Ground power supply network casting control circuit

Abstract

The invention belongs to the field of aviation power supply, and particularly relates to a ground power supply network casting control circuit. The circuit comprises a rapid overvoltage determination circuit module which is used for giving high and low level rapid overvoltage determination signals when three-phase AC signals of a ground power supply are overvoltage; the rapid overvoltage judgment signal is introduced to control a first network relay K1 and a second network relay K2; the output end of the rapid overvoltage determination circuit module is connected with the common end of a first auxiliary contact K11 of the first network relay K1, and the normally closed end of the first auxiliary contact K11 is connected to the output end of the protection circuit; a normally open end of a second auxiliary contact K12 of the first network relay K1 is connected with a plug seat jack F for external output, a common end of the second auxiliary contact K12 is connected with a normally closed end of a first auxiliary contact K21 of the second network relay K2, and a common end of the first auxiliary contact K21 is connected with a 28V working power supply. According to the invention, the safety of onboard electric equipment can be effectively guaranteed.

Description

Technical Field

[0001] The present application belongs to the field of aviation power supply, and specifically relates to a ground power grid control circuit. Background Art

[0002] Under the current technical background, the process of putting the ground power supply of a certain type of aircraft on and off the grid is as follows: first connect the main line of the ground power supply vehicle to the ground power socket of the aircraft, then start the ground power supply vehicle, and after the output voltage of the ground power supply vehicle is stable, close its switch, and finally close the ground power switch on the aircraft. At this time, the ground power supply monitor starts to work, monitors the quality of the ground power output by the ground power supply vehicle, decides whether to connect and disconnect the ground power supply contactor, and completes the ground power supply on and off the grid function. Specifically: after the ground power monitor is powered on, the internal sampling and judgment circuit detects the ground power voltage, frequency, and phase sequence to determine whether the ground power has over / under voltage, over / under frequency, and phase sequence faults. When the ground power output by the ground power vehicle that has initially started has a phase sequence fault, the ground power will not be put into the grid. When the ground power has no over / under voltage, over / under frequency, or phase sequence faults, or has an over / under voltage or over / under frequency fault but has not reached the corresponding fault delay time, the internal grid-connection control circuit of the ground power monitor will output 28V+ to the ground power contactor coil+, connect the ground power contactor, and the ground power supply will supply power to the onboard power grid. During operation, when the ground power has an over / under voltage or over / under frequency fault and reaches the corresponding delay time, the internal grid-connection control circuit of the ground power monitor will output an open circuit signal to the ground power contactor coil+, disconnect the ground power contactor, and the ground power will exit the onboard power grid.

[0003] like Figure 1 As shown, the onboard battery busbar power is applied to the H pin of the ground power monitor plug socket through the ground power switch on position and the ground power plug socket, serving as the working power of the ground power monitor. The power on the H pin is divided into two paths internally: one path is output to the ground power contactor coil + through the F jack, and the other path is stabilized to 15V voltage through the three-terminal integrated regulators N2 and N1, which is used as power supply for various protection circuits, called the power supply circuit module. Figure 1 In the power supply circuit module, surge diodes V31 and V34 are used to prevent the high voltage of the onboard battery bus from entering, prevent N2 from outputting high voltage, and avoid damaging the internal components of the ground power monitor. Capacitors C14 and C15 are used to filter and improve voltage characteristics.

[0004] When the ground power supply is normal (no fault protection signal), the OR gate circuit composed of diodes V10, V20, and V23 outputs a low level. After being filtered by capacitor C10, it is added to the base of transistor V26 through current limiting resistor R43. The base level is low, V26 is cut off, and the base level of transistor V27 is high. V27 is turned on, and the negative end of the coil of grid-connected relay K1 is pulled down to a low level. +28V is applied to the positive end of the coil of relay K1 through diode V30, and K1 starts to attract. V28 is a freewheeling diode. After K1 is attracted, the 28V power supply can enter the plug socket F. The output voltage of the plug socket F is about 28V. Thereafter, the ground power contactor is attracted, and the ground power supply is connected to the onboard power grid. When a fault protection signal exists, the protection signal outputs a high level through the OR gate circuit composed of V10, V20, and V23, and is added to the base of V26 through the current limiting resistor R43. V26 is turned on, V27 is turned off, and the grid-connecting relay K1 is released, disconnecting the channel between the 28V power supply and the plug socket F. The plug socket F is open and has no voltage. After that, the ground power contactor is disconnected, and the ground power exits the onboard power grid.

