Ben Palethorpe

A technique for power supply harmonic impedance estimation using a controlled voltage disturbance

A method for power system impedance estimation is presented. The method employs a power converter to inject a voltage transient onto the supply system. As the technique employs controlled power electronic devices it may be used as a stand alone piece of a portable measurement equipment, or it may be embedded into the functions of an active shunt filter for improved harmonic control. The impedance is estimated through correlation of the measured voltage and current transients. Simulations and experimental results demonstrate the measurement technique is highly accurate and effective.

Power system impedance measurement using a power electronic converter

This paper describes a method for on-line measurement of power system impedance to source. The method employs a power electronic circuit to inject a small current disturbance onto the energised power network, and the measurements of the disturbance current and resultant voltage transient are used to identify impedance. Simulation results demonstrate the effectiveness of the technique for identification of the impedance of transmission lines and linear loads. An alternative data processing technique is introduced in order to address the measurement problems associated with nonlinear loads. This technique is also illustrated using simulation.

Estimation of power supply harmonic impedance using a controlled voltage disturbance

A novel method for power system impedance estimation is presented. The method employs a power converter to inject a voltage transient onto the supply system. The impedance is estimated through correlation of the measured voltage and current transients. Simulations and experimental results demonstrate the effectiveness of this measurement technique.

Modular sensor architecture for unobtrusive routine clinical diagnosis

Clinical diagnosis of pathological conditions is accomplished regularly via the recording and subsequent analysis of a physiological variable from a subject. Problems with current common practice centre around the obtrusive and rigid nature of this process. These include the length, timing and location of the diagnostic recording session, transfer of data to clinical staff, liaison between clinical staff and subjects and the integration of such diagnostic check-ups into the overall health care process. We have designed a modular diagnostic monitor that is centered around a wearable computer system which, when integrated into a suitable computer network and database architecture, is capable of addressing the above problems. The system is modular, allowing researchers and practitioners to utilise various sensor modules, reconfigure the unit in terms of its on-board storage and wireless telemetry capabilities, select the appropriate level of data preprocessing (before archiving data) and choose the appropriate level and nature of feedback to the subject. The system is GRID enabled, supporting e-clinical-trials. GRID clients can display live data, historical data, or perform data mining.

Experimental evaluation of active filter control incorporating on-line impedance measurement

This paper describes the use of on-line impedance estimation for power quality improvement. The impedance measurement technique can be embedded into the normal operation of an active shunt filter, to provide regular updates to the estimate of the supply impedance to source. In this work, the supply impedance estimates are then use in conjunction with the measurement of supply voltage, to generate the reference currents for the active shunt filter. Experimental results show both the accuracy of the impedance measurement, and the effective operation of the active filter in reducing the voltage distortion at the point of connection.

A novel voltage control for active shunt power filters

In this paper a new voltage control for shunt active power filters is presented. The proposed system is able to compensate one harmonic current flowing into the electric network without the need for measuring the non linear load current, or supply line current. Only the line voltage is measured. The developed control sets, by means of a genetic algorithm, the suitable values of amplitude and phase of the harmonic compensating current used as reference signal for a carrier modulated PWM voltage source inverter. Simulation tests carried out using Simulink and the Power System Blockset, show the reliability and the effectiveness of the compensation action.