CN109412466B - Steam turbine emergency direct-current lubricating oil pump composite start-stop device and control method - Google Patents
Steam turbine emergency direct-current lubricating oil pump composite start-stop device and control method Download PDFInfo
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- CN109412466B CN109412466B CN201811497235.0A CN201811497235A CN109412466B CN 109412466 B CN109412466 B CN 109412466B CN 201811497235 A CN201811497235 A CN 201811497235A CN 109412466 B CN109412466 B CN 109412466B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
- H02P1/16—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
- H02P1/18—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual dc motor
- H02P1/20—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual dc motor by progressive reduction of resistance in series with armature winding
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P3/00—Arrangements for stopping or slowing electric motors, generators, or dynamo-electric converters
- H02P3/06—Arrangements for stopping or slowing electric motors, generators, or dynamo-electric converters for stopping or slowing an individual dynamo-electric motor or dynamo-electric converter
- H02P3/08—Arrangements for stopping or slowing electric motors, generators, or dynamo-electric converters for stopping or slowing an individual dynamo-electric motor or dynamo-electric converter for stopping or slowing a dc motor
- H02P3/12—Arrangements for stopping or slowing electric motors, generators, or dynamo-electric converters for stopping or slowing an individual dynamo-electric motor or dynamo-electric converter for stopping or slowing a dc motor by short-circuit or resistive braking
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Abstract
The utility model provides a compound start-stop device and control method of a turbine emergency direct-current lubricating oil pump, which comprises a main contact module, a BUCK circuit and a current limiting module which are connected in sequence, wherein the main contact module is configured to be used for cutting off or connecting in two direct-current buses so as to cut off or connect in direct-current voltage; the BUCK circuit comprises three parts, wherein the first part is a parallel connection structure of a direct current contactor and a power electronic switch, the parallel connection structure is connected to a certain direct current bus, the second part is a series connection structure of a fuse and a freewheeling diode, and the series connection structure is positioned on one side of the parallel connection structure and connected between two direct current buses in parallel; the third part is a bus capacitor, is arranged on the other side of the parallel structure and is connected between two direct current buses; the current limiting module is arranged on one direct current bus and performs a current limiting function on a load to be connected. The starting and stopping device has the advantages of smooth starting and stopping of the BUCK conversion type direct current motor starting and stopping device, and the overload resistance of the IGBT and the freewheeling diode is greatly improved.
Description
Technical Field
The disclosure relates to a compound starting and stopping device and a control method for a turbine emergency direct-current lubricating oil pump.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The steam turbine set of the power plant is designed with a perfect lubricating oil system, when the factory alternating current or alternating current oil pump fails, the factory direct current power supply system drives the emergency direct current lubricating oil pump to operate, and the oil pressure of the lubricating oil system is maintained, so that the steam turbine is prevented from oil break and tile burning accidents.
As the final emergency oil supply equipment of a turbine bearing, the reliable start and stop of a battery pack-powered crisis direct-current lubricating oil pump is extremely important, the failure rate of a direct-current motor is obviously higher than that of an alternating-current motor due to the existence of a direct-current motor commutator, if the direct-current motor is forcibly started (hard start) without any current-limiting and voltage-limiting measures, a motor loop can generate extremely large current surge and accompanying voltage spike, and all devices, equipment and instruments in the loop face to generate extremely large voltage or current impact, even damage is caused. For starting and stopping a crisis direct-current lubricating oil pump, two solutions are mainly adopted in the existing power plant.
The first scheme is to use a resistance type DC motor soft start device. In the initial stage of starting the direct current motor, the direct current motor is started by using the current limited by the resistor, and the current limiting resistor is short-circuited after the direct current motor is started; when the direct current motor needs to be shut down, the direct current contactor is used for forcibly shutting down (hard shutdown). The scheme has the advantages that the overcurrent resistance of the motor is particularly strong when the motor is started, and the starting current of the motor is limited; the starting current of the motor is still large, and the stored magnetic energy in the motor can cause serious arcing between contacts of the contactor when the motor is forcibly shut down, so that the contacts of the contactor can be seriously burnt and even adhered after a long time.
