Control system and method for preventing tripping of electric barring of steam turbine

Abstract

The invention provides a control system and method for preventing tripping of an electric barring of a steam turbine to solve the problem that in the prior art, the probability of tripping of the electric barring on the steam turbine side is large due to a barring device. Comprising an electric barring control cabinet, a displacement sensor and a rotor rotating speed sensor, and the electric barring control cabinet is electrically connected with a barring motor; the displacement sensor is arranged on the turning gear and used for collecting relative displacement between a connecting rod of the turning gear and a cylinder and converting the relative displacement into corresponding electric signals. The rotor rotating speed sensor is used for collecting the rotating speed of the turbine rotor and converting into electric signals; the electric barring control cabinet controls the rotating speed of the barring motor according to electric signals of the displacement sensor and the rotor rotating speed sensor. By reading signals of the displacement sensor and the rotor rotating speed sensor, the running state of the steam turbine electric barring can be known in detail, and meanwhile the barring rotating speed can be stabilized and barring tripping can be prevented in cooperation with the barring rotating speed control module in the electric barring control cabinet.

Description

Technical Field

[0001] The invention belongs to the field of electric turning gear control systems, and in particular relates to a control system and method for preventing a steam turbine electric turning gear from tripping. Background Art

[0002] The electric turning system of the steam turbine is an important guarantee for the safe and stable operation of the steam turbine as a whole. The use of the electric turning system before the turbine is started can check in advance whether there is any friction between the moving and static parts of the rotor or the rotor is bent. At the same time, it can also effectively reduce the bending deformation of the rotor caused by the temperature difference between the cylinder and the rotor due to reasons such as steam seal leakage and steam leakage of various valves and gate rods.

[0003] Generally speaking, the mechanical structure of the turbine side cranking device is mainly composed of a gear set (including the driving gear on the motor side and the cranking gear on the cranking side), a crank, a connecting rod, a handwheel, a travel switch, a spring, etc. However, for a single-shaft gas-steam combined cycle unit, when the combustion engine and the steam turbine are cranked at the same time before the unit is ignited, there is a high probability that the electric cranking device on the turbine side will be disengaged (that is, the meshed driving gear is separated from the cranking gear), which will affect the unit's operating stability and safety and delay the unit's power generation time, causing irreparable economic losses to the power plant. Summary of the invention

[0004] In view of this, the present invention provides a control system and method for preventing the electric turning gear of a steam turbine from tripping, so as to solve the problem in the prior art that when the turning device turns the combustion engine and the steam turbine at the same time before ignition of the unit, there is a high probability that the electric turning gear on the steam turbine side will trip (i.e., the meshed driving gear is separated from the turning gear), which affects the operating stability and safety of the unit and also delays the power generation time of the unit, causing irreparable economic losses to the power plant.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A control system for preventing tripping of an electric turning gear of a steam turbine, comprising:

[0007] An electric turning gear control cabinet, the electric turning gear control cabinet is electrically connected to the turning gear motor to control the operation of the turning gear motor, and the turning gear motor is used to drive the driving gear of the turning gear device to rotate;

[0008] A displacement sensor is provided on the turning device, and is used to collect the relative displacement between the connecting rod and the cylinder of the turning device during the turning device disengagement process and convert it into a corresponding electrical signal; the displacement information collected by the displacement sensor may also include the displacement of the travel switch, the relative displacement between the crank and the cylinder, and other displacement information with movement changes.

[0009] A rotor speed sensor, which is arranged on the turbine rotor bearing cover of the turning device, and is used to collect the speed of the turbine rotor and convert it into a corresponding electrical signal;

[0010] The electric turning gear control cabinet controls the speed of the turning gear motor according to the electrical signals of the displacement sensor and the rotor speed sensor to prevent the turning gear from tripping.

[0011] Preferably, the electric turning gear control cabinet is electrically connected to the turning gear motor through an export cable, and the electric turning gear control cabinet includes a turning gear drive mode selection module and a turning gear speed control module. The turning gear drive mode selection module is used to control the starting mode of the turbine turning gear, and the turning gear speed control module is used to realize the control of the turning gear motor speed by the electric turning gear control cabinet and is electrically connected to the rotor speed sensor and the displacement sensor respectively through the import cable.

