Low oil pressure self-starting platen regulating system for control circuit of direct current oil pump motor of power plant

Abstract

The application discloses a power plant DC oil pump motor control loop low oil pressure self-starting pressure plate adjusting system and particularly relates to the field of DC oil pump pressure plate adjusting, which comprises a pressure plate state monitoring module, a working condition decision module, a soft start execution module, a hard start straight-through module and a transient protection module. The power plant DC oil pump motor control loop low oil pressure self-starting pressure plate adjusting system realizes forced locking when the pressure plate has not been withdrawn through the pressure plate state monitoring module, avoids the risk that the armature winding bears full pressure impact and counter electromotive force impact when the IGBT is not ready; distinguishes the soft start and the hard start through the working condition decision module, avoids the response lag of a single soft start strategy in an emergency; and through the PID control algorithm of the soft start execution module, the IGBT conduction angle climbing rate is dynamically adjusted, the contactor time sequence is switched through the programmable timer control, the motor current is smoothly and gradually climbed, the bus voltage is stabilized, and the current impact and the counter electromotive force influence in the starting process are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of direct current oil pump pressure plate adjustment, and more particularly to a low-oil-pressure self-starting pressure plate adjustment system for a motor control circuit of a direct current oil pump of a power plant. BACKGROUND

[0002] With the increasing requirements of safety and transient stability of large generator sets for power supply, the anti-impact capability of the control circuit is particularly important. The traditional technology adopts a series resistance starting architecture based on a contactor switching, which is composed of an excitation winding contactor, an armature winding contactor, an IGBT module and a low-oil-pressure signal circuit. The current is slowly raised by adjusting the IGBT conduction angle through a controller. However, when the power is first supplied, the controller self-checking time is greater than or equal to 5 seconds and the oil pressure signal is directly connected, which causes the armature winding to be forced to start when the IGBT is not ready, resulting in frequent sticking and burning of the excitation winding contactor, which threatens the entire power distribution system.

[0003] To solve the problem of contactor burning caused by traditional series resistance starting, the current industry has developed an IGBT chopper soft starting technology without a bypass contactor. The technology uses a high-power power semiconductor device IGBT and a high-frequency chopper voltage reduction technology to start and stop the direct current oil pump without impact. After the starting is completed, the starting process is completed through the direct connection of the IGBT, the traditional direct connection contactor is cancelled, the failure rate of the contactor is reduced, the maintenance amount and failure rate are reduced, and the stability and reliability of the system are increased.

[0004] However, when actually used, it still has some disadvantages. For example, the low-oil-pressure signal can directly trigger the chopper circuit during the controller self-checking stage, causing the armature winding to withstand full pressure impact when the IGBT is not ready, resulting in back electromotive force impact and potential risk of bus voltage collapse. The single soft starting strategy cannot distinguish between the first start after maintenance and the emergency start in an accident, and the forced soft starting delay may exacerbate the consequences of unit accidents in emergency situations. Therefore, the present application proposes a low-oil-pressure self-starting pressure plate adjustment system for a motor control circuit of a direct current oil pump of a power plant to solve the above-mentioned residual problems. SUMMARY

[0005] In order to overcome the above-mentioned defects of the prior art, the present application provides a low-oil-pressure self-starting pressure plate adjustment system for a motor control circuit of a direct current oil pump of a power plant, which solves the problems raised in the background art by the following scheme.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] The low-oil-pressure self-starting pressure plate adjustment system for a motor control circuit of a direct current oil pump of a power plant comprises:

[0008] The pressure plate state monitoring module is configured to acquire the on-off state of the pressure plate in the control loop in real time through the voltage sensor and convert the on-off state into a digital signal to output a first adjustment state signal.

[0009] The working condition decision module is configured to execute a decision-making mechanism based on the combination logic of the first adjustment state signal and output a second adjustment state signal.

[0010] The soft start execution module is configured to execute a first start mechanism in a progressive time sequence in response to a soft start instruction in the second adjustment state signal.

[0011] The hard start straight-through module is configured to forcibly short the pressure plate path and execute a second start mechanism in response to a hard start instruction in the second adjustment state signal.

[0012] The transient protection module is configured to activate a transient voltage suppression circuit synchronously when any module triggers the main loop contactor to act, and forcibly turn off the power switch element when it is monitored that the bus voltage exceeds a safety threshold.