The second scheme is to use a direct current motor soft start and stop device based on a BUCK conversion circuit (voltage chopping technology). Wherein the BUCK conversion circuit includes two core power electronic switches (a main switch IGBT and a motor freewheeling diode). When the direct current motor is started, the duty ratio of the IGBT is gradually increased from 0 → 1, and the mean value of the armature voltage of the motor is gradually increased from 0 to the direct current bus voltage; when the direct current motor is turned off, the duty ratio of the IGBT is gradually decreased from 1 → 0, and the average value of the armature voltage is gradually decreased from the direct current bus voltage to 0. The scheme realizes smooth start and stop (soft start and stop) of the direct current motor; when the direct current motor is started, the current and voltage impact on instrument equipment (such as a direct current power supply, a contactor, the direct current motor and the like) in the whole loop can be effectively eliminated; when the direct current machine is shut down, the residual magnetic energy of the motor can be safely released. However, the power electronic components (whether IGBTs or freewheeling diodes) have limited voltage/current overload resistance, and are prone to short-circuit failure due to overvoltage or overcurrent (most of high-power electronic devices end up short-circuiting between internal poles when they fail), so that two serious problems can be caused: firstly, if the freewheeling diode is in short circuit, the whole direct current supply loop is in short circuit, and then tripping and power failure are caused, so that oil cut and tile burning accidents of a turbine bearing are caused; second, when the IGBT is shorted, the dc oil pump is hard started and the dc motor cannot be shut down.
Of course, there is also a parallel connection scheme of the two (resistance type and BUCK conversion type) dc motor soft start-stop devices mentioned in patent CN104707425A, a dual-motor parallel connection device of emergency dc oil pump starter in power plant and its control method. The scheme can increase the reliability of the direct current motor starting and stopping device to a certain extent. The working logic of the parallel direct current motor start-stop device is as follows: under normal conditions, the BUCK conversion type soft start-stop device is responsible for starting and stopping the emergency direct-current lubricating oil pump; when the device breaks down, the device is automatically switched to a resistance type direct current motor starting and stopping device. This solution still has the following problems: firstly, if the BUCK conversion fails and causes the circuit fuse to be blown, the parallel resistance type motor starting and stopping device is automatically started immediately, the delay of the process is generally about hundreds of milliseconds at least, and the delay is too long for the lubricating oil system of the steam turbine set of some brands (such as a western house); secondly, if the BUCK conversion breaks down, the circuit fuse is not fused, the direct current motor can be directly and hard started, the input of the parallel resistance type starting and stopping device loses significance, and under the condition, the two parallel resistance type starting and stopping devices can not be normally powered off. In addition, the scheme does not solve the problem that the power electronic switch is fragile and easy to burn out short circuit due to overvoltage or overcurrent.
Disclosure of Invention
The invention provides a composite starting and stopping device and a control method for a turbine emergency direct-current lubricating oil pump in order to solve the problems.
According to some embodiments, the following technical scheme is adopted in the disclosure:
the utility model provides a compound device that stops of steam turbine emergency direct current lubricating oil pump, is including the main contact module, BUCK circuit and the current-limiting module that connect gradually, wherein:
the main contact module is configured to cut off or switch in two direct current buses so as to cut off or switch in direct current voltage;
the BUCK circuit comprises three parts, wherein the first part is a parallel connection structure of a direct current contactor K2 and a power electronic switch Q1, the parallel connection structure is connected to a certain direct current bus, the second part is a series connection structure of a fuse F1 and a freewheeling diode D1, and the series connection structure is positioned on one side of the parallel connection structure and connected between the two direct current buses in parallel; the third part is a bus capacitor C1 which is arranged on the other side of the parallel structure and is connected between two direct current buses;
the current limiting module is arranged on one branch bus and is configured to perform a current limiting function on a load to be connected.
By way of further limitation, the main contact module is a direct current contactor K1 controlled by a power-off delay relay, wherein K1-1 and K1-2 are main contacts of the direct current contactor, K1-1 is used for cutting off or switching on a positive bus, K1-2 is used for cutting off or switching on a negative bus, and the direct current contactor K1 is configured to pull in normally open contacts K1-1 and K1-2 immediately when a control signal is generated; when the control signal disappears, the K1-1 and the K1-2 are released in a time delay of T seconds, and the time delay is adjustable.
