SU1245723A1 - Method of controlling turbine at load drops - Google Patents

Description

The invention relates to a power system and can be used to automate the control of steam turbines.

The purpose of the invention is to increase the durability of the turbine by reducing the operating time with an increased rotational speed,

The drawing shows a block diagram of a system for implementing the proposed method of controlling a turbine during load shedding.

The block diagram contains a rotor speed sensor 1, a generator disconnection sensor 2 from the mains and a maximum signal block 3 connected to the first input of the first switch 4 connected to the input of an electro-hydraulic converter 5 spool 6 of the servomotor 7 control valves 8, and the load dump sensor 2 connected to the second input of the first switch 4, and the output of the spool 6 through the first threshold element 9 is connected with the servo motor 10 shut-off valves 11 located behind the separator-superheater 12 of the turbine 13.h

The system also contains a proportional-integral controller 14, a forcing signal unit 15, a second switch 16, a second and third threshold elements 17 and 18, and a switch 1-9, the first input of which is connected to the output of the second threshold element 17, the second input is connected to the output of the third threshold element 18, the first output connected to the controller 14, and the second to the block 15 of the forcing signal associated with the input of the electro-hydraulic converter 5. The output of the third threshold element 18 is also connected to the third input of the first off body 4, and sensor 2 disconnecting the generator from the network is further connected to a second switch 16 that binds one sensor dscheni BE frequency to the inputs of the second and third threshold elements 17 and 18.

Block 3 generates a maximum control signal with an amplitude corresponding to the maximum possible speed of movement of control valves 8 (approximately three units of the degree of irregularity), and block 15 forms a forcing control signal with an amplitude equal to one unit of the degree of unevenness of the frequency-power characteristic. The decrease in the amplitude of the forcing signal in comparison with the amplitude of the maximum signal is due to a decrease in

torque on the rotor after closing the control valves, but this amplitude must be large enough to prevent the occurrence of an increased rotational frequency during its subsequent oscillations.

The threshold elements 17 and 18 form control signals when the input signal reaches the limit levels. The threshold element 9 generates signals for the opening of the servomotor 10 when the threshold value is exceeded by the input signal and the closure of the servomotor 10 when the input signal is below the threshold value.

The method is carried out as follows.

When the generator is disconnected from the network, sensor 2, acting on the first switch 4, connects the maxi-block,

signal to the electro-hydraulic converter 5 and, acting on the second switch 16, connects the speed sensor 1 to the second and third threshold elements 17 and 18.

The control signal of unit 3 by means of an electro-hydraulic converter 5, spool 6 and servo motor 7 causes the control valves 8 to close as quickly as possible. At this position, spool 6 changes. Since the input signal of threshold element 9 does not exceed the threshold value and the signal of threshold element 9 by the servomotor 10 5 causes the closing of the shut-off valves 11,

When the frequency of rotation of the turbine rotor 13 after the first casting reaches the lower limit level, for example, 98% of the nominal level, the third threshold element 18, acting on the first switch 4, turns off the maximum signal block 3 from the input of the electro-hydraulic converter 5 of the spool 6 and, acting on the switch 19, connects the regulator 14 to the on-go electro-hydraulic converter 5. The regulator 14 stabilizes the rotor speed at the nominal level. At that, the spool 6 reaches a position above the threshold value at which the first threshold element 9 forms. On the servomotor 10 of the shut-off valves 11, the control signal for opening the shut-off valves 11. When opening the shut-off valves 11, the steam from the separator-steam superheater 12 enters the turbine 13 , which leads to a secondary casting of the rotor speed. When the rotation frequency reaches the lower upper limit of the rotor speed, for example, equal to 103% of the nominal level, the second threshold element 17, acting on the switch 19, disconnects the regulator 14 from the input of the electro-hydraulic converter 5 and connects the forcing signal block 15 to the electro-hydraulic input -. razovatel. The control forcing signal, the amplitude of which is equal to one unit of the degree of unevenness, from block 15 through electro-hydraulic converter 5, spool 6 and servomotor 7 is fed to the regulator

Editor N. Margolin

Compiled by A. Kalashnikov Tehred L. Oleinik

Order 3972/23 Circulation 500 Subscription

VNIIPI State Committee. the USSR

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, Projecto st., 4

The shut-off valves 8 and closes them. In this case, the shut-off valves 11 are also closed. When the frequency of rotation of the turbine rotor after the second casting reaches the upper limit, the third threshold element, acting on the switch 19, turns off the forcing signal block 15 and connects the proportional-integral regulator to the input of the electro-hydraulic converter.

Then the adjustment process is repeated until after the next commissioning of the regulator 14, the rotor speed reaches the upper limit level and, therefore, the shut-off valves 11 are not closed. In this case, the controller 14 stabilizes the rotational speed at the nominal level, which allows, if necessary, to resynchronize and turn on the generator in the network.

Proofreader M.Sharoshi

Claims (1)

METHOD OF TURBINE REGULATION AT LOAD RESET by generating the maximum signal, applying it to the spool of the servo motor of the turbine control valves, continuously measuring the rotational speed po of the rotational speed at the nominal level using the proportional-integral controller and closing (opening) the shut-off valves of the turbine when the spool position is lower (above) ) a threshold value, characterized in that, in order to increase the durability of the turbine by reducing the operating time with an increased speed, additionally They form the boost signal, the upper and lower limit levels of the rotational speed, and stabilization of the rotational speed at the nominal level is carried out by alternately applying a boost signal to the spool, when the lower limit level of the rotational speed is reached from below, and the signal of the proportional-integral controller, when its lower limit level is reached above . torus, turning off the maximum signal when the speed reaches a preset value, stabilization 1245723 ΑΊ 1245723 2