PT Unknown
AU Alzatari, M
TI Power Electronic Control Device for High Voltage Test Transformers
PD 01
PY 2016
LA en
DE Partial discharge measurement; Total harmonic distortions; power electronic; PWM.
AB Electrical insulators reliability and age degradation estimation can be evaluated accurately by test. Beside other test procedures high voltage dielectric test(HV-DI) and partial discharge (PD) measurements are used for this purpose. Since the accuracy in test is an essential issue, HV-DI test and PD measurements have to be accomplished in nearly ideal signal quality of the test's voltage source, as well as controllable distortions(in presence of harmonics)in order to investigate all possible circumstances.
Performing the test using other frequencies(16,7 Hz, 50 Hz, 60 Hz) are also on market demand.

For the dimensioning of the power electronic system, the essential components of a HV test system need to be characterised. The characterisation focus on the properties relevant for the use cases High Voltage Dielectric Tests and Partial Discharge Measurements. Based on this characterisation the required parameters for a single phase DC-AC Inverter and the corresponding PWM parameters are derived.

The goal of spectral purity disallows the use of standard PWM schemes. Based on the Naturally Sampled PWM scheme as described in the literature [10], a new PWM scheme (Enhanced Unipolar PWM) is developed which allows its use for HV testing. The new driven algorithm is implemented in Digital Signal Processor (DSP) unit which is controlling an H-Bridge and an attached 100 kV, 5 kVA test transformer.

The fast Switch-Off unit in case of breakdowns is based on a detection algorithm which is implemented in a second DSP. The accurate detection of a breakdown uses signals from a current sensor in the primary circuit and the voltage signal from a HV divider.

Finally the functioning of the whole system is demonstrated in an experimental investigations.
ER