Integration of the EMT-H water conduit model with the turbine control system for power system dynamics

• Dynamic stability in hydro-generators including the water dynamics. • Faster gate rate change in governors with hydraulic equations. • Modern power droop versus traditional gate droop controllers in hydro governors. • The concept of a companion compensating plant for hydro governors with long pipes. Travelling pressure waves in hydraulic pipes in hydro generators can cause pressure transients that can implode or explode the pipes. These transients in the pipes limit the speed at which the mechanical power can be increased or decreased to compensate for transients in the electrical system. This paper uses the EMT-H hydraulic transients model developed in previous work in conjunction with the governor controller to more effectively dampen the electrical power system dynamics by coordinating the water transients with the electrical transients without damaging the pipes. The solution of EMT-H is very fast and can be incorporated into the control loop of the traditional controllers for an improved response. To test the new controller, the IEEE nine-bus, three-machine power system is used to solve a frequency stability problem during sudden load changes. From the hydraulic dynamics, we make observations on the adverse effects of the newer power-droop governor controllers compared to the traditional gate-droop controller and propose a new hybrid controller. We also consider the pooling of control loops of companion plants to improve the overall dynamics of the combined responses. Improved plant control dynamics are becoming more important with the decrease of mechanical inertia in IBR systems.