Gas turbine exhaust temperature control method and device

Abstract

The invention discloses a gas turbine exhaust temperature control method and device. The traditional gas turbine exhaust temperature control neglects the delay of thermocouple temperature measurement in an exhaust temperature measurement module, on the other hand neglects the impact of thermal stress generated by the temperature change of a thermal channel on parts, and if the limitation is carried out only by a single exhaust temperature maximum value, the strength requirement of the thermal parts of the gas turbine cannot be met. The method comprises the following steps that the gas turbine operation condition is selected, and the exhaust temperature limit value under the current operation condition is determined; according to the performance parameters of the gas turbine under the current working condition, the actually-measured exhaust temperature is obtained through calculation; based on the exhaust temperature limit value and the actually measured exhaust temperature, the exhaust temperature deviation value of the current working condition is calculated; and performing exhaust temperature control according to the relationship between the exhaust temperature deviation value and the reference value. The method is applied to gas turbine exhaust temperature control.

Description

Technical field:

[0001] The invention relates to a method and a device for controlling exhaust temperature of a gas turbine. Background technology:

[0002] A conventional gas turbine exhaust temperature control method or device usually sets a maximum upper limit of the exhaust temperature, adjusts the fuel flow rate through a control system, and controls the exhaust temperature not to exceed the maximum value. However, it has certain shortcomings. First, it ignores the delay in thermocouple temperature measurement in the exhaust temperature measurement module. On the other hand, it ignores the impact of thermal stress caused by temperature changes in the hot channel on components. If only a single maximum exhaust temperature is used to limit the exhaust temperature, the strength requirements of the thermal components of the gas turbine cannot be met. Therefore, in view of the above shortcomings, the present invention proposes a gas turbine exhaust temperature control method and device. Summary of the invention:

[0003] The object of the present invention is to solve the above-mentioned problems and thus provide a method and device for controlling the exhaust temperature of a gas turbine.

[0004] The above purpose is achieved through the following technical solutions:

[0005] A method for controlling exhaust temperature of a gas turbine, the method comprising the following steps:

[0006] Step 1: Select the gas turbine operating condition and determine the exhaust temperature limit value under the current operating condition;

[0007] Step 2: Calculate and obtain the actual exhaust temperature based on the performance parameters of the gas turbine under the current operating conditions;

[0008] Step 3: Calculate the exhaust temperature deviation under the current working condition based on the exhaust temperature limit value and the measured exhaust temperature;

[0009] Step 4: Control the exhaust temperature based on the relationship between the exhaust temperature deviation and the reference value.

[0010] In the method for controlling exhaust temperature of a gas turbine, the operating condition of the gas turbine is selected in step 1, and determining the exhaust temperature limit value under the current operating condition specifically includes calculating the rotor speed limit line and the exhaust temperature limit line in sequence; the calculated exhaust temperature limit line is an exhaust temperature relationship curve corresponding to each rotor speed of the gas turbine; the calculated speed limit line is a rotor speed limit relationship curve corresponding to each ambient temperature.

[0011] In the method for controlling exhaust temperature of a gas turbine, the measured exhaust temperature is calculated in step 2 according to the performance parameters of the gas turbine under the current operating conditions, and the performance parameters of the gas turbine under the current operating conditions include at least: ambient temperature, ambient pressure, rotor speed and exhaust temperature.

[0012] A control device for a gas turbine exhaust temperature control method, comprising an exhaust temperature measurement module, an exhaust temperature calculation module, an exhaust temperature correction module, an exhaust temperature control module and a fuel adjustment module;

[0013] The exhaust temperature measurement module is composed of N temperature thermocouples;

[0014] The exhaust temperature calculation module takes the arithmetic mean after removing the faulty thermocouple and correcting the time derivative;

[0015] The exhaust temperature correction module corrects the exhaust temperature to the standard condition;

[0016] The exhaust temperature control module performs optimization control with the exhaust temperature deviation equal to 0 as the goal, continuously sends instructions to the fuel regulation module, controls the opening of the fuel regulation valve in real time, and adjusts the fuel flow rate to control the exhaust temperature within the design range.