[0013] Preferably, the pressure plate state monitoring module acquires the first adjustment state signal, specifically including:

[0014] a voltage sensor having an input end connected in parallel to the contact points of the pressure plate, configured to convert the resistance state between the contact points into a voltage signal in real time; and

[0015] a voltage comparator circuit having an input end connected to the output end of the voltage sensor, configured to compare the voltage signal with a preset voltage threshold and generate the first adjustment state signal.

[0016] When the contact points present a high resistance state greater than 10 , the voltage comparator circuit outputs logic “1” as the first adjustment state signal to represent that the pressure plate is in an exit state; when the contact points present a conduction state less than 100 , the voltage comparator circuit outputs logic “0” as the first adjustment state signal to represent that the pressure plate is in a non-exit state.

[0017] Preferably, the working condition decision module executes a decision-making mechanism, specifically including:

[0018] acquiring a voltage signal proportional to the oil pressure change rate through a differential circuit;

[0019] acquiring a digital value representing the oil pressure change rate through an analog-to-digital converter;

[0020] The digital value is compared with an oil pressure threshold preset as 0.5 MPa / ms, and when the digital value exceeds the oil pressure threshold, it is determined that the emergency working condition occurs, and the hard start instruction is generated.

[0021] Preferably, the soft start execution module, the first start mechanism includes IGBT conduction angle slow rise and timing control, specifically including:

[0022] The IGBT conduction angle slow rise adopts a PID control algorithm, and at the starting moment of soft start, the initial conduction angle of IGBT is set as ;

[0023] Timing control is realized by a programmable timer, and the adjustable range of the programmable timer is 1-10 seconds.

[0024] Preferably, the soft start execution module, the PID control algorithm specifically includes:

[0025] In the slow rise process, the bus voltage fluctuation value As the calculation formula of the dynamic control target of the PID control algorithm, it is specifically expressed as:

[0026] ,

[0027] Among them, is expressed as the conduction angle of the IGBT applied by the controller at the moment , is expressed as the fluctuation difference value between the actual bus voltage at the moment and the reference target voltage , , , , respectively represent the proportional, integral, and differential coefficients of the PID controller, is expressed as the moment , and the index in the integral.

[0028] Preferably, the soft start execution module, the timing control is based on the double triggering conditions of time and current stability, and executes the timing switching process of the contactor, which is specifically expressed as:

[0029] ,

[0030] Among them, is expressed as the starting time of the soft start process, is expressed as the adjustable minimum delay time, is expressed as the second derivative of the current.

[0031] Preferably, the hard start-through module, performing the second start mechanism, specifically includes:

[0032] An electromagnetic relay, the control end of the coil of which is electrically connected with the output end of the hard start instruction, and the normally open contact of which is connected in parallel at both ends of the pressure plate, for forcibly short-circuiting the pressure plate when the hard start instruction is received; and

[0033] A contactor driving circuit, the output end of which is directly electrically connected with the coil of the main circuit contactor, and the activation path of which is configured to be independent of the conventional self-checking logic of the controller.

[0034] Preferably, the transient protection module is configured to include:

[0035] Comparing the preset safety threshold with the real-time monitored bus voltage;

[0036] The safety threshold is set to be ; and,

[0037] When the bus voltage exceeds the range defined by the safety threshold, a signal for shutting off the IGBT gate is generated and output.

[0038] The technical effects and advantages of the present application are:

[0039] 1. The present application realizes forced locking when the pressure plate has not been exited by real-time acquisition of the pressure plate on-off state by the pressure plate state monitoring module, generation of a logic signal, and forced cutting off of the oil pressure signal, prevents the low oil pressure signal from being directly connected to the chopping circuit during the self-checking period of the controller, and avoids the risk of the armature winding being subjected to full pressure impact and counter electromotive force impact when the IGBT is not ready;

[0040] 2. The present application distinguishes between soft start and hard start by checking the precondition and monitoring the oil pressure change rate through the working condition decision module, and avoids the response delay of a single soft start strategy in an emergency;

[0041] 3. The present application realizes smooth and progressive climbing of the motor current by dynamically adjusting the IGBT conduction angle climbing rate through the PID control algorithm of the soft start execution module, programmable timer control contactor timing switching, stabilizes the bus voltage, and reduces the current impact and counter electromotive force influence during the start-up process. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 A module block diagram of the low oil pressure self-starting pressure plate adjustment system of the power plant DC oil pump motor control circuit according to the embodiment of the present application is provided.

