Design of a Digital Electronic Load Controller (ELC) Unit for Micro-Hydro Power System
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UNIVERSITI MALAYSIA SARAWAK
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A micro-hydroelectric system, which is used for rural electrification, has a critical problem in that its output voltage is sensitive to load variation. The load variation causes the fluctuation of output voltage, and the electrical appliances could be malfunctioned due to low voltage and damaged due to overvoltage. Hence, an electronic load controller (ELC) is designed to maintain the output voltage at the nominal voltage of appliances by maintaining full load on the electrical generator. The criteria for an ELC used in rural micro-hydroelectric system should be simple and cost-effective in order to ensure the rural communities afford the system and able to support the ongoing maintenance cost. Therefore, this research proposed and presented a design of a simple and yet economical Arduino UNO based ELC system. The hardware implementation of the ELC, which included the calculation of component rating, was clearly demonstrated in this thesis. The control algorithm of the ELC was formulated by adopting the proportional-integral-derivative (PID) control concept. The digital implementation of PID control and the program code setup were also demonstrated in this thesis. The proposed ELC system was tested by using a motor-generator set, which is used to simulate the micro-hydroelectric system in the laboratory. First of all, the steady-state and transient behaviours of induction generator was studied. Then, the tuning effects of the three PID parameters proportional gain, integral gain, and derivative gain on the regulation of output voltage were investigated and analysed. During the PID tuning, it was found that there is no fix value for the time interval, which is included in the PID equations. In this research, tuning effect of the PID time interval was also investigated and studied, and the results showed that the ELC performed better by setting the time interval to its minimum value. By using the optimum values of PID parameters, the performance of the ELC was investigated using load variation test, and the results showed that the output voltage was kept v regulated at 240V despite the load variations. Lastly, a tuning guideline for the PID control in the ELC was developed based on the investigation of the tuning effects of the PID parameters.