A dual-channel inverter circuit and starting method for a gas turbine black start starting motor

Abstract

A dual-channel frequency converter circuit and a starting method for a fuel engine black start starting motor, relating to the technical field of frequency conversion control, solves the problem of how to design a dual-channel frequency converter circuit for a fuel engine black start starting motor on the basis of reducing cost and installation space so as to improve the reliability of a black start electrical system; through the first and second power units of the dual-channel frequency converter, the first and second control units cooperate with a plurality of switches to realize redundant control of a first starting motor M1 and a second starting motor M2; in normal operation, only one channel of the dual-channel frequency converter works, and the other channel is in hot standby; when a working channel fails, the faulty channel is immediately cut off, and the standby channel is immediately converted to the working channel, so that the frequency converter fails and is smoothly switched to a normal operating state; the reliability of frequency conversion operation is increased; only one set of control units and power units are added, so the cost is greatly reduced compared with adding a complete set of frequency converters, and the installation space of the frequency converter is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of variable frequency control, and more specifically to a dual-channel frequency converter circuit and a starting method for a starting motor of a combustion engine black start. Background Art

[0002] Black start refers to the process of gradually restoring the normal operation of the power system by using the self-starting units in the system or the power supply outside the system when the power system is completely shut down. Gas turbines and hydropower units are often used for black start. Compared with hydropower units, the gas turbine starting process requires a high-power starting motor to drive. If the starting motor is started directly, the black start failure will occur if the power supply capacity of the gas turbine black start is insufficient. Increasing the black start capacity will lead to a significant increase in costs, so using a high-voltage inverter to drive the starting motor will greatly reduce the black start cost.

[0003] High-voltage inverter refers to a series superimposed high-voltage inverter, that is, it outputs variable-frequency and variable-voltage high-voltage AC power by connecting multiple single-phase inverters in series. The high-voltage inverter consists of several parts: the main circuit is mainly composed of three-phase or single-phase rectifier bridge, smoothing capacitor, filter capacitor, IPM inverter bridge, current limiting resistor, contactor and other components.

[0004] Figure 1 This is the black start electrical system diagram. When the external network bus loses power, the gas turbine plant bus will lose power and the gas turbine auxiliary equipment will not be able to operate. At this time, the black start power supply is used to supply power to the gas turbine plant bus, and the high-voltage inverter on the bus will drive the starter motor and the gas turbine to rotate. When the gas turbine reaches the self-sustaining speed, the starter motor and inverter will exit.

[0005] like Figure 2 As shown, the current black start electrical system generally adopts the inverter redundant hot backup method to ensure the reliability of black start; however, one starting motor is generally equipped with one high-voltage inverter. Since there are many power electronic components in the high-voltage inverter, power component breakdown accidents are prone to occur, resulting in inverter paralysis and ultimately black start failure; and each starting motor is equipped with a complete set of high-voltage inverters, which greatly increases the cost, and configuring multiple sets of high-voltage inverters at the same time requires a large installation hole space.

[0006] In the prior art, the Chinese invention patent application "A Black Start Method for a Power Grid" with application number 201910457218.2 and publication number CN110165704A specifically discloses: keeping the first circuit breaker and the first switch in a pass state; keeping the second circuit breaker and the second switch in a pass state; withdrawing the gas turbine generator from low voltage protection and low frequency protection; starting the gas turbine generator so that the gas turbine generator and the external power grid busbar are raised from zero to the corresponding rated voltage. This invention patent application is used to avoid the resonance phenomenon of the no-load main transformer, the occurrence of a more serious resonant overvoltage or high-amplitude excitation inrush current, and the problem of the generator overvoltage protection or overcurrent protection being actuated and the circuit breaker tripping, thereby improving the success rate of the black start of the power grid. However, the technical solution of this invention patent application does not solve the above problems. Summary of the invention

[0007] The technical problem to be solved by the present invention is how to design a dual-channel inverter circuit for a gas turbine black start starting motor on the basis of reducing costs and reducing installation space to improve the reliability of the black start electrical system.