[0043] Figure 2 A multi-working condition judgment flowchart of the decision judgment mechanism in the working condition decision module according to the embodiment of the present application is provided. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0045] The terms used in the following embodiments of the present application are only for the purpose of describing the specific embodiments, and are not intended to be limiting to the present application. As used in the specification, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "and / or" as used herein refer to and encompass any or all possible combinations of one or more of the associated listed items.

[0046] Hereinafter, the terms "first", "second" are only for the purpose of description, and cannot be understood as implying or suggesting relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features, and in the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise specified.

[0047] As shown in the accompanying drawings Figure 1 The low-oil-pressure self-starting platen regulating system of the power plant DC oil pump motor control circuit includes a platen state monitoring module, a working condition decision module, a soft start execution module, a hard start straight-through module, and a transient protection module.

[0048] The platen state monitoring module is configured to collect the on-off state of the platen in the control circuit in real time through a voltage sensor, and convert the on-off state into a digital signal to output a first regulating state signal.

[0049] In the embodiment, the platen state monitoring module monitors the electrical state of the platen in real time by installing voltage sensors on both sides of the platen contacts. When the operator exits the platen according to the procedure, the voltage sensor detects the high-resistance state formed between the contacts and outputs a first regulating state signal with a logic value of "1". Conversely, if the operator forgets this step and the platen is in the on state, a logic "0" is output and a forced lock is immediately triggered, thereby converting the risk point that depends on human memory into a hardware lock mechanism and eliminating the major risk of the oil pressure signal straight-through during the controller self-checking period due to human negligence.

[0050] In one possible implementation, obtaining the first adjustment state signal includes: connecting the input terminal of a voltage sensor in parallel to the contacts of the pressure plate to convert the resistance state between the contacts into a voltage signal in real time; comparing the voltage signal with a preset voltage threshold using a voltage comparator circuit to generate the first adjustment state signal; when the resistance state between the contacts is greater than 10... When the voltage is in a high-impedance state, the voltage comparator circuit outputs a logic "1" as the first adjustment state signal to indicate that the pressure plate is in the disengaged state; when the contact points exhibit a resistance of less than 100... When the voltage comparator circuit is in the on state, it outputs a logic "0" as the first adjustment state signal to indicate that the pressure plate is in the non-removed state.

[0051] It should be noted that the voltage sensor has a range of 0–300. High precision It is responsible for real-time acquisition of the potential difference between the pressure plate contacts; the input terminal of the voltage comparator circuit is connected to the output terminal of the voltage sensor, and is implemented by a voltage comparator, specifically including a resistor voltage divider network and a comparator chip, which is used to convert the voltage analog signal acquired by the sensor into a digital logic signal.

[0052] Specifically, the resistor divider network consists of resistors with a resistance of 10... First resistor With a resistance of 2 The second resistor The first resistor is connected in series. One end serves as the network input, receiving the raw voltage signal output by the sensor. Its other end is connected to the second resistor. One end of the resistor is connected to form voltage divider output node A; the second resistor The other end is connected to the circuit's common ground, GND; to improve signal interference immunity, the capacitance value is 0.1. filter capacitor Connected in parallel to the second resistor The two ends form an RC low-pass filter to filter out high-frequency noise and transient interference superimposed on the signal; the output voltage of the resistor divider network The calculation formula followed is specifically expressed as follows:

[0053] ,

[0054] In this embodiment, when the pressure plate is at a value greater than 10... In the high-resistivity state, the differential pressure monitoring value is ≥220. After being converted by a voltage divider network ≥ 36.67V, exceeding the comparator 5V reference voltage, output logic '1'; when the pressure plate is less than 100 the on-state, the differential pressure monitoring value is ≤2.3, and the voltage division output ≤0.38V, lower than the 5V reference, output logic '0'; the filter capacitor has no attenuation to direct current and power frequency signals, and only suppresses high-frequency interference.

