A power supply control system and control method based on far-end compensation

Abstract

The application discloses a power supply control system and control method based on remote compensation, solves the problem that in the long-distance power supply process, the existing compensation voltage monitoring circuit is in short-circuit state when the filter X capacitor is charged, at this time, the high voltage output is almost all loaded on the over-compensation sampling resistor, and the resistor is often burned out due to over-power; the over-compensation control system comprises a power conversion unit, a power control unit, a system filter unit, an over-compensation sampling unit and a system control unit; the over-compensation sampling resistor is used for sampling the compensation voltage, and the over-compensation control circuit and the power control unit are used for controlling the compensation output, so that the problem that the sampling compensation resistor is burned out due to over-power can be solved.

Description

TECHNICAL FIELD

[0001] The application relates to a long-distance power supply over-compensation control method, in particular to a power supply control system and control method based on remote compensation. BACKGROUND

[0002] More and more industries need direct-current output long-distance power supply, and in the long-distance power supply process, due to the existence of line impedance, the final load end voltage is attenuated, the expected voltage value cannot be reached, and remote voltage compensation becomes a necessary function in this case.

[0003] In the process of voltage compensation for the remote load, in order to ensure that the compensation voltage is within the safe use range, the compensation voltage needs to be detected through the over-sampling compensation resistance connected to the load, and the commonly used circuit is as shown in the drawing. Figure 1 As shown in the drawing, the output voltage charges the filter X capacitor, the line impedance Rwire1 is relatively small, the filter X capacitor is in a short-circuit state at the moment of charging, at this moment, the output high voltage is almost all loaded on the over-compensation sampling resistance, so that the resistance often appears over-power and is burned out. SUMMARY

[0004] The application aims to solve the problem that in the case that the long-distance power supply exists loss, the existing compensation voltage monitoring circuit is used, the filter X capacitor is in a short-circuit state at the moment of charging, at this moment, the output high voltage is almost all loaded on the over-compensation sampling resistance, so that the resistance often appears over-power and is burned out, and provides a power supply control system and control method based on remote compensation.

[0005] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0006] A power supply control system based on remote compensation, which is characterized in that: comprising a power conversion unit, a power control unit, a system filter unit, an over-compensation sampling unit and a system control unit;

[0007] The system filter unit comprises a common mode inductor L1, a filter X capacitor CX2 and a time sequence control switch S1, the input high end and the input low end of the common mode inductor L1 are connected to the positive and negative poles of the output end of the power conversion unit respectively, the output high end of the common mode inductor L1 is connected to one end of the time sequence control switch S1, the other end of the time sequence control switch S1 is connected to the positive plate of the filter X capacitor CX2 and one end of the parallel machine load Rload, and the output low end negative pole of the common mode inductor L1 is connected to the negative plate of the filter X capacitor CX2 and the other end of the parallel machine load Rload.

[0008] The over-compensation sampling unit comprises two over-compensation sampling resistors Rbc, two over-compensation control circuits and a time sequence control switch S2; one end of the two over-compensation sampling resistors Rbc is connected to the positive and negative poles of the output end of the power conversion unit respectively; the other end of one of the over-compensation sampling resistors Rbc is connected to one end of the time sequence control switch S2, the other end of the time sequence control switch S2 is connected to one end of the parallel load Rload, and the other end of the other over-compensation sampling resistor Rbc is connected to the other end of the parallel load Rload; each of the over-compensation sampling resistors Rbc is connected in parallel with one of the over-compensation control circuits, which is used to regulate the output of the power conversion unit according to the voltage of the over-compensation sampling resistor Rbc; and both of the over-compensation control circuits are connected to the power control unit.

[0009] The system control unit is connected to the time sequence control switch S1, the time sequence control switch S2 and the power control unit.

[0010] The power control unit is connected to the power conversion unit, which is used to control the operation of the power conversion unit, and the input end of the power conversion unit is used to connect to the three-phase alternating current power grid.

[0011] Further, the power conversion unit comprises an AC / DC rectifier circuit, a DC / DC conversion circuit and a module internal filter unit connected in sequence, the input end of the AC / DC rectifier circuit is connected to the three-phase alternating current power grid, the control ends of the AC / DC rectifier circuit and the DC / DC conversion circuit are connected to the power control unit, the input high end and the input low end of the module internal filter unit are connected to one end of the two over-compensation sampling resistors Rbc respectively, and the output high end and the output low end of the module internal filter unit are connected to the input high end and the input low end of the common-mode inductor L1 respectively.

