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Abstract

This research’s main objective is to adapt transmission line models developed for the Electromagnetic Transients Program (EMT) in power transmission lines to model the pressure and flow transients in water (fluid) pipelines. Modelling of the propagation of the water waves from the dam to the generator will be incorporated into the control of the mechanical power input to the turbine as an additional control element to enhance the dynamic stability in large power systems. The transient flow equations used in typical hydraulic transient programs are based on flow continuity and momentum. Approaches to solving these classical quasi-linear hyperbolic partial differential equations analytically have been made by many authors, such as Rieutord (1982) [16], Wylie and Streeter (1993) [17], and Kim (2003, 2005, 2011) [18, 19, 20]. The most widely used methods in hydraulic transient programs are to solve the non-linear partial differential equations using the method of characteristics (MOC) or finite difference (FD) methods where discretization and linearization along the length of the pipe are required. This research differs from previous works in that it uses a travelling wave time-domain solution method that captures the main aspects of wave propagation instead of classical length discretization and linearization. With the EMT-H (Electromagnetic Transient-Hydraulic) model, the hydraulic travelling wave equations can be solved much more efficiently than with the traditional models based on the methods of characteristics (MOC) or finite differences (FD). In addition, the EMT-H method can be directly included in the equations for power system dynamics to consider the effect of hydraulic transients. Incorporating the hydraulic transients in the control equations, we discuss the adverse effects in the governor dynamics of the newer power-droop controllers versus traditional gate-droop controllers. We also suggest extending a control loop to a conjugate power plant, adding another dimension to enhance power system stability. Enhanced stability is particularly important in decreased inertia systems due to the penetration of non-conventional and non-dispatchable energy sources such as solar and wind.