By way of further limitation, the series arrangement is connected between positive and negative bus bars, with the anode of the freewheeling diode D1 connected to the positive bus bar if the freewheeling diode D1 is on, and the cathode of the freewheeling diode D1 connected to the negative bus bar otherwise.
By way of further limitation, the bus capacitor C1 acts as a filter and is connected between the positive and negative buses.
As a further limitation, the current limiting module is a parallel structure including a dc contactor K3 and a power resistor R1, the parallel structure is connected in series to the positive bus or the negative bus, and the value range of the power resistor R1 is 3% to 10% of the equivalent resistance of the load to be connected.
By way of further limitation, the direct current contactor K2 is a direct current contactor controlled by an electrified delay relay, the action logic of the direct current contactor is configured to delay the normally open contact to be closed for N seconds when a control signal is generated, and the delay is adjustable; when the control signal disappears, the normally open contact of the control signal is released immediately.
By way of further limitation, the direct current contactor K3 is a direct current contactor controlled by an electrified delay relay, the action logic of the direct current contactor is configured to delay the normally open contact to close for S seconds when a control signal is generated, and the delay is adjustable; when the control signal disappears, the normally open contact of the control signal is released immediately.
The starting control method based on the starting and stopping device comprises the following steps:
after a remote or local starting command is sent out, two normally open contacts K1-1 and K1-2 of the direct current contactor K1 are attracted immediately, the direct current contactors K2 and K3 are kept in an open-circuit state, and the power electronic switch Q1 is kept in a closed-circuit state;
the power electronic switch Q1 does not perform on/off action under the control of the PWM control signal, the duty ratio thereof is gradually changed from 0 to 1, and the full-off state is gradually transited to the full-on state, the equivalent resistance thereof gradually decreases from approaching infinity to 0, so that the voltage at the load end and the terminal voltage of the current limiting resistor R1 are also gradually increased from zero;
after the power electronic switch Q1 is transited to a full-conducting state, the power electronic switch Q1 is attracted by the contactor K2 at another moment, the power electronic switch Q1 is short-circuited by the K2, and all current passes through the K2 contact;
and the direct current contactor K3 pulls in at the later moment.
As a further limitation, when the power electronic switch Q1 has a fault and is short-circuited, the startup control process is equivalent to the startup process of a resistance-type dc motor start-stop device, the current limiting resistor of the device is R1, and the current limiting time S is adjustable.
As a further limitation, when the power electronic switch Q1 fails and opens, the startup control process is equivalent to that a resistance-type dc motor startup device is started after delaying S seconds, and the current limiting time of the current limiting resistor R1 is S-N seconds, which is adjustable.
The shutdown control method based on the start-stop device comprises the following steps:
after a shutdown instruction is sent remotely or locally, normally open contacts of the direct current contactors K2 and K3 are released immediately; at the moment, the voltage at the load end is decreased in a step manner, the terminal voltage of the power resistor R1 generates a small step increase from zero, and the increase of the voltage is equal to the decrease of the voltage;
the power electronic switch Q1 continuously performs on/off action under the control of the PWM control signal, the duty ratio thereof gradually changes from 1 to 0, the full on state gradually transits to the full off state, and the equivalent resistance thereof gradually increases from 0 Ω to approaching infinity; meanwhile, the voltage of the load end and the terminal voltage of the current limiting resistor R1 also gradually drop to 0;
after the power electronic switch Q1 is transited to a full-off state, the direct-current contactor K1 is released at another moment, the shutdown process is finished, and the load end is cut off from the circuit.
As a further limitation, when the power electronic switch Q1 has a fault and is short-circuited, the process is equivalent to the shutdown process of a resistance-type dc motor start-stop device, the current limiting resistance of the device is R1, and the current limiting time T is adjustable.
By way of further limitation, when the power electronic switch Q1 fails open, the shutdown process is a forced shutdown process.
Compared with the prior art, the beneficial effect of this disclosure is:
1. because the resistance type and BUCK conversion type direct current motor start-stop device is cascaded in the circuit structure, the device disclosed by the invention is ensured that the loop impedance characteristic is basically equal to the loop impedance characteristic of the BUCK conversion type device when the device is started and stopped, namely the loop resistance is gradually changed from large to small or from small to large, and the smooth start and stop of the motor are realized.
