Robert Kowalak

Influence of shunt compensation with SVC devices on resonance risk in power systems

Many analyses are required to locate a new reactive power source in a power system. The choice of a location is a very complex matter which requires various aspects to be considered. Selecting a location also entails the necessity to assess it from the point of view of the selected compensators structure as well as the systems performance in various states with the new device on. The paper presents the issues of assessing compensator location from the point of view of resonance phenomena. It indicates the factors which affect a circuits resonance conditions, including a change in network configuration and compensators structure.

Harmonics produced by traction substations – computer modelling and experimental verification

Voltage and current harmonics have a detrimental effect on the components of a power system. Current harmonics may result in the overload and damage to power transformers. Voltage harmonics may result in, for example, damage to capacitor banks used to compensate reactive power. Devices which contribute to both current and voltage distortion include traction rectifiers. This paper presents results of the computer investigation of the effect of these rectifiers on the power supply network. The results of the computer investigation have been compared with the result of experimental study.

Magnetic and capacitive couplings influence on power losses in double circuit high voltage overhead transmission line

Purpose The paper aims to discuss problems of power and energy losses in a double-circuit overhead transmission line. It was observed from energy meters’ readings, that in such a line, active power losses can be measured as “negative”. The “negative” active power losses appear when the active power injected to the circuit is lower than the active power received at the circuit end. The purpose of this paper is to explain this phenomenon. Design/methodology/approach Theoretical considerations based on mathematical model of the transmission line of π-type confirming that effect are presented. Power losses related to series impedance of the line and to shunt admittance are calculated. The theoretical considerations are confirmed by measurements done on the real transmission line. Findings The calculations allow to indicate components of the active power losses, i.e. related to electromagnetic coupling among wires of a given circuit, related to electromagnetic coupling between circuits and related to shunt capacitance asymmetry. The authors indicate the influence of the line/wires geometry on the active power losses in a double-circuit overhead transmission line. Originality/value Explanation of the effect of “negative” active power losses’ measurement in a double-circuit overhead transmission line is provided in this paper.

Computer-aided analysis of resonance risk in power system with Static Var Compensators

Static Var Compensators operation in a power system may significantly improve voltage profiles in nodes and the reactive power balance, as well as ensure greater system stability in emergency conditions. However these devices may be a cause of a resonance in the system. The aim of this paper is to call attention to the need to include resonance phenomena in a compensators location evaluation process. The analysis performed in the paper indicates the factors which affect a circuits resonance conditions, including a change in network configuration and compensators structure. Streszczenie. Kompensatory SVC mogą znacząco poprawic poziom napiecia w wezlach systemu elektroenergetycznego, bilans mocy biernej, a takze stabilnośc napieciową systemu w warunkach zakloceniowych. Jednakze urządzenia te mogą przyczynic sie do powstania rezonansu. Celem artykulu jest zwrocenie uwagi na potrzebe analizy zagrozenia rezonansem przy doborze kompensatorow SVC. Wskazano czynniki, ktore wplywają na powstanie rezonansu - nalezą do nich m.in. moc i struktura kompensatorow oraz zmiana konfiguracji sieci elektroenergetycznej. (Wspomagana komputerowo analiza zagrozenia rezonansem w systemie elektroenergetycznym z kompensatorami SVC)

SVC and power transformers controllers coordination

The use of shunt compensators such as FACTS (for example SVC) in power systems gives possibility of fast and flexible control of voltage or reactive power. An efficient cooperation between a transformer and compensator connected to busbars, or transformers tertiary winding, requires a proper coordination of controls. The article contains theoretical considerations and simulation results which indicate that such coordination is necessary. The principal recommendations for the transformer and compensator controllers settings and the coordination between control systems have been presented.

Study of the operation of synchronous generator voltage regulator during the creation of post blackout start-up path

This paper presents the influence of automatic voltage regulator (AVR) of synchronous generator on the process of creation of post black-out start-up path. Two elements of AVR have a significant impact on this process underexcitation limiter (UEL) and load compensation (LC). The authors present a theoretical investigation and simulation results that illustrate how the mentioned elements of AVR affect voltage levels in a power system during the creation of start-up path. The results of the study show that present procedures of the preparation of start-up path in Polish Power System should be modified.