RU2298653C2 - Method to control speed of turbine connected by generator to power supply system (versions) and device for implementing the method (versions) - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention is designed to control speed of turbine. According to proposed method, high speeds of load changes in operation of turbine are detected, then at least one valve of turbine is throttled for a short time and turbine speed is controlled relative to new working load after change of load. Device for implementing the method contains actuating unit for short time throttling of at least one valve of turbine and computer unit to control speed of rotation after change of load by means of which at least two operating signals for setting turbine valve can be formed. First operating signal serves to open turbine valve and second one, to close turbine valve.

EFFECT: improved reliability of power supply.

21 cl, 2 dwg

Description

The invention relates to a method, as well as to a device for controlling the speed of a turbine.

The present invention relates to the technical field of regulating non-electric quantities, in particular to devices for controlling the speed of a turbine, and is intended to prevent emergency situations in power systems.

The electric power supply network for supplying electric energy to a large territory is formed in most cases by combining many power plants into a single system so that in case of high demand for power from consumers connected to the power supply network, the supply of electric energy is provided without an emergency failure of the power supply network due to overload.

Further, such an electric power supply network can also fail, for example, due to short circuits in one or many sections of the power supply network, since high short-circuit currents that appear, in particular, during such short circuits, could overload power plants connected to the power supply network.

In such emergency situations, in most cases it is necessary to disconnect at least part of the consumers and / or some of the supply lines of the electric power supply network in order to prevent the complete failure of the power supply network.

In many emergency cases at one or many power plants, the power supply networks, for safety reasons, in most cases, the turbines are automatically disconnected from the power supply network and, therefore, out of sync, in particular, to prevent the rotational speeds that are established after a sudden discharge and, under certain circumstances, do not decay higher nominal (= turbine spacing). Each shutdown of the turbine means a loss of electrical power, which can be instantly provided by the power supply network.

The more power plants and the more powerful power plants are combined into a power supply network, the higher the reliability of the power supply network, as individual malfunctions are unlikely to lead to disconnection of turbines from the power supply network.

In contrast, the above-mentioned malfunctions in less-connected power supply networks, in which only a small number of power plants are integrated into a single system, lead to frequent failures of such a power supply network, or at least its parts.

A known method is to stabilize the mode of operation of a turbogenerator in emergency situations (patent RU No. 20166460, class H02J 3/24, 1991), which is based on measuring the difference in power of the turbine and generator and on the formation of signals that affect the change in the load of the turbine.

This method does not provide sufficient control accuracy.

Closest to the proposed method is a method of protecting steam turbines from emergency situations, which consists in measuring controlled values, comparing them with a predetermined set value and generating a signal that acts on the actuator unit, as well as a protection system that contains a measuring device, a comparison device and an executive unit (patent RU No. 2062330, class F01D 21/02, 1996).

This method and this device can be considered as the closest prior art (prototype) for the present invention.

The known method of protecting steam turbines, as well as the known protection system, have limited functionality, since they do not take into account the speed at which the controlled value changes, which can lead to a decrease in the reliability of protection.

The invention is therefore based on the task of providing a method and apparatus for controlling a rotational speed of a turbine connected by means of a generator to an electric power supply network, which provide particularly high reliability of power supply.

The problem is solved in that the method of controlling the speed of a turbine connected to an electric power supply network by means of a generator, according to the invention, comprises the following operations:

during the operation of the turbine, it is continuously determined whether there is a change in the load of the turbine;

if a change in load is detected, then the rate of this load change is determined,

if the rate of change of the load modulo is greater than the predetermined maximum rate of change of the load, and the load changes in the direction of a lower load, then through the actuating action, at least one turbine valve is actuated for a short time in the direction of its closed position and wherein at least one turbine valve is briefly closed; and

the turbine speed relative to the current working load, which is obtained after the load changes, is regulated by means of a regulating action on at least one turbine valve.

