Josef Tlusty

A novel weight-improved particle swarm optimization algorithm for optimal power flow and economic load dispatch problems

The optimization problems of optimal power flow (OPF) and the economic load dispatch (ELD) with valve-point effects in power systems are recently solved by some types of artificial intelligent (AI) algorithms. In this paper, based on improving the function of weight parameters, we present a novel weight-improved particle swarm optimization (WIPSO) method for computing two above problems. To evaluate the accuracy, convergence speed and applicability of the proposed method, we first compare the OPF results of proposed method to those of traditional particle swarm optimization (PSO), genetic algorithm (GA), differential evolution (DE), ant colony optimization (ACO) methods on the standard IEEE 30-bus system. We second compare our results of ELD problem to those of classical evolutionary programming (CEP), improved fast evolutionary programming (IFEP), and various improved particle swarm optimization methods on the IEEE 13-unit and 40-unit systems. The tested results indicate that the proposed method is more efficient than the others in terms of total fuel costs, total losses and computational times. Thus it can be applied to large power systems.

Topologies and control of active filters for flicker compensation

The paper deals with the analysis of topologies and control strategies of active filters (AF) for voltage flicker compensation. The strategies based on parallel and series active filters, both working with the reactive power compensation (without an energy storage device) have been analyzed and compared. The basic operational characteristics for the parameters of a real distribution power system with an arc furnace and a static VAr compensator have been calculated to promote the installation of an active filter for the mitigation of the voltage fluctuation. The control strategies of the active filters have been analyzed in the frequency domain as well. Neither the parallel AF nor the series AF, both working with the reactive power compensation and without the static VAr compensator (SVC), do not represent an appropriate solution in the case of the study: the parallel AF would need a high power rating, while the series AF has a too narrow working area. The combined application of the current SVC and the AF is a beneficial solution, the series AF being preferred to the parallel one for a substantial reduction of the AF power rating.

Evaluation of IRP, FBD, SD, and generalized non-active power theories

Most of modern power equipments connected to the grid must be viewed as non-linear loads producing voltage and current harmonics, subharmonics, and quasi-periodic and stochastic disturbances even under normal operation conditions. An analysis and comparison of usage of different power theories for the parallel compensation of periodic and non-periodic disturbances is presented in the paper. Different reference voltage vectors and averaging time intervals are applied in the power theories.

New approach of thermal field and Ampacity of Underground cables using adaptive hp-FEM

In this paper, we present the new approach to the thermal fields and Ampacity of underground cables in steady state using the adaptive Higher-Order Finite Element Method (hp-FEM). Where, the Delaunay algorithm based on the distance function is used for creating the adaptive mesh in the domain surrounding cables. In particular, for increasing the accuracy of solution, the higher-order elements (up to 7th order) are applied in our procedure. The advantages of the coupled Delaunay mesh and higher-order elements are to obtain the higher accurate solution and can decrease the CPU time. The proposed method has tested to two practical models of single- and double-circuit buried cables in the homogenous soil. The numerical results of this work were compared to the ones that obtained by Boundary Element (BEM), Finite Difference Methods (FDM) and the data of cable manufacturer.

Comparative review of reactive power compensation technologies

The quality of electrical power in a network is a major concern which has to be examined with caution in order to achieve a reliable electrical power system network. Reactive power compensation is a means for realising the goal of a qualitative and reliable electrical power system. This paper made a comparative review of reactive power compensation technologies; the devices reviewed include Synchronous Condenser, Static Var Compensator (SVC) and Static Synchronous Compensator (STATCOM). These technologies were defined, critically examined and compared, the most promising technology is recommended for the realisation of an effective, efficient, sustainable, qualitative and reliable electrical power network.

Synchronous phasors monitoring system application possibilities

The paper deals with some tasks of advanced methods to achieve security and reliability of transmission power systems. There are discussed advanced principles and techniques in monitoring systems. The paper main part is devoted to possible applications of PMUs (Phasor Measurement Unit) and their integration into WAMPaC systems (Wide Area Monitoring, Protection and Control). Significant transmission system states were analyzed in several case studies. PMUs utilization for voltage monitoring is demonstrated for three cases - standard system state, high-load state and islanding. Here the attention is paid to the possibilities of power system observability improvement using measuring chain error elimination. Other possible applications in transmission systems include ampacity determination of transmission corridors, the calculation of line electrical parameters using synchrophasor measurement, state estimation issues and power system stability. The power system model was established for methods and algorithms verification purposes. The appropriate algorithms and their parameters were found using simulation outputs to create the local automatics, e.g. Automatic Power System Stabilizer (PSS).

Harmonic voltage mitigation in power systems by using cooperative control of active power filters without mutual communication

The procedure for calculating controller parameters of the APFs implemented into a multibus industrial power system for harmonic voltage mitigation is presented. The node voltage detection control strategy is applied and the basic controller parameters are found under the condition that demanded THD factors at the buses where the APFs are placed will be obtained. A cooperative control of several APFs without mutual communication is proposed, simulated and experimentally verified. By tuning the controller gains without considering the power circuit parameters, all APFs used tend to share harmonic load currents approximately equally regardless the operation modes of the non-linear loads in different parts of the power system.

Using renewable MV wind energy resource to supply reactive power in MV distribution network

This paper deals with the use of Medium Voltage (MV) renewable wind energy source to optimize reactive power in a distribution network, it describes the increase of power factor when the reactive power is controlled at a wind farm increase in power factor allows improvement in the stability of distribution networks, and the increase in power factor is used as new methodology to reduce power losses, Matlab/Simulink program is used to show the results of the analysis.

Harmonic Voltage Mitigation in Industrial Power Systems by Using Multiple Active Power Filter Configuration

The procedure for calculating optimum controller parameters of the APFs, which are implemented into a multibus industrial power system for harmonic voltage mitigation, is presented. The node voltage detection control strategy is applied and the optimum controller parameters are found by solving the multiple APF-multiple harmonic problem. Thus, the best places for several APFs may be proposed, taking into account also a real control strategy as well as APF controller parameters

Advantageous positioning of wind turbine generating system in MV distribution network

This paper presents a new method for achieving voltage stability and reduction of power losses with renewable wind turbine generating system (WTGS) installed at different position on a Medium Voltage (MV) distribution system. The proposed network is a three-phase system consisting of 0.4 kV low voltage (LV) feeder with an active power (P) of 8 MW and a negative VAR (Qc) of 0.5 MV AR. And a 20 kV MV feeder with an active power (P) of 22 MW and a negative VAR (Qc) of 1.5 MV AR. The 0.4 kV and 20 kV feeders has varying positive VAR values of 2, 2.25, 2.5 and 6, 6.5, 7 MVARs respectively. Three sets of datas were observed; data 1, 2, and 3, the feeders are connected to a 20 kV MV distribution network, which is then linked to a 20 kV substation. Thereafter, a 20 kV MV renewable WTGS energy source with IGBT converters is integrated to the network for effective reactive power compensation. Three different Cases have been analyzed; First is the case with the proposed power system network analyzed without any WTGS attached to the network, in other words when the WTGS is switched off (this is designated as Case 1). Second is the situation with the WTGS positioned at the terminal end of the 20 kV MV distribution network (point 1, which is designated as Case 2) and Third is the situation when the position of the wind energy source is changed and stationed at the beginning of the terminal of the 20 kV MV power line (point 2, which is designated as Case 3). Matlab/Simulink software is used for the simulation of the system model. Simulation results for each of the case studies is analyzed and it is observed that research findings for Case 2 is more efficient in achieving improved voltage stability and power losses reduction in medium voltage electric-power distribution network.