[0012] Preferably, the turning gear speed control module also includes a logic circuit trigger and a frequency converter, wherein the logic circuit trigger makes a logical judgment based on the output signal of the displacement sensor to control the start and stop of the frequency converter; the frequency converter has a logic editing function, and when the frequency converter is started, the speed of the turning gear motor is controlled according to the built-in logic.

[0013] The beneficial effect of adopting the above further scheme is that the existence of the cranking speed control module prevents the electric cranking on the steam turbine side from tripping when the cranking device cranks the gas turbine and steam turbine at the same time before the unit is ignited, which greatly enhances the stability and safety of the unit operation.

[0014] Preferably, the turbine cranking start-up modes include: manual cranking mode, manual electric cranking mode and automatic electric cranking mode.

[0015] In this technical solution, it should be noted that the turning gear drive mode selection module also includes a manual turning gear mode, a manual electric turning gear mode, an automatic electric turning gear mode and a corresponding switching switch. The manual turning gear mode means that the turning gear control cabinet does not output an electrical signal to the turning gear motor, that is, the turning gear motor does not start, and the entire turbine turning process is completed manually; the manual electric turning gear mode means that the turning gear control cabinet only controls the rotation of the turning gear motor, and the engagement of the driving gear on the motor side and the turning gear on the turning gear side requires manual operation; the automatic electric turning gear mode means that the engagement of the turning gear and the rotation of the turning gear motor are controlled by the turning gear control cabinet; the switching switch is installed on the turning gear control cabinet for switching between the above three modes.

[0016] Preferably, the rated power of the turning motor should match the maximum torque required by the turning device and should not be too large.

[0017] In this technical solution, it should be noted that the use of a motor with a suitable rated power can avoid problems such as deformation of the mechanical structure of the turning device caused by excessive starting torque of a high-power motor. Specifically, the relationship between the motor torque T and the motor power P can be calculated using the following formula:

[0018] T=9550P / (a*n)(a>1)

[0019] In the formula: T is the turning motor torque (N*m), P is the turning motor power, a is the safety factor, generally a is 1.1~1.3, and n is the turning motor speed (r / min).

[0020] Preferably, the displacement sensor should be a digital sensor, with an initial output signal of 0 and an output domain of {0,1}. When the relative displacement between the connecting rod and the cylinder of the turning device reaches a set value, a flipping operation is performed to change the output signal.

[0021] The beneficial effect of adopting the above further solution is that the displacement sensor simplifies the changing displacement value into two digital output signals of 0 or 1, which greatly simplifies the judgment logic in the turning speed control module.

[0022] A control method for preventing a steam turbine electric turning gear from tripping, comprising:

[0023] Step 1: The relative displacement between the connecting rod and the cylinder of the turning device is collected in real time through the displacement sensor. The displacement sensor is a digital sensor with an initial output signal of 0 and an output domain of {0,1}. When the relative displacement between the connecting rod and the cylinder reaches the set value, the displacement sensor changes the output signal from 0 to 1 and sends the digital signal to the logic circuit trigger;

[0024] Step 2: The logic circuit trigger receives the digital signal 1 of the displacement sensor, controls the inverter to start, and the inverter reads the output signal of the rotor speed sensor; the inverter controls the speed of the rotor based on the output signal of the speed sensor and the built-in function until the electric turning gear does not trip within the specified time. The built-in function is shown in the following formula:

[0025] n=kf=k*f0*(2-n1 / n0)(0≤n1≤2n0)

[0026] In the formula: n is the speed of the cranking motor (r / min), f is the output power of the inverter (Hz), k is the cranking motor coefficient, which is determined by the properties of the motor itself, f0 is the output power of the inverter during normal cranking (Hz), n1 is the output signal of the rotor speed sensor (r / min), and n0 is the rotor speed during normal cranking (r / min).

[0027] In step 2, the prescribed time is obtained by the following formula:

[0028] t = β * |n0 - n1|

[0029] Where: n1 is the output signal of the rotor speed sensor (r / min), n0 is the rotor speed during normal barring (r / min), and β is the correction factor. Generally, β is taken as 1 - 2.