By the method according to the invention, it must in particular be prevented that a load shedding during operation of the turbine, in particular, a sudden partial load shedding due to a failure of the electric power supply network, leads to a desynchronization and thereby to a complete load shedding and a quick shutdown of the turbine.

In the method according to the invention, therefore, it is provided that during the operation of the turbine it is possible to register possible load changes and the resulting load change rates and if the load change rate is too high during partial load shedding, quickly act on the turbine valve and briefly throttle it, if necessary, close it completely briefly .

This prevents dangerous turbine desynchronization, which threatens, in particular, after a sudden partial load shedding, to establish a mode of operation with a speed higher than the nominal one. Short-term throttling of the turbine valve prevents dangerous turbine spacing by reducing the flow of fluid to the turbine. The turbine valve may be, for example, a fresh steam valve of the turbine, by means of which the working steam generated by the steam generator is supplied to the turbine.

After briefly throttling the turbine valve, the turbine speed can then be adjusted, respectively, in the new operating situation after the load is relieved, for example, by means of a turbine regulator that acts on at least one turbine valve.

The implementation of the method with short-term closing by means of the actuating action of at least one turbine valve and short-term throttling of the turbine valve is the most optimal and therefore effectively counteracts, in particular, partial load shedding with a very high rate of change. By means of this embodiment, therefore, it is possible to cope especially well with turbine operation cases in which a very fast and very large partial load shedding takes place.

In a particularly preferred embodiment of the invention, the at least one valve of the turbine is controlled by at least two actuating signals, the actuating in the direction of the opening position being achieved by means of the first actuating signal from the at least two actuating signals a turbine valve, and by means of a second actuating signal from at least two actuating signals, actuation in the closed position direction is achieved thia valve turbine.

The use of two separate actuating signals for actuating at least one turbine valve gives the advantage of increased installation accuracy. In this way, a turbine speed control, for example, can be carried out especially precisely, for example by means of a turbine regulator.

Preferably, the actuating signals comprise electric current output data, in particular a current strength in the range of 0-20 mA, and accordingly the current outputted electric current strength is a measure for the degree of opening or closing of the turbine valve.

In this embodiment, the turbine valve is controlled by two current signals as actuating signals, the entire opening or closing range of the turbine valve being covered by a current range of 0-20 mA.

There are a number of suitable blocks for diverting such current signals. Typically, current signals are provided to a signal amplifier unit, which then provides the necessary power signal to drive a turbine valve.

Preferably, the method according to the invention is carried out by means of a cyclically operating digital computing device, in particular a programmed control means from a memory device.

Such computing devices are available in various forms of execution and, due to their modular design, can be easily adapted to implement the method of the invention.

The problem is also solved using an embodiment of another method corresponding to the invention.

To this end, in the method for controlling the rotational speed of a turbine shaft connected by means of a generator to an electric power supply network, which is based on measuring the rotational speed, comparing it with the nominal rotational speed and generating a control signal based on the comparison results, according to the invention, the value and also the direction where the measured speed deviates from the nominal speed, measure and continuously calculate the rate of change of the rotational speed of the turbine shaft, and It compares with a given value; when exceeding the limit value previously established relative to the speed of changing the rotational speed, a control signal is generated to change the position of the turbine valve; in this case, two control signals are generated per turbine valve, one of which changes the position of the turbine valve in the "open" direction, and the other in the "closed" direction.

It is possible for the control signal to change the position of at least one turbine valve.

Moreover, the generated control signal and the speed at which the rotational speed of the turbine shaft changes are proportional to each other, and this is a current strength of 0 to 20 mA, which determines the degree of opening or closing of at least one turbine valve for setting the turbine speed at rated load.

You can also generate a digital control signal, which provides work with digital machinery.

