RU2362031C2 - Electric starter for starting-up gas turbine installations - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering and particularly to electric starters for starting up gas turbine installations, used in gas pumping units and electric power plants. The output of the device for connecting the said electric starter, containing a one-way action coupling clutch, reducing gear, asynchronous motor, connected to a power supply through a frequency converter, equipped with a device for measuring rotational speed of the electric starter, is connected to the control input of the frequency converter, which sets the moment of the electric starter, through a regenerative integrator and an adder. The output of the device for measuring rotational speed of the electric starter is connected to the second input of the adder through an inverter and a threshold device. The third input of the adder is connected to the second output of the device for connecting the electric starter. The electric starter provides for smooth engagement with the one-way action coupling clutch and prevents transmission overloading.

EFFECT: obtaining smoothly changing torque of the electric starter in accordance with the start-up mode of the rotor of the gas turbine installation.

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Description

The invention relates to the field of electrical engineering, in particular to electric starters for starting gas turbine plants used in gas pumping units and power plants.

Gas turbine engines have a large moment of inertia of the turbine rotor (up to 30 kg · m ² ), so their spin-up time at startup reaches 100 s or more. When turned on, well-known electric starters develop a rapidly increasing starting torque, which in magnitude can exceed the moment necessary to spin the gas turbine installation, which leads to shock in the single-acting cam coupling of the starter at the beginning of movement during engagement and during the process of spinning of the gas turbine engine and entails failure transmissions. At the same time, the moment developed by the electric starter becomes excessive at the end of the spin-up, when the gas turbine installation begins to enter the operating mode, which leads to overloading the transmission and overheating of the starter and gearbox.

Thus, a direct current electric starter for starting an aircraft gas turbine installation [1], comprising a single-acting cam clutch, a gearbox, a motor device made on a collector electric motor, and a starter switching device, does not provide shockless turning on and spinning of the rotor of a gas turbine installation, has low reliability and low power, which does not ensure the launch of gas turbine units of high power.

In an electric starter [2] containing a single-acting cam clutch, a gearbox, a motor device made on an asynchronous electric motor connected to the mains through a frequency converter equipped with an electric starter speed meter, and an electric starter engaging device, shock is also observed in the one-way cam clutch actions during coupling and in the process of spinning a gas turbine plant.

The task is to ensure shock-free engagement of a single-acting cam clutch and to prevent transmission overload.

The technical result, to which the invention is directed, consists in obtaining a smoothly varying torque of the electric starter in accordance with the spin mode of the gas turbine installation.

The required properties are possessed by an electric starter containing a single-acting cam clutch, a gearbox, an asynchronous electric motor connected to the power buses via a frequency converter equipped with an electric starter speed meter, and an electric starter switch device, characterized in that the first output of the electric starter switch device is connected to the control input of the converter frequency setting the moment of electric starter, through the integrator with positive feedback and the adder, while m the output of the speed meter of the electric starter is connected to the second input of the adder through an inverter and a threshold device. If you need to set an additional level of torque, the second output of the electric starter switch is connected to the third input of the adder.

Figure 1 presents the electric starter of a gas turbine installation. One-way cam coupling 1 through a reducer 2 is connected to an asynchronous electric motor 3, which is connected via a converter 4 to three-phase alternating current power supply buses with voltage of 380 V and a frequency of 50 Hz. The first output "a" of the starting device of the electric starter 5 is connected through an integrator with positive feedback 6 and the adder 7 at the input "b" with the control input of the frequency converter 4, which determines the rotation time of the electric starter. The output of the speed meter of the electric starter of the converter 4 through the inverter 8 and the threshold device 9 is connected to the second input "c" of the adder 7, and the third input "d" of the adder 7 is connected to the second output "e" of the starter switch 5, which sets the additional moment of the electric starter.

Figure 2 presents the plot of the signals at the inputs of the adder 7:

U _b - voltage at the first input "b" generated by the integrator 6;

U _{with the} voltage at the second input "s" generated by the threshold device 9;

U _d is the voltage at the third input "d" supplied from the output "e" of the switching device 5.

Figure 3 presents:

U is the voltage of the signal specifying the rotation moment of the starter and coming from the output of the adder 7 to the control input of the converter 4;

M - torque developed by an electric starter;

N is the speed of the electric starter.

Electric starter works as follows.

In the initial state, the device for starting the electric starter 5 does not give signals. The electric motor 3 does not rotate, the movement through the gearbox 2 is not transmitted, the cam clutch 1 is disengaged and the rotor of the gas turbine installation is not untwisted.