[0012] Further, the module internal filter unit comprises a power filter common-mode inductor L2, a filter resistor R2, a filter capacitor C2 and a filter X capacitor CX1, the input high end of the power filter common-mode inductor L2 is connected to the positive pole of the output end of the DC / DC conversion circuit and one end of one of the over-compensation sampling resistors Rbc, the input low end of the power filter common-mode inductor L2 is connected to the negative pole of the output end of the DC / DC conversion circuit and one end of the other over-compensation sampling resistor Rbc; the output high end of the power filter common-mode inductor L2 is connected to one end of the filter resistor R2, the other end of the filter resistor R2 and the output low end of the power filter common-mode inductor L2 are connected in parallel with the filter capacitor C2 and the filter X capacitor CX1, and the two plates of the filter X capacitor CX1 are connected to the input high end and the input low end of the input end of the common-mode inductor L1 respectively.

[0013] Further, the filter resistor R2 is connected in parallel with a control switch S3, which is used to charge protection of the filter capacitor C2 and the filter X capacitor CX1 when the internal filter unit of the module is started.

[0014] Further, each of the over-compensation control circuits comprises a diode D1, a zener diode D2, a protection resistor R1 and an optocoupler U1; the diode D1 is connected in parallel across the corresponding over-compensation sampling resistor Rbc, and the positive terminal of the diode D1 is connected to one end of the over-compensation sampling resistor Rbc and the time sequence control switch S2; the positive terminal of the zener diode D2 is connected to one end of the protection resistor R1, and the negative terminal of the zener diode D2 is connected to the negative terminal of the diode D1; the other end of the protection resistor R1 is connected to the positive terminal of the diode D1; the input high terminal of the optocoupler U1 is connected to the positive terminal of the zener diode D2, and the input low terminal of the optocoupler U1 is connected to the other end of the protection resistor R1; the output high terminal of the optocoupler U1 is connected to the power control unit, and the output low terminal of the optocoupler U1 is grounded.

[0015] A power supply control method based on remote compensation, using a power supply control system based on remote compensation, and the special features of which are as follows:

[0016] Step 1: connect the input end of the power conversion unit to a three-phase AC power grid, close the time sequence control switch S1 and open the time sequence control switch S2 through the system control unit, convert AC power into DC power through the power conversion unit, and charge the filter X capacitor CX2 after passing through the common-mode inductor L1;

[0017] Step 2: set the charging time, and after the charging time, close the time sequence control switch S2 through the system control unit, and supply power to the parallel load Rload through the power conversion unit and the over-compensation sampling unit;

[0018] Step 3: detect the voltage across the over-compensation sampling resistor Rbc through the over-compensation control circuit, and send the detected voltage to the power control unit; the power control unit adjusts the output voltage of the power conversion unit according to the detected voltage to compensate the remote power supply voltage in real time.

[0019] Further, step 3 is specifically as follows:

[0020] The over-compensation control circuit detects the voltage across the over-compensation sampling resistor Rbc and sends the detected voltage to the power control unit; the power control unit judges whether the detected voltage exceeds the preset voltage Vbc, if not, the power control unit increases the output voltage of the power conversion unit according to the detected voltage, so that the voltage across the over-compensation sampling resistor Rbc reaches the preset voltage Vbc, and the remote power supply voltage compensation for the parallel load Rload is performed; if yes, the output voltage of the power conversion unit is no longer increased.

[0021] Further, the charging time in step 2 is 5RC, wherein R represents the internal resistance of the filter X capacitor CX2, and C represents the capacity of the filter X capacitor CX2.

[0022] The beneficial effects of the present application are:

[0023] 1. The power supply control system based on remote compensation of the present application samples the compensation voltage through the over-compensation sampling resistor and controls the compensation output through the over-compensation control circuit and the power module-control unit, which is simple in structure and can solve the problem of over-powering and burning of the over-compensation sampling resistor.