[0030] In step 2, when the electric barring still trips within the specified time, an additional 2 s is added to the specified time. If the barring still cannot solve the tripping problem after the time is increased, the frequency converter will output a tripping signal to the electric barring control cabinet to cause the overall reset of the barring speed control module and stop the operation of the electric barring, realizing a complete tripping operation.

[0031] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0032] 1. In the present invention, by reading the signals of the displacement sensor and the rotor speed sensor, the operating state of the steam turbine electric barring can be understood in more detail. At the same time, with the cooperation of the barring speed control module in the electric barring control cabinet, the electric barring control cabinet can not only set the barring start mode and provide the starting voltage or current, but also further stabilize the barring speed and prevent barring tripping, ensuring the stability and safety of the operation of the single-shaft gas-steam combined cycle unit;

[0033] 2. The present invention proposes a control system and method for preventing tripping of a steam turbine electric barring, which can automatically realize the operation of preventing barring tripping. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be described by way of examples with reference to the accompanying drawings, where:

[0035] Figure 1 is a schematic diagram of the system structure of an embodiment of the present invention.

[0036] Figure 2 is a schematic diagram of the circuit structure of the barring drive mode selection module of the present invention.

[0037] Figure 3 is a logic diagram of the barring speed control module of the present invention.

[0038] Figure 4 is a schematic diagram of the built-in programming logic of the frequency converter in the barring speed control module of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0042] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0043] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0044] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0045] Example 1

[0046] like Figure 1-Figure 4 As shown, an embodiment of the present invention discloses a control system for preventing a steam turbine electric turning gear from tripping, comprising:

[0047] An electric turning gear control cabinet, the electric turning gear control cabinet is electrically connected to the turning gear motor to control the operation of the turning gear motor, and the turning gear motor is used to drive the driving gear of the turning gear device to rotate;

[0048] A displacement sensor is provided on the turning device, and is used to collect the relative displacement between the connecting rod and the cylinder during the turning device disengagement process and convert it into a corresponding electrical signal; the displacement information collected by the displacement sensor may also include the displacement of the travel switch, the relative displacement between the crank and the cylinder, and other displacement information with movement changes.

[0049] A rotor speed sensor, which is arranged on the turbine rotor bearing cover and is used to collect the speed of the turbine rotor and convert it into a corresponding electrical signal;

[0050] The electric turning gear control cabinet controls the speed of the turning gear motor according to the electrical signals of the displacement sensor and the rotor speed sensor to prevent the turning gear from tripping.

[0051] In this embodiment, the electric turning gear control cabinet is electrically connected to the turning gear motor through an export cable. The electric turning gear control cabinet includes a turning gear drive mode selection module and a turning gear speed control module. The turning gear drive mode selection module is used to control the starting mode of the turbine turning gear. The turning gear speed control module is used to realize the control of the turning gear motor speed by the electric turning gear control cabinet and is electrically connected to the rotor speed sensor and the displacement sensor respectively through the import cable.

[0052] In this embodiment, the cranking speed control module also includes a logic circuit trigger and a frequency converter. The logic circuit trigger makes a logic judgment according to the output signal of the displacement sensor to control the start and stop of the frequency converter; the frequency converter has a logic editing function, and when the frequency converter is started, the speed of the cranking motor is controlled according to the built-in logic. The beneficial effect of adopting the above further scheme is that the existence of the cranking speed control module prevents the electric cranking on the steam turbine side from tripping when the cranking device cranks the gas turbine and the steam turbine at the same time before the unit is ignited, which greatly enhances the stability and safety of the unit operation.

[0053] In this embodiment, the starting modes of the turbine cranking include: manual cranking mode, manual electric cranking mode and automatic electric cranking mode. It should be noted that the cranking drive mode selection module also includes manual cranking mode, manual electric cranking mode, automatic electric cranking mode and corresponding switching switches. The manual cranking mode means that the cranking control cabinet does not output an electrical signal to the cranking motor, that is, the cranking motor does not start, and the entire process of turbine cranking is completed manually; the manual electric cranking mode means that the cranking control cabinet only controls the rotation of the cranking motor, and the engagement of the driving gear on the motor side and the cranking gear on the cranking side requires manual operation; the automatic electric cranking mode means that the engagement of the cranking gear and the rotation of the cranking motor are controlled by the cranking control cabinet; the switching switch is installed on the cranking control cabinet to switch the above three modes. The switching switch can be a knob type, and the connected circuit is changed by rotating the knob to achieve the selection of different cranking drive modes. The circuit structure diagram is shown in the attached figure. Figure 2 The electric turning gear control cabinet provides multiple modes to choose from, which can effectively meet the operation needs of the steam turbine electric turning gear in various stages such as commissioning, operation, and maintenance.

