Intake of the Zagorsk and Kaisiadorys pumped-storage stations

Abstract

No. 61 (1978The intakes of pumped-storage stations (PSSs) equipped with reversible units operate under complex hydraulic conditions with convergent (turbine) and divergent (pump) flow regimes in the conduit. The latter are characterized by nonuniformity of the velocity and pressure fields, increase of energy losses in the outlet with large angles of divergence, and worsening of the operating conditions of the mechanical equipment. Cases of failure of the conduit lining and bars of the trash racks are known. The hydraulic conditions in the offtake can considerably worsen in the case of a nonuniform vertical velocity distribution at its inlet (in the presence of an elbow in the transition between the intake and conduit). That is, when designing an intake-offtake a certain conflict occurs between the requirement of providing minimum losses in the compressed convergent inlet portal of the turbine intake with preservation of the standard velocities Vr ~ 1.5 m/sec at the site of the rack (the degree of constriction of the section reaches m = ~in/mcon = 5-7) and the striving to reduce losses in this same section in a pump operating regime by reducing the expansion angles of the diverging duct (the degree of expansion should not exceed m ~ 3). This conflict can be resolved either by increasing the dimensions (length) of the intake or by increasing the permissible velocities of the trash rack (decreasing the inlet area). Obviously, the problem is solved on the basis of a technical and economic comparison of variants with the use of the initial data on the energy characteristics of the intake.For the Zagorsk and Kaisiadorys PSSs equipped with large reversible units with a capacity of 200/217 MW and discharges of 226/189 mS/sec a model investigation was carried out for numerous layouts of the intakes with various dimensions (L i = 5-1ODcon, B = l-2Dcon) , angles of convergence of the inlet section ~ = 40-6 ~ and shapes and configurations of the boundaries and transition sections. Minimization of the enery loss function in turbine and pump regimes was the basis for selecting the optimal variant.The investigations showed that intake schemes with angles of total divergence 8-12 ~ correspond to minimum total losses, which radically differs from the geometry of the intakes of hydroelectric stations. Accordingly, for the Zagorsk PSS a variant of a compressed intake (Fig. i) with the following dimensions was designed: total length of intake L i = 60.15 m = 8.17Dcon; angle of total convergence (divergence) ~ = 8.1~ length of inlet section 11 = 22.2 m = 2.95Dcon; angle of convergence (divergence) of the inlet section a~ = 17.5~ angle of convergence in plan B~ = 7.2~ configuration of the upper face of the portal radially R = 4Dcon; length of the straight section Z2 = 20.15 m = 2.87Dcon; width Of the straight section b= = 7.5 m = Dcon; length of the transition from square to round Is = 15.5 m = 2.0Dcon; angle of convergence (divergence) of the transition ~3 = 4 ~ A special feature of the design of the intake is an overhanging portal ...