[0024] 2. The power supply control system and control method based on remote compensation of the present application set the timing control switch S1 in the system filter unit and the timing control switch S2 in the over-compensation sampling unit, and the system control unit controls the timing of the two switches, thereby effectively avoiding the problem of burning the over-compensation resistor caused by charging the filter X capacitor during the starting stage. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the voltage starting process of the existing compensation voltage monitoring circuit.

[0026] Figure 2 It is a module structure diagram of the power supply control system based on remote compensation of the present application.

[0027] Figure 3 It is a circuit structure schematic diagram of the power supply control system based on remote compensation of the present application.

[0028] In the figure, 1. power conversion unit, 1-1. AC / DC rectifier circuit, 1-2. DC / DC conversion circuit, 1-3. internal filter unit of the module; 2. power control unit; 3. system filter unit; 4. over-compensation sampling unit; 5. system control unit. DETAILED DESCRIPTION

[0029] The technical solutions of the present application will be described clearly and completely below in combination with the drawings and embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0030] The present embodiment is a power supply control system based on remote compensation, as shown in the figure, comprising a power conversion unit 1, a power control unit 2, a system filter unit 3, an over-compensation sampling unit 4 and a system control unit 5. Figure 2

[0031] As shown in the figure, the power conversion unit 1 comprises an AC / DC rectifier circuit 1-1, a DC / DC conversion circuit 1-2 and a module internal filter unit 1-3 connected in sequence, the input end of the AC / DC rectifier circuit 1-1 is connected to a three-phase alternating current grid, the control ends of the AC / DC rectifier circuit 1-1 and the DC / DC conversion circuit 1-2 are connected to the power control unit 2, the input high end and the input low end of the module internal filter unit 1-3 are connected to one end of two over-compensation sampling resistors Rbc respectively, the output high end and the output low end of the module internal filter unit 1-3 are connected to the input high end and the input low end of a common-mode inductor L1 respectively, and the module internal filter unit 1-3 is used for internally filtering the direct current output by the DC / DC conversion circuit 1-2. Figure 2 As shown in the figure, it is part of the circuit structure of the DC / DC conversion circuit 1-2 and the module internal filter unit 1-3, wherein the module internal filter unit 1-3 comprises a power filter common-mode inductor L2, a filter resistor R2, a filter capacitor C2 and a filter X capacitor CX1, the input high end of the power filter common-mode inductor L2 is connected to the positive electrode of the output end of the DC / DC conversion circuit 1-2 and one end of one of the over-compensation sampling resistors Rbc, the input low end of the power filter common-mode inductor L2 is connected to the negative electrode of the output end of the DC / DC conversion circuit 1-2 and one end of the other over-compensation sampling resistor Rbc; the positive electrode of the output end of the power filter common-mode inductor L2 is connected to one end of the filter resistor R2, the other end of the filter resistor R2 is connected to the negative electrode of the output end of the power filter common-mode inductor L2, and the two polar plates of the filter X capacitor CX1 are connected to the input high end and the input low end of the input end of the common-mode inductor L1 respectively.

[0032] Figure 3 A control switch S3 is connected in parallel to the filter resistor R2, which is used for controlling the charging of the filter capacitor C2 and the filter X capacitor CX1. The filter capacitor C2 and the filter X capacitor CX1 are protected.

[0033] The filter resistor R2 is connected in parallel to the control switch S3, which is used for controlling the charging of the filter capacitor C2 and the filter X capacitor CX1. The filter capacitor C2 and the filter X capacitor CX1 are protected.

[0034] ​​The system filter unit 3 comprises a common-mode inductor L1, a filter X capacitor CX2 and a time control switch S1. The input high end and the input low end of the common-mode inductor L1 are connected to the positive and negative poles of the output end of the power conversion unit 1 respectively. The output high end of the common-mode inductor L1 is connected to one end of the time control switch S1. The other end of the time control switch S1 is connected to the positive plate of the filter X capacitor CX2 and one end of the parallel load Rload. The output low end negative pole of the common-mode inductor L1 is connected to the negative plate of the filter X capacitor CX2 and the other end of the parallel load Rload.

