In recent years, in the design of divided-fall hydroelectric plants with long penstocks there has been a tendency toward elimination of surge tanks, in order to reduce construction costs. In this connection, to reduce the magnitude of the water hammer to an allowable value when the loads are dropped, the closure time of the turbine control is increased; this leads in turn to an increase in the maximum value of the rotative speed of the unit. Since, in general under present-day conditions, cutting-off of a unit from a power system is not attended by operation of a hydroelectric plant with an internal load, the allowable increase in the rotational speed is determined only by the strength of the generator rotor. The current norms GOST 5616-63 stipulate that the generator rotor should be sufficiently strong for a maximum speed not less than 1.75 times the rated speed. From this condition, the closure time of the turbine control can be increased.The elimination of surge tanks leads to an increase in the travel distance of the impact wave in the penstocks, which entails an increase in the inertia of the water mass enclosed in the high-pressure stretch. This inertia is characterized by the rime constant of the inertia for the penstockin which L i and V i are, respectively, the length and velocity of the flow at different sections of the high-pressure stretch.The first experience in our country with construction of hydroelectric plants having increased values of T w and of the closure time of the turbine controls was provided by the plants in the Kuban' system. The results of tests at the first two hydroelectric plants in this system indicated that increasing the length of the penstocks does not cause an increase in the pressure pulsations in the internal passage of the turbine or a deterioration of the vibration characteristics of the unit; from this standpoint, it is entirely admissible to increase the length of the penstocks. This circumstance provided grounds for revising the norms stipulating the values of T w for design of hydroelectric plants. The current norms permit using T w = 5 sec and over [1] for hydroelectric plants whose capacity does not exceed 2~o of the capacity of the power systems; formerly, values of over 2 sec were seldom used for T w.Of great practical importance, in the light of the foregoing considerations, is an examination of the question of the effect of the value ofT w on the regulating characteristics of hydraulic units under different operating regimens. A well-known approach is Professor G. I. Krivchenko's method [2] of quantitative evaluation of the time response of variations in the output unit, according to which the time response is evaluated from the equivalent time lag At e of the output (Fig. 1). This criterion was the basis for full-scale evaluation of the regulating characteNs'tics of the units at the Kuban' hydroelectric plants.The rate ofvatiationof unit output is of great significance under emergency conditions. Let us try to establish the applicability of the above-mentioned ...

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As has been shown by many years of experience, gained from tests conducted on hydropower turbogenerators by the All-Unlon Power Engineering Association (Soyuztekhenergo), at most of the newly commissioned hydropower stations equipped with plvotlng-vane hydraulic turbines, the combinatorial function established by the manufacturing factories from model data does not correspond to the optimum relationship and, as a result, additional energy losses occur.For its refinement it is usual to derive propeller characteristics from the results of full-scale tests, during which measurements must be made of, minimally, three parameters: power, head, and discharge. In order to simplify the tests, measurements can be made of the pressure drop (which is proportional to it) at two points in the scroll casing, or the average flow velocity. The method of determirnLng the optimum combinatorial function from the turbine's propeller characteristics gained wide acceptance and is fairly comprehensively deserlbed in the technical literature and in manuals on methods [1-3].

The governor system of Kaplan turbines should provide a relationship between the runnerblade angle and opening of the gate apparatus so that a maximum turbine efficiency for a given load is obtained.The governor mechanism used for this purpose at all Soviet hydrostations provides a static relationship only between the position of the servomotors of the gate apparatus and the runner of the Kaplan turbines~The magnitude of inaccuracy of realizing the prescribed governor relationship is determined by three components:i. inaccuracy of the governor mechanism (ime); 2. inaccuracy of the drive mechanism of the gate apparatus (iga) ; 3. inaccuracy of the drive mechanism of the runner blades.In conformity with the block diagram (Fig. I), the general expression for inaccuracy of the governor system reduced to the runner-blade angle has the form:where ig s is the inaccuracy of the governor system; A, inaccuracy of manufacturing the cam of the governor system; is, inaccuracy caused by the dead zone of transmission from the servomotor of the guide apparatus 1 to the cam roller of the governor system 2; ky, coefficient of transmission of motion from servomotor 1 to roller 2; ih, inaccuracy caused by the dead zone of transmission of the system correcting the wedge of the governor system with respect to the head 3; kh, coefficient of transmission of the wedge-correcting systems with respect to the head 3; kg, coefficient of transmission from the roller of the governor system to the main slide valve or the runner 4; kfb, coefficient of transmission of feedback of the hydromechanical servo system of the runner 4, 5, 6; kr, coefficient of transmission from the servomotor of the runner to the blades; iz, inaccuracy caused by the dead zone in feedback 5 of the hydromechanical servo system of the runner; ifb is the inaccuracy caused by the dead zone in the feedback 6 of the hydromechanica! servo system of the runner; kgl, coefficient of transmission of the governor linkage, determining the relationship between the runner-blade angle and opening of the gate apparatus; iy and i~ , inaccuracies of the drive of the gate apparatus; iy and i , inaccuracies of the drive of the gate apparatus 8 and runner blades 7; kry and kr~ , coefficients of transmission between the position of the gate apparatus and runner blades and active power.The inaccuracy of the governor mechanism (ime) is represented by the expression enclosed in brackets.St consists of two components:i. inaccuracy of the profile of the cam and its drive;2. inaccuracy of the hydromechanical servo system, consisting of a slide-valve system, runner servomotor, and direct feedback.To provide the required accuracy, of the indicated quantities the variable ones are, as a rule, the coefficients of transmission from the servomotor of the gate apparatus to the roller and from the latter to the main slide valve of the runner, and also the inaccuracy caused by the dead zone of the runner servomotor i z.At hydrostations that have been operating for a long time (Narva, Kakhovka, etc.) overlaps...