[0055] Optionally, the pressure plate state monitoring module is integrated with a digital isolation circuit composed of an HCPL-3700 optical coupler, and the voltage comparator output is transmitted to the working condition decision module after being isolated by the optical coupler.

[0056] Further, when the voltage comparator fails, its default output is logic '0', which forces the system into a locked state, thereby avoiding potential risks of misoperation.

[0057] Further, the first adjustment state signal is directly connected to the enable end of the working condition decision module in a hardware direct connection manner; when the output logic is '1', the relay K2 will be immediately triggered to act, thereby forcibly cutting off the transmission path of the oil pressure signal at the hardware level, that is, the oil pressure signal channel will also be forced to maintain in an open state during the stage when the controller self-checking is not completed, thereby effectively preventing the oil pressure low signal from directly triggering the chopping circuit when the IGBT is not ready.

[0058] The working condition decision module is configured to execute a decision judgment mechanism based on the combination logic of the first adjustment state signal and output a second adjustment state signal, wherein the second adjustment state signal includes a hard start, a soft start and a lock instruction.

[0059] In this embodiment, the working condition decision module actively checks two prerequisites, i.e., 'the pressure plate state monitoring module output is 1' and 'the controller self-checking is completed'; only when both of them are met at the same time, the instruction is sent to the soft start execution module; at the same time, the emergency judgment ability of the oil pressure change rate is introduced, and once the oil pressure change rate is monitored to exceed 0.5MPa / ms, all the normal logic is skipped, and the hard start is directly triggered, thereby solving the strategic defect of the original scheme in the emergency response lag.

[0060] Specifically, the working condition decision module, when receiving an input signal, solves the risk of self-checking period oil pressure signal straight through by signal preprocessing technology; the first adjustment state signal from the pressure plate state monitoring module is processed through optical coupling isolation and Schmidt trigger shaping to eliminate potential interference in the signal transmission process; the oil pressure rate of change signal is enhanced through a differential amplification circuit, and is converted into a signal reflecting the instantaneous change speed of the oil pressure by combining an RC differential circuit; the controller self-checking state signal is directly input to the general input / output port of the FPGA after level conversion, ensuring accurate alignment with the IGBT readiness time window.

[0061] In one possible implementation, the decision-making mechanism includes: processing an analog signal from an oil pressure sensor through a differential circuit to obtain a voltage signal proportional to the oil pressure rate of change; quantizing the obtained voltage signal through an analog-to-digital converter to obtain a digital value representing the oil pressure rate of change; comparing the digital value with a preset oil pressure threshold of 0.5 MPa / ms, and determining that the emergency working condition occurs and generating the hard start instruction when the digital value exceeds the oil pressure threshold.

[0062] It should be noted that the oil pressure threshold is based on analysis of a large amount of fault recording data, and the oil pressure drop rate under accident working conditions is usually greater than or equal to 0.48 MPa / ms, so the threshold is set to 0.5 MPa / ms, leaving a margin of 0.02 MPa / ms to prevent false triggering.

[0063] Further, by judging whether the oil pressure rate of change is greater than 0.5 MPa / ms, if the condition is met, a hard start instruction is immediately output to deal with emergency accident working conditions; if the oil pressure rate of change does not exceed the oil pressure threshold, it is further judged whether the pressure plate state is "1" and whether the controller self-checking has been completed, and only when both conditions are met, a soft start instruction is output, which is used for the first start after maintenance; in all other scenarios that do not meet the start conditions, the KM33 drive will be forcibly locked and an alarm will be triggered.

[0064] In this embodiment, the working condition decision module outputs different types of instructions according to the decision result, and strictly follows the corresponding output specifications: the hard start instruction is coded as 2'b10 and is output through optical coupling isolation, with a response time less than or equal to 0.5 ms, ensuring instantaneous response in emergency situations; the soft start instruction is coded as 2'b01 and is output through the RS485 / CAN interface, with a response time less than or equal to 1 ms; and the lock instruction is coded as 2'b00 and is output through a hardware dry contact, with a response time less than or equal to 0.1 ms, to achieve the fastest fault isolation.