2. Since the resistance type and BUCK conversion type direct current motor starting and stopping devices are cascaded on the circuit structure, the contact points of three contactors K1/K2/K3 of the device disclosed by the disclosure can be disconnected with zero current; considering that most faults of the contactor are caused by flashover generated by inductive current of a loop when the contact is cut off, the zero-current turn-off of the contactor in the device disclosed by the disclosure completely eliminates the problem of contact flashover, thereby greatly prolonging the service life of the contactor and substantially improving the reliability, service life and safety level of the device disclosed by the disclosure.
3. Because the resistance type and BUCK conversion type direct current motor start-stop device are cascaded on a circuit structure, when a power electronic switch Q1 works, a current-limiting resistor R1 is connected in series in a loop, so that the peak value of transient current and voltage generated when the Q1 is switched is obviously reduced, the reliability of Q1 is greatly improved, and the reliability, the service life and the safety level of the device are substantially improved.
4. In the device disclosed by the invention, although the resistance type and BUCK conversion type direct current motor starting and stopping devices are cascaded in a circuit structure, the resistance type and BUCK conversion type direct current motor starting and stopping devices are connected in parallel in operation logic, so that even if the relatively fragile BUCK conversion type direct current motor starting and stopping devices fail accidentally, the device disclosed by the invention still finishes starting and stopping of the direct current motor as usual, and only operates in the mode of the resistance type direct current motor starting and stopping devices, and the reliability and the safety level of the device disclosed by the invention are improved due to the parallel mode in operation logic.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.
FIG. 1 is a block diagram of an apparatus of the present disclosure;
FIG. 2 is a schematic diagram illustrating a boot process of the apparatus of the present disclosure;
FIG. 3 is a schematic diagram of the apparatus shutdown process of the present disclosure;
FIG. 4 is a schematic diagram of the boot process of the present disclosure when Q1 is shorted by a fault;
FIG. 5 is a schematic diagram of the shutdown process of the present disclosure when Q1 fault is shorted;
FIG. 6 is a schematic diagram of the boot process of the present disclosure when Q1 fails open;
FIG. 7 is a schematic diagram of the shutdown process of the present disclosure when Q1 fails open;
the specific implementation mode is as follows:
the present disclosure is further described with reference to the following drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
In the present disclosure, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only relational terms determined for convenience in describing structural relationships of the parts or elements of the present disclosure, and do not refer to any parts or elements of the present disclosure, and are not to be construed as limiting the present disclosure.
In the present disclosure, terms such as "fixedly connected", "connected", and the like are to be understood in a broad sense, and mean either a fixed connection or an integrally connected or detachable connection; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present disclosure can be determined on a case-by-case basis by persons skilled in the relevant art or technicians, and are not to be construed as limitations of the present disclosure.
The steam turbine emergency direct current lubricating oil pump start-stop device that this embodiment provided is the ingenious integration of a resistance-type direct current motor start-stop device and the soft start-stop device of BUCK transform formula direct current motor, and both are cascaded on circuit structure to a bus master switch K1 is shared.
Specifically, as shown in fig. 1, a compound start-stop device of an emergency direct-current lubricating oil pump of a steam turbine comprises: the main contactor module, the BUCK conversion circuit module and the current limiting resistance module are cascaded in the sequence shown in figure 1.
The main contactor module is a direct current contactor K1, wherein K1-1 and K1-2 are main contacts of the direct current contactor, K1-1 is used for cutting off or switching on a bus marked with a mark of "+" in the figure, and K1-2 is used for cutting off or switching on a bus marked with a mark of "-" in the figure.
The BUCK conversion circuit module is a BUCK conversion circuit unit; the module comprises the following three parts. The first part is a parallel structure of a direct current contactor K2 and a power electronic switch Q1; the parallel structure can be connected with the bus marked with a plus sign in series as shown in the figure, and can also be connected with the bus marked with a minus sign in series, and meanwhile, the positions of Q1 and K2 can be interchanged up and down. The second part is a series structure of a fuse F1 and a freewheeling diode D1; the series arrangement is located to the right of the parallel arrangement of K2 and Q1, connected between the bus bars "+" and "-"; if D1 is on, the anode of D1 is connected to the bus "+", and if F1 is on, the cathode of D1 is connected to the bus "-". The third part is a bus capacitor C1 which plays a role of filtering and is positioned at the left side of the parallel structure of the K2 and the Q1 and is connected between the bus bar "+" and the bus bar "-", and the positive pole of the third part is connected with the bus bar "+".
