The Analyzation Performance of Control Technique Power Converter for Partial Discharge Testing System

Abstract

This paper proposes the analyzation performance of control technique between 3-level converter with using unipolar Pulse Width Modulation (PWM) technique and 5-level converter with using PODPWM stands for Phase Opposition Disposition Pulse Width Modulation. The power converter develops for partial discharge (PD) testing system as use for a High-Voltage (HV) testing process. For potential transformer (PT) PD tests, the power frequency converter was connected to an HV transformer. The power frequency converter was composed of a three-phase rectifier which had high performance more than single-phase rectifier because of the lower ripple voltage. Furthermore, the power converter based on 5-level PODPWM with switching technique has the best performance result because it has the lowest number of background noise. On the other hand, the power converter with a high noise level, which affects the PD test system, is a critical problem in the HV and PD test systems. For example, PT, distribution transformer, and so on. If the efficiency of a PD testing system developed from a power converter is used for PD testing, there is a greater benefit. In this paper, we will look at the requirements as follows: The total harmonic distortion (THD) must be less than 5&#x0025;, and the background noise level must be less than 50&#x0025; of the permitted PD levels for oil-insulated PTs. The oil-type PT was chosen as the test object, and the allowable PD level of standards is 5 pC. According to the standard requirements, the developed system is of excellent quality. The total harmonic distortion of voltage <tex>${(\text{THD}_{\mathrm{v}})}$</tex> is less than 1&#x0025; and the background noise is less than 2.5 pC during a test voltage of 40 <tex>${{\text{kV}}_{\text{rms}}}$</tex>. An appropriate switching frequency of 3.2 kHz and an amplitude modulation index <tex>${(\mathrm{m}_{\mathrm{a}})}$</tex> of 1 were also studied. Furthermore, the designed system has been successfully tested in a real PT partial discharge test. The developed system is an attractive choice for use in HV and PD tests due to its positive results.