Automatic Control System for Hydroelectric Power Stations

a complex system which automatically determines the optimum number of connected generating units in a multiunit hydroelectric station, for the purpose of attaining maximum efficiency in the entire hydroelectric power station.

Factors taken into account include the characteristics of the generating units and of the pressure head, the duration of operation of each generator, the scheme of primary commutation of the hydroelectric station and the various limitations imposed by cavitation zones of the generating units, and equipment conditions, which in turn determine the starting or stopping sequence of the generating units. In hydroelectric stations which do not have water reservoirs, the action of the automatic control system is based on the flow of water. Basically, two types of automatic control systems are used which differ in the form or the presentation of information: analog and digital.

In an automatic control system of the analog type, the characteristics of the generating units are fed in by means of nonlinear elements. Such an automatic control system for hydroelectric power stations consists of the central control unit, the unit for determining the starting (stopping) sequence of the generators, the pressure head unit, and the power sensors and water flow sensors. The basic disadvantages of an analog automatic control system are low accuracy in determining characteristics and the fact that the selection of the starting sequence of the generators is done by the operator. Furthermore, an analog automatic control system does not take into account the duration of operation of each generator. The advantages of an analog automatic control system are its simplicity, high reliability, and low cost. The first automatic control systems of the analog type were installed in hydroelectric power stations during the 1950’s—for example, the automatic control system for the Tsimliansk Hydroelectric Power Station.

In an automatic control system of the digital type, which includes a digital computer, the characteristics of the generators and other data utilized for its operation are loaded into the program and stored in the machine’s memory bank. Such an automatic control system not only takes into account a large number of factors which determine the operating conditions of the hydroelectric power station but also makes it possible to collect and evaluate statistical information, which prevents the short-term operation of connected generators due to power oscillations in an electrical energy system. The advantages of digital automatic control systems indicate promise for their use not only in solving problems of automatic control of the modes of operation of high-capacity, multiunit hydroelectric power plants, but also (in solving a large number of systems problems) in combination with control devices installed at the central control stations of power systems and grids.