The problem is also solved in that the device for controlling the speed of a turbine connected by means of a generator to an electric power supply network, according to the invention, comprises a sensor unit by means of which a change in the load of the turbine is detected, a computing unit by which the speed of the detected change in load is calculated, an execution unit by which, in the case of a rate of change of load in the direction of a lower load, which is modulo greater than the predetermined maximum load change rate is at least one turbine valve momentarily actuated in the direction of its closing position, and at least one turbine valve is momentarily closed; and a computing unit, by which at least two actuating signals for setting at least one turbine valve are generated, wherein, by means of the first actuating signal from at least two actuating signals, actuation in the direction of the valve opening position is provided the turbine and by means of a second actuating signal from the at least two actuating signals, actuation in the direction of the closing position of the turbine valve is provided.

In the device according to the invention, by means of an actuating unit, in case of a too high load change rate, for example, due to a sudden partial load shedding, directly throttle, if necessary, even shut off at least one turbine valve briefly so that threatening unsynchronization and / or quick shutdown of the turbine.

In order to be able to reliably control the speed of the turbine after changing the load through the computing unit, two actuating signals are provided for actuating at least one turbine valve, the first of these at least two actuating signals acts only in the direction of the turbine valve opening position and the second of these at least two actuating signals acts only in the direction of the closing position of the turbine valve. Thus, the position of the turbine valve during operation of the turbine is particularly well controlled. To generate the said executive signals in the computing unit, for example, a turbine control program can be implemented, and by means of the executive signals, the speed of the turbine is adjusted to the desired speed value.

In a preferred embodiment, the actuating signals comprise electric current output, in particular a current in the range of 0-20 mA, the current output electric current correspondingly being a measure of the degree of opening or closing of the turbine valve.

Especially preferred is the implementation of the device in the form of control with programming from the memory.

The solution to this problem is also provided in an embodiment of a device for controlling the speed of a turbine connected by means of a generator to a power supply network, comprising a signal receiving unit proportional to the power of the generator and a signal of a limit value of the rotational speed of the turbine shaft, the outputs of which are connected to a control signal generating unit, which has two outputs: an output for the current speed, and an output for the current speed, the value of which lies in the preset a specified range of speed in which, according to the invention, a processor is integrated that generates a signal at the outputs when the nominal value of the rotational speed changes temporarily and a signal when the specified value is exceeded relative to the maximum temporary rotational speed change, connected to the input of the control signal generating unit, the second input of which is connected to setpoint sensor for the permissible speed of change of the turbine shaft rotation frequency and the outputs of which are connected to the valve control inputs turbine, one of which acts on the turbine valve in the "open" position and the other in the direction of "closed".

Preferably, the control signal generating unit is executed with a current output at which the current values and the rate of change of the rotational speed of the turbine shaft are proportional to each other.

No less preferably, the control signal generating unit is implemented as a programmable control unit.

In the following, two exemplary embodiments of the invention are presented in more detail.

At the same time, they show:

figure 1 - a device according to the invention for regulating the speed of a turbine, and

figure 2 is another device according to the invention.

Figure 1 shows, according to the invention, a device 1 for controlling the speed of a turbine 3 connected by means of a generator 5 to an electric power supply network.

The device 1 according to the invention comprises a sensor unit 7, which for detecting changes in the load of the turbine, for example, is connected to the device 25 of the turbine control technology and receives from it the current operating parameters of the turbine.

In the case of a detected change in the load of the turbine, the computing unit 9 serves to calculate the current rate of change of the load 10 of the detected change in load. If the rate of change of the load 10 calculated by means of the computing unit 9 is less than the predetermined maximum rate of change of the load 13, then the throttle valve 15 is briefly throttled by the actuation unit 11, in particular, the situation is prevented so that the speed is too high load changes, in particular, after a sudden partial load shedding, led to desynchronization and / or rapid shutdown of the turbine 3, thus, by short-term By throttling the supply of the working medium (for example, steam) to the turbine 3, an unacceptable increase in the frequency of rotation of the turbine 3 above the nominal value is prevented.

