Thyristor Switch Research Articles

Finite Element Analysis for Stress and Magnetic Field of a 40 kA Protection Inductor

The protection inductor serves for limiting the peak current in order to protect the thyristor switch of the pulsed magnetic field facility in case of a short circuit. Because of the high current and strong magnetic field, the Lorentz force in the protection inductor is large. This paper describes the calculation of the inductance and the optimization of the stresses in the protection inductor. A finite element analysis with the ANSYS software is used to calculate the magnetic field and stresses in the protection inductor. A three-dimensional static finite element analysis model of the inductor has been built for calculating the stresses in the copper coils and stainless steel rings as well as the static inductance. Furthermore, a harmonic finite element analysis model has been built to analyse effects such as the influence of eddy currents in the copper wires and induced current in the stainless steel rings on stress and inductance. Eddy currents cause an uneven distribution of stresses; induced current can decrease the stresses in the copper coils but increase those in the stainless steel rings. Both effects reduce the inductance. The typical maximum stresses in our design are 70 MPa in the copper coils and 210 MPa in the stainless steel rings; these are both below the yield strength of these materials. The inductance is 1.05 mH at the frequency of 50 Hz. The protection inductor has been manufactured according to the design and the performance testing has been successfully completed.

25 kV/40 kA Protection Inductor for Capacitor Bank of the Wuhan Pulsed High Magnetic Field Facility

A 25 kV/40 kA protection inductor with low stray field was designed and the first prototype was fabricated. The protection inductor protected the thyristor switch in the capacitor bank, limit the current at 40 kA in case of a short circuit. It was designed as a toroidal system consisting of 12 coils evenly distributed in the perimeter of a circle. The inductance could be changed easily by adjusting the number of coils. The structure of coils was optimized to withstand the great electromagnetic force produced by the 40 kA current. The coils were wound by a 4 45 mm copper strip standing on edge. Each coil was externally reinforced by a stainless steel ring tightly enclosing the coil. The first prototype was fabricated. Its inductance and magnetic field were tested. The prototype has been mounted in the 1 MJ module and is now in operation. In this paper, the structure design, fabrication and testing of a new protection inductor are presented. The testing results are discussed. Tested inductance was 1.05 mH and direct resistance was 16 . The first prototype was proved to be successful and 13 more protection inductors will be made after some improvements.

Correction to “An Adaptive Controller for Power System Stability Improvement and Power Flow Control by Means of a Thyristor Switched Series Capacitor (TSSC)” [Feb 10 381-391

An Adaptive Controller for Power System Stability Improvement and Power Flow Control by Means of a Thyristor Switched Series Capacitor (TSSC) (vol 25, pg 381, 2010)

Note: Design and tests of a 13 kA-6.5 kV thyristor switch for a pulsed inductive vacuum ultraviolet source

In this paper, the design, construction, and test procedure of a closing switch prototype based on thyristors is described. In particular, details are given about the design criteria and about the triggering board architecture, which is a high side biased, self supplied unit using the electrical energy derived from a local snubber network for the gate drive. The structure guarantees a hard firing gate pulse for the required high dI/dt application. Further, the results of the prototype tests are presented and discussed. The stack assembly has a holding voltage of 6.5 kV and is used for switching a series resonant circuit with a ringing frequency of 12 kHz for a pulsed inductive vacuum ultraviolet source. Maximum current amplitudes of 13 kA and pulse energies of more than 600 J were switched during the test procedure.

Progress in the Development of the Wuhan High Magnetic Field Center

Since April 2008 the Wuhan High Magnetic Field Center (WHMFC) has been under development at the Huazhong University of Science and Technology (HUST) at Wuhan, China. It is funded by the Chinese National Development and Reformation Committee. Magnets with bore sizes from 12 to 34 mm and peak fields in the range of 50 to 80 T have been designed. The power supplies for these magnets are a capacitor bank with 12 modules of 1 MJ, 25 kV each and a 100 MVA/100 MJ flywheel pulse generator. The objective of the facility is to accommodate external users for extensive experiments in pulsed high magnetic fields. Up to seven measurement stations will be available at temperatures in the range from 50 mK to 400 K. The first prototype 1 MJ, 25 kV capacitor bank with thyristors, crowbar diodes and a mechanical switch has been developed and successfully tested. For the protection of the thyristor switch, a toroidal inductor is developed to limit the current at 40 kA. Five magnets have been wound with CuNb and copper wires and internal reinforcement by Zylon fiber; external reinforcement is a stainless steel shell encased by carbon fiber composite. Two Helium flow cryostats have been successfully tested and reached temperatures down to 4.2 K. Measurement stations for magneto-transport and magnetization are in operation. The design, construction and testing of the prototype system are presented.