[0008] The present invention solves the above technical problems through the following technical solutions:

[0009] A dual-channel inverter circuit for a fuel engine black start starter motor comprises: a motor power supply, a switch K1 of a switch cabinet, a first starter motor M1, a second starter motor M2, a phase-shifting rectifier transformer inlet switch K2, a dual-channel inverter, a motor power frequency operation switch K3, an inverter channel 1 output power switch K4, an inverter channel 2 output power switch K5, a first motor variable frequency operation switch K6, and a second motor variable frequency operation switch K7; the motor power supply is connected to the switch K1 of the switch cabinet, and one end of the motor power frequency operation switch K3 is connected to the switch K1 of the switch cabinet. The first end of the dual-channel inverter is connected to the first starting motor M1, and the other end is connected to the first starting motor M1; the dual-channel inverter includes a phase-shifting rectifier transformer T1, a first power unit (S11), a second power unit (S21), a first control unit (S12), and a second control unit (S22); the first power unit (S11) and the second power unit (S21) are respectively connected to the phase-shifting rectifier transformer T1, and the first power unit (S11) and the second power unit (S21) share a phase-shifting rectifier transformer T1; the first control unit (S12) and the first The power unit (S11) is connected; the second control unit (S22) is connected to the second power unit (S21); one end of the phase-shifting rectifier transformer inlet switch K2 is connected to the common connection point of the switch cabinet switch K1 and the motor power frequency operation switch K3, and the other end is connected to the primary side of the phase-shifting rectifier transformer T1; the inverter channel one output power switch K4 is connected in series with the first motor variable frequency operation switch K6, the non-series end of the inverter channel one output power switch K4 is connected to the first power unit (S11), and the first motor variable frequency operation switch K6 The non-series end is connected to the first starting motor M1; the inverter channel two output power switch K5 is connected in series with the second motor variable frequency operation switch K7, the non-series end of the inverter channel two output power switch K5 is connected to the second power unit (S21), and the non-series end of the second motor variable frequency operation switch K7 is connected to the second starting motor M2; the series common point of the inverter channel one output power switch K4 and the first motor variable frequency operation switch K6 is connected to the series common point of the inverter channel two output power switch K5 and the second motor variable frequency operation switch K7 by a wire.

[0010] Redundant control of the first starter motor M1 and the second starter motor M2 is achieved by cooperating with the first power unit (S11), the second power unit (S21), the first control unit (S12), the second control unit (S22) of the dual-channel frequency converter with the motor industrial frequency operation switch K3, the frequency converter channel 1 output power switch K4, the frequency converter channel 2 output power switch K5, the first motor variable frequency operation switch K6, and the second motor variable frequency operation switch K7. In normal operation, only one channel of the dual-channel frequency converter works, and the other channel is in hot standby. When the working channel fails, the faulty channel is immediately cut off, and the standby channel is immediately converted to the working channel, so that the frequency converter fails and is smoothly switched to a normal operating state. Only one set of control units and power units is added, which greatly reduces the cost compared to adding a complete set of frequency converters. At the same time, the installation space of the frequency converter is greatly reduced, and the reliability of variable frequency operation is increased. In addition, the circuit can also drive two motors to run at the same time.

[0011] As a further improvement of the technical solution of the present invention, the first power unit (S11) and the second power unit (S21) have the same structure and both include multiple power modules; the multiple power modules are divided into three groups, and after each group is connected in series in sequence, the input ends of the three groups of power modules are respectively connected to the three phases of the secondary side of the phase-shifting rectifier transformer T1, and the positive poles of the output ends of the three groups of power modules constitute U, V, and W phases, respectively, and are connected to the stator of the starting motor, and the negative poles of the output ends are connected together to form a neutral point.

[0012] As a further improvement of the technical solution of the present invention, the power module includes a three-phase uncontrolled rectifier circuit and a single-phase inverter bridge. The three-phase AC voltage on the secondary side of the phase-shifting rectifier transformer T1 is converted into a DC voltage through the three-phase uncontrolled rectifier circuit, and a single-phase voltage with variable frequency is output through the single-phase inverter bridge.