[0017] Beneficial effects:

[0018] 1. The present invention solves the hysteresis of exhaust temperature thermocouple measurement by taking the derivative of the measured value of the gas turbine exhaust temperature with respect to time. On the one hand, considering that the rapid temperature change of the hot channel of the gas turbine will affect the strength of the components, the exhaust temperature of the gas turbine is controlled and corrected in real time to avoid excessive temperature rise of the gas turbine and excessive thermal stress, which will affect the life of the gas turbine components, thereby improving the reliability and durability of the gas turbine. Description of the drawings:

[0019] Figure 1 is a flow chart of the present invention;

[0020] Figure 2 It is the exhaust temperature limit curve;

[0021] Figure 3 It is the calculation speed limit curve diagram;

[0022] Figure 4 It is the allowable control area curve of gas turbine exhaust temperature. Specific implementation method:

[0023] Reference Figure 1 , a gas turbine exhaust temperature control method, the method comprising the following steps:

[0024] Step 1: Select the gas turbine operating condition and determine the exhaust temperature limit value under the current operating condition;

[0025] Step 2: Calculate and obtain the actual exhaust temperature based on the performance parameters of the gas turbine under the current operating conditions;

[0026] Step 3: Calculate the exhaust temperature deviation under the current working condition based on the exhaust temperature limit value and the measured exhaust temperature;

[0027] Step 4: Control the exhaust temperature based on the relationship between the exhaust temperature deviation and the reference value.

[0028] In the gas turbine exhaust temperature control method, the measured exhaust temperature is calculated in step 2 according to the performance parameters of the gas turbine under the current working condition, and the performance parameters of the gas turbine under the current working condition at least include: ambient temperature, ambient pressure, rotor speed and exhaust temperature;

[0029] The exhaust temperature is obtained by arithmetic averaging of several measuring points, and the exhaust temperature must be corrected according to the ambient temperature. Calculate the exhaust temperature:

[0030]

[0031] T 04 =T0 04m α 2

[0032]

[0033] Where: N is the number of exhaust temperature measurement points;

[0034] T 04i is the i-th exhaust temperature measurement correction value;

[0035] T 04m is the average exhaust temperature;

[0036] T 04 Exhaust temperature correction value;

[0037] T 01m is the average atmospheric temperature;

[0038] If the exhaust temperature measuring thermocouple fails, the thermocouple will be excluded from the calculation.

[0039] The temperature value of each measuring point takes into account the temperature loss caused by time lag, and the temperature of each measuring point is calculated as follows:

[0040] T 04i =T′ 04i ·+k·(dT′ 04i / dt)

[0041] Where: T′ 04i is the exhaust temperature measured after the low-pressure turbine;

[0042] dT′ 04i / dt is the derivative of the exhaust temperature measured after the low-pressure turbine;

[0043] k is the correction factor;

[0044] Reference Figure 2-Figure 3 , selecting the gas turbine operating condition, and determining the exhaust temperature limit value under the current operating condition specifically includes calculating the rotor speed limit line and the exhaust temperature limit line in sequence; the calculated exhaust temperature limit line is to determine the exhaust temperature relationship curve corresponding to each rotor speed of the gas turbine; the calculated speed limit line is the rotor speed limit relationship curve corresponding to each ambient temperature.

