Optimization of turbine start-up sequence of a full size frequency converter variable speed pump-turbine

Abstract

The stability of the electricity grid will be disrupted by the massive integration of new renewable energies. Hydropower plants have a major role to play in this transformation of the electricity market by increasing their operational flexibility and their ability to provide ancillary services. However, this flexibility may lead to an accelerated degradation of mechanical components. By changing the turbine operating point far from the best efficiency point or by increasing the number of transient manoeuvres such as start and stop sequences, unsteady flow phenomena, cavitation development and additional wear and tear stress the unit’s components and impact its lifetime. The present work aims to provide preliminary insight on the optimization of the start-up sequence of a 5 MW reversible Francis pump-turbine equipped with a Full Size Frequency Converter (FSFC). The goal of the optimization approaches are to determine a start-up sequence which minimizes the runner damage, the penstock fatigue and the water losses. The objective functions are evaluated by 1D hydraulic transient simulations with the SIMSEN software and which it allow to compare the relative mitigation between the conventional fixed-speed start-up and the linear variable-speed start-up equipped with a Full Size Frequency Converter.

A New Aggregation Methodology for the HPP Health Index

“…Zhang and Tongji (2011) redesigned the hardware of the hydropower station hydraulic monitoring system Tianqiao hydropower to achieve multi-channel data acquisition, multi-functional analysis, and visualisation operations. To minimize the runner damage, the penstock fatigue and the water losses in a pumpturbine, Schmid et al (2022) proposed an optimisation approach to determine a start-up sequence. Valentín et al (2022) compared the hybrid mode and the standard mode (non-hybrid) in terms of mileage and wear and tear of the guide vanes and runner blades servomotors.…”

Power Plant Transients including Hydraulic Short Circuit Operation Mode

“…Various studies include transient water hammer simulations for the entire hydro power plant with all water-bearing elements such as the piping system, valves, bifurcations, surge tanks, and hydraulic units for all operating points [4], control processes [5][6][7], and emergency scenarios.…”