[0013] As a further improvement of the technical solution of the present invention, the output power switch K4 of the inverter channel 1 and the output power switch K5 of the inverter channel 2 are interlocked with each other, and only one switch is allowed to be closed at the same time.

[0014] As a further improvement of the technical solution of the present invention, the first motor variable frequency operation switch K6 and the second motor variable frequency operation switch K7 are interlocked with each other, and only one motor is allowed to operate with variable frequency at the same time.

[0015] As a further improvement of the technical solution of the present invention, the motor power frequency operation switch K3 and the first motor variable frequency operation switch K6 are interlocked with each other, and the motor is not allowed to run in parallel at power frequency and variable frequency at the same time.

[0016] A starting method for a dual-channel inverter circuit for a starting motor of a gas turbine black start, comprising the following steps:

[0017] 1) When the black start process starts the first starter motor M1: the switch cabinet switch K1 is closed, and after the switch cabinet switch K1 is detected to be in the closed position, the phase-shifting rectifier transformer inlet switch K2 is closed, the first control unit (S12) controls the first power unit (S11) to start, and closes the inverter channel 1 output power switch K4 and the first motor variable frequency operation switch K6, the output frequency of the inverter circuit increases, and the speed of the first starter motor M1 gradually increases to the working speed;

[0018] 2) When the frequency converter is required to start the second starter motor M2: after the output frequency of the frequency converter circuit rises to the industrial frequency, the first motor variable frequency operation switch K6 is disconnected, and the motor industrial frequency operation switch K3 is closed, and the first starter motor M1 is operated at the industrial frequency; after the output frequency of the frequency converter circuit drops to 0, the second motor variable frequency operation switch K7 is closed, the output frequency of the frequency converter circuit rises, and the speed of the second starter motor M2 gradually rises to the working speed;

[0019] 3) When the first power unit (S11) fails, the first control unit (S12) immediately blocks the pulse, and at this time, the output power switch K4 of the inverter channel 1 is opened, and the output power switch K5 of the inverter channel 2 is closed. The second control unit (S22) controls the second power unit (S21) to start working, the output frequency of the inverter circuit increases, and the speed of the second starter motor M2 gradually increases to the working speed.

[0020] As a further improvement of the technical solution of the present invention, the output power switch K4 of the inverter channel 1 and the output power switch K5 of the inverter channel 2 are interlocked with each other, and only one switch is allowed to be closed at the same time.

[0021] As a further improvement of the technical solution of the present invention, the first motor variable frequency operation switch K6 and the second motor variable frequency operation switch K7 are interlocked with each other, and only one motor is allowed to operate with variable frequency at the same time.

[0022] As a further improvement of the technical solution of the present invention, the motor power frequency operation switch K3 and the first motor variable frequency operation switch K6 are interlocked with each other, and the motor is not allowed to run in parallel at power frequency and variable frequency at the same time.

[0023] The advantages of the present invention are:

[0024] (1) Redundant control of the first starter motor M1 and the second starter motor M2 is achieved by cooperating with the first power unit (S11), the second power unit (S21), the first control unit (S12), the second control unit (S22) of the dual-channel frequency converter with the motor industrial frequency operation switch K3, the frequency converter channel 1 output power switch K4, the frequency converter channel 2 output power switch K5, the first motor variable frequency operation switch K6, and the second motor variable frequency operation switch K7. During normal operation, only one channel of the dual-channel frequency converter works, and the other channel is in hot standby. When a working channel fails, the faulty channel is immediately cut off, and the standby channel is immediately converted to the working channel, so that the frequency converter can be smoothly switched to a normal operating state after a failure, thereby increasing the reliability of variable frequency operation.

[0025] (2) The circuit only adds one set of control unit and power unit, which greatly reduces the cost compared to adding a complete set of inverters.