[0065] The soft start execution module is configured to respond to a soft start instruction in the second adjustment state signal and execute a first start mechanism in a progressive timing relationship:

[0066] In the embodiment, the implementation of the soft start execution module includes dynamically adjusting the climbing rate by bus voltage feedback PID in the IGBT conduction angle slow rising phase, which significantly improves the transient stability; the programmable adaptive delay of the FPGA is used to avoid the counter electromotive force peak of the excitation winding; at the same time, the sequential attraction process of the KM2 / KM1 contactor is optimized by the driving interlocking circuit, which ensures that KM2 is attracted at least 10 ms earlier than KM1, effectively reduces the arc energy by 60%, and prolongs the service life of the contactor.

[0067] Specifically, the soft start execution module responds to the soft start instruction issued by the working condition decision module, realizes the smooth and gradual climbing of the motor current by accurately controlling the conduction angle of the IGBT, and ensures the stability of the bus voltage in the whole starting process. The hardware carrier of the soft start execution module mainly includes an IGBT drive board and a programmable timer with an accuracy of ± 1%, which can be adjusted in the range of 1-10 seconds and is used to accurately control the timing in the starting process.

[0068] In a possible implementation, the IGBT conduction angle slow rising adopts a PID control algorithm, which is configured to set the initial conduction angle of the IGBT to at the starting moment of soft start; and in the whole slow rising process, the bus voltage fluctuation value is taken as the dynamic control target of the PID control algorithm to realize closed-loop adjustment of the conduction angle climbing rate.

[0069] In a possible implementation, the calculation formula of the bus voltage fluctuation value as the dynamic control target of the PID control algorithm is specifically represented as:

[0070] ,

[0071] wherein, represents the conduction angle of the IGBT applied by the controller at the moment , represents the fluctuation difference between the actual bus voltage and the reference target voltage at the moment , , represents the moment , , , PID controller, respectively; the proportional, integral, and differential coefficients of the PID controller in this embodiment can be set to , , .

[0072] It should be noted that the PID control algorithm will immediately respond when a large drop in bus voltage is monitored, i.e. , the output of the PID controller will significantly suppress the climbing rate of the conduction angle ; in this embodiment, when reaches 10 , the climbing rate is dynamically suppressed to , effectively slowing down the impact of the load on the power supply, thereby stabilizing the bus voltage and avoiding system collapse.

[0073] Further, the motor will generate a back electromotive force during the speed climbing process, and by establishing a coupling model of armature current and conduction angle and applying strict constraint conditions, the influence of the back electromotive force is actively suppressed; the instantaneous value of the armature current can be expressed as:

[0074] ,

[0075] wherein, represents the armature resistance, represents the actual bus voltage, represents the motor constant, represents the angular velocity of the motor, represents the conduction angle of the IGBT applied by the controller at the time ; at the same time, in order to achieve smooth starting, the current is subjected to double constraints, including: current amplitude constraint: ; current change rate constraint: .

[0076] In one possible implementation, in order to achieve impact-free switching from soft start to full-pressure straight-through, a double trigger condition based on time and current stability is adopted to execute the timing switching process of the contactor, which is specifically expressed as:

[0077] ,

[0078] wherein, represents the starting time of the soft start process, represents the adjustable minimum delay time, which is set to 5 seconds in this embodiment, represents the second derivative of the current.

[0079] It should be noted that the adjustable minimum delay time It needs to ensure enough time to complete the necessary self-checking procedures, avoiding false triggering caused by incomplete controller self-checking. In a physical sense, it is expressed as the acceleration of current change, and when its absolute value is less than the preset threshold 5A / ms², it indicates that the current has entered a steady growth state, which is the best time to switch.

[0080] Further, the non-impact switching from soft start to full pressure direct-through includes a pre-switching phase, a switching preparation phase, a mode switching phase, and an IGBT off phase; the IGBT conduction angle of the pre-switching phase has reached 80% of the rated value, and the armature current is stable at 128A, ensuring that the motor has entered a stable running state; the programmable timer KTI of the switching preparation phase starts a 5-second delay to avoid the peak reverse electromotive force that the excitation winding may generate at the initial stage of starting, creating a safety window for the subsequent contactor switching; the KM2 contactor is attracted in the mode switching phase, and the KM1 contactor is attracted 10ms after the KM2 contactor is attracted, completing the switching of the power supply circuit from IGBT soft start to contactor direct-through; in the IGBT off phase, the IGBT conduction angle is zero, and the power supply circuit is completely exited.