[0054] In this embodiment, the rated power of the turning motor should match the maximum torque required by the turning device and should not be too large. It should be noted that the use of a motor with a suitable rated power can avoid problems such as deformation of the mechanical structure of the turning device caused by excessive starting torque of a high-power motor. Specifically, the relationship between the motor torque T and the motor power P can be calculated using the following formula:

[0055] T=9550P / (a*n)(a>1)

[0056] In the formula: T is the turning motor torque (N*m), P is the turning motor power, a is the safety factor, generally a is 1.1~1.3, and n is the turning motor speed (r / min).

[0057] In this embodiment, the displacement sensor should be a digital sensor, the initial output signal is 0, the output domain is {0,1}, and when the relative displacement between the connecting rod and the cylinder of the turning device reaches the set value, the output signal is changed by performing a flipping operation. The beneficial effect of adopting the above further scheme is that the displacement sensor simplifies the changing displacement value into two digital output signals of 0 or 1, which greatly simplifies the judgment logic in the turning speed control module.

[0058] Example 2

[0059] This embodiment provides a control method for preventing a steam turbine electric turning gear from tripping, comprising:

[0060] Step 1: The relative displacement between the connecting rod of the barring gear and the cylinder is collected in real time through a displacement sensor. The displacement sensor is a digital sensor with an initial output signal of 0 and an output range of {0, 1}. When the relative displacement between the connecting rod and the cylinder reaches the set value, the displacement sensor changes the output signal from 0 to 1 and sends the digital signal to the logic circuit trigger;

[0061] Step 2: The logic circuit trigger of the barring speed control module receives the digital signal 1 from the displacement sensor and controls the frequency converter to start. The frequency converter reads the output signal of the rotor speed sensor; the frequency converter controls the speed of the rotor based on the output signal of the speed sensor and the built-in function until the electric barring does not trip within the specified time. The specific schematic diagram of the built-in programming logic of the frequency converter is as attached Figure 4 shown, where the built-in function is as follows:

[0062] n = kf = k * f0 * (2 - n1 / n0) (0 ≤ n1 ≤ 2n0)

[0063] In the formula: n is the speed of the barring motor (r / min), f is the output power of the frequency converter (Hz), k is the barring motor coefficient, which is determined by the nature of the motor itself, f0 is the output power of the frequency converter during normal barring (Hz), n1 is the output signal of the rotor speed sensor (r / min), and n0 is the rotor speed during normal barring (r / min).

[0064] In Step 2, the specified time is obtained through the following formula:

[0065] t = β * 丨n0 - n1丨

[0066] In the formula: n1 is the output signal of the rotor speed sensor (r / min), n0 is the rotor speed during normal barring (r / min), and β is a correction coefficient. Generally, β takes 1 - 2.

[0067] In Step 2, when the electric barring still trips within the specified time, an additional 2 s is added to the specified time. If the barring still cannot solve the tripping problem after the time is increased, the frequency converter will output a tripping signal to the electric barring control cabinet to cause the overall reset of the barring speed control module and stop the operation of the electric barring, realizing a complete tripping operation.

[0068] Specifically, the logic schematic diagram of the barring speed control module is as attached Figure 3As shown, the logic circuit trigger can be formed by a XOR gate and a D flip-flop in series, and the control logic is: when the displacement sensor output signal is "1", the XOR gate outputs a "1" signal to the D flip-flop triggered by the rising edge, so that the D flip-flop outputs a signal "1" to the inverter to prompt the inverter to read the output signal of the rotor speed sensor and work. After completing the anti-tripping operation with the help of the inverter, the inverter will output a reset signal "0" to the reset end of the D flip-flop, so that the D flip-flop outputs a signal "0" to the inverter 13 to prompt the inverter to reset.