The current limiting resistor module is a parallel structure of a direct current contactor K3 and a power resistor R1; the parallel structure can be connected in series with a bus "-" as shown in the figure, and can also be connected in series with a bus "+", and the bus "-" and the bus "+" are equivalent in circuit function; wherein R1 should be in the range of RLThe resistance value is between 3 and 10 percent.
The direct current motor M1 is a rear turbine emergency direct current lubricating oil pump (direct current motor load); considering that its field winding is not relevant to the present disclosure, only the armature winding of M1 is drawn in the figure in relation to the present disclosure; for convenience, the actual output of M1 at runtime is defined hereinEquivalent resistance corresponding to power is RL。
The power electronic switch Q1 is a full-control electronic device IGBT, and the control signal is a PWM pulse signal with adjustable duty ratio, which can be realized by a special PWM pulse generating circuit and a small MCU system through programming.
The series circuit structure of the fuse F1 and the freewheeling diode D1 is a freewheeling circuit of a rear direct-current lubricating oil pump M1, and a freewheeling loop is provided for M1 when Q1 is turned off; when the D1 is short-circuited due to overcurrent or overvoltage, the fuse F1 is blown to prevent the whole loop from being broken down due to short circuit.
The disclosed direct current contactor K1 is a direct current contactor controlled by a power-off delay relay, the K1 comprises two main contacts K1-1 and K1-2, and the action logic of the K1 is as follows: when the control signal is generated, the normally open contacts K1-1 and K1-2 are immediately attracted; when the control signal disappears, the K1-1 and the K1-2 are released in a time delay of T seconds, and the time delay is adjustable.
The direct current contactor K2 is a direct current contactor controlled by an electrified delay relay, and the action logic of the direct current contactor is as follows: when the control signal is generated, the normally open contact is delayed for N seconds to be closed, and the delay is adjustable; when the control signal disappears, the normally open contact of the control signal is released immediately.
The direct current contactor K3 is a direct current contactor controlled by an electrified delay relay, and the action logic of the direct current contactor is as follows: when the control signal is generated, the normally open contact is closed in a delayed way for S seconds, and the delay is adjustable; when the control signal disappears, the normally open contact of the control signal is released immediately.
The control system of the DC contactor K1/K2/K3 and the control system of the Q1 are independent from each other, and only have time sequence connection and no logic connection.
The control method and the process of the compound starting and stopping device of the turbine emergency direct-current lubricating oil pump are as follows:
1. boot process (as shown in fig. 2):
A. after a power-on command (high level in the figure) is sent remotely or locally, the two normally open contacts K1-1 and K1-2 of the contactor K1 are attracted immediately (low level in the figure); at this time, the contactors K2 and K3 are still open, and the power electronic switch Q1 is still off.
B. Then Q1 does not perform on/off action under the control of PWM control signal, and the duty ratio gradually changes from 0 → 1, and gradually changes from the full-off state to the full-on state, and the equivalent resistance gradually decreases from about ∞ to 0 Ω; the armature voltage of the M1 and the terminal voltage of the current limiting resistor R1 are gradually increased from zero.
C. After Q1 is transited to a full-conduction state, the contactor K2 is closed at the time of t 1; at this time, Q1 is short-circuited by K2 and the current is all passed through the K2 contact.
D. When the contactor K3 is closed at the time of t2, the armature voltage of M1 generates a small step rise, and the rise amplitude can be calculated through the value of R1.
Shutdown procedure (as shown in fig. 3):
A. after a shutdown command is sent remotely or locally, normally open contacts of the contactors K2 and K3 are released immediately; at this time, the armature voltage of M1 will have a small step-down, and the terminal voltage of R1 will have a small step-up from zero, with the step-up being equal to the step-down.