The New Developed Components Tests for 1 MJ Capacitor Power Supply System in Wuhan High Magnetic Field Facility

A new 1 MJ, 25 kV, 40 kA pulsed capacitor power supply system for the Wuhan High Magnetic Field Facility (WHMFF) has been achieved. The desire for 70 or higher tesla magnetic field to support a lot of scientific researches based on it is just now beginning to be realized. The system consists of charger, capacitor bank, polarity changing switches, protective inductor, thyristor switch, crowbar, dump circuit and so on.

半導体化インパルスジェネレータの大容量化と高機能化に関する研究

Enlargement of capacity and functionality of the pulse power generator are hoped due to its use expansion to the industrial fields. We have developed the high repetitive static impulse generator using technologies of a successive trigger operation and resonant/parallel charging method and Thyristor switches. In this paper, we propose reliable and high functional trigger circuit system with a provision for miss-operation of trigger circuit due to the surge voltage, wide range operation voltage and high speed operation. And using five, seven, ten, and seventeen stage IG, we demonstrated its feasibility. In addition, replacing to IGBT with Thyristor, we improved its properties of rice time and voltage amplification ratio.

An Adaptive Controller for Power System Stability Improvement and Power Flow Control by Means of a Thyristor Switched Series Capacitor (TSSC)

In this paper, a controller for a thyristor switched series capacitor (TSSC) is presented. The controller aims to stabilize the power system by damping interarea power oscillations and by improving the transient stability of the system. In addition to this, a power flow control feature is included in the controller. The power oscillation damping controller is designed based on a nonlinear control law, while the transient stability improvement feature works in open loop. The damping controller is adaptive and estimates the power system parameters according to a simplified generic model of a two-area power system. It is designed for systems where one poorly damped dominant mode of power oscillation exists. In the paper, a verification of the controller by means of digital simulations of one two-area, four-machine power system, and one 23-machine power system is presented. The results show that the controller improves the stability of both test systems significantly in a number of fault cases at different levels of interarea power flow.

An educational software package for Thyristor Switched Reactive Power Compensators using Matlab/Simulink

In this paper, an educational software package called TSCOM (Thyristor Switched Reactive Power Compensators) has been developed. The TSCOM software package contains simulation models of Thyristor Switched Capacitor (TSC) and Thyristor Switched Reactor (TSR)-based Static VAr Compensator (SVC) which are two of the shunt Flexible AC Transmission Systems (FACTS) devices. The design and simulations of TSC and TSR-based SVC are proposed using the Matlab/Simulink 7.04® and SimPowerSystems. The TSC and TSR-based SVC devices are demonstrated at two bus, three bus, infinite-bus, single-phase, three-phase, static load, dynamic load and stair-case load conditions. The effects of TSC and TSR-based SVC devices on load voltage are also analyzed. Student feedback indicates that this package is user-friendly and considerably effective for students and researchers to study theory of switched compensators, the reactive power control and voltage regulation. The proposed package will help to design the practical prototypes for students and researchers.

Proposed hybrid superconducting fault current limiter for distribution systems

In this paper, a new hybrid fault current limiter is proposed for primary distribution systems. It incorporates a high temperature superconducting element in parallel with other two branches. The first is an inductive impedance to share the fault current with. The second branch is a gate-turn-off thyristor switch controlled to work in either of two modes. For the main mode, it controls the temperature of the superconducting element and protect it against damaging excessive heating. Instead, it keeps the device applicable without that superconducting element in the auxiliary operation mode. The design, control and operation of the device is addressed. Its performance in 11 kV distribution systems with DG is investigated. The factors affecting the device behavior for different scenarios are explored.

Switching of thyristors in AC voltage relay-pulsed control circuits

Switching processes are considered and their parameters are calculated for two circuits for ac voltage relay-pulsed control. A comparative analysis of these circuits is conducted for their use in a resistance welding machine.