[0045] Determine the rotor speed limit value according to the ambient temperature under the current operating condition of the gas turbine, and then determine the exhaust temperature limit value;

[0046] n HP =f(T 01m )

[0047]

[0048] in: Low-pressure turbine exhaust temperature limit value;

[0049] n HP High pressure rotor speed;

[0050] The exhaust temperature deviation of the current working condition is determined based on the exhaust temperature limit value and the measured exhaust temperature:

[0051]

[0052] Where: ΔT 041 The low-pressure turbine exhaust temperature exceeds the limit;

[0053] ΔT 042 The low-pressure turbine exhaust temperature is insufficient;

[0054] The exhaust temperature is controlled according to the relationship between the actual exhaust temperature deviation and the reference deviation:

[0055] At this time, the gas turbine parameters meet the unit design index requirements and do not need to be changed;

[0056] It is the setting value of low-pressure turbine exhaust temperature exceeding the limit;

[0057] It is the setting value of low-pressure turbine exhaust temperature deficiency;

[0058] If the exhaust temperature deviation is greater than the reference deviation, the fuel amount of the gas turbine needs to be adjusted to keep the exhaust temperature deviation within the reference value:

[0059] (1) When the measured exhaust temperature is greater than the exhaust temperature limit value, that is, The amount of fuel for gas turbines should be reduced;

[0060] (2) When the measured exhaust temperature is less than the exhaust temperature limit value, that is, The amount of fuel for gas turbines should be increased;

[0061] A control device for a gas turbine exhaust temperature control method, comprising an exhaust temperature measurement module, an exhaust temperature calculation module, an exhaust temperature correction module, an exhaust temperature control module and a fuel adjustment module;

[0062] The exhaust temperature measurement module is composed of N temperature thermocouples;

[0063] The exhaust temperature calculation module takes the arithmetic mean after removing the faulty thermocouple and correcting the time derivative;

[0064] The exhaust temperature correction module corrects the exhaust temperature to the standard condition;

[0065] The exhaust temperature control module is optimized to achieve the exhaust temperature deviation of 0, continuously sends instructions to the fuel adjustment module, controls the fuel adjustment valve opening in real time, and adjusts the fuel flow rate to control the exhaust temperature within the design range. Figure 4 Shadow area.

Claims

1. A gas turbine exhaust temperature control method, characterized in that: The method comprises the following steps: Step 1: Select the gas turbine operating condition and determine the exhaust temperature limit value under the current operating condition; Step 2: Calculate and obtain the actual exhaust temperature based on the performance parameters of the gas turbine under the current operating conditions; Step 3: Calculate the exhaust temperature deviation under the current working condition based on the exhaust temperature limit value and the measured exhaust temperature; Step 4: Control the exhaust temperature based on the relationship between the exhaust temperature deviation and the reference value.

2. A gas turbine exhaust temperature control method according to claim 1, characterized in that: In the step 1, the gas turbine operating condition is selected, and determining the exhaust temperature limit value under the current operating condition specifically includes calculating the rotor speed limit line and the exhaust temperature limit line in sequence; the calculated exhaust temperature limit line is to determine the exhaust temperature relationship curve corresponding to each rotor speed of the gas turbine; the calculated speed limit line is the rotor speed limit relationship curve corresponding to each ambient temperature.

3. A gas turbine exhaust temperature control method according to claim 2, characterized in that: In the step 2, the measured exhaust temperature is calculated based on the performance parameters of the gas turbine under the current operating conditions. The performance parameters of the gas turbine under the current operating conditions include at least: ambient temperature, ambient pressure, rotor speed and exhaust temperature.

4. A control device using a gas turbine exhaust temperature control method according to any one of claims 1 to 3, characterized in that: Its components include an exhaust temperature measurement module, an exhaust temperature calculation module, an exhaust temperature correction module, an exhaust temperature control module and a fuel adjustment module; The exhaust temperature measurement module is composed of N temperature thermocouples; The exhaust temperature calculation module takes the arithmetic mean after removing the faulty thermocouple and correcting the time derivative; The exhaust temperature correction module corrects the exhaust temperature to the standard condition; The exhaust temperature control module performs optimization control with the exhaust temperature deviation equal to 0 as the goal, continuously sends instructions to the fuel regulation module, controls the opening of the fuel regulation valve in real time, and adjusts the fuel flow rate to control the exhaust temperature within the design range.

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