RU2225945C2 - Method of preventing deviation of parameters of power turbine of turbomachine set at abrupt complete or partial shedding of load - Google Patents

Abstract

FIELD: mechanical engineering; protection of turbomachine sets. SUBSTANCE: invention relates to protection of turbomachine sets including gas-turbine sets (gas turbines and machines, for instance, generators driven by said gas turbines) from dangerous overspeeds at abrupt complete or partial shedding of load. Proposed method includes supply of signals indicating power turbine rotor speed (n_pt), gas generator rotor speed (n_gg) and one of load parameters, shaping of signal to control fuel consumption in combustion chamber, and, according to invention, value of thermodynamic parameter of gas generator is additionally determined and compared with corresponding threshold value and in case of simultaneous supply of signal indicating that parameter value exceeds threshold value and signal indicating abrupt complete or partial shedding of load, is received, order is sent to switch on ignition for preset time and switch off fuel delivery into combustion chamber, and value n_gg is additionally compared with corresponding threshold value n $\genfrac{}{}{0ex}{}{\text{thr}}{\text{gg}}$ , and value n_pt is compared with corresponding threshold value n $\genfrac{}{}{0ex}{}{\text{thr}}{\text{pt}}$ , first derivative of power turbine rotor speed n_pt is found and compared with corresponding threshold value n $\genfrac{}{}{0ex}{}{\text{thr}}{\text{pt}}$ and increment of rotor speed Δn_pt shedding of load is found, and further, if n_pt<n $\genfrac{}{}{0ex}{}{\text{thr}}{\text{pt}}$ ;|n_pt|<n $\genfrac{}{}{0ex}{}{\text{thr}}{\text{pt}}$ ,Δn_pt<0 and n_gg>n $\genfrac{}{}{0ex}{}{\text{thr}}{\text{gg}}$ , signal is supplied to switch of fuel delivery into combustion chamber. Thermodynamic parameter of gas generator and/or parameter of load gas generator rotor speed n_gg or gas generator rotor speed n_{gg red} reduced to temperature at inlet. Full air pressure after compressor P $\genfrac{}{}{0ex}{}{\text{*}}{\text{c}}$ can serve as thermodynamic parameter of gas generator, and power of electric generator P_gen set into operation by power turbine of turbomachine set serve as load parameter. EFFECT: improved safety owing to prevention of overspeeding of power turbine which can damage equipment, input personnel or cut off power supply by short-time cutting off fuel delivery into combustion chamber. 4 cl, 1 dwg

Description

The invention relates to the field of protection of turbomachinery units, including gas turbine units (gas turbines and the machines they drive, for example, generators), from dangerous speed overruns during a sudden full or partial load shedding.

Known methods of preventing the promotion of a power turbine of a turbomachine by stopping the supply of fuel to the combustion chamber when a threshold value of the speed of rotation of the power turbine is reached / 1 /.

However, the use of the known method in some cases leads to unreasonable shutdown of the gas turbine unit and the unit driven by it, which is economically disadvantageous, because forces consumers of energy (or substance) from the driven unit to stand idle or switch to other sources of energy (substance).

There is also a method of preventing the spin of a power turbine, which consists in measuring the frequency of rotation of the power turbine (n _st ), determining the first-order derivative in time (n _st ) with the subsequent determination of the difference between the power transmitted to the shaft of the power turbine and the power taken from the power shaft turbines, and the formation of a signal to change the magnitude of the adjustable parameter / 2 /.

However, the known method cannot be used if the difference between the power transmitted to the shaft of the power turbine and the power removed from the shaft of the power turbine exceeds a value of about 50% of the power transmitted to the shaft of the power turbine.

Closest to the claimed one is a method of preventing deviations of the rotational speed in a gas turbine unit containing a gas turbine and having a variable load and variable fuel consumption, including receiving a pre-emptive signal about a sudden full or partial load shedding and reducing fuel consumption in a gas turbine by this signal / 3 / .

With full or partial load shedding, the speed of the power turbine increases. The equation from which the change in rotational speed is determined has the form:

where I is the total moment of inertia of all parts rotating together with the shaft of the power turbine;

n _st - the frequency of rotation of the shaft of the power turbine;

R _t - power transmitted to the shaft of the power turbine;

P _L is the power taken from the shaft of the power turbine.

Calculations show that when implementing this method, taking into account the maximum possible reduction in fuel consumption in the combustion chamber (to the minimum fuel consumption necessary to maintain the flame in the combustion chamber) and with P _L <0.5Р _t, in some cases power promotion can not be prevented turbines above threshold n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{st}}$ .

This method does not prevent the promotion of a power turbine that can damage equipment, injure maintenance personnel.