[0026] (3) At the same time, the installation space of the inverter is greatly reduced. In addition, the circuit can also drive two motors to run at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the black start electrical system diagram;

[0028] Figure 2 It is a schematic diagram of the traditional redundant hot backup black start motor circuit;

[0029] Figure 3 A circuit diagram of a dual-channel frequency converter for a combustion engine black start starter motor according to an embodiment of the present invention;

[0030] Figure 4 is a circuit diagram of a dual-channel frequency converter according to an embodiment of the present invention;

[0031] Figure 5 FIG. 4 is a circuit diagram of a power module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. 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.

[0033] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments:

[0034] Embodiment 1

[0035] like Figure 3 As shown, a novel dual-channel inverter circuit for a black-start starter motor of a gas turbine includes: a motor power supply, a switch cabinet switch K1, a first starter motor M1, a second starter motor M2, a phase-shifting rectifier transformer incoming line switch K2, a phase-shifting rectifier transformer T1, a first power unit S11, a first control unit S12, a second power unit S21, a second control unit S22, a motor power frequency operation switch K3, an inverter channel one output power switch K4, an inverter channel two output power switch K5, a first motor variable frequency operation switch K6, and a second motor variable frequency operation switch K7.

[0036] The motor power supply of this embodiment comes from a 6kV switch cabinet, and the motor power supply is connected to the switch cabinet switch K1. One end of the motor power frequency operation switch K3 is connected to the switch cabinet switch K1, and the other end is connected to the first starter motor M1; one end of the phase-shifting rectifier transformer inlet switch K2 is connected to the common connection point between the switch cabinet switch K1 and the motor power frequency operation switch K3, and the other end is connected to the primary side of the phase-shifting rectifier transformer T1; the input end of the first power unit S11 is connected to the secondary side of the phase-shifting rectifier transformer T1, the output end is connected to the inverter channel one output power switch K4, and the control end is connected to the first control unit S12; the input end of the second power unit S21 is connected to the phase-shifting rectifier transformer T1 The secondary side is connected, the output end is connected to the inverter channel two output power switch K5, and the control end is connected to the second control unit S22; one end of the first motor variable frequency operation switch K6 is connected to the output end of the inverter channel one output power switch K4, and the other end is connected to the first starting motor M1; one end of the second motor variable frequency operation switch K7 is connected to the output end of the inverter channel two output power switch K5, and the other end is connected to the second starting motor M2; the connection common point between the inverter channel one output power switch K4 and the first motor variable frequency operation switch K6 and the connection common point between the inverter channel two output power switch K5 and the second motor variable frequency operation switch K7 are connected by a wire.

[0037] The interlocking relationship between the switches is as follows:

[0038] The inverter channel one output power switch K4 and the inverter channel two output power switch K5 are interlocked with each other, and only one switch is allowed to be closed at the same time; the first motor variable frequency operation switch K6 and the second motor variable frequency operation switch K7 are interlocked with each other, and only one motor is allowed to operate with variable frequency at the same time; the motor industrial frequency operation switch K3 and the first motor variable frequency operation switch K6 are interlocked with each other, and the motor is not allowed to operate at industrial frequency and variable frequency in parallel at the same time.

[0039] The working principle of the dual-channel inverter circuit is as follows:

[0040] 1) When the black start process starts the first starter motor M1: the switch cabinet switch K1 is closed, and after the switch cabinet switch K1 is detected to be in the closed position, the phase-shifting rectifier transformer incoming line switch K2 is closed, the first control unit S12 controls the first power unit S11 to start, and closes the inverter channel 1 output power switch K4 and the first motor variable frequency operation switch K6, the output frequency of the inverter circuit slowly increases, and the speed of the first starter motor M1 gradually increases to the working speed.

[0041] 2) When the frequency converter is required to start the second starter motor M2: after the output frequency of the frequency converter circuit rises to the industrial frequency, the first motor variable frequency operation switch K6 is disconnected, and at the same time, the motor industrial frequency operation switch K3 is closed, and the first starter motor M1 operates at the industrial frequency; after the output frequency of the frequency converter circuit decreases to near 0, the second motor variable frequency operation switch K7 is closed, the output frequency of the frequency converter circuit slowly rises, and the speed of the second starter motor M2 gradually rises to the working speed.