[0081] The hard start direct-through module is used to respond to the hard start instruction in the second adjustment state signal, forcibly short-circuit the platen path, and execute the second start mechanism.

[0082] In this embodiment, the hard start direct-through module is adapted for emergency scenarios, i.e., in the event of an accident, a 5-second self-checking is still required to automatically trigger hard start when the oil pressure drops suddenly, with a response time less than or equal to 0.5 seconds, thereby directly skipping the controller self-checking process and directly driving the KM1 / KM2 contactor to attract, thereby completely solving the problem of delayed response in an emergency and ensuring that the unit can respond in time at critical moments.

[0083] In a possible implementation, the hardware carrier that executes the second start mechanism includes: an electromagnetic relay, the control end of the coil of which is electrically connected to the output end of the hard start instruction, and the normally open contact thereof is connected in parallel to both ends of the platen, for forcibly short-circuiting the platen when the hard start instruction is received; and a contactor drive circuit, the output end of which is directly electrically connected to the coil of the main circuit contactor, and the activation path thereof is configured to be independent of the conventional self-checking logic of the controller.

[0084] Specifically, the hard start direct-through module responds to the hard start instruction issued by the working condition decision module and completes the emergency start within 0.5 seconds through physical level path switching; when the hard start instruction is received, the electromagnetic relay K1 is immediately attracted, and the normally open contact thereof is connected in parallel to both ends of the platen, forcibly short-circuiting the platen contacts through the metal bridge, at this time the resistance between the contacts is less than 10 Once the platen is shorted, the oil pressure signal will be directly conducted, and then the KM1 and KM2 contactors will be triggered to be momentarily attracted, thus completing the emergency start of the motor.

[0085] It should be noted that, in order to ensure that the forced short-circuit action for simulating the platen input state can be momentarily completed after the hard start instruction is issued, the response time of the electromagnetic relay is modeled and calculated, and the response time of the electromagnetic relay is which is determined by the mechanical movement of the armature and the electromagnetic effect of the contact, and is specifically represented as:

[0086] ,

[0087] wherein, is the rotational inertia of the armature of the electromagnetic relay, and in the embodiment, the value is , is the maximum angular velocity of the armature, and in the embodiment, the maximum value is 120 , is the electromagnetic torque constant of the coil, and in the embodiment, 0.05 , is the coil driving current, is the contact arc extinction time.

[0088] Further, when the hard start instruction is valid, it will directly act on the driving IC of the KM1 and KM2 contactors, thereby skipping the 5-second self-checking process of the controller; after receiving the instruction, the KM1 and KM2 contactors, i.e. the main circuit contactor, must be nearly perfectly synchronized to be attracted, and any slight timing deviation can cause a huge transient voltage on the un-closed phase, thereby causing a strong arc. In order to quantify this synchronization requirement, a synchronization driving constraint equation is constructed, which is specifically represented as:

[0089] ,

[0090] wherein, is the maximum difference of the allowed KM1 and KM2 action time, is the minimum arc voltage of the air medium, which is about , is the bus peak voltage, is the power frequency; in the embodiment, a single driving chip is used to drive two contactor coils in parallel, thereby ensuring the homogeneity and consistency of the driving signals.

[0091] Further, to prevent the contactor coil from being damaged by the back electromotive force generated when the power is off or interfering with the bus voltage, a TVS diode is connected in parallel across the coil in the embodiment, and the selection of the TVS diode is based on the energy absorption capacity which must be greater than the total energy released when the coil is powered off, which is specifically expressed as:

[0092]

[0093] wherein, represents the minimum energy that the TVS diode needs to absorb, represents the inductance of the contactor coil, represents the holding current of the contactor, represents the distributed capacitance in the circuit, represents the DC voltage of the bus; so that the back electromotive force generated by the coil under any working condition can be completely absorbed and clamped, thereby effectively protecting the drive circuit and maintaining the stability of the bus voltage, avoiding the risk of voltage collapse.

[0094] The transient protection module is used to activate the transient voltage suppression circuit synchronously when any module triggers the main loop contactor to act, and forcibly turn off the power switching element when the bus voltage is monitored to exceed the safety threshold.