After this quick alignment of the operation of the turbine after a partial load shedding, the speed of the turbine 3 is adjusted in accordance with the new load situation after a partial load shedding by means of the computing unit 17. For this, the computing unit 17 during operation of the turbine 3, if necessary, is continuously driven by two actuators the signals 19, 21 of the valve 15 of the turbine, and by means of the first Executive signal 19 is achievable actuation of the valve 15 of the turbine in its direction the opening position and by means of the second actuating signal 21, it is achievable to actuate the turbine valve 15 in the direction of its closing position.

By using two separate actuator signals 19, 21 to install the turbine valve 15 during the speed control process, the accuracy of the installation of the turbine valve 15 is improved, since both the opening and closing of the turbine valve 15 have the entire width of the range of actuating signals 19 or 21 respectively.

As shown in the drawing, the Executive unit 11 and the computing unit 17 can be implemented together, for example, by means of an electronic circuit.

Further, the second actuation signal 21 can be applied to actuate the turbine valve 15 in the direction of its closing position, also for according to the invention, short-term throttling of the turbine valve 15 by means of the actuation unit 11; however, it is also possible to provide separate signals for this.

According to the invention, the device 1 is preferably implemented by means of a programmable control from the memory. The processing of analog signals in this case occurs preferably with a cycle time of about 13 ms. Short-term throttling of the turbine valve 15 preferably lasts of the order of 6.5 ms after exceeding the maximum rate of change of load 13 is established.

Figure 2 shows schematically an embodiment of a device for controlling the speed of a turbine.

A device for controlling a turbine rotation speed includes a block 30 that defines a change in the load of the turbine 32, a sensor 34 for a threshold value of the turbine shaft rotation frequency signal, a block 36 for generating a control signal to the valves 38 of the turbine 32, a processor 40, which generates a load change rate signal connected between the sensor 34 of the signal of the threshold value of the rotational speed of the turbine shaft and the block 36 for generating a control signal to the valves 38, block 42 for setting the permissible rate of change of load connected to the second at the input of the control signal generating unit 36 to the valves 38, the unit 36 having two outputs that are connected to the inputs for controlling the position of the turbine valves 38, one of which acts on at least one of the valves 38 in the "closed" direction, and on the other of the valves in the "open" direction.

The essence of the method lies in the fact that during operation of the turbine constantly monitor the change in the load of the turbine. If a change in load is detected, then the speed with which the load changes is determined, and then it is compared with the maximum allowable, and the direction of the load change is controlled.

If the load changes in the decreasing direction, then by means of a control action, at least one of the turbine valves is controlled in the “closed” direction, and the turbine speed is set to the rated load.

A device for controlling the speed of a turbine operates as described below.

The device is based on a processor 40, which operates according to a program loaded into its storage device, and the regulation of the turbine speed in accordance with the change in the load of the turbine is provided in such a way that it leads it to a nominal value.

The load change is determined by the block 30, which sets the load change of the turbine, the signal of which about the load change, the processor 40 calculates the speed of the load; when the maximum permissible value is exceeded, the control signal generating unit 36 generates one of the control signals to the valve 38 of the turbine 32. In the case of a signal from the block 30 indicating a change in load in the decreasing direction, an action is generated to open the valve 38, in the case of a signal from the block 30 load in the direction of increase, the control signal generating unit 36 to the valves 38 generates a signal for closing the valve 38.

A turbine valve 38 may be installed, for example, in a steam supply channel, and through this valve, steam from a steam generator can be directed to the turbine.

After a brief change in valve position, the turbine speed can be adjusted according to the newly arisen working situation.

With this embodiment of the device, at least one valve of the turbine changes its state due to a control action.

Short-term closing of the valve 38 of the turbine ensures that there is opposition to partial load shedding at a very high rate of change, while improving the behavior of the turbine during operation, since the load of the turbine can be well controlled.

The use of two separate control signals for controlling at least one turbine valve 38 improves control accuracy.

The control signals may be in the form of electric current signals, in particular with a current strength of 0 to 20 mA, depending on the value of the error signal.

