A Control Scheme for Variable-Speed Micro-Hydropower Plants

The aim of this work was to design and build a control system to control the performance of the Pelton wheel and synchronous generator system at different upstream water flow and electrical load conditions. The turbine output power is determined by the upstream water flow and spear valve, whilst the generator output power is determined by the turbine output power and the electrical load. A spear valve is used to control the generator output power at different water and load conditions. An autotuning proportion integration (PI) arithmetic-based controller was built using a relay feedback tuning method. An on⁻off relay was used in the program in order to oscillate the system. The optimal PI gains can be estimated via the Ziegler⁻Nichols method. A fully open test was used to test the tuned PI gains. The performance of the original gains and the new tuned gains were discussed. A controller was used to maintain the frequency or voltage of the output power by automatic regulation of the turbine valve. The program could search for the maximum generation efficiency by entering the output current value of the generator into the program manually