The Influence of Pulsed Magnet Heating on Maximal Value of Generated Magnetic Field

The influence of pulsed magnet heating on the maximal value of the generated magnetic field is described. The operation of pulsed generator consisting of a capacitor bank, thyristor switch and wire wound pulsed inductor was analysed. The maximum value of the generated magnetic field and pulse duration of pulsed magnet was limited by Joule heating and mechanical stresses. Using Matlab£ Simulink£ software, a flexible model for simulation of thermodynamic processes in pulsed magnet was developed. The calculated results of the maximal value and distribution of magnetic field were verified experimentally and acceptable compliance was achieved using calibrated array of four pick up inductive coils for measurements of axial magnetic field and a current shunt for pulsed current measurements.

All-Solid-State Power Modulator for Pulsed Corona Plasma Reactors

Atmospheric pressure pulsed corona plasma (PCP) reactors of wire-plate design offer novel solutions to environmental issues and to a number of industrial processes. Emerging applications include indoor air sterilization and odor removal in air conditioning systems, chemical synthesis in non-thermal plasmas, and plasma reforming of gaseous fuels. We previously reported on experimental investigations of a laboratory size, wire-plate plasma reactor for pulsed corona treatment of gas flows. Operation with gas flow, at pulse repetition frequencies of between 10 pps and 200 pps, has been achieved at pulse voltage amplitudes of between 10 and >30 kV, at pulse durations of around 0.3 mus (FWHM). High efficiencies of up to 70 g/kWh have been reported using an all-solid-state pulse generator. In this work, we report on the development of all-solid-state power modulators for use with nonlinear loads like pulse corona plasmas. The pulse generators are based on a fast thyristor switch discharging pulse capacitors, a pulse step-up transformer, and one or two stages of magnetic pulse compression. At pulse repetition rates of up to 200 pps, amplitudes of > 30 kV into a resistive-capacitive load (1 kOmega200 pF) have been achieved, at risetimes of about 80 ns and a pulse width of 0.3 mus. The pulse generator is insensitive to load variations, in particular to sparking in the reactor. An advanced generator version uses two magnetic pulse compression stages resulting in even shorter rise times. The modulator and its performance concerning experimental results will be described in detail when driving a pulsed corona reactor.

Coupled circuit–field formulation for analysis of parallel operation of converters with interphase transformer

This paper deals with the coupled circuit–field analysis of an interphase transformer (IPT) required for two three-pulse controlled converters operating in parallel for the typical low voltage high current electrolysis application. Two-dimensional nonlinear transient finite element (FE) model of the IPT is coupled with external power electronic circuit comprised of switching thyristors. Output current is maintained constant at 6000 A by implementing current feedback control system. The resulting system of transient nonlinear equations is solved by backward Euler and Newton–Raphson methods, and analyzed under balanced, unbalanced and short circuit conditions. The results obtained from short circuit condition are verified with experimental results and design values, making them helpful for design purpose.

Research of the Ga and Al double-impurity doping technique for making fast switching thyristor

We describe a novel technique for producing the p-type semiconductor. The homogeneous impurity doping of Ga and Al in the n-type silicon wafer is achieved by means of the combination of two technical processes namely aluminum emulsion coating and vaporizing Ga. This Ga-Al double-impurity doping technique, as well as its effect on the quality of the produced semiconductor devices, is investigated theoretically and tested in practice. The principle of the doping technique is also discussed in detail. By using SRP, four-probe needle and thyristor analyzer, we have examined the Ga-Al impurity concentration distribution within the silicon wafer, thin layer resistance RS, and other useful parameters of the fast switching thyristors made by this technique. The turn-off time of the fast switching thyristors, toff is 31.2—38.6 μs, turn-on time ton is 4.6—5.9 μs, and the forward voltage drop VTM measured is 1.9—2.1 V. Both experiment and some real applications indicated that this technique may obviously improve the semiconductor device in the overall performance, the electrical parameter uniformity and the end product rate. It provides a feasible technique for making fast switching thyristors.

