Quadrature Booster Research Articles

Impact of Quadrature Booster on Power-System State Estimation in Polar Coordinates

The paper concerns the estimation of the state of a power system in which there is a phase shifter called a quadrature booster. The aim of the paper is a comparative analysis of two different cases including the quadrature booster in the state estimation. In the first case, the quadrature booster is represented by a model consisting of two real voltage sources, one in series with a power line and the other in a shunt branch. In the second case, in the power system model, the real branch with the quadrature booster is represented as off at the end where the considered quadrature booster is actually installed. The state estimation is assumed to be carried out in the polar coordinate system. The properties of the state estimation are characterized by: the number of iterations in the calculation process, the index of conditioning of the matrix of coefficients in the equations to be solved (cond(G)), and ratio Je/Jm, which is a measure of the accuracy of the estimation. Using IEEE 14-bus test system, investigations are carried out in such a way as to cover the entire state space of the power system as possible. In the investigations, Monte Carlo experiments are carried out for each of the considered cases of the state estimation. Each of these cases is also analyzed from the point of view of the assumed definition of the state estimation. Investigations show that in the first of the previously described cases, the state estimation is more accurate, but there are more iterations in the calculations and worse conditioning of the estimation process. The comparative analysis also shows that, the accuracy of the results obtained in each of the considered cases is practically independent of the coordinate system in which the estimation calculations are performed. Taking into account the number of iterations in the estimation process and index cond(G), it can be concluded that the implementation of each of the above-mentioned estimation cases in the rectangular coordinate system is more reasonable.

Performance evaluation of phase-shifting transformer for integration of renewable energy sources

In recent years, the installed power capacity of renewable power plants has been increasing because of the technological developments, industrialization and rapid population growth. This case has led to the extension of electric transmission networks. Extending transmission networks, on the other hand, means the long transmission lines and line losses. The efficient control of electricity transmission systems can be achieved through an efficient selection of devices used in transmission lines as well as the proper management of networks. These devices, called Flexible Alternating Current Transmission System (FACTS) devices, are integrated into transmission lines and provide energy efficiency in the transmission system. In this study, a novel Two-Core Asymmetric Phase-Shifting Transformer (APST) model, which is a serial FACTS device developed for the efficient use of transmission lines, will be realized. The most important factor in the selection of the Two-Core APST model is to obtain a general model that is valid for all quadrature and non-quadrature dual-core APSTs instead of Quadrature Booster type APSTs, which are frequently used in the literature. The designed Two-Core APST model will be tested in an electrical transmission system consisting of a 154 kV source voltage level and loads. Moreover, this model will be applied in IEEE 9-bus system in MATLAB program and changes in transferred power will be examined. Changes in active power transfer and voltage will be observed by the step change of the APST.

Comparative Study of Quadrature Booster in Different Locations

Comparative Study of Quadrature Booster in Different Locations

Properties of State Estimation for Power System with Quadrature Booster in Rectangular Coordinates

The paper presents a state estimation of a power system with a phase shifter. A new versatile model of the phase shifter for steady state analyses is introduced. The mentioned model allows for consideration of different types of phase shifters. In the paper, original investigations of properties of the state estimation for a power system with a quadrature booster (to be one of types of phase shifters) are performed. The state estimation is considered in the rectangular coordinate system. During the investigations, impact of data redundancy on such parameters of the state estimation as: the number of iterations, a condition number of a coefficient matrix, parameters characterizing accuracy of calculation results are taken into account. At the end of the paper, conclusions from the conducted investigations are presented. DOI: http://dx.doi.org/10.5755/j01.eie.24.1.20155

A high-power PWM quadrature booster phase shifter based on a multimodule AC controller

Pulse-width-modulated (PWM) phase shifters allow the smooth control of power flow in a transmission line. This paper analyzes a PWM quadrature booster phase shifter based on a multimodule AC controller structure to attain high voltage levels and improve the harmonic spectrum. The modules are based on a three-phase PWM AC controller topology that employs only four force-commutated switches and is controlled by duty-cycle variation. The PWM technique is carrier based and the individual modules are gated through phase-shifted triangular carriers. As a result, harmonic cancellation takes place in the input current and output voltage. Low-order harmonics are therefore eliminated and the amplitude of remaining components reduced. An additional operating mode with negligible harmonic generation and step-like control is identified. The feasibility and advantages of the proposed phase shifter are demonstrated by means of a power system simulator.

Dynamic quadrature booster as an aid to system stability

Quadrature boosters (QB) have been widely used to control the power flow distribution between parallel transmission lines. The advent of very fast thyristor/vacuum switch tap changers makes the dynamic quadrature booster a powerful FACTS device for the improvement of the transient and dynamic stability of power systems. The basic concepts of the dynamic QB operation, the modelling aspects of a multimachine power system in which dynamic QB are situated, the ideal control strategy and practical considerations are presented. Simulations show that in a small, simple, power system the QB can substantially suppress disturbances before swings in load angle have become large. In a large interconnected system the action is less successful.

Thyristor-controlled quadrature boosting

With reference to the conventional quadrature booster transformer, this paper describes a way of achieving continuous phase-shift control based on point-on-wave thyristor switching. The proposed unit can provide continuous and practically instantaneous power-transfer control in transmission circuits. The theoretical waveforms are verified by experimental tests and computer studies. Consideration is also given to the harmonic content produced.