When the electric starter is turned on, the switching device 5 provides a signal from the first output “a” to the integrator with positive feedback 6, which at its output generates the signal U _b shown in FIG. 2, which is supplied to the first input “b” of the adder 7. In this case, U _b (0) = 0. At the second input “c” of the adder 7, the signal U _c coming from the output of the threshold device 9 is equal to zero, as shown in FIG. 2, since the electric motor 3 does not rotate yet and the signal at the output of the electric starter speed meter located in the converter 4 is equal to zero, which, in turn, provides a zero signal at the output of the inverter 8. At the third input “d” of the adder 7, the zero voltage level of the signal U _{d is} provided by the signal from the output “e” of the starter switch 5. Therefore, initially, the input control moment q converter 4 receives a zero signal U, U (0) = 0, as shown in figure 3, and the motor does not generate torque. Over time, the integrator 6 begins to smoothly increase the signal voltage U _b (see figure 2) at the first input "b" of the adder 7, from the output of which a smoothly increasing signal U will also arrive at the input of the converter 4 (see figure 3 ) The Converter 4 slowly increases the frequency and magnitude of the voltage supplied to the electric motor 3, and the torque M (see FIG. 3) begins to increase smoothly and the electric motor also smoothly starts to increase the speed N (see FIG. 3), transmitting movement through the gear 2 on a single-acting cam coupling 1. Clutch 1 selects free play, its cams engage and the starter starts spinning the rotor of the gas turbine installation. Thus, the smoothness of the rise of the torque signal U, and hence the torque developed by the electric starter, excludes knocks during the clutch of the single-acting cam clutch and excludes transmission failure. Further, the intensity of the voltage increase of the signal U _b (see figure 2) at the output of the integrator 6 increases due to positive feedback and by about 5 seconds its value becomes maximally preset and remains constant, respectively, the starter motor spins the rotor of the gas turbine installation with constant torque , which eliminates the fluctuation of the cams of the coupling 1 and knocks in the process of promotion.

As the electric starter spins up, the signal at the output of the electric starter frequency meter by the frequency converter 4 increases linearly, is inverted by the inverter 8, and when the threshold value is reached, the signal U _s starts to arrive at the second input “c” of the adder 7 (see Fig. 2), subtracted from the signal U _b at the first input. This occurs at approximately 70 seconds of spinning of the turbine rotor. At the output of the adder 7, the signal U arriving at the input of the converter 4 specifying the rotation moment of the starter will decrease, and therefore, the moment M developed by the electric starter will decrease with increasing frequency (see Fig. 3). The electric starter will work with constant power at the output link, which eliminates the overload of the transmission.

In the case when it is necessary to increase the torque of the electric starter, for example, at the moment of fuel supply at the start of the gas turbine installation, the starter switch 5 from the output "e" gives a signal U _d (see figure 2) to the third input "d" of the adder 7 and its output, the driving moment of rotation of the electric starter, the signal U arriving at the input of the converter 4 increases, and the starter with an increased moment M will spin the rotor of the gas turbine installation. In Fig. 3, changes in the signals U and M in this case are shown by dashed lines.

After spinning the rotor of the gas turbine installation, the switching device 5 removes the output signals and the electric starter returns to its original state.

Thus, a smooth change in the torque of the electric starter is achieved in accordance with the spin mode of the gas turbine installation, which provides shock-free engagement of the single-acting cam clutch and eliminates transmission overload.

Industrial implementation of electric starter. Asynchronous motor 3 is performed at a speed 8 times higher than the frequency of the industrial network, and the converter is driven at a frequency of the output voltage of 400 Hz, which provides an increase in the energy output of the starter motor by more than 10 times. So, for example, an electric starter with a built-in asynchronous electric motor 5AVCHKr160V4, IM5010 with an axis height of 160 mm, having a mass of 140 kg, develops a power of 240 kW instead of 18.5 kW. The electric motor is manufactured by VEMZ OJSC, Vladimir.

The electric starter used a frequency converter with magnetic field vector control IE-9011 series, manufactured by Vesper, Moscow.

The integrator 6, adder 7, inverter 8 and threshold device 9 are built on operational amplifiers, but can also be implemented on digital microcontrollers.

The starter switch 5 is implemented on electromagnetic relays that give signals to turn on the electric starter and remove them in time or in the rotational speed of the rotor of the gas turbine plant. The starter switching device can also be implemented on contactless elements of microelectronics.

Positive feedback of the integrator 6 can be performed in various ways, in the described electric starter it is connected to the output of the adder 7, the signal from which sets the magnitude of the moment developed by the electric starter.

Information sources

1. Starter-generator STG-12TMV // Technical description, technical operation manual. - Kirov, - OJSC "Electric Drive", - 1964.

2. Volokitina EV, Nikitin VV, Noskov N.V., Shalaginov V.F. Electric starter for starting gas turbine units // Electronics and electrical equipment of transport. - 2005. - No. 5. - p. 39-42.

Claims (2)

1. An electric starter for starting a gas turbine installation, comprising a single-acting cam clutch, a gearbox, an asynchronous electric motor connected to the power supply via a frequency converter equipped with an electric starter speed meter, and an electric starter switching device, characterized in that the output of the electric starter switching device is connected to the control the input of the frequency converter that sets the moment of the electric starter, through the integrator with positive feedback and the adder, while the output of the speed meter of the electric starter is connected to the second input of the adder through an inverter and a threshold device. 2. The electric starter according to claim 1, characterized in that the third input of the adder is connected to the second output of the device for switching on the electric starter.

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