Damping and Resonance in a High Power Switching Circuit (original) (raw)

The resonance analysis caused by harmonics in power systems including thyristor controlled reactor

The static V AR compensators having fixed capacitor thyristor controlled reactor (FC-TCR) used to improve voltage stability in power systems are nonlinear elements. The fixed capacitor group will produce reactive power while the thyristor controlled reactor will consume reactive power in compensators having FC-TCR. Changing the firing angles of TCR provides the reactive power variation of the system since the reactive power production of capacitors is fixed at a determined voltage level. In some cases, the variation of these firing angles will cause the harmonics in the system. In this study, TCR's are discussed to be harmonic sources and the resonance case caused by harmonics has been investigated with Fourier Matrix Model and MA TLAB Software.

Stability and harmonics in thyristor controlled reactors

IEEE Transactions on Power Delivery, 1990

Harmonics that arise from the interaction of thyristor controlled reactors (TCRs) and power systems can sometimes cause stability problems. The stability problems are hard to analyze since the harmonics are affected by the power system. The classical method for calculating harmonics is to calculate the harmonic current assuming an infinite bus at the high side of the TCR transformer. This current is then used as a harmonic current source on the ac system. The basic problem with this method is that many of the interactions between the ac system and the TCR are neglected. In this paper two methods for studying the neglected interactions are described. The first uses state variables to analyze the circuit containing the TCR. The resulting equations are linear differential equations with periodic coefficients. This formulation allows the study of stability, periodic operation, and resonance which can not be achieved by other methods. The second method uses a Fourier matrix description of the TCR. In this model the coupling between the different harmonics due to the switching is clearly shown.

Switching time bifurcations in a thyristor controlled reactor

IEEE Transactions on Circuits and Systems I: Fundamental Theory and Applications, 1996

Thyristor controlled reactors are high power switching circuits used for static VAR control and the emerging technology of flexible ac transmission. The static VAR control circuit considered in the paper is a nonlinear periodically operated RLC circuit with a sinusoidal source and ideal thyristors with equidistant firing pulses. This paper describes new instabilities in the circuit in which thyristor turn off times jump or bifurcate as a system parameter varies slowly. The new instabilities are called switching time bifurcations and are fold bifurcations of zeros of thyristor current. The bifurcation instabilities are explained and verified by simulation and an experiment. Switching time bifurcations are special to switching systems and, surprisingly, are not conventional bifurcations. In particular, switching time bifurcations cannot be predicted by observing the eigenvalues of the system Jacobian. We justify these claims by deriving a simple formula for the Jacobian of the Poincare map of the circuit and presenting theoretical and numerical evidence that conventional bifurcations do not occur.

IJERT-Analysis and Minimization of Harmonics of Thyristor Controlled Reactor (TCR)

International Journal of Engineering Research and Technology (IJERT), 2015

https://www.ijert.org/analysis-and-minimization-of-harmonics-of-thyristor-controlled-reactor-tcr https://www.ijert.org/research/analysis-and-minimization-of-harmonics-of-thyristor-controlled-reactor-tcr-IJERTV4IS100430.pdf This paper proposes a firing angle range control and minimization of harmonics in thyristor controlled reactor (TCR). A typical Static Var Compensator generally consists of a Thyristor Controlled Reactor (TCR) & a Thyristor Switched Capacitor (TSC) which compensates loads through generation or absorption of reactive power. The operation of Thyristor Controlled Reactors at appropriate conduction angles can be used advantageously to meet the phase-wise unbalance and varying load reactive power demand in a system. However, such an operation deteriorates the quality of power supply through percolation of harmonic currents into the mains. This paper presents an approach to minimize harmonic generation internally by different combinations of Delta connected TCR by using MATLAB SIMULATION. In particular harmonics will be investigated and range of firing angle fixed for satisfactory operation.

Characterization of a thyristor controlled reactor

Electric Power Systems Research, 1997

This paper characterizes the operation of a thyristor controlled reactor (TCR) which consists of an inductance and a bi-directional thyristor switch connected in parallel. Firing angle control of the thyristor switches regulates the time for which the inductance is included in the circuit. This controls the average value of the inductance. The continuously regulated inductance can be used for line flow regulation and short circuit current reduction. It can also be used for series compensation when the TCR is connected in series with a fixed capacitor and when the combination is inserted in series with transmission lines. This paper analysis the operation of the TCR using equations and EMTP simulations.The analysis shows that a series compensator using TCR regulates the level of compensation from inductive to capacitive and the system response is faster than the recently commercialized ‘Advanced Series Compensation’ (ASC) scheme. Also, the problems of resonance and harmonic instability associated with the ASC are eliminated. The TCR can control short circuit current within half cycle.

VAR Compensation on Load Side using Thyristor Switched Capacitor and Thyristor Controlled Reactor

2021

Generally, AC loads are the inductive loads which are reactive in nature. These loads, thus, demand and draw reactive power from the supply source. If these loads draw large lagging current from the source, this will cause excessive voltage drop in the line, which can even cause the voltage collapsing in the line itself if the drop in the line is excessively high. VAR compensation means efficient management of reactive power locally to improve the performance of AC power systems. In this paper, Static VAR Compensator, using TSC (Thyristor Switched Capacitor) and TCR (Thyristor Controlled Reactor), is designed and simulated in MATLAB to maintain the power factor of power system nearly to unity at all times. TSC and TCR are basically shunt connected capacitors and inductor respectively whose switching (of capacitors) and firing angle control (of inductor) operations are carried out using thyristors. The purpose of capacitors is to supply lagging VAR as per the demand by the connected ...