B. Then Q1 does not perform on/off action under the control of PWM control signal, and the duty ratio gradually changes from 1 → 0 to the full-on state and gradually changes to the full-off state, and the equivalent resistance gradually increases from 0 omega to nearly infinity; at the same time, the armature voltage of M1 and the terminal voltage of the current limiting resistor R1 also gradually drop to 0.
C. After the Q1 is transited to the full-off state, K1 is released by the time point t1, the shutdown process is finished, and M1 is cut off from the circuit.
Boot-up procedure when Q1 fault shorts (as shown in fig. 4):
q1 is an IGBT, and is susceptible to internal short circuits when overvoltage or overcurrent occurs. Assuming that Q1 is short-circuited (worst case) at time t0, the device of the present disclosure is turned on as shown in fig. 4 and described as follows:
A. after a power-on command is sent remotely or locally, the normally open contacts K1-1 and K1-2 of the contactor K1 are immediately attracted.
B. The Q1 loses the linear voltage regulation function due to short circuit, and then the armature voltage of the M1 generates step-like sudden rise, but the starting current of the M1 is limited by the R1 in the process, and the larger the R1 is, the smaller the peak value is.
C. After S seconds, at the time t1, the contactor K2 is closed, Q1 is short-circuited, and all current flows through the K2.
D. The contactor K3 is attracted at the time of t2, the armature voltage of M1 generates a small step rise along with the attraction, and the rise amplitude can be calculated through the value of R1; the entire boot process is complete.
It can be seen that when Q1 is short-circuited, the device disclosed in the present disclosure no longer has a soft start function with gradually rising voltage when starting up, which is equivalent to a start-up process of a resistance-type dc motor start-stop device, and at this time, the current-limiting resistance of the device is R1, and the current-limiting time S is adjustable.
Shutdown procedure when Q1 fault short (as shown in fig. 5):
still assuming the worst case scenario (Q1 has been shorted by a fault since time t 0), the shutdown process of the apparatus of the present disclosure is illustrated in fig. 5 as follows:
A. when a shutdown command is remotely or locally sent, the normally open contacts of the contactors K2 and K3 are immediately released, the armature voltage of M1 is reduced in a small step, and the terminal voltage of R1 is increased in a constant step.
B. After T seconds, Q1 loses its voltage regulation effect due to short circuit, and the armature voltage of M1 will remain stable.
C. Until the time K1 is released at t1, M1 is forcibly turned off, and residual magnetic energy is gradually released after freewheeling through F1 and D1; by this time the entire shutdown process is over, M1 is completely cut out of the circuit.
It can be seen that when Q1 is short-circuited, the device disclosed by the present disclosure no longer has a soft stop function of voltage gradual decrease when the device is turned off, which is equivalent to a turn-off process of a resistance-type dc motor start-stop device, and at this time, the current-limiting resistance of the device is R1, and the current-limiting time T is adjustable.
Boot process when Q1 fails open (as shown in fig. 6):
q1 rarely exhibits an open circuit condition, but is listed as a fault condition. Still assuming the worst case scenario, the boot process of the device according to the present disclosure is illustrated in fig. 6, which is explained as follows:
A. after a remote or local starting command is sent, the two normally open contacts K1-1 and K1-2 of the contactor K1 are immediately attracted.
B. The armature of the M1 remains open for the next S seconds due to the Q1 opening, corresponding to the device being turned on for S seconds.
C. And (3) closing the contactor K2 at the time of t1, short-circuiting the Q1 by the K2, generating step sudden change of the armature voltage and current of the M1, and limiting the starting current by the resistance value of the R1.
D. When the power is switched on at the time K3 of t2, the armature voltage of M1 slightly rises, and the rising amplitude can be calculated through the value of R1, so that the whole shutdown process is finished.
It can be seen that when Q1 is open, the device of the present disclosure, when starting up, is equivalent to a resistor-type dc motor starting device starting up after delaying S seconds, and the current limiting time of the current limiting resistor R1 of the device is S-N seconds, the current limiting time is still adjustable.
Shutdown procedure when Q1 fails open (as shown in fig. 7):
still assuming the worst case scenario, the shutdown process of the apparatus of the present disclosure is illustrated in fig. 7 as follows:
A. after a shutdown command is sent remotely or locally, normally open contacts of the contactors K2 and K3 are released immediately; since Q1 has been opened, M1 is directly forced to power down, and the series connection of D1 and F1 is responsible for the subsequent freewheeling operation of M1.
