A Matlab/Simulink Model of Self Excited Induction Generator for an Electrical Brake Application

This paper presents a MATLAB/Simulink dynamic model of an induction generator, which makes simulation studies possible for the design of fuzzy logic controllers for the purpose of controlling the retarding torque output of the generator in an electrical brake application, using the fuzzy logic toolbox of MATLAB. Electrical braking has been proposed in the literature as an alternative to the mechanical braking systems with an advantage of providing lower maintenance costs. An induction generator, acting as a brake, converts the kinetic energy of a vehicle to electrical energy, which can be dissipated in a resistor bank or used in a regenerative mode.The Simulink model developed will be used to design and test controllers for an effective control of the output torque of the electrical brake system

An autonomous, low cost, distributed method for observing vehicle track interactions

Experience and field studies have shown that track geometry alone is not a good predictor of rail vehicle response. This paper describes a family of "Health Card" devices - an autonomous device that can be distributed on rolling stock to analyse the vehicle responses. As a distributed system is desired, and the intent is to apply this technology widely across a vehicle fleet, a low initial capital cost and low operating cost solution is desirable. As a consequence the Health Card performs all its sensing operations on the car body and avoids the costs and complications of sensing below the car body especially on unsprung components. Health Cards use solid-state transducers including accelerometers and angular rate sensors with a coordinate transform to resolve car body motions into six degrees of freedom. They then apply spectrogram techniques to obtain a time-frequency representation of the car body motion. These representations are autonomously analyzed to detect and classify transient dynamic events and to infer track degradation or operational risk

State variable implementation of stationary reference frame filters for active filter systems

Wolfs, PJ ORCiD: 0000-0001-7048-1231This paper presents a novel and elegant implementation of a synchronous reference frame filter for power system harmonic extraction. This filter does not require the sine and cosine terms normally required of SRF filters. The novelty of this approach is the use of a state variable representation to develop the filter structure. Filters based in the stationary reference frame have been presented based on classical control approaches, but these filters tend to be inelegant in their implementation. Another beauty of this approach is that a structural relationship exists between the SRF filter and its stationary frame state variable implementation, which allows the approach to be easily extended to higher order filters or controller structures

Active filter capable of eliminating multiple harmonics with a single tuned branch

A hybrid active/passive filter with a single tuned branch using an active element in parallel with the inductor is presented. Simulations and experimental results demonstrate the filter's capacity to remove a range of line current harmonics with a low active component rating

Approach to Harmonic Flow Control using Hybrid Series ActiveIPassive Topologies

Abstrac

Analysis and design of a multiple-loop control system for a hybrid active filter

Wolfs, PJ ORCiD: 0000-0001-7048-1231This paper investigates the control of a hybrid active filter consisting of a single tuned resonant branch and an active element. This filter is capable of suppressing multiple harmonics using a multiple-loop control system. Linear continuous-time models are first developed in the dq reference frame. This results in a two-input/two-output system with cross coupling. The continuous model is discretized and the design of a multiple-loop discrete-time controller is examined. Wideband current feedback loops are shown to affect the coupling between the d and q axis controllers and provide a resistance-like damping effect. Variations in stability with processing delay times are examined. Finally, this work is extended to include narrowband harmonic specific controls. The results of the control study are confirmed by simulation and experimental results

An Active Power Filter Method to Improve the Line Current Spectrum of PWM Locomotive Rectifiers with Load Unbalance

Locomotives in heavy haul and high speed passenger operations represent several megawatts of electrical load. Single phase power collected by a pantograph is typically rectified by multiple PWM converters. The converter switching instants are phased to ensure ripple current cancellation, assuming that the converter loads are balanced. Partial failures may result in unbalanced operation with reduced cancellation. The resulting harmonics may adversely impact the signalling systems and/or result in over voltage effects due to resonance in the overhead supply system. This paper examines a 4 MW locomotive with three rectifier modules and a device switching frequency of 900 Hz. This results in a5400 Hz ripple frequency in the mains current. Ideal balanced operation of converters is compared to anunbalanced operation case. Unbalanced cases include rectifier failures, inverter failures and changes in the relative balance of power delivered to each axle of the locomotive. This paper will consider what may be the most frequently occurring case; that of loss of load in one traction motor due to wheel slip. Current ripple cancellation is partially lost in this case and lower frequency current components can be produced. An active filter is proposed as a means to retain an acceptable harmonic performance for the locomotive

Control of traction supply power quality using locomotive PWM converter controls

Wolfs, PJ ORCiD: 0000-0001-7048-1231Railway traction systems are highly susceptible to severe harmonic distortion, poor voltage regulation and line resonances. Electric locomotives, which are concentrated high power loads, move continuously along the supply line, rendering the topography of the supply system, a time-variable. Under those conditions, the resonant impedances vary as the traction vehicle moves along the track. Parallel resonances with feeder line inductance and capacitance between feeder line and earth, cause harmonic magnification. This paper will examine the use of small retrofit converters to improve the performance of multiphase PWM rectifiers as found in locomotive applications

Capacity enhancement for aging distribution systems using single wire earth return

Wolfs, PJ ORCiD: 0000-0001-7048-1231Single wire earth return systems, (SWER), are the low cost technology for rural power distribution and have global application. In the Australian setting, voltage regulation is becoming the determining factor for older SWER systems. In long systems, directly connected shunt reactors are used to compensate the effects of line to ground capacitance. The replacement of fixed shunt reactors with controllable reactors provides an opportunity to approximately double the capacity of an aging infrastructure. Three case studies based on the North Jericho system are presented and a range of practical implementation issues are discussed