[0095] Specifically, the transient protection module is connected in parallel across the KM33 coil by the TVS absorption circuit to absorb the back electromotive force energy; a differential sampling circuit is used to obtain the bus voltage in real time, and the IGBT is turned off immediately when the bus voltage exceeds or is lower than the safety threshold, thereby protecting the power device; if the abnormality continues, the KM1 and KM2 contactor drives are further cut off; through the feedback optimization of voltage and PID, the soft start parameters are dynamically adjusted according to the bus voltage fluctuation value.

[0096] The hardware carrier of the transient protection module in the embodiment is composed of a transient voltage suppression circuit composed of a diode array, a microsecond-level response high-speed voltage comparator, and a matching differential sampling and driving circuit; the transient voltage suppression circuit is composed of a TVS diode and a transient absorption resistor connected in series, and the whole series circuit is connected in parallel across the coil of the contactor.

[0097] In a possible implementation, the voltage monitoring of the bus voltage includes: comparing a preset safety threshold with the real-time monitored bus voltage; wherein the safety threshold is set to be of the rated bus voltage value; and when the bus voltage exceeds the range defined by the safety threshold, a signal for turning off the IGBT gate is generated and output.

[0098] It should be noted that a protection system is constructed for the bus voltage collapse, and the protection system includes: energy clamping of the TVS, when the back electromotive force exceeds 350​ TVS in 100 ms, IGBT off, when the bus voltage exceeds the safe threshold, the high-speed voltage comparator will force the IGBT gate off in 10 ms, and cut off the current path; contactor breaking, if the bus voltage exceeds 50 V for more than 50

[0099] In the first start-up after maintenance, the pressure plate state monitoring module outputs logic "1" when the operator manually exits the pressure plate. After power-on, the working condition decision module automatically sends a soft start instruction to the soft start execution module when it detects that the pressure plate state is "1" and the controller completes the 5-second self-test. The soft start execution module then smoothly increases the IGBT conduction angle based on the optimized curve of the bus voltage PID feedback, allowing the motor current to rise from 12 amperes to 128 amperes. After the current stabilizes, the programmable timer delays for 5 seconds to accurately switch the KM2 and KM1 contactors, and the TVS circuit of the transient protection module is activated simultaneously to absorb the back electromotive force generated during the switching transient. Finally, the ideal effect of a start-up current less than 130 amperes and a stable bus voltage of 220V±5V is achieved.

[0100] In the emergency start-up in case of an accident, a sudden rupture of the lubricating oil pipe occurs during operation, causing the oil pressure to drop at a rate exceeding 0.5MPa / ms. The hardware comparator of the working condition decision module instantly captures this change and immediately forces the output of a hard start instruction. The hard start-through module completes the physical short-circuit of the pressure plate path within milliseconds after receiving the instruction, skips the controller self-test, and directly drives the KM1 and KM2 main contactors to attract, allowing the oil pump motor to start under full pressure. At the same time, the TVS circuit of the transient protection module is activated simultaneously to effectively suppress the bus voltage impact caused by the direct start. Finally, the oil pressure is quickly restored within 0.35 seconds, successfully avoiding the unit shutdown accident caused by response delay.

[0101] Secondly, the drawings of the disclosed embodiments only involve the structures related to the disclosed embodiments, and other structures can be referred to the usual design. In the case of no conflict, the same embodiment and different embodiments of the present application can be combined with each other;

[0102] Finally, the above-mentioned is only the preferred embodiment of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A low oil pressure self-starting platen regulating system for a control circuit of a direct current oil pump motor of a power plant, characterized by, Comprise: Platen state monitoring module: for real-time acquisition of the on-off state of the platen in the control loop by the voltage sensor, and converting into a digital signal to output the first adjustment state signal; Working condition decision module: for executing a decision-making mechanism based on the combination logic of the first adjustment state signal and outputting the second adjustment state signal, which includes hard start, soft start and lockout instructions; The working condition decision module actively checks the two prerequisites of "platen state monitoring module output is 1" and "controller self-checking is completed"; only when both are met at the same time, the instruction is sent to the soft start execution module; at the same time, the emergency judgment ability of oil pressure change rate is introduced, once the oil pressure change rate is monitored to exceed the oil pressure threshold, all normal logic is skipped and the hard start is directly triggered; Soft start execution module: for responding to the soft start instruction in the second adjustment state signal and executing the first start mechanism according to the progressive time sequence relationship; Hard start straight-through module: for responding to the hard start instruction in the second adjustment state signal, forcibly short-circuiting the platen path and executing the second start mechanism; Transient protection module: for synchronously activating the transient voltage suppression circuit when any module triggers the main loop contactor action, and forcibly turning off the power switching element when the bus voltage is monitored to exceed the safety threshold.

