Reconstruction and refit of the UST’-Khantaiskaya HPP

Abstract

In November 2005 the Ust’-Khantaiskaya hydropower plant, which is one of the world’s northernmost ones, celebrated 35 years since the beginning of commercial operation. The Ust’-Khantaiskaya HPP was built in a record-short term even for that time (1963 – 1976) and commissioned with the following parameters: installed capacity 441 MW, mean annual output 2.032 billion kW · h, hydraulic turbines PL5a-VM-410, hydrogenerators SV 780 137-32. The Ust’-Khantaiskaya HPP, together with the Kureya HPP, covers over 40% of the demand of the “Norilskenergo” power system, where the main consumer is the Norilsk Mining Company, and also performs the functions of emergency and frequency backup and frequency control. In addition, the Ust’-Khantaiskaya and Kureyskaya HPP supply electric power to the nearest settlements and the town of Igarka. The output of the Ust’-Khantaiskaya HPP covers 20% of the total power consumption in the region. The TE-NE power center has no electric links with the UPS of Siberia, from which it is removed by 1500 km. Such links will be absent in the foreseeable future. Due to the absence of operating conditions of a synchronous condenser, the units of the Ust’-Khantaiskaya HPP serve for up to 20% of the time with deviations from the design conditions at reduced efficiency. The hydraulic turbines of type PL-60 5a-V-410 produced by the Syzran Turbine Plant were mounted in 1970 – 1972. The flow-thorough part of a turbine at the Ust’-Khantaiskaya HPP with runner PL5a is designed so that the blades of the distributor are located at a shorter distance with respect to the runner than it is required today. The closeness of the runner to the distributor is responsible for the fact that the nonuniformity of the flow from the distributor is transferred to the vane system of the runner causing dynamic stresses of vane frequency (75 Hz) in the vanes [1]. It can be seen from Table 1 and Fig. 1 that maximum vibrations arise in the optimum (with respect to the power) zone of operation of the unit (Pu = 50 – 60 MW). Dynamic loads of vane frequency are the main cause of accumulation of fatigue in the metal of the vanes and of the kinematics of the runner and have repeatedly caused failures at units equipped with runners of type PL5a. For this reason fracture (separations, cracks) of the peripheral tip of runner vanes occurred in the initial period of operation of the turbines. In 1973 – 1974 the peripheral tips of the vanes were trimmed, which resulted in further decrease in the efficiency of the turbines. However, in 1979 vane No. 3 of unit 2G failed (half of the vane broke from the root section over diagonal to the exit tip). The vane was replaced. Analysis of the damage of main assemblies of the hydraulic turbines of the Ust’-Khantaiskaya HPP (Table 2) in the entire period of operation shows that breakage of exit tips of vanes was accompanied by damage inevitably appearing Power Technology and Engineering Vol. 39, No. 6, 2005