The main positive effects on the use of electrical machines with a variable rotation frequency are considered using the example of the Zagorsk pumped-storage power plant. It is shown that the possibility of regulating the electric active power, both in the generator and the pump modes, makes the power plant with asynchronous generator-motors more effective compared with units with synchronous generator-motors and enables it to provide services with normalized primary frequency regulation.Progress in the field of high-powered electronic devices has enabled highly reliable frequency converters to be produced. This, in combination with the development of microprocessor regulation and control devices, construction methods, and the use of new materials and technologies in electrical machines, has enabled electrical machines operating with variable rotation frequency to be designed.Of the variety of electrical machines operating with a variable rotation frequency, the most economical technical designs for a change in the rotation frequency not exceeding ±10% synchronous, is the asynchronous machine [1].The essential advantages of such hydroelectric apparatus with respect to economy, reliability, and controllability compared with hydromachines operating at a constant rotation frequency have been confirmed theoretically and experimentally.For the Russian hydropower system, the use of aggregates with asynchronous machines is important both for reconstructing existing power plants and constructing new ones [2].In this paper we investigate the possibility of pumped storage power plants with asynchronous generator-motors participating in normalized primary frequency regulation.The participation of a pumped-storage power plant with asynchronous generator-motors in normalized primary frequency regulation is considered, taking into account the operating conditions at the Zagorsk pumped-storage power plant when the synchronous generator-motor is replaced by an asynchronous one.The choice of the Zagorsk power plant as the example is governed by the fact that this power plant, practically unique in Russia, has characteristics that are available in the open literature, and in which, in the near future, will have its equipment modernized.The characteristics of the Zagorsk hydroelectric apparatus when operating with a variable rotation frequency. The universal characteristics of hydroelectric equipment operating with turbines and its working characteristic in the pump mode at a rotation frequency of 150 rpm are given in [3,4]. The diameter of the turbine D = 6.3 m, the nominal power in the turbine mode N T = 205 MW, and the nominal power in the pump mode N p = 217 MW.The net pressure heads in the turbine mode are: maximum -111 m, calculated -100 m, and minimum -91 m.The working pressure heads in the pump mode are as follows: maximum -115 m, average -105 m, and minimum -96 m.The rotation frequency n s = 250 rpm is synchronous for apparatus with synchronous generator-motors.
The possibility of using asynchronized machines, operating with a variable rotor rotation frequency, as counter-emergency control and high-speed regulation of the active power, is shown. The problems involved in using asynchronized machines to increase the active power and frequency regulation quality, and also to improve the dynamic characteristic of power systems, are considered.The use in power plants of units operating with an adjustable rotation frequency, based on asynchronized generators, proposed by the power systems of the USSR [1], has been widely used during the past few years by a number of foreign companies and power-supply enterprises [2,3].The main effect of the use of such units is an increase in the efficiency as a result of operating at an adjustable rotation frequency with a variable pressure. Moreover, the vibration is reduced and the units themselves can be employed for high-speed regulation of the active power, which enables the quality of the frequency regulation in the power system to be increased, as is confirmed by successful experience in using an asynchronized compensator with a flywheel on the shaft in Japan [4].The property of an asynchronized machine of rapidly adjusting the distributed or consumed active power is an urgent one for Russian power systems in both hydroelectric and thermal power plants. In this paper we investigate the possibilities of asynchronized machines for counter-emergency control and frequency regulation in a power system.Asynchronized electrical machines differ from synchronous machines in the fact that they have a two-phase or three-phase excitation winding (Fig. 1). A multiphase excitation winding enables "vector" control of the excitation current by an asynchronized method to be achieved, i.e., one can control the reactive and active powers separately. In this way, not only is the control quality increased, but it also becomes possible to regulate the active power of the machine as rapidly as the reactive power.In an asynchronized machine with a symmetrical winding on the loaded rotor it is possible to regulate the rotation frequency. The excitation system then supplies the rotor winding with an adjustable current. The power of the excitation system is proportional to the maximum slippage of the rotor.In a synchronous generator, the active power delivered to the network can only be adjusted by regulating the turbine power. For a synchronous hydrogenerator the rate of adjustment of the electric active power is determined by the rate of control of the adjusting apparatus of the turbine.In an asynchronized machine, due to the particular features of the construction, the asynchronized-machine principle for controlling and exciting the adjustable current provides the possibility of controlling the electric active power independently of the turbine power, and independently of the mechanical power on the shaft. The active power delivered to the circuit or consumed from the circuit is regulated practically instantaneously. A change in the electromagnetic power of t...
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