[0042] 3) When the first power unit S11 fails, the first control unit S12 immediately blocks the pulse, and at this time, the output power switch K4 of the inverter channel 1 is opened, and the output power switch K5 of the inverter channel 2 is closed. The second control unit S22 controls the second power unit S21 to start working, and the output frequency of the inverter circuit slowly increases, and the speed of the second starter motor M2 gradually increases to the working speed.

[0043] Figure 4 It is a structural diagram of a high-voltage inverter, wherein the high-voltage inverter comprises a phase-shifting rectifier transformer T1, a first power unit S11, and a second power unit S21; the first power unit S11 and the second power unit S21 are respectively connected to the phase-shifting rectifier transformer T1, and the first power unit S11 and the second power unit S21 share a phase-shifting rectifier transformer T1; the first power unit S11 and the second power unit S21 have the same structure, and both comprise a plurality of power modules; the plurality of power modules are divided into three groups, and after each group is sequentially connected in series, the input ends of the three groups of power modules are respectively connected to the three phases of the secondary side of the phase-shifting rectifier transformer T1, and the positive poles of the output ends of the three groups of power modules respectively constitute U, V, and W phases, which are connected to the stator of the starter motor, and the negative poles of the output ends are connected together to form a neutral point.

[0044] Figure 5 The internal schematic diagram of the power module includes a three-phase uncontrolled rectifier circuit and an IGBT inverter bridge. The three-phase AC voltage on the low-voltage side of the phase-shifting rectifier transformer T1 is converted into a DC voltage through the three-phase uncontrolled rectifier circuit, and a single-phase voltage with variable frequency is output through the IGBT inverter bridge.

[0045] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual-channel inverter circuit for a gas turbine black start starter motor, characterized in that: include: Motor power supply, switch cabinet switch K1, first starter motor M1, second starter motor M2, phase shift rectifier transformer incoming line switch K2, dual-channel frequency converter, motor power frequency operation switch K3, frequency converter channel one output power switch K4, frequency converter channel two output power switch K5, first motor variable frequency operation switch K6, second motor variable frequency operation switch K7; the motor power supply is connected to the switch cabinet switch K1, one end of the motor power frequency operation switch K3 is connected to the switch cabinet switch K1, and the other end is connected to the first starter motor M1; the dual-channel frequency converter includes a phase shift rectifier transformer inlet switch K2, a dual-channel frequency converter, a motor power frequency operation switch K3 ... The first power unit (S11) and the second power unit (S21) are connected to the phase-shifting rectifier transformer T1, respectively, and the first power unit (S11) and the second power unit (S21) share a phase-shifting rectifier transformer T1; the first control unit (S12) is connected to the first power unit (S11); and the second control unit (S22) is connected to the second power unit (S21); One end of the phase-shifting rectifier transformer inlet switch K2 is connected to the common connection point of the switch cabinet switch K1 and the motor power frequency operation switch K3, and the other end is connected to the primary side of the phase-shifting rectifier transformer T1; the inverter channel 1 output power switch K4 is connected in series with the first motor variable frequency operation switch K6, the non-series end of the inverter channel 1 output power switch K4 is connected to the first power unit (S11), and the non-series end of the first motor variable frequency operation switch K6 is connected to the first starter motor M1; the inverter channel 2 output power switch K5 is connected in series with the second motor variable frequency operation switch K7, the non-series end of the inverter channel 2 output power switch K5 is connected to the second power unit (S21), and the non-series end of the second motor variable frequency operation switch K7 is connected to the second starter motor M2; the series common point of the inverter channel 1 output power switch K4 and the first motor variable frequency operation switch K6 is connected to the series common point of the inverter channel 2 output power switch K5 and the second motor variable frequency operation switch K7 by a wire.

