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The paper proposes a current source based Dynamic VAR Compensator (DVC) control strategy. The switching unit in this DVC topology is composed of series connected switch and diode also termed as the “current switch”. The proposed controller has been designed to force discontinuous conduction mode operation thus fundamentally different from the traditional constant current source based control system...
A fuzzy reasoning based decision maker is developed in this study in order to determine the optimal capacitor location and sizing in radial distribution systems for the purpose of minimizing the power loss and capacitor cost with voltage limit constraints. The solution methodology includes two main parts. The first part is a fuzzy expert system that selects suitable candidate buses for capacitor locations...
The need for a low-cost, high reliability power flow control technology is becoming exceedingly clear in the face of increased renewable penetration and electrification of automobiles. This paper proposes a power routing technology called the compact dynamic phase angle regulator (CD-PAR) for dynamic control of active/reactive power. The proposed device is a hybrid solution realized by pairing a fractionally-rated...
In this paper, a radial-chordal decomposition (RCD) technique is proposed to decouple the power angle and voltage control of a smart load based on the use of electric springs (ES). The paper gives a highlight of the decoupling feature and the merit of achieving multiple functionalities within a single ES. This RCD control method has been tested on a 2 kW small-scale power system. Experimental results...
The concept of Double-Delta Sourced Transformer (DDST) had been proposed to eliminate passive filters in large-scale power conversion systems. For the grid connection, active and reactive powers in DDST must be under control. In this paper, the power modulation method is proposed for DDST through the current regulation. And, it is also considered when one of converters is disconnected from the transformer...
Photovoltaic power plants (PV) are equipped with anti-islanding algorithms, embedded in the converters controller, to avoid the island operation. However, the current trends in the development of the future electrical networks evidence that it is technically feasible and economically advantageous to keep feeding islanded systems under these situations, without cutting the power supply to the loads...
Nowadays, to improve power quality and meet the energy demand, several studies point to the widespread use of Distributed Generation (DG) units equipped with power line conditionning capability. This work proposes a simplified structure and its related control system for Photovoltaic (PV) generation that embodies an Active Power Line Conditioner (APLC), allows harmonic minimization and active power...
There is a need for microinverters that support non-unity factor operation in response to recently issued regulations. In this paper, a topology is proposed for a low cost and efficient single phase microinverter that can supply reactive power. The microinverter is controlled to ensure smooth current flow to/from the grid where a three-stage operation is used. Despite their low complexity, the proposed...
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...
This paper proposes a control system design for cooperated stabilizing control of PMSG based grid connected wind farm. In this study, a wind farm composed of PMSGs and SCIGs is considered to be connected to multi-machine power system. Though outputs of the SCIG based wind turbines are collected on AC network, PMSG based wind turbines are integrated in DC network with single grid side converter. In...
The increase of renewable energy sources and distributed generation may have a negative impact on power systems, specially on weak ones. Therefore, their control systems are acquiring growing importance, with new proposals that aim to contribute to the control and stability of the power system as conventional generating units. This paper studies the effect that a PV system using a synchronous power...
Micro-grid should be able to operate in both islanding mode and grid-connected mode, but how to transfer smoothly between these two modes is a question. This paper presents a seamless transition strategy for droop-controlled inverters to operate in both islanding and grid-connected modes and transfer smoothly between these two modes. The control principle and pre-synchronization control strategy are...
In this paper, an improvement in power sharing for Autonomous Microgrid is well established. All previous studies were based on voltage and frequency droop control to share power between distributed generators. This paper develops a new robust voltage and angle droop control to share power, where its advantage over the common frequency droop is in less frequency variation. The synchronization of Power...
Stator wound field synchronous machines (SWFSMs) are gaining more and more research and application interest recently due to the absence of expensive rare earth magnet materials. These machines are characterized by a doubly salient structure, and both the DC field winding and the three phase armature windings are located in the stator. In this paper, taking the basic structure of stator DC excited...
This paper presents a modular multilevel cascade converter (MMCC) based on chopper-cells for a grid-connected photovoltaic (PV) application suitable to medium and high voltage systems without line-frequency transformers. This converter is characterized by a modular arm structure composed by cascaded chopper-cells with floating dc capacitors, each one connected to a photovoltaic panel. This paper proposes...
In highly microgrid (MG) integrated distribution systems, problems such as a sudden cut out of the MGs due to grid faults may lead to adverse effects to the grid. As a consequence, ancillary services provided by MGs are preferred since it can make the MG a contributor to ride through the faults. In this paper, a voltage support strategy based on negative sequence droop control, which regulate the...
In order to enhance the redundancy and reliability for distributed generation, a grid-tied photovoltaic (PV) generation system based on series-connected module integrated inverters (SC-MIIs) is proposed in this paper. In the proposed system, each MII is interfaced with a PV panel with independent maximum power point tracking (MPPT) to harvest maximum solar energy. The outputs of MIIs are at AC-line...
The high penetration level of power electronics interfaced Distributed Generation (DG) systems creates great ancillary services potential through the DG interfacing converters (IFCs) such as the grid unbalanced voltage compensation. However, the unbalanced voltage compensation may cause adverse effects on the IFCs' operation such as output active power oscillation and DC link voltage variations. Moreover,...
This paper presents the application of a Delta-Connected Cascaded H-Bridge Converter in unbalanced load compensation. The compensation includes positive sequence reactive power current and negative sequence current compensation. The controller designed based on the detail power flow analysis which can achieve dc capacitor voltage balancing control by zero sequence current injection even when compensating...
Modular cascaded multilevel converter is a promising option for high power solar photovoltaic (PV) system due to its modularity, scalability, and distributed maximum power point tracking (MPPT) capability, etc. Nevertheless, inherent mismatch and varied operating conditions (both called module-mismatch) are still the issues to be disclosed. Asymmetrical active power harvesting among individual PV...
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