Modelling of water conduit dynamics using the electromagnetic transient program line model

Almost all electrical power systems literature assumes that the shaft mechanical torque of a water turbine is linearly proportional to the wicket gate position and ignores the dynamics in the shaft torque due to the propagation of the water from the reservoir to the turbine. This propagation is usually modelled very simply using the water start-time equation and ignoring the travelling wave dynamics along possibly long conduits. This simplified modelling may introduce significant errors in the frequencies of oscillation which are in the range of 0.5-2 Hz and often fall within the range of slow oscillations in power system dynamics. This paper introduces the EMTP-H model for water dynamics based on the analogy between the hydraulic equations and the EMTP transmission line equations. The proposed model is validated with a field test and is applied to a simple power system frequency dynamics case.