2. A dual-channel inverter circuit for a gas turbine black start starter motor according to claim 1, characterized in that: The first power unit (S11) and the second power unit (S21) have the same structure and both include multiple power modules; the multiple power modules are divided into three groups, and after each group is connected in series, the input ends of the three groups of power modules are respectively connected to the three phases of the secondary side of the phase-shifting rectifier transformer T1, and the positive poles of the output ends of the three groups of power modules constitute U, V, and W phases respectively, which are connected to the stator of the starting motor, and the negative poles of the output ends are connected together to form a neutral point.

3. A dual-channel inverter circuit for a gas turbine black start starter motor according to claim 2, characterized in that: The power module includes a three-phase uncontrolled rectifier circuit and a single-phase inverter bridge. The three-phase AC voltage on the secondary side of the phase-shifting rectifier transformer T1 is converted into a DC voltage through the three-phase uncontrolled rectifier circuit, and a single-phase voltage with variable frequency is output through the single-phase inverter bridge.

4. A dual-channel inverter circuit for a gas turbine black start starter motor according to claim 1, characterized in that: The inverter channel 1 output power switch K4 and the inverter channel 2 output power switch K5 are interlocked with each other, and only one switch is allowed to be closed at the same time.

5. The dual-channel inverter circuit for a gas turbine black start starter motor according to claim 1, characterized in that: The first motor variable frequency operation switch K6 and the second motor variable frequency operation switch K7 are interlocked with each other, and only one motor is allowed to operate with variable frequency at the same time.

6. A dual-channel inverter circuit for a gas turbine black start starter motor according to claim 1, characterized in that: The motor power frequency operation switch K3 and the first motor variable frequency operation switch K6 are interlocked with each other, and the motor is not allowed to run in parallel at power frequency and variable frequency at the same time.

7. A starting method for a dual-channel inverter circuit for a black start starter motor of a gas turbine according to any one of claims 1 to 6, characterized in that: The following steps are involved: 1) When the black start process starts the first starter motor M1: the switch cabinet switch K1 is closed, and after the switch cabinet switch K1 is detected to be in the closed position, the phase-shifting rectifier transformer inlet switch K2 is closed, the first control unit (S12) controls the first power unit (S11) to start, and closes the inverter channel 1 output power switch K4 and the first motor variable frequency operation switch K6, the output frequency of the inverter circuit increases, and the speed of the first starter motor M1 gradually increases to the working speed; 2) When the frequency converter is required to start the second starter motor M2: after the output frequency of the frequency converter circuit rises to the industrial frequency, the first motor variable frequency operation switch K6 is disconnected, and the motor industrial frequency operation switch K3 is closed, and the first starter motor M1 is operated at the industrial frequency; after the output frequency of the frequency converter circuit drops to 0, the second motor variable frequency operation switch K7 is closed, the output frequency of the frequency converter circuit rises, and the speed of the second starter motor M2 gradually rises to the working speed; 3) When the first power unit (S11) fails, the first control unit (S12) immediately blocks the pulse, and at this time, the output power switch K4 of the inverter channel 1 is opened, and the output power switch K5 of the inverter channel 2 is closed. The second control unit (S22) controls the second power unit (S21) to start working, the output frequency of the inverter circuit increases, and the speed of the second starter motor M2 gradually increases to the working speed.

8. The starting method of the dual-channel inverter circuit for the black start starting motor of a gas turbine according to claim 7 is characterized in that: The inverter channel 1 output power switch K4 and the inverter channel 2 output power switch K5 are interlocked with each other, and only one switch is allowed to be closed at the same time.

9. The starting method of the dual-channel inverter circuit for the black start starting motor of a gas turbine according to claim 7, characterized in that: The first motor variable frequency operation switch K6 and the second motor variable frequency operation switch K7 are interlocked with each other, and only one motor is allowed to operate with variable frequency at the same time.

10. The starting method of the dual-channel inverter circuit for the black start starting motor of a gas turbine according to claim 7, characterized in that: The motor power frequency operation switch K3 and the first motor variable frequency operation switch K6 are interlocked with each other, and the motor is not allowed to run in parallel at power frequency and variable frequency at the same time.

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