B. And releasing at a time K1 at T1 after T seconds, and finishing the whole shutdown process.
It can be seen that when Q1 is open, the shutdown process of the apparatus of the present disclosure is a forced shutdown process.
When the F1 fault opens, its power-on process and power-off process:
when the F1 is blown out due to the short circuit of the D1, the Q1 in the device of the present disclosure is determined to be broken down by the induced high voltage at the moment of turning off because there is no free-wheeling path, so once the F1 is opened, the device of the present disclosure is determined to be only a resistance-type dc motor start-stop device, and the start-up process and the shut-down process are the same as those in fig. 6 and fig. 7.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Although the present disclosure has been described with reference to specific embodiments, it should be understood that the scope of the present disclosure is not limited thereto, and those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure.
Claims (7)
1. The utility model provides a compound device that opens and stops of steam turbine emergency DC lubricating-oil pump which characterized by: including the main contact module, BUCK circuit and the current-limiting module that connect gradually, wherein:
the main contact module is configured to cut off or switch in two direct current buses so as to cut off or switch in direct current voltage;
the BUCK circuit comprises three parts, wherein the first part is a parallel connection structure of a direct current contactor K2 and a power electronic switch Q1, the parallel connection structure is connected to a certain direct current bus, the second part is a series connection structure of a fuse F1 and a freewheeling diode D1, and the series connection structure is positioned on one side of the parallel connection structure and connected between the two direct current buses in parallel; the third part is a bus capacitor C1 which is arranged on the other side of the parallel structure and is connected between two direct current buses;
the current limiting module is arranged on one direct current bus and is configured to perform a current limiting function on a load to be connected;
the direct current contactor K2 is a direct current contactor controlled by an electrified delay relay, the action logic of the direct current contactor is configured to be that when a control signal is generated, a normally open contact of the direct current contactor is pulled in a delayed manner for N seconds, and the delay is adjustable; when the control signal disappears, the normally open contact is released immediately;
the main contact module is a direct current contactor K1 controlled by a power-off delay relay, wherein K1-1 and K1-2 are main contacts of the direct current contactor, K1-1 is used for cutting off or switching on a positive bus, K1-2 is used for cutting off or switching on a negative bus, and the direct current contactor K1 is configured to pull in normally open contacts K1-1 and K1-2 immediately when a control signal is generated; when the control signal disappears, the K1-1 and the K1-2 are released in a time-delay T second mode, and the time delay is adjustable;
the current limiting module is of a parallel structure comprising a direct current contactor K3 and a power resistor R1, the parallel structure is connected in series with a positive bus or a negative bus, and the value range of the power resistor R1 is 3% -10% of the equivalent resistance of a load to be connected;
when a power-on command is sent remotely or locally, the two normally open contacts K1-1 and K1-2 of the direct current contactor K1 are attracted immediately, the direct current contactors K2 and K3 are kept in an open-circuit state, and the power electronic switch Q1 is kept in a turn-off state; the power electronic switch Q1 does not perform on/off action under the control of the PWM control signal, the duty ratio thereof is gradually changed from 0 to 1, and the full-off state is gradually transited to the full-on state, the equivalent resistance thereof gradually decreases from approaching infinity to 0, so that the voltage at the load end and the terminal voltage of the current limiting resistor R1 are also gradually increased from zero; after the power electronic switch Q1 is transited to a full-conducting state, the power electronic switch Q1 is attracted by the contactor K2 at another moment, the power electronic switch Q1 is short-circuited by the K2, and all current passes through the K2 contact; and the direct current contactor K3 pulls in at the later moment.
2. The compound starting and stopping device of the turbine emergency direct-flow lubricating oil pump as claimed in claim 1, characterized in that: the series structure is connected between the positive bus and the negative bus, if the freewheeling diode D1 is on, the cathode of the freewheeling diode D1 is connected with the positive bus, otherwise, the anode of the freewheeling diode D1 is connected with the negative bus.