Blocks are used to divert current signals.

The control of the turbine shaft speed can be done through cyclically operating digital machinery.

According to the invention, the device in accordance with figure 2, as well as the corresponding method can be described as follows.

The invention is aimed at expanding the functionality by registering the speed at which the controlled value changes when the speed is controlled, which leads to increased reliability of protection in emergency situations.

A method for controlling the rotational speed of a turbine shaft connected by means of a generator to an electric power supply network is based on measuring the rotational speed and comparing it with the nominal rotational speed, monitoring the value, as well as the direction in which the measured rotational speed deviates from the nominal rotational speed, on a continuous calculating the speed at which the rotational speed of the turbine shaft changes, and comparing it with a predetermined value, the control signal changing the position of at least one a turbine valve. The generated control signal and the speed with which the speed of the turbine shaft changes are proportional to each other, and in the case of the control signal we are talking about a current from 0 to 20 mA or a digital control signal that provides operation with digital machinery.

A device for controlling a turbine rotational speed comprises a block 30 specifying changes in the load of the turbine 32, a sensor 34 for the signal of the limiting value of the rotational speed of the turbine shaft, a control signal generating unit 36 for valves 38 of the turbine 32, a processor 40 for calculating the rate of change of load connected between the signal sensor 34 the limit value of the rotational speed of the turbine shaft and the control signal generating unit 36 for the valves 38, a unit 42 defining an allowable load change rate connected to the second input of the bl ka 36 generating a control signal for valves 38, and the control signal generating unit 36 for valves 38 has two outputs that are connected to inputs for controlling the position of the turbine valves 38, one of which acts on the turbine valve in the "closed" direction and the other in direction "open".

Claims (21)