[0035] The over-compensation sampling unit 4 comprises two over-compensation sampling resistors Rbc, two over-compensation control circuits and a time control switch S2. One end of each of the two over-compensation sampling resistors Rbc is connected to the positive and negative poles of the output end of the power conversion unit 1 respectively. The other end of one of the over-compensation sampling resistors Rbc is connected to one end of the time control switch S2. The other end of the time control switch S2 is connected to one end of the parallel load Rload. The other end of the other over-compensation sampling resistor Rbc is connected to the other end of the parallel load Rload. Each over-compensation sampling resistor Rbc is connected in parallel with an over-compensation control circuit, which is used to regulate the output of the power conversion unit 1 according to the voltage of the over-compensation sampling resistor Rbc. The two over-compensation control circuits are connected to the power control unit 2.

[0036] Each over-compensation control circuit comprises a diode D1, a zener diode D2, a protection resistor R1 and an optocoupler U1. The diode D1 is connected in parallel across the corresponding over-compensation sampling resistor Rbc. The positive end of the diode D1 is connected to one end of the over-compensation sampling resistor Rbc which is connected to the time control switch S2. The positive end of the zener diode D2 and one end of the protection resistor R1 are connected. The negative end of the zener diode D2 and the negative end of the diode D1 are connected. The other end of the protection resistor R1 and the positive end of the diode D1 are connected. The input high end of the optocoupler U1 is connected to the positive end of the zener diode D2. The input low end of the optocoupler U1 is connected to the other end of the protection resistor R1. The output high end of the optocoupler U1 is connected to the power control unit 2. The output low end of the optocoupler U1 is connected to the ground.

[0037] The system control unit 5 is connected to the time control switch S1, the time control switch S2 and the power control unit 2.

[0038] The power control unit 2 is connected to the power conversion unit 1, which is used to control the operation of the power conversion unit 1. The input end of the power conversion unit 1 is used to connect to the three-phase alternating current power grid.

[0039] The power control system based on remote compensation of the embodiment can effectively control the switching time sequence of the remote compensation sampling signal and the output power switch, and solve the problem of over-compensation sampling resistor burnout in the application of requiring remote voltage compensation and output power filtering after the output of the power conversion unit 1.

[0040] Wherein, the power conversion unit 1 can adopt the way of multiple power conversion units 1 in parallel, the main power conversion unit 1 is connected to the remote voltage compensation signal, and the other slave power conversion units 1 follow the main power conversion unit 1 to control the current sharing.

[0041] The embodiment is a power supply control system based on remote compensation. Due to the long output cable and the impedance of the cable, the output voltage of the module cannot reach the preset voltage value at the remote parallel load after passing through the output cable. The remote compensation can ensure that the output voltage of the remote parallel load is always the output set voltage Vload. The remote compensation system can determine the voltage Vbc across the over-compensation sampling resistor according to the cable loss voltage and timely increase the output voltage Vmk of the power conversion unit 1 to compensate for the voltage loss on the cable.

[0042] The over-compensation protection principle of the control system in the embodiment is as follows: the system is pre-set to reach the compensation cable voltage VBC, VBC=Vmk-Vload. The over-compensation sampling resistor Rbc is connected in series in the compensation sampling loop. When the compensation cable voltage VBC is reached, the voltage across the over-compensation sampling resistor Rbc is Vbc. The system detects the voltage across Rbc. When it is found that the voltage exceeds the compensation voltage Vbc, the stable voltage diode D2 is turned on, the optocoupler U1 is turned on, the over-compensation signal on the triode side of the optocoupler U1 changes from high to low, and this signal is sent to the power control unit 2 for processing. Under normal circumstances (no over-compensation occurs), the over-compensation signal is high. When the over-compensation signal is low, the power control unit 2 no longer controls the output voltage Vmk of the power conversion unit 1 to increase the output, thereby achieving the purpose of over-compensation.

