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Microgrid has lots of advantages and effective methods in usage and control of DGs, and has developed rapidly at each country. Electric Vehicles regarded as new traffic method has been paid more common attention. Batteries of electric vehicles can be regarded as mobile power storage devices, which will affect the stability of the power grid when paralleled in the grid. A common structure of the microgrid...
Stability issues are a major concern in railway grids. Although these problems are most experienced in 16.7-Hz applications, low-frequency oscillations also occur in 50-Hz railway grids. In this paper, an advanced multivariable control concept is presented. Beside achieving very good dynamic behavior, the approach improves the introduced stability problem. The proper operation of the control is verified...
Stability aspects are a major concern in railway-traction applications. It is well-known that low-frequency oscillations occur in 16.7-Hz railway-grids. They can be initiated either by impedance variation or by multiple traction vehicles active in one feeding section. This paper focuses on the emulation of many traction vehicles starting up in the same feeding section and hereby causing instability...
It is proposed in this paper a methodology to obtain optimal controllers gains for the rotor-side converter of doubly fed induction generators (DFIGs) using a genetic algorithm approach. The main objective is to enhance the operational security and robustness of the power system, by a more effective contribution of the DFIG controllers to the system controllability. To reach this goal, the crow-bar...
The following topics are dealt with: voltage control, state estimation, congestion management, resource planning, wind energy, substation automation, energy storage, power security, transient stability, time simulation, voltage stability, plug-in hybrid electric vehicles, unit commitment, PMU applications, controlled islanding, power electronics, distributed generation, measurement latency, and system...
This paper presents a comparative study of dynamic performance of conventional VSC based HVDC and Modular Multilevel Converter (MMC) VSC based HVDC operating in back to back configuration. Voltage and rotor angle stability of the generator during power systems fault is analyzed. The simulated power system is composed by a back-to-back HVDC based on conventional VSC and the MMC connecting two weak...
This paper addresses the problem of coordinating voltage control in a large-scale power system partitioned into control areas operated by independent utilities. Two types of coordination modes are considered to obtain settings for tap changers, generator voltages, and reactive power injections from compensation devices. First, it is supposed that a supervisor entity, with full knowledge and control...
Margin sensitivity is useful in determining the effectiveness of different parameters for the purpose of enhancing system loading margin. The paper shows that determining margin sensitivity is equivalent to a predictor stage of a continuation technique similar to CPF and that for cases in which sensitivity is not adequately accurate adding a few corrector steps would leads to better results. The paper...
This paper explores the performance of alternative voltage control strategy applied to direct drive synchronous wind generators, more specifically with permanent magnetic (PMSG). The reactive power control of the grid-side converter is investigated for voltage control purposes. In Brazil, the Grid National Operator (ONS) requires that wind turbines stay connected to the grid during voltage dips, but...
A Multilayer Perceptron (MLP) neural network based approach for estimation of the voltage stability L-index in a power system with Plug-in Electric Vehicles (PEVs) is presented. This technique overcomes the limitations of direct calculation of L-index from measurements at a load bus. The L-index calculation is dependent upon the no-load voltage phasor for any given system topology and operating condition...
The paper investigates the possibility of ranking synchronous generators in a power system according to their contribution to system angular and voltage stability. The aim of this research is to establish fast semi-analytical methodology, i.e., avoiding transient simulations, to determine which synchronous generators can be safely disconnected from the network or replaced by other types of generators,...
In this paper we propose a local, completely autonomous protection system against voltage instability that can be readily integrated in the controller of each bulk power delivery LTC transformer. The protection system will identify an imminent voltage instability and will subsequently apply the necessary corrective measures to restore stable operation by properly adjusting the distribution voltage...
This paper investigates the use of multi-linear regression models (MLRMs) and machine learning techniques for online voltage stability margin prediction. The methodology relies upon the relationship between system wide reactive power reserves and voltage stability margin. A comprehensive voltage stability assessment considering an extensive contingency list and several load increase directions is...
Due to growing competition in the electricity market, the drive for efficient, stable and secure grid operation makes voltage control in the transmission grid relevant. A solution that has potential is to increase the effectiveness of the ancillary service by automatic fast control. The paper describes a Wide Area Voltage Regulation (V-WAR) that fits this framework. The V-WAR is based on Secondary...
Wind farms typically contain a variety of voltage control equipment including tap-changing transformers, switched capacitors, SVCs, STATCOMs, and the generators themselves. This paper focuses on the control of this equipment by addressing three major issues. The first is the ability of wind turbines to provide reactive power; voltage saturation in the collector system often limits the reactive power...
This paper discusses a novel approach for damping interarea oscillations in a bulk power network using multiple unified power flow controllers (UPFCs) utilizing ultracapacitors, also known more generally as electrochemical capacitors (ECs). In this paper, a new control is introduced to mitigate interarea oscillations by directly controlling the UPFCs' sending and receiving bus voltages that better...
This paper introduces a differential evolution particle swarm optimization (DEPSO) method for dealing with optimal reactive power dispatch aiming at power loss reduction and voltage stability improvement. The optimum reactive power dispatch of power systems is to allocate reactive power control variables so that the objective function composed of power losses is minimized and the prescribed voltage...
In this modern power system the power quality issue is important issue. Problem of power quality is diverse both in nature and also in terms of the power that must consider. In traditional power system FACTS controllers are used to improve power transfer capabilities and stability performance of the power system. This paper presents a case study of mitigation of power quality problems such as voltage...
Heavily loaded condition may lead to power system instability either due to sudden increase in load or tripping of adjacent transmission line. When load increases, the apparent impedance decreases accordingly depending on the nature of load, similar instances can be observed during short circuit event. In addition, the system may also experience voltage instability originating from high power flow...
This paper presents artificial neural network (ANN) based controller model to simulate the automatic voltage regulator (AVR) response for the transient stability analysis. Two different models are simulated considering single machine connected to an infinite bus (SMIB) to check the response of NN behaviour with conventional controller. Based on simulation results, it is found that NN controller gives...
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