Soft-started induction motor modeling and heating issues for different starting profiles using a flux linkage ABC frame of reference

In order to mitigate the adverse effects of starting torque transients and high inrush currents in induction motors, a popular method is to use electronically controlled soft-starting voltages utilizing series-connected silicon-controlled rectifiers (SCRs). Investigation of semioptimum soft-starting voltage profiles was implemented using a flux linkage ABC frame of reference model of a soft-started three-phase induction motor. A state-space model of the soft-starter thyristor switching sequence for the motor and load was developed and implemented in a time-domain simulation to examine winding heating and shaft stress issues for different starting profiles. Simulation results of line starts and soft starts were compared with measured data through which validation of the model was established. In this paper, different induction machine soft-start profiles are shown, and comparisons of starting times, torque profiles, and heating losses are made. Discussion of these results and conclusions as to the near-optimum types of profiles are delineated based on peak torque, starting times, and winding heating criteria

Two-Layer Supervisory Controller-Based Thyristor-Controlled Braking Resistor for Transient Stability Crisis

In this paper, a supervisory two-layer control structure is synthesized with network elements as control means for thyristor-controlled braking resistor (BR) of multimachine power system operating in transient emergency state. This creates a multiple local feedback controller that can be realistically implemented using only local measurements and whose performance is consistent with respect to changes in network configuration, loading, and power transfer conditions. Following a major disturbance, the rotor angle and rotor speed of each generator unit are determined and the firing angle of the thyristor switch associated with the BR is computed by the local controllers. By controlling the firing angle of the thyristor, the BR controls the accelerating power in each generator and, thus, enhances the stability margins and damping oscillations. Since the local controllers rely only on measurements particular to their own subsystem, interconnection effects and the nonlinearities introduced by them are accounted for by the supervisory layer. The two-layer controller was tested on the IEEE Western States Coordinating Council (WSCC) test system. Results show that the controller is capable of bringing the system under control when starting with inherently unstable conditions, even when the severity of the disturbances is increased.

Dual Gate Emitter Switched Thyristor의 전기적 특성

Two dimensional MEDICI simulator is used to study the electrical characteristics of Dual Gate Emitter Switched Thyristor. The simulation is done in terms of the current-voltage characteristics with the variations of p-base impurity concentrations and current flow. Compared with the other power devices such as MOS Controlled Cascade Thyristor(MCCT), Conventional Emitter Switched Thyristor(C-EST) and Dual Channel Emitter Switched Thyristor(DC-EST), Dual Gate Emitter Switched Thyristor(DG-EST) shows to have tile better electrical characteristics, which is the high latch-up current density and low forward voltage-drop. The proposed DG-EST which has a non-planer u-base structure under the floating N+ emitter indicates to have the better characteristics of latch-up current and breakover voltage in spite of the same turn-off characteristics.

Conducted Emissions From FACTS Equipment Operational Within Substations—Part II

Electromagnetic interference (EMI) may be caused by the fast switching of thyristors and gate turn-off thyristors (GTOs), which are used in static var compensators (SVCs) and static synchronous compensators (STATCOMs) to control reactive power generation and absorption to and from the transmission system. As a result, high levels of electrical disturbance may be coupled into the electrical ports of auxiliary electronic equipment, and if the levels are above the immunity level of the equipment, maloperation that may lead to a trip can occur. This study sought to measure typical conducted EMI levels in four selected SVC-based and one static synchronous compensator (STATCOM)-based substation. The results and their correlation to the existing IEC 61000-4 EMC Standards series are discussed, and indications of changes to the immunity tests are presented.

Hybrid switch to suppress the inrush current of AC power capacitor

This paper proposes a hybrid switch to suppress the inrush current of an ac power capacitor. This hybrid switch consists of a thyristor switch and an electromagnetic switch connected in parallel. The thyristor switch is used as an auxiliary switch during the transient state of turning on and turning off the ac power capacitor, and the electromagnetic switch is used as the main switch in the steady state. The proposed hybrid switch can avoid the inrush current of the ac power capacitor in the process of turning on and avoid the electrical arc in the process of turning off. The current rating of the thyristor switch and the electromagnetic switch used in the proposed hybrid switch is very small compared with a conventional thyristor switch or an electromagnetic switch used for switching ac power capacitor individually. Moreover, the proposed hybrid switch can extend the life of the ac power capacitor and the electromagnetic switch. A prototype is developed to demonstrate its performance. The test results show that the proposed hybrid switch module for ac power capacitor has the expected performance.