[0043] A power supply control method based on remote compensation, comprising the following steps:

[0044] Step 1, connect the input end of the power conversion unit 1 to the three-phase alternating current power grid, close the time sequence control switch S1 and open the time sequence control switch S2 through the system control unit 5, convert the alternating current into direct current through the power conversion unit 1, and charge the filter X capacitor CX2 after the common-mode inductor L1;

[0045] Step 2, set the charging time. After the charging time, close the time sequence control switch S2 through the system control unit 5, and supply power to the parallel load Rload through the power conversion unit 1 and the over-compensation sampling unit 4;

[0046] Step 3, the over-compensation sampling resistor Rbc is detected by the over-compensation control circuit, and the detected voltage is sent to the power control unit 2; the power control unit 2 judges whether the detected voltage exceeds the preset voltage Vbc, if not, the power control unit 2 raises the output voltage of the power conversion unit 1 according to the detected voltage, and compensates the remote power supply voltage of the parallel load Rload; if it exceeds, the output voltage of the power conversion unit 1 is no longer raised.

[0047] The application controls the closing timing of the remote compensation signal and the power output switch, and a timing control switch S2 is connected in series on the signal line of the remote compensation voltage sampling. After the circuit is started, the timing control switch S2 is in an open state before the timing control switch S1 is closed. When the timing control switch S1 is closed, the main power loop charges the filter X capacitor CX2. After the filter X capacitor CX2 is charged, the timing control switch S2 is closed again. In this way, the loop of charging the filter X capacitor CX2 through the remote compensation voltage sampling signal line during the starting process is avoided. Similarly, in the open timing, the timing control switch S2 is opened first, and then the timing control switch S1 is opened. According to this logical control scheme, the problem of burning the over-compensation sampling resistor in the starting and shutting down processes of the previous scheme is effectively solved, and a safe and reliable technical scheme is provided for such applications.

[0048] In the embodiment, the charging time in step 2 is 5RC, which can ensure that the filter X capacitor is fully charged, and the test verification is as follows:

[0049] The time of closing the timing control switch S2 needs to be determined according to the charging time of the filter X capacitor CX1. The expression of the charging time of the filter X capacitor CX1 is: Vt=Vmk*[1-exp(-t / RC)]; Vmk is the output voltage of the power conversion unit 1.

[0050] As can be seen from the above formula, because the exponential value can only be infinitely close to 0, but never equal to 0, it takes infinite time to fully charge the capacitor.

[0051] When t=RC, Vt=0.63Vmk;

[0052] When t=2RC, Vt=0.86Vmk;

[0053] When t=3RC, Vt=0.95Vmk;

[0054] When t=4RC, Vt=0.98Vmk;

[0055] When t=5RC, Vt=0.99Vmk;

[0056] From the above, after 3-5 RC, the charging process is basically completed, in order to reliably ensure that the capacitor charging is completed, the time length of the capacitor charging completion in the application is t=5RC.

[0057] The input end of the power conversion unit 1 in this embodiment is connected to 380V / 50Hz alternating current, and outputs 270Vdc voltage after AC-DC conversion. After filtering by the internal filtering unit 1-3, the system filtering unit 3 is input again, and then input to the parallel load (Vload=270Vdc). Because the parallel load cable is long, the impedance on the cable (2*Rwire: the parallel load cable is 2) causes voltage loss VBC, which causes the voltage at the parallel load end to not reach 270Vdc. In order to keep the voltage at the parallel load end at 270Vdc, the over-compensation sampling resistance voltage Vbc needs to be determined according to the cable loss, and the power module output voltage Vmk is adjusted in real time, so that Vmk=VBC+270Vdc.

[0058] At the same time, VBC=Ilaod*2*Rwire, (Iload: parallel load current)

[0059] Vmk=Ilaod*2*Rwire+270Vdc

[0060] Iload is a real-time change, so Vmk is also a real-time change.

[0061] This embodiment needs to achieve two effects.

[0062] Effect 1: Real-time adjustment of output voltage Vmk according to real-time change of parallel load current Iload. Vmk=Ilaod*2*Rwire+270Vdc.

[0063] Effect 2: Limit the over-compensation of single-sided cable to 5Vdc, and the total compensation voltage is 10Vdc (VBC). When the compensation voltage of any one cable exceeds 5Vdc, over-compensation is no longer performed.

[0064] Implementation of effect 2: When the cable is long enough, Rwire will continue to increase. Or the parallel load current Ilaod continuously increases under certain conditions. According to Vmk=Ilaod*2*Rwire+270Vdc, the power conversion unit 1 output voltage Vmk will continue to increase. Vmk cannot be adjusted indefinitely, and excessive adjustment will cause damage to the components in the circuit. In order to protect the circuit structure, the over-compensation of single-sided cable is limited to 5Vdc, and when the compensation voltage exceeds 5Vdc, over-compensation is no longer performed. The output is 2 cables, that is, the range of Vmk is 270Vdc~280Vdc.

