Magnetically controlled reactors (MCRs) are usually used as three-phase shunt reactors. They have low harmonic distortion independent of the third harmonic current because most three-phase MCRs are delta connected. However, as arc suppression coils, MCRs are operated in the single-phase mode, and the harmonics can be much higher than those of three-phase MCRs. In this paper, the structure and the mathematical model of a two-stage saturable MCR (TSMCR) are proposed. There are two stages with different lengths and areas in the iron cores. The stages saturate at different times when the TSMCR outputs reactive current. The current harmonics of the first saturated stage can be compensated for when the second stage begins to saturate, to reduce the total harmonics of the output current. The mathematical model that reveals the distribution characteristics of the current harmonics for the TSMCR is also presented. A study of the mathematical model indicates that there are two key factors that affect the total current harmonics of the TSMCR. One is the parameter k, which represents the area ratio of the second stage to the first stage. The other one is the parameter m, which represents the ratio of the length of the first stage to the total length of the magnetic valve in the iron core. The simulations and experiments show that the maximum current harmonics of the novel MCR can be limited to 3.61% of the rated output current when k and m are chosen according to the theoretical mathematical model.

Modeling and Harmonic Optimization of a Two-Stage Saturable Magnetically Controlled Reactor for an Arc Suppression Coil

In the case of motors and generators, the benefits of using high-temperature superconducting (HTS) coils could be represented by the reduction of 50% in both losses and sizes compared to the conventional machines of the same rating. However, it is hard to establish the quench detection and protection devices for the HTS coils applied to the rotors of motors and generators. Therefore, the stability of the coils is lower than the quiescent coils applied to NMR, MRI, and so on. Therefore, it is important to improve the self-protection ability of HTS coils. We have been developing a novel self-protection method, which removes the insulation turn-turn winding and inserts various metal tapes instead of the insulation. In our previous research, the higher self-protection ability for the thermal disturbances in the HTS coils removed the insulation and inserted Cu tape has been proved. This paper presents the results of an experimental study for the quench current using the insulated, the noninsulated, and the Brass tape inserted HTS coils in liquid nitrogen and background magnetic fields. Also, the measured quench currents of each coil will be discussed.

The Transient Stability of HTS Coils With and Without the Insulation and With the Insulation Being Replaced by Brass Tape

Indirect current controlled shunt active power filter for power quality improvement

Renewable energy sources are widely available on Earth; hence they have attracted much interest in both research and practical applications. In the large scale renewable energy system, power quality into the grid, especially harmonics and flicker, impacts on grid system significantly. In recent years, magnetically controlled shunt reactors (MCSRs) have been widely used to solve the problems of the power quality caused a failure or malfunction of the end-user equipment. MCSR can simplify the system reactive power and voltage control in the super / special high-voltage power grid, suppress power frequency and operation over voltage, eliminating generator self excitation, dynamically compensate charging the power in a transmission line, suppress the secondary arc current, damping system resonance and so on, which can meet the various needs of the system, it has a very broad application prospects. This paper presents a comprehensive review of MCSR configurations, the control strategies, the selection of components, other related economic and technical considerations, and their selection for specific applications. It is aimed at providing a broad perspective on the status of MCSR technology to the researchers and the application engineers dealing with power quality issues. A list of more than 130 research publications on the subject is also appended for a quick reference.

A review of magnetically controlled shunt reactor for power quality improvement with renewable energy applications

The traditional unidirectional, passive distribution power grids are rapidly developing into bidirectional, interactive, multi-coordinated smart grids that cover distributed power generation along with advanced information communications and electronic power technologies. To better integrate the use of renewable energy resources into the grid, to improve the voltage stability of distribution grids, to improve the grid protection and to reduce harmonics, one needs to select and control devices with adjustable reactive power (capacitor batteries, transformers, and reactors) and provide certain solutions so that the photovoltaic (PV) converters maintain due to voltage. Conventional compensation methods are no longer appropriate, thus developing measures are necessary that would ensure local reactive and harmonic compensation in case an energy quality problem happens in the low voltage distribution grid. Compared to the centralized methods, artificial intelligence (heuristic) methods are able to distribute computing and communication tasks among control devices.

Review of Voltage and Reactive Power Control Algorithms in Electrical Distribution Networks

Comparison of magnetically controlled reactor (MCR) and thyristor controlled reactor (TCR) from harmonics point of view

Static VAR compensators (SVC) are currently used for voltage stabilization of power systems in many countries around the world. One of the problems, which is solved during the implementation of SVCs, is the selection of tuning parameters (amplification coefficients and regulator time constants) to ensure the stable operation of SVCs. Methods based on numerical differential equations describing the SVCs are applied to solve this problem. On the other hand, this problem can be solved using the D-decomposition method, which refers to the frequency calculation methods. It allows determining the whole range of values of tuning parameters of the regulator without solving the system of differential equations describing SVC, at which the control system will be stable. The present paper focuses on developing this area of study and considers the case when one of the tuning parameters is set.

R.R. Karymov

Papers

Comparison of magnetically controlled reactor (MCR) and thyristor controlled reactor (TCR) from harmonics point of view

Application of the D-decomposition method using one parameter to select tuning parameters of Static VAR Compensators