2. The low oil pressure self-starting platen regulator system for an electric plant DC oil pump motor control circuit according to claim 1, wherein: The platen state monitoring module acquires the first adjustment state signal, specifically comprising: A voltage sensor, the input end of which is connected in parallel to the contact points of the platen, for converting the resistance state between the contact points into a voltage signal in real time; and A voltage comparator circuit, the input end of which is connected with the output end of the voltage sensor, for comparing the voltage signal with a preset voltage threshold and generating the first adjustment state signal; wherein said voltage comparator circuit outputs a logic "1" as said first regulation status signal to signify that said platen is in an exit state when said contacts present a high resistance state greater than 10 kΩ and outputs a logic "0" as said first regulation status signal to signify that said platen is in a non-exit state when said contacts present a low resistance state less than 100 kΩ.

3. The low oil pressure self starting platen regulator system for an electric plant DC oil pump motor control circuit of claim 1, wherein: The working condition decision module executes a decision-making mechanism, specifically comprising: Obtaining a voltage signal proportional to the oil pressure change rate through a differentiating circuit; Obtaining a digital value representing the oil pressure change rate through an analog-to-digital converter; Comparing the digital value with a preset oil pressure threshold of 0.5 MPa / ms, and determining that an emergency working condition occurs and generating the hard start instruction when the digital value exceeds the oil pressure threshold.

4. The low oil pressure self starting platen regulator system for an electric plant DC oil pump motor control circuit of claim 1, wherein: The first start mechanism of the soft start execution module includes IGBT conduction angle slow rise and time sequence control, specifically comprising: The IGBT conduction angle slow rise adopts a PID control algorithm, and at the starting moment of soft start, the initial conduction angle of IGBT is set to 0°; The time sequence control is realized by a programmable timer, and the adjustable range of the programmable timer is 1-10 seconds.

5. The low oil pressure self starting platen regulator system for an electric plant DC oil pump motor control circuit of claim 4, wherein: The PID control algorithm of the soft start execution module, specifically comprising: In the process of slow rise, with bus voltage fluctuation value The calculation formula of the dynamic control target of the PID control algorithm is specifically represented as follows: wherein, represents the on angle of the IGBT applied by the controller at the time instant , represents the actual voltage of the bus at the time instant , represents the fluctuation difference between the actual voltage of the bus and the reference target voltage , , , respectively represent the proportional, integral, and derivative coefficients of the PID controller, represents the index in the integral at the time instant .

6. The low oil pressure self starting platen regulator system for an electric plant DC oil pump motor control circuit of claim 4, wherein: The time sequence control of the soft start execution module is based on the dual trigger conditions of time and current stability to execute the time sequence switching process of the contactor, specifically represented as: wherein denotes the start time of the soft start procedure, denotes the adjustable minimum delay time, denotes the second derivative of the current.

7. The low oil pressure self starting platen regulator system for an electric plant DC oil pump motor control circuit of claim 1, wherein: The hard start straight-through module executes the second start mechanism, specifically comprising: An electromagnetic relay, the control end of the coil of which is electrically connected with the output end of the hard start instruction, and the normally open contact of which is connected in parallel to the two ends of the platen, for forcibly short-circuiting the platen when receiving the hard start instruction; and A contactor drive circuit having an output directly electrically connected to a coil of a main circuit contactor and having an activation path configured to be independent of regular self-test logic of the controller.

8. The low oil pressure self starting platen regulator system for an electric plant DC oil pump motor control circuit of claim 1, wherein: The transient protection module, the configuration includes: Comparing the preset safety threshold with the real-time monitored bus voltage; wherein the safety threshold is set to be 1.1 times of the rated bus voltage value ; and, When the bus voltage exceeds the range defined by the safety threshold, a signal for shutting off the IGBT gate is generated and output.

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