[0065] When the cable voltage drop is between 0-5Vdc, the output voltage Vmk of the dynamic adjustment module is adjusted so that the output terminal can be kept at 270Vdc.

[0066] When the cable voltage drop is greater than 5Vdc, the output voltage Vmk of the maintenance module is kept at a maximum of 280Vdc, at which time, the 270Vdc of the parallel load terminal is no longer guaranteed. The circuit plays a protective role.

[0067] As shown in Figure 3 , when three-phase alternating current is sent to the power conversion unit 1, the power control unit 2 (as shown in Figure 2 ) sends a start-up instruction to the power conversion unit 1, and the power conversion unit 1 outputs a Vmk direct current voltage. When the system detects that the output Vmk is established, the system control unit 5 sends a closing instruction to the timing control switch S1, and the filter X capacitor CX2 starts to charge the capacitor. After the charging lasts for t=5RC time, the system control unit 5 sends a closing instruction to the timing control switch S2, at which time, the remote compensation mechanism starts. According to the remote output sampled voltage Vload and the power conversion unit 1 output voltage Vmk, the power control unit 2 is combined to dynamically compensate the value of Vmk, so that Vload=270Vdc. The purpose of dynamic compensation is achieved.

[0068] Through the remote compensation sampling circuit, when the system detects that the system is over-compensated at a certain time, the over-compensation circuit of the power module sends a low-level signal to the power module control unit to adjust and control the output Vmk to keep at a maximum of 280Vdc, thereby achieving the purpose of over-compensation protection.

[0069] The power supply control system based on remote compensation of the embodiment has been applied in products in batches, and achieves the functions of real-time dynamic compensation and real-time over-compensation protection. The use effect is good, and the performance is stable and reliable.

[0070] The above is only a specific embodiment of the present application, and the effect of the related comparative examples is compared, but the protection scope of the present application is not limited to this. Any change or replacement within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A power supply control method based on far-end compensation, characterized by, The application discloses a power supply control system based on remote compensation, which comprises a power conversion unit (1), a power control unit (2), a system filter unit (3), an over-compensation sampling unit (4) and a system control unit (5). The system filter unit (3) comprises a common-mode inductor L1, a filter X capacitor CX2 and a time sequence control switch S1, the input high end and the input low end of the common-mode inductor L1 are connected with the positive pole and the negative pole of the output end of the power conversion unit (1) respectively, the output high end of the common-mode inductor L1 is connected with one end of the time sequence control switch S1, the other end of the time sequence control switch S1 is connected with the positive plate of the filter X capacitor CX2 and one end of a parallel machine load Rload, and the output low end negative pole of the common-mode inductor L1 is connected with the negative plate of the filter X capacitor CX2 and the other end of the parallel machine load Rload. The over-compensation sampling unit (4) comprises two over-compensation sampling resistors Rbc, two over-compensation control circuits and a time sequence control switch S2, one end of the two over-compensation sampling resistors Rbc is connected with the positive pole and the negative pole of the output end of the power conversion unit (1) respectively, one end of one of the over-compensation sampling resistors Rbc is connected with one end of the time sequence control switch S2, the other end of the time sequence control switch S2 is connected with one end of the parallel machine load Rload, and the other end of the other over-compensation sampling resistor Rbc is connected with the other end of the parallel machine load Rload, each over-compensation sampling resistor Rbc is connected with one over-compensation control circuit in parallel, and the over-compensation control circuit is used for regulating and controlling the output of the power conversion unit (1) according to the voltage of the over-compensation sampling resistor Rbc, and the two over-compensation control circuits are connected with the power control unit (2). The system control unit (5) is connected with the time sequence control switch S1, the time sequence control switch S2 and the power control unit (2). The power control unit (2) is connected with the power conversion unit (1) and is used for controlling the working of the power conversion unit (1), and the input end of the power conversion unit (1) is used for connecting a three-phase alternating current power grid. The method comprises the following steps: Step 1, connecting the input end of the power conversion unit (1) with the three-phase alternating current power grid, closing the time sequence control switch S1 and opening the time sequence control switch S2 through the system control unit (5), converting alternating current into direct current through the power conversion unit (1), and charging the filter X capacitor CX2 after the common-mode inductor L1; Step 2, setting a charging time, closing the time sequence control switch S2 through the system control unit (5) after the charging time, and supplementally supplying power to the parallel machine load Rload through the power conversion unit (1) and the over-compensation sampling unit (4); Step 3, detecting the voltage between the two over-compensation sampling resistors Rbc through the over-compensation control circuit, and sending the detected voltage to the power control unit (2), and adjusting the output voltage of the power conversion unit (1) according to the detected voltage, and real-time compensating the remote power supply voltage, specifically as follows: The over-compensation control circuit detects the voltage across the over-compensation sampling resistor Rbc and sends the detected voltage to the power control unit (2); the power control unit (2) judges whether the detected voltage exceeds the preset voltage Vbc, if not, the power control unit (2) adjusts the output voltage of the power conversion unit (1) to increase, and compensates the remote power supply voltage for the parallel load Rload; if it exceeds, the output voltage of the power conversion unit (1) is no longer increased.