In addition, in the case of using an electric generator as a driven mechanism, the value of n _st may exceed 110-112% of the nominal value with a sudden discharge of more than 50% of the load. With this value of the rotor speed, the power plant protection system will disconnect the generator from the consumer. Such a shutdown will be an obstacle that impedes the use of the known method in power plants, because leads to unreasonable shutdown of energy consumers.

The technical problem to which the invention is directed is to increase the safety of the method by preventing the spinning of a power turbine of a turbomachine unit that can damage equipment, injure maintenance personnel or turn off power to consumers, by shortly shutting off the fuel supply to the combustion chamber.

, сравнивают ее величину с соответствующим пороговым значением

, а также определяют величину приращения частоты вращения ротора Δn_ст после сброса нагрузки, и далее, в случае, если n_ст<n $\genfrac{}{}{0ex}{}{\text{порог}}{\text{ст}}$ ;

, Δn_ст<0 и n_гг>n $\genfrac{}{}{0ex}{}{\text{порог}}{\text{гг}}$ , подают сигнал на включение подачи топлива в камеру сгорания.The essence of the invention lies in the fact that in the method of preventing deviation of the parameters of the power turbine of the turbomachine during a sudden full or partial load shedding, including the supply of signals about the values of the rotor speed of the power turbine (n _st ), the rotor speed of the gas generator (n _g ) and one of load parameters, as well as the formation of a signal for controlling fuel consumption in the combustion chamber, according to the invention, additionally determine the value of the thermodynamic parameter of the gas generator, comparing t of it with the corresponding threshold value, and with the simultaneous receipt of a signal about the excess of the parameter value over its threshold value and a signal about the sudden complete or partial load shedding, commands are sent to turn on the ignition for a given period of time and to turn off the fuel supply to the combustion chamber, and additionally compare the value of n _g with the corresponding threshold value n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{gg}}$ and the value of n _article with the corresponding threshold value n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{st}}$ determine the first derivative of the rotor speed of the power turbine

compare its value with the corresponding threshold value

, and also determine the magnitude of the increment of the rotor speed Δn _st after load shedding, and then, if n _st <n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{st}}$ ;

, Δn _st <0 and n _gg > n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{gg}}$ give a signal to turn on the fuel supply to the combustion chamber.

In addition, the thermodynamic parameter of the gas generator and / or the load parameter are the rotational speed of the rotor of the gas generator n g _, or the frequency of rotation of the rotor of the gas generator n g _{, etc.,} reduced to the inlet temperature.

The thermodynamic parameter of the gas generator can also be the total air pressure behind the compressor P _k *, and the load parameter is the power of the electric generator P _gene driven by the power turbine of the turbomachine unit.

In the prototype method, shutting off the fuel supply in the event of a full or partial load shedding on the shaft of the power turbine is not provided. Such a shutdown is necessary to prevent the spin of the power turbine above an acceptable value with a significant difference in the values of P _t and P _L.

In the claimed technical solution, the fuel supply is switched off in the event of a signal about the “high” mode of operation of the gas generator. Therefore, the ignition is turned on at the same time as the fuel supply is turned off so that when the fuel is restored to the combustion chamber, a flame breakdown does not occur, which can cause the gas generator to stop. The ignition can be switched on for a specified period of time (about 10 s for gas generators of the PS-90, D-30 engine).

_cт и Δn_cт необходимо для анализа условий, позволяющих включить (возобновить) подачу топлива в камеру сгорания с целью исключения необоснованного выключения газотурбинной установки.An additional determination of the thermodynamic parameter of the gas generator allows you to identify the “high” mode of operation of the gas generator and generate a signal by which, when there is a signal about the load shedding on the shaft of the power turbine, a command is generated to turn off the fuel supply to the combustion chamber and a signal to turn on the ignition for a specified period of time. The definition of n _gg ,

_ct and Δn _{ct are} necessary for the analysis of conditions allowing to turn on (resume) the supply of fuel to the combustion chamber in order to prevent unjustified shutdown of the gas turbine unit.

The drawing shows a flowchart illustrating the implementation of the proposed method.

Block 1 is a block comparing the thermodynamic parameter with its threshold value, the signal I ₁ from the output of which is fed to the input of block 2.

Block 2 is an “AND” type logic device with two inputs and one output. In the case of n _gg > n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{gg}}$ , or n _{gg ave.} > n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{gg pr}}$ , or Р _к *> Р _к * ^threshold , the first input of block 2 receives a signal I ₁ = 1 about the gas generator being in the zone of “high” operating modes. In the case of a sudden full or partial load shedding, a signal I ₂ = 1 is received at the second input of the block. If there are signals I ₁ = 1 and I ₂ = 1 at the output of block 2, a signal I ₃ is generated to turn off the fuel supply, and at the same time a command is sent to turn on the ignition for a given period of time.