[0005] against Figure 1 The ground power grid control circuit gradually exposed three technical defects during use:

[0006] On the one hand, if the ground power output after the ground power vehicle is started has an over / under voltage or over / under frequency fault, when the ground power monitor starts working, the ground power monitor will control the ground power contactor to close within a few milliseconds, and the ground power will be put into the grid until the ground power is detected to have an over / under voltage or over / under frequency fault and the corresponding delay time is reached or the onboard ground power switch is disconnected. The ground power monitor will then control the ground power contactor to disconnect. That is, when an over / under voltage or over / under frequency fault occurs, due to the characteristics of the delay, Figure 1 The grid-connecting relay K1 in the circuit is first energized and then released, so that the ground power supply goes through the grid-connection-working-grid-exit scenario;

[0007] Secondly, when the ground power supply has an over / under voltage or over / under frequency fault and reaches the corresponding delay time, after the grid-dropping relay K1 in the grid-dropping control circuit inside the ground power monitor is released, its auxiliary contacts stick together, causing the contacts to be unable to disconnect, which will indirectly cause the 28V+ output by the grid-dropping control circuit inside the ground power monitor to be applied to the positive end of the ground power contactor coil, and it is unable to output an open-circuit signal to the positive end of the ground power contactor coil, thereby causing the ground power contactor to be unable to disconnect, and the ground power cannot be withdrawn from the onboard power grid;

[0008] Thirdly, the control design of the grid-dropping relay K1 has no margin. Once the control fails, the ground power contactor will not be able to disconnect and the ground power will be disconnected from the grid due to a single point failure. The faulty ground power will continue to apply electrical stress to the electrical equipment end of the onboard power grid, causing serious consequences such as equipment failure or complete failure. Summary of the invention

[0009] In order to solve the above problems, the present application provides a ground power supply grid control circuit, which mainly includes:

[0010] The fast overvoltage determination circuit module is used to lead out the three-phase AC signal of the ground power supply and output a fast overvoltage determination signal after passing through the voltage regulator tube V37. The voltage regulator tube V37 is configured so that when the three-phase AC signal of the ground power supply is overvoltage and exceeds the set value, the output fast overvoltage determination signal is high level, otherwise it is low level;

[0011] The first grid-drop relay K1 has a positive terminal connected to a 28V working power supply, and a negative terminal grounded by a transistor control group. The control terminal of the transistor control group is connected to the output terminal of the protection circuit of the ground power supply. When the ground power supply fails, the output terminal of the protection circuit outputs a high level, and the negative terminal of the first grid-drop relay K1 is grounded through the transistor control group, and the first grid-drop relay K1 is energized.

[0012] The second network relay K2 has a positive terminal connected to a 28V working power supply, and a negative terminal controlled by a transistor V24 to be grounded. The control terminal of the transistor V24 is connected to the output terminal of the protection circuit of the ground power supply. When the ground power supply fails, the output terminal of the protection circuit outputs a high level, and the negative terminal of the second network relay K2 is grounded through the transistor V24, and the second network relay K2 is energized.

[0013] Among them, the output end of the fast overvoltage judgment circuit module is connected to the common end of the first auxiliary contact K11 of the first network relay K1, and the normally closed end of the first auxiliary contact K11 is connected to the output end of the protection circuit; the normally open end of the second auxiliary contact K12 of the first network relay K1 is connected to the external output plug socket F, the common end of the second auxiliary contact K12 is connected to the normally closed end of the first auxiliary contact K21 of the second network relay K2, and the common end of the first auxiliary contact K21 is connected to the 28V working power supply.

[0014] Preferably, the set value is selected between 124V-128V.

[0015] Preferably, the fast overvoltage determination circuit module comprises:

[0016] A follower circuit consisting of operational amplifier N3 and diode V36;

[0017] The peak holding circuit is composed of resistor R10 and capacitor C18.

[0018] Preferably, the protection circuit of the ground power supply is an OR gate circuit composed of an overvoltage protection circuit, an undervoltage and over-frequency protection circuit, and a phase sequence protection circuit.

[0019] Preferably, the transistor control group includes transistor V26 and transistor V27, the base of transistor V26 is connected to the output end of the protection circuit, the emitter is grounded, and the collector is connected to the 28V working power supply via resistor R42, the base of transistor V27 is connected to the collector of transistor V26, the emitter is grounded, and the collector is connected to the negative end of the first grid-connecting relay K1.