1. A method for controlling the speed of a turbine (3) connected by means of a generator (5) to an electric power supply network, characterized in that the following operations are provided: a) during operation of the turbine (3), it is continuously determined whether there is a change in the load of the turbine (3) ), b) if a load change is detected, the speed (10) of this load change is determined, c) if the speed (10) of the load change is modulo larger than the preset maximum speed (13) of the load change, and the change load pro descends in the direction of a lower load, then, by means of an actuating action, at least one valve (15) of the turbine is momentarily actuated in the direction of its closing position, and at the same time, at least one valve (15) of the turbine is momentarily closed, and d) the speed of rotation of the turbine (3) relative to the current working load, which is obtained after changing the load, is regulated by means of a regulatory action on at least one valve (15) of the turbine. 2. The method according to claim 1, characterized in that the regulatory effect on at least one valve (15) of the turbine is provided by at least two actuating signals (19, 21), moreover, by means of the first actuating signal (19) from at least two actuating signals, actuation in the direction of the opening position of the valve (15) of the turbine is achieved, and by means of the second actuating signal (21) of at least two actuating signals, actuation in the direction of the closing position of the cl Pan (15) of the turbine. 3. The method according to claim 2, characterized in that the Executive signals (19, 21) contain the output data of the electric current, in particular, the current strength in the range from 0-20 mA, and accordingly, the current outputted electric current strength is a measure for the degree of opening or closing the valve (15) of the turbine. 4. The method according to claim 1, characterized in that the method is implemented by means of a cyclically operating digital computing device. 5. The method according to claim 2, characterized in that the method is implemented by means of a cyclically operating digital computing device. 6. The method according to claim 3, characterized in that the method is implemented by means of a cyclically operating digital computing device. 7. A method for controlling the rotational speed of a turbine shaft connected by means of a generator to an electric power supply network, which is based on measuring the rotational speed, comparing with the nominal rotational speed and generating a control signal based on the comparison results, characterized in that the value and the direction in which the measured the rotational speed deviates from the nominal rotational speed, and the rate of change of the rotational speed of the turbine shaft is continuously calculated, and a comparison is made with the reference nym value; when the limit value specified with respect to the speed of rotation speed is exceeded, a control signal is generated to change the position of the turbine valve, and two control signals are generated per turbine valve, one of which changes the position of the turbine valve in the "open" direction and the other in the " closed". 8. The method according to claim 7, characterized in that the control signal changes the position of at least one valve of the turbine. 9. The method according to claim 7, characterized in that in proportion to the change in the speed of the rotational speed of the turbine shaft, a control signal is generated in the form of a current with a force from 0 to 20 mA, which determines the degree of opening or closing of at least one turbine valve for setting the frequency rotation of the turbine at rated load. 10. The method according to claim 8, characterized in that in proportion to the change in the speed of the turbine shaft rotational speed, a control signal is generated in the form of a current with a force from 0 to 20 mA, which determines the degree of opening or closing of at least one turbine valve for setting the frequency rotation of the turbine at rated load. 11. The method according to claim 7, characterized in that in proportion to the change in the speed of the rotational speed of the turbine shaft, a control signal is generated in the form of a current with a force from 0 to 20 mA, which determines the degree of opening or closing of at least one turbine valve for setting the frequency rotation of the turbine at rated load. 12. The method according to claim 7, characterized in that form a digital control signal, which provides a mode of operation with digital machinery. 13. The method according to claim 8, characterized in that form a digital control signal, which provides a mode of operation with digital machinery. 14. The method according to claim 7, characterized in that form a digital control signal, which provides a mode of operation with digital machinery. 15. The method according to claim 9, characterized in that form a digital control signal, which provides a mode of operation with digital machinery. 16. A device for controlling the speed of a turbine (3) connected via a generator (5) to an electric power supply network, characterized in that it comprises a sensor unit (7) by which a change in the load of the turbine is detected, a computing unit (9), by which is the calculated load change rate (10) of the detected load change, the execution unit (11), whereby in the case of the load change speed (10) in the direction of the lower load, which is modulo more than h at a predetermined maximum speed (13) of the load change, it is briefly actuated by at least one valve (15) of the turbine in the direction of its closed position, while at least one valve (15) of the turbine is briefly closed and the computational block (17), through which at least two actuating signals (19, 21) are generated for installing at least one turbine valve (15), and by means of the first actuating signal (19) from at least two executive of the signals, driving in the direction of the opening position of the turbine valve (15) is provided, and by means of a second actuating signal (21) of the at least two actuating signals, driving in the direction of the closing position of the valve (15) of the turbine is provided. 17. The device according to clause 16, characterized in that the actuating signals (19, 21) contain the output data of the electric current, in particular, the current strength in the range 0-20 mA, and the current output electric current strength is a measure for the degree of opening or closing valve (15) of the turbine. 18. The device according to p. 16 or 17, characterized in that the device (1) is a controlled means of regulation with programming from the memory. 19. A device for controlling the speed of a turbine connected by means of a generator to an electric power supply network, which contains a unit for receiving a signal proportional to the power of the generator and a signal of the limit value of the rotational speed of the turbine shaft, the outputs of which are connected to a control signal generating unit (36), which has two outputs: an output for the current speed, and an output for the current speed, the values of which lie in a given range of speed, characterized in that the device comprises a processor (40), which generates a signal at the outputs when the nominal speed changes temporarily and a signal when the set value is exceeded relative to the maximum temporary speed changes, connected to the input of the control signal generating unit (36), the second input of which is connected to the sensor ( 42) the set value for the permissible rate of change of the rotational speed of the turbine shaft and the outputs of which are connected to the control inputs of the valves (38) of the turbine, and one of them acts a valve (38) of the turbine in the direction "open" and the other in the direction of "closed". 20. The device according to claim 19, characterized in that the control signal generating unit (36) is made with a current output at which the current value and the rate of change of the rotational speed of the turbine shaft are proportional to each other. 21. The device according to any one of paragraphs.19 or 20, characterized in that the Converter (36) of the control signal is made in the form of a programmable control unit.

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