Block 3 is a functional device with two inputs and one output. The inputs of block 3 receive signals about the value of one of the load parameters, for example, P _gene , and about the value of n _st . Taking into account the magnitude of the load parameter and the value of n _ct , an output signal I ₄ is generated in block 3, which is a command to control the fuel consumption in the combustion chamber.

Block 4 is a device for generating a command to change fuel consumption under the influence of various parameter limiting circuits, such as the gas temperature behind the gas generator turbine, air pressure behind the compressor, gas generator rotor speed, power turbine rotor speed, etc. When any of the limited parameters reaches the corresponding threshold value in block 4, an output signal I ₅ is generated to change the fuel consumption entering the combustion chamber.

Block 5 is a selection block that selects the smallest or largest output signals I ₄ , I ₅ from blocks 3 and 4, depending on the sign of the signal change to the fuel supply task. The output signal I ₆ serves as a command to control the fuel supply valves (fuel consumption).

Block 6 - a comparator that compares the actual value of n _st with its threshold value n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{st}}$ . When n _st <n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{st}}$ at the output of block 6, a signal is formed to turn on the fuel supply (I ₇ = 1), which is fed to the 1st input of block 12. When n _st ≥ n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{ct}}$ the signal is formed I ₇ = 0.

Block 7 - block for calculating the magnitude of the increment of the rotor speed Δn _ct after load shedding, the output signal I ₈ from which is fed to the input of block 10. Block 7 generates a signal I ₈ = 1 with a negative value of the increment of the rotational speed Δn _st <0 in successive processing cycles signal about the value of n _Art .

Δn _st = n _sti -n _{sti - 1} - this is the difference between the values of the subsequent and previous after the reset by the rotation frequencies of the power turbine in the signal processing cycles n _st .

If Δn _Art ≥ 0, then I ₈ = 0.

, сигнал I₉ с которого поступает на вход блока 9.Block 8 is a differentiator in which the first time derivative n _st is calculated

, the signal I ₉ from which is fed to the input of block 9.

с ее пороговым значением

. При

формируется сигнал I₁₀=1, поступающий на вход блока 10. При

формируется сигнал I₉=0.Block 9 - a comparator that compares the actual value

with its threshold value

. At

a signal is formed I ₁₀ = 1, which is input to the input of block 10. When

the signal is formed I ₉ = 0.

Block 10 is a logical device of the type “I” with two inputs and one output. Upon receipt of the signals I ₈ = 1 and I ₁₀ = 1 at both inputs, the signal I ₁₁ = 1 is formed at the output of block 10 to turn on the fuel supply.

Block 11 - a comparator that compares the actual value of n _yy with its threshold value n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{gg}}$ . When n _gg > n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{gg}}$ at the output of block 11, a signal is formed to turn on the fuel supply I ₁₂ = 1, fed to the input of block 12.

Block 12 is a logical block of the type “I” with three inputs and one output. When the signals I ₇ = 1, I ₁₁ = 1 and I ₁₂ = 1 are received at the inputs of block 12, a signal I ₁₃ = 1 is formed at the output of block 12 to turn on the fuel supply.

Block 13 - block on-off shut-off valve. When a signal I ₃ = 1 arrives at the 1st input of block 13, the shut-off valve is turned on (closed), which turns off the fuel supply to the combustion chamber. When a signal I ₁₃ = 1 arrives at the 2nd input of block 13, the shut-off valve is turned off (opened) and the fuel supply to the combustion chamber is resumed.

The inventive method is as follows.

In block 1, the actual value of the thermodynamic parameter of the gas generator is constantly recorded during operation of the power turbine of the turbomachine unit. Such a parameter can serve as the rotational speed of the rotor of the gas generator n _g , or the frequency of rotation of the rotor of the gas generator n _{g pr} , reduced to the inlet temperature, or the total air pressure behind the compressor R _k *.

The value of one of the above parameters in block 1 is compared with the corresponding threshold value. If the actual value of the parameter of its threshold value is exceeded, at the output of block 1, a signal I ₁ = 1 is generated, which is fed to the input of block 2. In the event of a sudden full or partial load shedding, the signal I ₂ = 1 is received at the second input of block 2.

Upon receipt of information about the location of the generator in the zone of “high” operating modes and the receipt of information about a sudden load shedding, i.e. the signals l ₁ = 1 and I ₂ = 1 arrive at the inputs of block 2, a command is formed to turn on the ignition for a given period of time, and at the same time a signal is sent to turn off the fuel supply to the input of block 13, thereby preventing the power turbine from spinning when it suddenly or partial load shedding due to a sharp decrease in energy supply from the gas generator to the power turbine.