2. The power supply control method based on remote compensation according to claim 1, characterized in that: The power conversion unit (1) comprises an AC / DC rectifier circuit (1-1), a DC / DC conversion circuit (1-2) and a module internal filter unit (1-3) connected in sequence, the input end of the AC / DC rectifier circuit (1-1) is connected to a three-phase alternating current power grid, the control ends of the AC / DC rectifier circuit (1-1) and the DC / DC conversion circuit (1-2) are connected to the power control unit (2), the input high end and the input low end of the module internal filter unit (1-3) are connected to one end of two over-compensation sampling resistors Rbc, and the output high end and the output low end of the module internal filter unit (1-3) are connected to the input high end and the input low end of the common-mode inductor L1.

3. The power supply control method based on remote compensation according to claim 2, wherein the module internal filter unit (1-3) comprises a power filter common-mode inductor L2, a filter resistor R2, a filter capacitor C2 and a filter X capacitor CX1, one end of the power filter common-mode inductor L2 is connected to the positive electrode of the output end of the DC / DC conversion circuit (1-2) and one end of one of the over-compensation sampling resistors Rbc, the input low end of the power filter common-mode inductor L2 is connected to the negative electrode of the output end of the DC / DC conversion circuit (1-2) and one end of the other over-compensation sampling resistor Rbc; one end of the power filter common-mode inductor L2 is connected to one end of the filter resistor R2, the filter capacitor C2 and the filter X capacitor CX1 are connected in parallel between the other end of the filter resistor R2 and the output low end of the power filter common-mode inductor L2, and the two plates of the filter X capacitor CX1 are connected to the input high end and the input low end of the input end of the common-mode inductor L1.

4. The method of claim 3, wherein the method further comprises: The filter resistor R2 is connected in parallel with a control switch S3 for charging protection of the filter capacitor C2 and the filter X capacitor CX1 when the module internal filter unit (1-3) is started.

5. The method of claim 1, wherein the method further comprises: Each of the over-compensation control circuit comprises a diode D1, a stabilizing diode D2, a protection resistor R1 and an optical coupler U1; the diode D1 is connected in parallel across the corresponding over-compensation sampling resistor Rbc, and the positive terminal of the diode D1 is connected to one end of the over-compensation sampling resistor Rbc and the time sequence control switch S2, the positive terminal of the stabilizing diode D2 is connected to one end of the protection resistor R1, the negative terminal of the stabilizing diode D2 is connected to the negative terminal of the diode D1, the other end of the protection resistor R1 is connected to the positive terminal of the diode D1, the input high end of the optical coupler U1 is connected to the positive terminal of the stabilizing diode D2, the input low end of the optical coupler U1 is connected to the other end of the protection resistor R1, the output high end of the optical coupler U1 is connected to the power control unit (2), and the output low end is grounded.

6. The method of claim 1, wherein the power supply control method is based on remote compensation. The charging time in step 2 is 5RC, wherein R represents the internal resistance of the filter X capacitor CX2, and C represents the capacity of the filter X capacitor CX2.

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