop control is an effective power sharing control scheme of distributed generation (DG) inverters in islanding AC microgrid, which can stabilize the grid as long as the distributed generation systems have sufficient residual power. On the contrary, many loads have equipped with power conversion circuits in front to improve the operational efficiency, e.g. air conditioners and LED lighting, which...
The operation of micro-grid based renewable energy usually considers efficiency and economy in comprehensive. The control strategy based on master micro-source (MS) constant voltage constant frequency (CVCF) networking is introduced. The voltage and frequency of micro-grid is established by the master MS, and the slave MS operated on the maximum power point tracking mode, in order to achieved micro-grid...
This paper proposes a control strategy for grid interactive Power Conditioning System (PCS) which has a feedforward voltage control based on grid frequency detection. The PCS should supply the power to the critical load, regardless of the grid condition. In order to provide the power to the critical load continuously, the PCS should operate two modes. One is Grid-Connected mode and the other is Stand-Alone...
This paper deals with a novel way to provide dynamic frequency support to isolated power systems by a fast control of the load through the grid voltage. Following the promising results of a preliminary analysis based on dynamic simulations, a field test was carried out in the archipelago of Guadeloupe at the beginning of 2014. It confirmed that the proposed control can significantly improve the transient...
This work evaluates the performance of a nonlinear control strategy of a modular photovoltaic (PV) plant that is used to support grid frequency control. The PV plant is designed based on a real study case and it has a modular structure consisting in several generating units. Each generating unit consists in PV arrays interfaced to the grid with a three-phase three-level cascaded H-bridge converter...
This work presents a case study of a modular photovoltaic (PV) plant where PV panel arrays are connected to the grid through cascaded single-phase current-source inverters. It is shown that, under non-uniform insolation conditions of the PV arrays, the output voltages of the cascaded inverters become unbalanced. Therefore, a dc voltage elimination control loop is proposed to balance the output voltage...
Massive effective integration of renewable energies into the electric grid is an issue in almost all electric power systems. These renewable energy sources (RES) are usually based on wind and solar photovoltaic generation and cannot maintain a power reference due to variations in wind and solar irradiance. Currently the integration of these renewable energy sources is possible in strong power systems...
This paper discusses the operation of the central controller for a microgrid. The central controller is responsible to maintain the voltage and frequency of the microgrid within the acceptable ranges while the distributed energy resources supply the required power demand of the loads based on the droop control. The desired ratio among the output active power of the distributed energy resources is...
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