At the same time, the load parameter is measured, which can be either the power of the electric generator P _gene driven by the power turbine of the turbomachine unit, or the rotor speed of the gas generator rotor n _g , or the speed of rotation of the rotor of the gas generator n _{g pr} , reduced to the inlet temperature.

A signal about the value of one of the listed parameters, for example, P _gene , is fed to the 1st input of block 3, the second input of which receives a signal about the magnitude of the rotor speed of the power turbine n _ct . In block 3, based on the value of the load parameter and the value of n _ct , an output signal 14 is generated, which is a command to control the fuel consumption in the combustion chamber. The signal I _{4 is} fed to the input of block 5. The signal I ₅ from block 4 is fed to the second input of block 5, in which a command is generated to change the fuel consumption when various parameter limiting circuits act (for example, gas temperature behind the gas generator turbine, gas generator rotor speed, rotor speed of a power turbine).

In block 5, one of the input signals I ₄ and I _{5 is} selected (the smallest or largest, depending on the sign of the change in signal I ₅ ). The selected signal in the form of an output signal I ₆ serves as a command to control the flow of fuel supplied to the combustion chamber, ensuring the maintenance of the required value of n _ct with smooth changes in the load on the shaft of the power turbine.

. При n_ст<n $\genfrac{}{}{0ex}{}{\text{порог}}{\text{ст}}$ на выходе блока 6 формируется сигнал I₇=1. Если

, то на выходе блока 9 формируется сигнал I₁₀=1.In blocks 6-9, changes in the values of n _st and its first time derivative are analyzed

. When n _st <n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{st}}$ at the output of block 6, a signal I ₇ = 1 is formed. If

, then at the output of block 9, a signal I ₁₀ = 1 is formed.

If Δn _article <0, then I ₈ = 1. The logic unit 10 analyzes the incoming signals I ₈ and I ₁₀ . If I ₈ = 1 and I ₁₀ = 1, then the output signal I ₁₁ = 1 is formed. When n _gg > n _gg ^threshold at the output of block 11, the signal I ₁₂ = 1 is formed.

When the fuel supply is turned off during a sharp load shedding (I ₂ = 1) in the zone of “high” operating modes (I ₁ = 1) according to the analysis of changes in the values of n _st and n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{ct}}$ in case of three signals I ₇ = 1, I ₁₁ = 1 and I ₁₂ = 1 to the inputs of block 12, a command I ₁₃ = 1 is generated to block 13 to turn on (resume) the fuel supply to the combustion chamber.

Sources of information

1. Fundamentals of the technology of creating gas turbine engines for long-haul aircraft, M., “Aviatekhinform”, 1999, p. 56.

2. US Patent No. 5609465, F 01 D 17/06, 1997

3. RF patent No. 2168044, F 02 C 9/28, 1997

Claims (4)

1. A method of preventing deviation of the parameters of the power turbine of the turbomachine unit during a sudden full or partial load shedding, including the supply of signals about the values of the rotor speed of the power turbine (n _ct ), the rotor speed of the gas generator (n _g ) and one of the load parameters, as well as the formation of signal for controlling fuel consumption in the combustion chamber, characterized in that it further determines the value of the thermodynamic parameter of the gas generator, compare it with the corresponding threshold value, and while a signal is received on exceeding the parameter above its threshold value and the signal of the sudden full or partial reset load command the fuel off the combustion chamber and switching on the ignition for a predetermined period of time, and further comparing the value n _gg with the corresponding threshold value n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{gg}}$ and the value of n _ct with the corresponding threshold value n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{st}}$ , determine the first derivative of the rotational speed of the rotor of the power turbine in time

_st , compare its value with the corresponding threshold value

$\genfrac{}{}{0ex}{}{\text{threshold}}{\text{st}}$ , and also determine the magnitude of the increment of the rotor speed Δn _st after load shedding, and then, if n _ct <n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{st}}$ ; | n _st | <

$\genfrac{}{}{0ex}{}{\text{threshold}}{\text{st}}$ , Δn _st <0 and n _gg > n $\genfrac{}{}{0ex}{}{\text{threshold}}{\text{gg}}$ give a signal to turn on the fuel supply to the combustion chamber. 2. The method of preventing deviation of the parameters of the power turbine of the turbomachine according to claim 1, characterized in that the thermodynamic parameter of the gas generator and / or the load parameter are the rotor speed of the gas generator rotor n _g or the inlet temperature of the rotor of the gas generator reduced to n inlet temperature _{, etc.} 3. The method of preventing deviation of the parameters of the power turbine of the turbomachine according to claim 1, characterized in that the thermodynamic parameter of the gas generator is the total air pressure behind the compressor p _to *. 4. The method of preventing deviation of the parameters of the power turbine of the turbomachine unit according to claim 1, characterized in that the load parameter is the power of the electric generator P _gene driven by the power turbine of the turbomachine unit.

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