| Small power systems based on renewable energy sources such as low head water falls, wind, solar and ocean tides can be made economically more viable if non-conventional control techniques like direct load control are used. A real-time, networked microprocessor controller has been developed which when complemented with a conventional automatic voltage regulator provides stable voltage and frequency for a stand-alone, run-of-the-river small hydroelectric power plant with no input control, i.e. no input governors or conventional gates and guide vanes.; The control objectives include stable frequency and maximizing the generation using directly controllable loads, usually semi-or fully-automated processes producing locally usable commodities. These loads are switched based on availability of power above the base load level to maintain a high (nearly 100%) load factor on the generator. A digital control model of such a system has been presented and analyzed. The PADS (Predicting, Adjusting to one of the Dual States) control algorithm has been developed to maintain frequency within 5% of the nominal. This algorithm predicts the machine frequency for the next sampling period and if the predicted value is out of the error bounds, an immediate correction is applied else a correction is applied, if needed, after every 100 samples. Analysis on a 100kW generating station and the results of the machine behavior using PADS algorithm for various step load changes are presented.; The controller is based on a 16-bit microprocessor system as a master and up to four 8-bit microprocessor systems as remote slaves. The master provides all executive and generator control tasks while the slaves are dedicated to load control tasks. The processors are networked on a communications bus organized as a star with the master at the hub. The operating system developed has the capabilities of real-time as well as background processing in addition to the communication processing and human interface. |
