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In the paper the role of anti-aliasing filters is revised based on control quality assessment of PID controllers when using average sampling versus instantaneous sampling without any analog filter. Numerical results show that contrary to common belief possible benefits gained from anti-aliasing devices are very restricted.
The precise prediction of changes in load flows, currents and voltage magnitudes due to changes in power is important for forecasting and managing grid congestions, voltage deviations and minimizing grid losses for example. This paper describes three different methods and further variants of those for state prediction and compares their approximations, neglects and quality of prediction. Since PTDFs...
A surge of needs for the low carbon society promotes a spread of electric vehicle (EV). EVs could be charged at night simultaneously, as a result, severe voltage drop may happen. The authors have proposed the method which can compensate the voltage drop caused by EV charging by means of adjusting charging schedules and controlling reactive power. However, though the method can avoid the voltage violation,...
Reactive power optimization has been a hard problem for years. However, the existed optimization algorithms are usually complex in calculation and not obvious in physical meaning. To study a simple and effective method for reactive power optimization, this paper puts forward a concept of optimal reactive load, and proposes a method called power circle method. With power circles, this paper presents...
The large demand of dynamic reactive power for MIDC recovery is a big challenge to voltage stability of the receiving system. Thus, the research on active power (P) and reactive power (Q) characteristics of inverter station in the recovery process of multi-infeed HVDC (MIDC) attracts more and more attention. With the CIGRE HVDC benchmark, this paper studies the P and Q responses under various faults...
When several high voltage direct current (HVDC) systems simultaneously recover after severe faults, absorbing large amounts of reactive power from the receiving AC systems, presents new challenges for the transient voltage stability of multi-infeed HVDC (MIDC) systems. Actually DC power recovery characteristics could be controllable to some extent by selecting voltage dependant current order limiter...
In this paper, we are aimed to search the Pareto front of multi-objective optimal reactive power dispatch by the primal dual interior point method. In the front part are the introductions of optimal reactive power dispatch model, the concepts of Pareto optimum solution and Pareto front, and the primal dual interior point method. In the rear part, the process of searching Pareto front will be presented,...
This paper succeeds in solving the optimal reactive power dispatch (ORPD) of power system where the units contains wind turbines. Two types of wind turbine are taken into account in the ORPD, and they are the variable speed wind turbine (VSWT) and the fixed speed wind turbine (FSWT). Besides, the primal dual interior point method is introduced to serve as the algorithm to solve ORPD, since it performs...
Power transfer through long distance transmission lines faces voltage stability and power flow issues in an interconnected system. These issues can be minimized by placing suitable compensators at appropriate locations. Conventional load flow analysis that are carried out to find line flows and voltage in the system, does not consider compensators. This paper deals with the modification of load flow...
This paper presents a comparison analysis among some methodologies in which aims to solve the selection of pilot buses for Secondary Voltage Control. For this purpose, a brief review of methodologies for both identifying voltage control areas and pilot buses selection are described. The validation of the results is done through the standard deviation applied to the variation of the voltage magnitude...
Granger Causality (GC) is an effective tool for determining functional connectivity in time-series data. However, application of GC is limited by the curse of dimensionality in many applications, e.g. Gene Regularity Networks (GRN). Various methods have been proposed to overcome this limitation. To the best of our knowledge, there is no detailed comparative study of such methods. We aim to perform...
This paper highlights the importance of measuring systemic risk of commercial banks. Conditional Value-at-Risk (CoVaR) is used to measure the degree of "risk externalities" that a specific bank contributes to the whole banking system. Our analysis not only presents current levels of systemic risk of individual banks but also the changes with time passes. There is some evidence that larger...
The presence of distributed generators with DC output power and the advancement in power electronics devices have motivated system planners and grid operators to move towards integration of DC microgrids into conventional AC grid. In this paper, we address the optimal power flow (OPF) problem in AC-DC networks. The goal of the AC-DC OPF problem is to jointly minimize the total electricity generation...
A new method to design a Voltage Source Inverter (VSI) for power factor correction with three phase induction machine as load is proposed. The machine parameters are obtained from practical induction machine. These parameters are employed for the simulation of induction machine. The control strategy presented in this paper is based on instantaneous reactive power theory. Simulation is carried out...
This paper presents a unified power quality conditioner (UPQC) and its control strategy for assisting the fault ride-through operation of large-scale photovoltaic (PV) power station. The output voltage of PV station can be controlled to its rated value with UPQC under high grid voltage fault condition. Moreover, it can absorb reactive power from the grid under high voltage condition to support the...
As the distributed generators are connected together through inverter interface in the microgrid, the control of the control of the interface inverter has an important influence on the operating performance of microgrid. In the paper, the study focuses on the control of the interfaced inverter, when microgrid operates in the islanded mode. In order to make the microgrid property similar to the utility...
The authors define the power components under sinusoidal and unbalanced conditions in three-phase, 4-wires circuits proposed as: dissymmetry power S-, and asymmetry power S0 as components of total unbalanced power Sunbalanced due to negative and zero currents components. The physical meaning of the power losses in unbalanced regimes is based on the losses on the neutral wire and on the increased losses...
The aim of optimal power flow is to discover an operating point that minimizes the generation cost while satisfying multiple operating constraints. Over the years, several techniques have been introduced to solve this non-linear optimization problem. In this paper, genetic algorithm deploying optimum non-uniform mutation rate and elitism has been used to solve this problem. After implementation of...
In this paper, a new method for controlling power factor in permanent magnet synchronous motor has been proposed in order to improve efficiency and decrease losses. In order to reach a in-time control for power factor, we have focused on parameters like current angle, torque angle, stator voltage and current in d axis stator. To this end, current angle, torque angle and stator voltage are considered...
The problem of multi-cell multi-user uplink sum-power minimization with required quality of service (QoS) under imperfect Channel State Information (CSI) and Probabilistic Contraints (PrCons) is solved. This paper is an extension of our previous work on statistical-CSI and PrCons. Deterministic constraints at times are infeasible or too expensive to implement, further, the CSI could be imperfect due...
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