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Solid state transformers using selective harmonic elimination technique for solar farm applications
Author(s)
Khemmook, Panya
Date Issued
January 1, 2020
Type
Article
Abstract
Solid state transformers using selective harmonic elimination technique for solar farm applications are presented in this paper. As known, the usage of photovoltaic to generate electricity in the form of solar power plants in Thailand is one of the major renewable energy resources. In addition, a Solid-State Transformer (SST) with the application on the solar power plant in Thailand begins to be considered as an alternative solution. Since an SST has the ability to eliminate the core losses during non-operating condition, it can gain more efficiency compared to a conventional transformer. In addition, an SST is smaller and lighter than a conventional transformer because it will normally operate at high frequency. In addition, an SST has a variety of functions, which can be ancillary service devices for an electrical system to help maintain electrical stability, harmonic filter, power fluctuation regulator, power flow controller and increasing of the limitation of transmission lines etc. An SST can gain higher efficiency by using Selective Harmonics Elimination (SHE) techniques for generating Pulse Width Modulation (PWM) signals. This technique offers several advantages such as simple implementation, uncomplicated techniques, and compatibility with various sequences harmonic elimination in a seven-level cascaded h-bridge multilevel inverter. The proposed SHE technique can search a set of angles that gives the lowest percentage of the total harmonic distortion voltage (%THDv). Then, the calculated angles can be used to fine tune again for optimal angle in the proposed controllers. The proposed seven-level cascaded h-bridge multilevel inverter is developed to validate the proposed controller for transferring power via a High Frequency Transformer (HFT) at 10 kHz. The results show that the power losses with the SHE technique using the optimal angles can be reduced up to 1.45% at HFT comparing to quasi-square waveform techniques. The performance of this proposed SST is validated with both simulation and experimental results. The validated results illustrate that the developed SST is a promising solution for a solar farm application.
Citation
International Review of Electrical Engineering, 15(6), 443-455, 2020