Operation and design of control system for the cascaded Kainji-Jebba hydropower system poses a great challenge to researchers and engineers. The difficulties arose from the fact that the system is affected by several nonlinear interacting factors such as variations in inflows, stochastic factors that are weather related, availability of the turbo-alternators, and numerous other constraints that are influenced by the system dynamics. All these makes the mathematical representation of the system difficult. This paper presents the development of a dynamical model for the operation and optimal control of the operating heads of the cascaded system. The mathematical models were developed from energy conversion equation and Bernoulli’s equation. The model was calibrated and tuned using measured data. Upon validation by comparing the response of the model with measured head, a deviation within  was observed, making it a good prediction of the system response and appropriate for control system design. Keywords— Control model, Discharge, inflows, Operating head, Turbo-alternators

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The Nigerian power system consists of several sets of aged turbo-alternators (TAs) associated with frequent failures and limited installed capacity. This paper presents the results of a study of the performance of the turbo-alternators at one of the most important power stations in the country. The energy conversion characteristic of each of the turbo-alternators is studied by comparing the electrical power output with the total hydro-energy available on a daily basis. Similarly the availability was examined by generating the stochastic sequence of up-times for each TA. The results indicate that energy conversion remained essentially linear throughout the third decade of operations. Availability was however found to vary considerably from year to year with the worst performances occurring in the first five years -an indication of poor state of repair of the machines during that quinquennium. In conclusion, the results indicate that despite their age the TAs have many more years of service left provided maintenance is carried out diligently. Enhanced maintainability will however require both retro-fitting and a forward looking maintainability strategy.

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Electricity generation at the hydropower stations in Nigeria has been below the expected value. While the hydro stations have a capacity to generate up to 2,380 MW, the daily average energy generated in 2017 was estimated at around 846 MW. A factor responsible for this is the lack of a proper control system to manage the transfer of resources between the cascaded Kainji-Jebba Hydropower stations operating in tandem. This paper addressed the optimal regulation of the operating head of the Jebba hydropower reservoir in the presence of system constraints, flow requirement and environmental factors that are weather-related. The resulting two-point boundary value problem was solved using the progressive expansion of domain technique as against the shooting or multiple shooting techniques. The results provide the optimal inflow required to keep the operating head of the Jebba reservoir at a nominal level, hence ensuring that the maximum number of turbo-alternator units are operated.