[0020] Preferably, the negative terminal of the first grid relay K1 is connected to the positive terminal of the first grid relay K1 through a freewheeling diode V28, and the negative terminal of the second grid relay K2 is connected to the positive terminal of the second grid relay K2 through a freewheeling diode V25.

[0021] Preferably, the common end of the second auxiliary contact K22 of the second grid-dropping relay K2 is connected to the ground, and the normally open end of the second auxiliary contact K22 is connected to the collector of the transistor V24.

[0022] This application can effectively ensure the safety of onboard electrical equipment and improve the safety of onboard ground power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the schematic diagram of the existing ground power grid control circuit.

[0024] Figure 2 It is a circuit schematic diagram of a fast overvoltage determination circuit module of a preferred embodiment of the ground power supply grid control circuit of the present application.

[0025] Figure 3 It is a circuit schematic diagram of the ground power grid control circuit of the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the implementation of this application will be described in more detail in combination with the drawings in the implementation of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and cannot be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in combination with the drawings.

[0027] The present application provides a ground power supply grid control circuit, such as Figure 2 and Figure 3 As shown, it mainly includes:

[0028] The fast overvoltage determination circuit module is used to lead out the three-phase AC signal of the ground power supply and output a fast overvoltage determination signal after passing through the voltage regulator tube V37. The voltage regulator tube V37 is configured so that when the three-phase AC signal of the ground power supply is overvoltage and exceeds the set value, the output fast overvoltage determination signal is high level, otherwise it is low level;

[0029] The first grid-drop relay K1 has a positive terminal connected to a 28V working power supply, and a negative terminal grounded by a transistor control group. The control terminal of the transistor control group is connected to the output terminal of the protection circuit of the ground power supply. When the ground power supply fails, the output terminal of the protection circuit outputs a high level, and the negative terminal of the first grid-drop relay K1 is grounded through the transistor control group, and the first grid-drop relay K1 is energized.

[0030] The second network relay K2 has a positive terminal connected to a 28V working power supply, and a negative terminal controlled by a transistor V24 to be grounded. The control terminal of the transistor V24 is connected to the output terminal of the protection circuit of the ground power supply. When the ground power supply fails, the output terminal of the protection circuit outputs a high level, and the negative terminal of the second network relay K2 is grounded through the transistor V24. The second network relay K2 is energized, and the second network relay K2 remains in the energized state until the ground power monitor is powered off and reset;

[0031] Among them, the output end of the fast overvoltage judgment circuit module is connected to the common end of the first auxiliary contact K11 of the first network relay K1, and the normally closed end of the first auxiliary contact K11 is connected to the output end of the protection circuit; the normally open end of the second auxiliary contact K12 of the first network relay K1 is connected to the external output plug socket F, the common end of the second auxiliary contact K12 is connected to the normally closed end of the first auxiliary contact K21 of the second network relay K2, and the common end of the first auxiliary contact K21 is connected to the 28V working power supply.

[0032] In some optional embodiments, the transistor control group includes transistor V26 and transistor V27, the base of transistor V26 is connected to the output end of the protection circuit, the emitter is grounded, and the collector is connected to the 28V working power supply via resistor R42, the base of transistor V27 is connected to the collector of transistor V26, the emitter is grounded, and the collector is connected to the negative end of the first grid-connected relay K1.

[0033] In view of the scenario of ground power supply being put into operation-exited from the grid due to overvoltage conditions in the defects of the prior art, the present application adds a fast overvoltage judgment circuit module to the original ground power supply control circuit, hoping that when the ground power supply is overvoltage for the first time, the ground power supply will not be put into the grid first, and will be put into the grid after it stabilizes. Based on this purpose, the present application aims at overvoltage protection, and the longest delay time is the slight overvoltage protection delay near the overvoltage protection action point, that is, the overvoltage protection within (124~128)V, and the protocol requires a delay of no more than 7s. In the specific production and debugging process, the overvoltage protection point is generally set at around 127V, and the delay is generally more than 3s. Therefore, in some optional implementations of the present application, the set value is selected between 124V-128V, preferably 127V, and UT can be selected within this interval as the threshold value of the fast overvoltage judgment circuit.

