Design of BFA-optimized fuzzy electronic load controller for micro hydro power plants

Abstract

With the volatile oil prices and the need to reduce the emission of greenhouse gases, renewable energy resources are a very attractive alternative. Africa has a good potential for micro hydroelectric power generation. However, only a small proportion of this potential has been harnessed. As a result, most rural areas in Africa have limited access to electric power. Unfortunately, those rural communities privileged to be connected to the grid also have unreliable and expensive grid power. To meet their energy needs, some of the communities have installed and operate Pico or Micro Hydro Power Plants (MHPPs) based on the Build-Own-Operate (BOO) model. In any power generation plant, a speed governor is required for regulating the frequency of supply under varying load conditions. However, this is the single most expensive component in a MHPP and most of the community owned plants can hardly afford it and thus, have no means of continuously regulating frequency. An Electronic Load Controller (ELC) is a device used to control the sharing of constant generator output power between the consumer and dummy loads and hence, maintain the frequency of a MHPP constant. This replaces the expensive and complex speed governor. In this paper, the design and implementation of an ELC is presented. Magnetostrictive Amorphous Wire (MAW) is used as a frequency sensor. An amplifier and a signal conditioning circuit were designed to convert the analog signal from the MAW to a digital signal that is fed to microcontroller. In addition, optimal Proportional-Integral (PI) gains are determined to serve as reference gains to the microcontroller so as to generate a Pulse Width Modulation (PWM) signal to control the firing angle of the switching circuit of the ELC. The laboratory experimental test results obtained clearly show the effectiveness of the ELC to dump excess power to the damper load when the consumer load changes, and maintain the supply frequency between 49.5 and 50.5 Hz. Also, from the results, it was observed that the MAW sensor was able to measure the frequency effectively with high accuracy when compared to the frequency measurement from the tachometer. This is a key finding of the suitability of MAW sensor application in ELC for MHPPs. The designed controller is cheaper and yet able to control the frequency very effectively when compared to other ELCs and speed governors that are currently on the market.