3. The compound starting and stopping device of the turbine emergency direct-flow lubricating oil pump as claimed in claim 1, characterized in that: the direct current contactor K3 is a direct current contactor controlled by an electrified delay relay, the action logic of the direct current contactor is configured to be that when a control signal is generated, a normally open contact of the direct current contactor is pulled in by delaying for S seconds, and the delay is adjustable; when the control signal disappears, the normally open contact of the control signal is released immediately.
4. A start-up control method based on the start-up and stop device according to any one of claims 1 to 3, characterized in that: the method comprises the following steps:
after a remote or local starting command is sent out, two normally open contacts K1-1 and K1-2 of the direct current contactor K1 are attracted immediately, the direct current contactors K2 and K3 are kept in an open-circuit state, and the power electronic switch Q1 is kept in a closed-circuit state;
the power electronic switch Q1 does not perform on/off action under the control of the PWM control signal, the duty ratio thereof is gradually changed from 0 to 1, and the full-off state is gradually transited to the full-on state, the equivalent resistance thereof gradually decreases from approaching infinity to 0, so that the voltage at the load end and the terminal voltage of the current limiting resistor R1 are also gradually increased from zero;
after the power electronic switch Q1 is transited to a full-conducting state, the power electronic switch Q1 is attracted by the contactor K2 at another moment, the power electronic switch Q1 is short-circuited by the K2, and all current passes through the K2 contact;
and the direct current contactor K3 pulls in at the later moment.
5. The power-on control method according to claim 4, wherein: when the power electronic switch Q1 has a fault and is short-circuited, the starting-up control process is equivalent to the starting-up process of a resistance type direct current motor starting and stopping device, the current limiting resistance of the device is R1 at the moment, and the current limiting time S is adjustable;
or, when the power electronic switch Q1 is open due to a fault, the power-on control process is equivalent to the power-on of a resistance-type dc motor starting device after the delay of S seconds, and the current-limiting time of the current-limiting resistor R1 is S-N seconds, which is adjustable.
6. A method for controlling the shutdown of a start-stop arrangement according to any of claims 1 to 3, characterized by: the method comprises the following steps:
after a shutdown instruction is sent remotely or locally, normally open contacts of the direct current contactors K2 and K3 are released immediately; at the moment, the voltage at the load end is decreased in a step manner, the terminal voltage of the power resistor R1 generates a small step increase from zero, and the increase of the voltage is equal to the decrease of the voltage;
the power electronic switch Q1 continuously performs on/off action under the control of the PWM control signal, the duty ratio thereof gradually changes from 1 to 0, the full on state gradually transits to the full off state, and the equivalent resistance thereof gradually increases from 0 Ω to approaching infinity; meanwhile, the voltage of the load end and the terminal voltage of the current limiting resistor R1 also gradually drop to 0;
after the power electronic switch Q1 is transited to a full-off state, the direct-current contactor K1 is released at another moment, the shutdown process is finished, and the load end is cut off from the circuit.
7. The power-off control method according to claim 6, wherein: when the power electronic switch Q1 has a fault and is short-circuited, the fault is equivalent to the shutdown process of a resistance type direct current motor starting and stopping device, the current limiting resistance of the device is R1, and the current limiting time T is adjustable;
alternatively, when the power electronic switch Q1 fails open, the shutdown process is a forced shutdown process.
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| CN201811497235.0A CN109412466B (en) | 2018-12-07 | 2018-12-07 | Steam turbine emergency direct-current lubricating oil pump composite start-stop device and control method |
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| CN201811497235.0A CN109412466B (en) | 2018-12-07 | 2018-12-07 | Steam turbine emergency direct-current lubricating oil pump composite start-stop device and control method |
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| CN110071664B (en) * | 2019-04-17 | 2020-09-22 | 辽宁石油化工大学 | Braking device and method for direct current motor with constant current and controllable falling speed |
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| DE102005060859A1 (en) * | 2005-12-20 | 2007-06-28 | Robert Bosch Gmbh | Method and device for controlling an electric motor |
| CN103560677A (en) * | 2013-10-25 | 2014-02-05 | 南京航空航天大学 | High-voltage direct-current power distribution unit and control method thereof |
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| CN208046489U (en) * | 2018-01-04 | 2018-11-02 | 陕西意联电气设备有限公司 | A kind of direct current oil pump soft starting device of none-disk terminal contactor |
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