[0069] The circuits, electronic components and modules involved are all prior art and can be fully implemented by those skilled in the art. Needless to say, the content protected by the present invention does not involve improvements to software and methods.

[0070] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0071] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control system for preventing the electric turning gear of a steam turbine from tripping, characterized in that: Comprising: An electric barring control cabinet, which is electrically connected to a barring motor to control the operation of the barring motor. The barring motor is used to drive the rotation of the driving gear of the barring device. A displacement sensor, which is arranged on the barring device. The displacement sensor is used to collect the relative displacement between the connecting rod of the barring device and the cylinder during the barring trip and convert it into a corresponding electrical signal. A rotor speed sensor, which is arranged on the bearing cover of the steam turbine rotor. The rotor speed sensor is used to collect the speed of the steam turbine rotor and convert it into a corresponding electrical signal. Wherein, the electric barring control cabinet controls the speed of the barring motor according to the electrical signals of the displacement sensor and the rotor speed sensor to prevent barring trip.

2. A steam turbine electric turning gear anti-tripping control system according to claim 1, characterized in that: The electric barring control cabinet is electrically connected to the barring motor through an outlet cable. The electric barring control cabinet includes a barring drive mode selection module and a barring speed control module. The barring drive mode selection module is used to control the starting mode of the steam turbine barring. The barring speed control module is used to realize the control function of the electric barring control cabinet for the speed of the barring motor and is electrically connected to the rotor speed sensor and the displacement sensor respectively through an inlet cable.

3. A steam turbine electric turning gear anti-tripping control system according to claim 2, characterized in that: The barring speed control module further includes a logic circuit trigger and a frequency converter. The logic circuit trigger makes a logical judgment according to the output signal of the displacement sensor to control the start and stop of the frequency converter. The frequency converter has a logic editing function and controls the speed of the barring motor according to the built-in logic when the frequency converter starts.

4. A steam turbine electric turning gear anti-tripping control system according to claim 2, characterized in that: The starting modes of the steam turbine barring include: manual barring mode, manual start of electric barring mode, and automatic start of electric barring mode.

5. A control method for preventing a steam turbine electric turning gear from tripping, which is implemented by a control system for preventing a steam turbine electric turning gear from tripping as claimed in claims 1 to 4, characterized in that: Comprising: Step 1: The relative displacement between the connecting rod of the barring device and the cylinder is collected in real time through the displacement sensor. The displacement sensor is a digital sensor, the initial output signal is 0, and the output range is {0, 1}. When the relative displacement between the connecting rod and the cylinder reaches the set value, the displacement sensor changes the output signal 0 to 1 and sends the digital signal to the logic circuit trigger. Step 2: The logic circuit trigger receives the digital signal 1 from the displacement sensor and controls the start of the frequency converter. The frequency converter reads the output signal of the rotor speed sensor. The frequency converter controls the speed of the rotor based on the output signal of the rotor speed sensor and the built-in function until the electric barring does not trip within the specified time. The built-in function is shown as follows: n = kf = k * f0 * (2 - n1 / n0) (0 ≤ n1 ≤ 2n0) In the formula: n is the speed of the barring motor (r / min), f is the output power of the frequency converter (Hz), k is the barring motor coefficient, which is determined by the nature of the motor itself, f0 is the output power of the frequency converter during normal barring (Hz), n1 is the output signal of the rotor speed sensor (r / min), and n0 is the rotor speed during normal barring (r / min).

6. A control method for preventing electric turning gear of a steam turbine from tripping according to claim 5, characterized in that: In Step 2, the specified time is obtained through the following formula: t = β * 丨n0 - n1丨 In the formula: n1 is the output signal of the rotor speed sensor (r / min), n0 is the rotor speed during normal barring (r / min), and β is a correction coefficient. Generally, β takes 1 - 2.

7. A control method for preventing electric turning gear of a steam turbine from tripping according to claim 5, characterized in that: In step 2, when the electric winch still trips within the specified time, an additional 2s will be added to the specified time. If the electric winch still cannot solve the tripping phenomenon after the increase in time, the inverter will output a tripping signal to the electric winch control cabinet to reset the winch speed control module as a whole and stop the electric winch to achieve a complete tripping operation.

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