SU914778A1 - Method of protecting turbomachine at load drop - Google Patents

Description

The invention relates to a power system and can be used to automate the process of protecting turbomachines from an unacceptable increase in the frequency of rotation of the rotor.

Known methods of protection of the turbomachine during load shedding by measuring the speed and acceleration of the rotor, the formation of protective signals with an unacceptable increase in these values and the operation of protective bodies in the presence of simultaneously generated signals GO.

However, in these methods, to close the stop valves, it is sufficiently unacceptable to increase the speed of the rotor, which does not prevent false closures during oscillations in the power system.

The closest to the invention to the technical essence is a way to protect the turbomachine during load shedding by measuring the speed and acceleration of the rotor, forming

2

protective signals with an unacceptable increase in these values and closing of the stop valves in the presence of all the generated protective signals simultaneously [2].

The disadvantage of this method is the relatively high verb *., The possibility of falsely closing the valves when swinging in the power system ..

The purpose of the invention is to reduce the likelihood of false closing of valves during oscillations in the power system.

To achieve this goal, according to the method, the magnitude of the acceleration gradient of the rotor is additionally measured, and if it does not exceed the specified value, an additional protective signal is generated.

The drawing shows a block diagram of a device that implements the proposed method.

In the device containing the sensor

1 speed turbomachine rotor, differentiator 2, logic elements

3

914778

four

3 and 4, the conjunction element 5, the shut-off valve closing switch 6, additionally installed a block 7 of generating a signal that the acceleration gradient 5 does not exceed the threshold value. Unit 7 consists, for example, of pulse element 8, delay element 9 of subtraction element 10, latch 1.1 of zero order and logic element 12. · 0

The method is as follows.

The signals from the rotor speed sensor 1 directly ^ feed the logic element 3, which forms a protective signal that the speed setpoint is exceeded to the first input of the conjunction element 5 and through differentiator 2 to logic element 4, which forms a protective signal about exceeding the specified value of the acceleration to the second input of the element 5 of the conjunction; With the help of block 7, a signal is continuously generated that the threshold value of the acceleration gradient does not exceed 25. To this end, the magnitude of the acceleration gradient is continuously measured by converting the continuous signal of differentiator 2 into a discrete pulse element in te-8, the signal from the output of which is fed to the subtraction element 10 directly and through the delay element 9, and the output discrete signal of the subtraction element 10 is converted into ₃₅ non-continuous in latch 11 poryadka.Velichinu zero gradient is compared with a threshold in the logic element 12 ,. the input of which is fed to the output signal of the latch up to 11, on the basis of which, additionally, a protective signal is formed that the threshold value is not exceeded, and is fed from the output of the logic element 12 to the third input of the element 5 conjunct '45th. In the presence of the three-named signals at the inputs of the element 5 of the conjunction from the output of the element 5, the control signal is supplied to the switch 6 for closing the stop valves.

So more completely exclude - false closing of valves during oscillations in the power system, since continuous analysis of the magnitude of the acceleration gradient makes it possible to use an additional feature of load shedding, namely: the magnitude of the acceleration gradient for a certain time interval during load shedding is always less than a predetermined threshold value.

In addition, the proposed method simplifies the physical implementation of the corresponding device in comparison with the known, since there is no need to choose the setting of the relay element and its changes in the regulatory process.

Claims (1)

Claim method of protection of a turbomachine when load shedding by measuring the speed and acceleration of the rotor, generating protective signals with an unacceptable increase in these quantities and closing the stop valves with all the protective signals that are simultaneously formed, characterized in that, in order to reduce the likelihood of false closing of the valves during oscillations in the power system, the gradient is additionally measured acceleration of the rotor, and if it does not exceed the specified value form an additional protective signal.