[0034] When the AC power supply of the ground power supply vehicle>UT, the fast overvoltage judgment circuit module determines that the ground power input is overvoltage, and it is expected that the ground power supply will not be connected to the onboard power grid to prevent the ground power supply from being put into operation-exited due to a slight overvoltage delay. When the AC power supply of the ground power supply vehicle is ≤UT, the fast overvoltage judgment circuit module determines that the ground power supply is normal and has no overvoltage, and it is expected that the ground power supply will be connected to the onboard power grid; at the same time, it is expected that the fast overvoltage judgment circuit module will be immediately cut off to prevent it from competing with the normal protection circuit. During the working process after the ground power supply is put into operation, if the AC power supply of the ground power supply vehicle ≥UT appears again, the protection function in the original ground power supply control circuit is relied on to control the first grid relay K1 to be released after the overvoltage fault occurs and the delay time is reached, the ground power contactor is disconnected, and the ground power supply vehicle exits the onboard power grid.

[0035] Fast overvoltage judgment circuit module Figure 2 As shown, the ground power three-phase AC input in the original ground power grid control circuit is divided and the three-phase half-wave rectified signal GPU_Uz is led out, and the fast overvoltage judgment signal is output through the voltage regulator tube V37, as shown Figure 2 The Fast_OV_Judge signal is a high-low level signal. The high level indicates that the ground power supply voltage has reached the threshold value of the fast overvoltage judgment circuit, and the low level indicates that the threshold value of the fast overvoltage judgment circuit has not been reached. It will be input to Figure 3 The common end of the first auxiliary contact K11 of the first network relay K1 shown will be controlled by the first network relay K1 and connected to the normally closed end or normally open end of the first auxiliary contact K11.

[0036] In some optional implementations, the fast overvoltage determination circuit module includes:

[0037] A follower circuit consisting of operational amplifier N3 and diode V36;

[0038] The peak holding circuit is composed of resistor R10 and capacitor C18.

[0039] like Figure 2 As shown, the fast overvoltage determination circuit module of the present application can improve the load capacity and anti-interference ability of the GPU_Uz signal through the following circuit, and the peak value of the signal output by the following circuit can be maintained through the peak holding circuit. At this time, the selection of the voltage regulator V37 should match the threshold value of the fast overvoltage determination circuit and the parameters of the half-wave rectification, following and peak holding circuits.

[0040] For example, 127V AC is selected as the threshold value of the fast overvoltage judgment circuit. When the ground power supply is three-phase 115V AC, the output waveform of the three-phase half-wave rectification in the power-on fast overvoltage judgment circuit is about 10V. When the ground power supply is three-phase 127AC, the output waveform of the three-phase half-wave rectification in the power-on fast overvoltage judgment circuit is about DC 11V. Therefore, the voltage regulator V37 preferably selects a voltage regulator with a voltage regulation value exceeding 11V.

[0041] In some optional implementations, the common end of the second auxiliary contact K22 of the second grid-dropping relay K2 is connected to the ground, and the normally open end of the second auxiliary contact K22 is connected to the collector of the transistor V24.

[0042] As mentioned above, when the AC power supply of the ground power car is > UT, the voltage regulator tube V37 is turned on, and the Fast_OV_Judge signal is high level. Figure 3 , the high-level signal is connected to the base of transistor V26, the base of transistor V26 is pulled high and turned on, the base of transistor V27 is pulled low and not turned on, the first network relay K1 is not energized, and at the same time, the high-level Fast_OV_Judge signal will turn on transistor V24, and the second network relay K2 will be energized. After the second network relay K2 is actuated, the common end of the first auxiliary contact K21 of the second network relay K2 is connected to the normally open end, that is, the path between the 28V on-board power supply and the plug socket F is disconnected at the second network relay K2, and the normally closed end of the second auxiliary contact K22 of the second network relay K2 is connected to the normally open end of the second auxiliary contact K22. The common ends are connected in the released state and are both connected to the ground. After the AC power supply of the ground power supply vehicle>UT and the second grid-connected relay K2 is actuated, the normally open end of the second auxiliary contact K22 is connected to the common end of the second auxiliary contact K22 and is both connected to the ground, so that the coil of the second grid-connected relay K2 is always in an effective power supply state and remains locked in the attracted state until the ground power supply monitor is powered off and reset. This process effectively avoids the inability of the ground power supply contactor to disconnect and the ground power supply to go offline due to a single point failure under the condition of a ground power failure, so that the faulty ground power supply can be reliably disconnected from the onboard power grid electrical equipment to prevent serious consequences such as equipment failure or complete failure.

[0043] When the AC power supply of the ground power car is ≤UT, the voltage regulator tube V37 is not turned on, the Fast_OV_Judge signal is low level, and the signal returns to Figure 3 , the base of transistor V26 is at a low level and is not turned on, the base of transistor V27 is pulled high and turned on, the first network relay K1 is energized, the common end of the first auxiliary contact K11 of the first network relay K1 is connected to the normally open end, and the fast overvoltage judgment signal Fast_OV_Judge signal is no longer supplied to the base of transistor V24, that is, the fast overvoltage judgment circuit module is quickly cut off, which does not affect the original other circuit functions, and the on and off of transistor V24 is controlled by the low level output from the output end of the original protection circuit. Transistor V24 is not conducting, the coil of the second grid-connecting relay K2 has no voltage or current, the second grid-connecting relay K2 is not energized, and the common end of the first auxiliary contact K21 of the second grid-connecting relay K2 is connected to the normally closed end. At the same time, since the first grid-connecting relay K1 is energized, the common end of the second auxiliary contact K12 of the first grid-connecting relay K1 is connected to the normally open end. The 28V on-board power supply can be smoothly connected to the plug socket F, and the plug socket F outputs 28V+ to the ground power contactor, and the ground power supply is powered on and grid-connected normally.

[0044] In view of the defect that after the first grid-drop relay K1 is energized, the auxiliary contacts are stuck, resulting in the ground power supply being unable to exit the onboard power grid after the fault and the delay time are reached, and the technical defect of the control without margin design of the grid-drop relay, this application adds a margin control circuit to the original ground power grid-drop control circuit, that is, a control circuit composed of resistor R44, transistor V24, diode V25 and the second grid-drop relay K2, and leads out the fault protection signal Fault_Pro in the original ground power grid-drop control circuit. The signal Fault_Pro is a high and low level signal. The high level represents a fault and the delay time is reached, and the low level represents no fault or a fault but the delay time is not reached. When selecting the second grid-drop relay K2, a relay with a different model and material from the first grid-drop relay K1 should be selected. The probability of contact adhesion of the two types of relays at the same time is greatly reduced compared with the contact adhesion of the first grid-drop relay K1. At the same time, the margin control also greatly improves the task reliability of the grid-drop control of the ground power monitor.

[0045] When the ground power supply is normal (no fault protection signal), as mentioned above, the OR gate circuit composed of diodes V10, V20, and V23 outputs a low level, and then is divided into two paths: one path is added to the base of transistor V24 through the current limiting resistor R44, and the base level is also low, the transistor V24 is cut off, the coil of the second network relay K2 has no voltage and current, K2 remains in the released state, the auxiliary contact does not operate, and the common end of the first auxiliary contact K21 of K2 is connected to its normally closed end, and the normally closed end and the second auxiliary contact K1 of the first network relay K1 are connected to each other. 2; the other way is added to the base of the transistor V26 through the current limiting resistor R43, the base level is also low, the transistor V26 is cut off, the transistor V27 is turned on, the first grid-casting relay K1 is actuated, the plug socket F is connected to the normally open end of the second auxiliary contact K12 of the first grid-casting relay K1, thus, the 28V on-board power supply is connected to the plug socket F through the first auxiliary contact K21 and the second auxiliary contact K12, the plug socket F outputs a voltage of about 28V, the ground power contactor is energized, and the ground power supply is connected to the on-board power grid.

[0046] When a fault protection signal exists, the protection signal outputs a high level through the OR gate circuit composed of diodes V10, V20, and V23, and then is divided into two paths: one path is added to the base of transistor V24 through the current limiting resistor R44, the transistor V24 is turned on, the coil of the second network relay K2 is energized, the first auxiliary contact K21 is actuated, and the common end where the +28V on-board power supply is located is switched from a normally closed contact to a normally open contact, and the second network relay K2 outputs an open circuit signal connected to the common end of the second auxiliary contact K12 of the first network relay K1, that is, One circuit breaker is provided here, and the normally open end of the second auxiliary contact K12 of the group is connected to the plug socket F. The other circuit is added to the base of the transistor V26 through the current limiting resistor R43. The transistor V26 is turned on, the transistor V27 is turned off, the first grid-connecting relay K1 is released, and the common end of the second auxiliary contact K12 is connected to the normally open end. That is, another circuit breaker is provided here, and the circuit breaker is in an effective locked and held state. The two circuit breakers effectively avoid the phenomenon that the faulty ground power supply cannot be disconnected from the grid due to single point failures such as adhesion of the auxiliary contacts of the grid-connecting relay or control failure.

[0047] In some optional implementations, the protection circuit of the ground power supply is an OR gate circuit composed of an overvoltage protection circuit, an undervoltage and over-frequency protection circuit, and a phase sequence protection circuit.

[0048] In some optional embodiments, the negative end of the first network relay K1 is connected to the positive end of the first network relay K1 through a freewheeling diode V28 to prevent a higher voltage from being applied to the transistor V27 and causing device damage when the coil of the first network relay K1 is powered off, and the negative end of the second network relay K2 is connected to the positive end of the second network relay K2 through a freewheeling diode V25 to prevent a higher voltage from being applied to the transistor V24 and causing device damage when the coil of the second network relay K2 is powered off.

[0049] Although the present application has been described in detail above with general descriptions and specific implementation schemes, it is obvious to those skilled in the art that some modifications or improvements may be made to the present application. Therefore, these modifications or improvements made without departing from the spirit of the present application all fall within the scope of protection claimed in the present application.

Claims

1. A ground power supply grid control circuit, characterized in that: include: The fast overvoltage determination circuit module is used to lead out the three-phase AC signal of the ground power supply and output a fast overvoltage determination signal after passing through the voltage regulator tube V37. The voltage regulator tube V37 is configured so that when the three-phase AC signal of the ground power supply is overvoltage and exceeds the set value, the output fast overvoltage determination signal is high level, otherwise it is low level; The first grid-drop relay K1 has a positive terminal connected to a 28V working power supply, and a negative terminal grounded by a transistor control group. The control terminal of the transistor control group is connected to the output terminal of the protection circuit of the ground power supply. When the ground power supply fails, the output terminal of the protection circuit outputs a high level, and the negative terminal of the first grid-drop relay K1 is grounded through the transistor control group, and the first grid-drop relay K1 is energized. The second network relay K2 has a positive terminal connected to a 28V working power supply, and a negative terminal controlled by a transistor V24 to be grounded. The control terminal of the transistor V24 is connected to the output terminal of the protection circuit of the ground power supply. When the ground power supply fails, the output terminal of the protection circuit outputs a high level, and the negative terminal of the second network relay K2 is grounded through the transistor V24, and the second network relay K2 is energized. Among them, the output end of the fast overvoltage judgment circuit module is connected to the common end of the first auxiliary contact K11 of the first network relay K1, and the normally closed end of the first auxiliary contact K11 is connected to the output end of the protection circuit; the normally open end of the second auxiliary contact K12 of the first network relay K1 is connected to the external output plug socket F, the common end of the second auxiliary contact K12 is connected to the normally closed end of the first auxiliary contact K21 of the second network relay K2, and the common end of the first auxiliary contact K21 is connected to the 28V working power supply.

2. The ground power supply control circuit according to claim 1, characterized in that: The set value is selected between 124V-128V.

3. The ground power supply control circuit according to claim 1, characterized in that: The fast overvoltage determination circuit module comprises: A follower circuit consisting of operational amplifier N3 and diode V36; The peak holding circuit is composed of resistor R10 and capacitor C18.

4. The ground power supply control circuit according to claim 1, characterized in that: The protection circuit of the ground power supply is an OR gate circuit composed of an overvoltage protection circuit, an undervoltage and over-frequency protection circuit, and a phase sequence protection circuit.

5. The ground power supply control circuit according to claim 1, characterized in that: The transistor control group includes transistor V26 and transistor V27. The base of transistor V26 is connected to the output end of the protection circuit, the emitter is grounded, and the collector is connected to the 28V working power supply via resistor R42. The base of transistor V27 is connected to the collector of transistor V26, the emitter is grounded, and the collector is connected to the negative end of the first grid-connecting relay K1.

6. The ground power supply control circuit according to claim 1, characterized in that: The negative terminal of the first grid relay K1 is connected to the positive terminal of the first grid relay K1 through a freewheeling diode V28, and the negative terminal of the second grid relay K2 is connected to the positive terminal of the second grid relay K2 through a freewheeling diode V25.

7. The ground power supply control circuit according to claim 1, characterized in that: The common end of the second auxiliary contact K22 of the second grid-dropping relay K2 is connected to the ground, and the normally open end of the second auxiliary contact K22 is connected to the collector of the transistor V24.

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