DC remote power supply system with multiple backups suitable for high-speed electromechanical equipment

Abstract

The present invention provides a DC remote power supply system with multiple backups suitable for high-speed electromechanical equipment, which includes at least one remote machine, and the remote machine includes: a front-end circuit unit: used to assist in controlling the working mode of the remote machine and stabilize the DC voltage transmitted by the local machine; a controller: used to connect to the front-end circuit unit and control the working mode of the remote machine; an off-grid inverter unit: used to invert the DC voltage stabilized by the front-end circuit unit into a stable AC power to power the load. The present invention has high reliability, and is equipped with three backups: photovoltaic panels, batteries, and nearby local machines. It can provide uninterrupted power supply to the load when the local machine fails or the power supply connected to the local machine is cut off, thereby improving the power supply reliability; the remote machine can automatically control the working mode, realize automatic control of local machine power supply, photovoltaic power supply, and battery charging and discharging, and has a high degree of automation.

Description

Technical Field

[0001] The invention relates to the technical field of direct current power supply, and in particular to a direct current remote power supply system with multiple backups suitable for high-speed electromechanical equipment. Background Art

[0002] There are various electromechanical equipment installed on highways, such as cameras, variable information boards, vehicle inspection devices, meteorological sensors, radars, etc. The power supply lines for various electromechanical equipment installed on highways have problems such as long transmission distances and difficulty in obtaining power locally.

[0003] Currently, there are several main ways to provide AC power to electromechanical equipment on highways.

[0004] AC power supply: AC power is taken from substations along the highway, boosted, and transmitted to the remote end by laying power cables. After the voltage is reduced at the power-consuming equipment end, AC power is provided to electromechanical equipment. However, long-distance AC power supply requires multiple voltage reduction conversions, large power losses, poor stability, low security levels, and is plagued by power outages. In addition, it is difficult to achieve mixed power supply for high-power electromechanical equipment and low-power electromechanical equipment.

[0005] Wind-solar complementary power supply: solar energy is converted into direct current through photovoltaic panels, or wind energy is converted into direct current through wind turbines, and then direct current is converted into alternating current through inverters to provide power for electromechanical equipment. However, this method is highly restricted by natural conditions, requires frequent replacement of batteries, has high operating and maintenance costs, can only provide a small capacity of electricity, and has low power supply reliability.

[0006] DC remote power supply: AC power is taken from substations along the highway, converted into high-voltage DC power through AC / DC, and transmitted over long distances through laid power cables. At the power-consuming equipment end, the DC power is inverted into AC power to provide AC power for electromechanical equipment. This method has the advantages of long transmission distance, low loss, simple system, and high reliability. In recent years, it has been increasingly used in the field of power supply for electromechanical equipment on highways.

[0007] The invention with application number 201610045529.4 discloses a power supply system and method for an AC local terminal of a direct current remote power supply for a highway, comprising: dividing the power supply area required for the highway into a number of power supply units according to a set distance; arranging at least one AC local terminal in each power supply unit, the AC local terminal comprising a voltage conversion module having an AC input terminal and a DC output terminal, the AC input terminal being connected to an AC power frequency or medium frequency voltage source; the DC output terminal outputting at least one DC voltage; starting from the AC local terminal, the remote terminals arranged at each load position required to be powered in the power supply unit are connected in sequence through a transmission cable; the remote terminal converts the received DC voltage into the voltage required by the load to supply power to the load. The operation and maintenance cost of this invention is lower than that of other power supply methods. In principle, as long as the power supply is not broken, no maintenance is required. However, once the power supply fails, all electromechanical equipment in the power supply unit will be unable to operate, and the reliability is not high.

[0008] The utility model with application number 201620065566.7 discloses a DC remote power supply AC local terminal and a power supply system using the AC local terminal, including: a voltage conversion module with an AC input terminal and a DC output terminal, the AC input terminal is connected to an AC power frequency or medium frequency voltage source at any power supply point; the DC output terminal outputs at least one DC voltage; the voltage conversion module at least includes a filter unit, an AC / DC rectifier unit and at least one power module composed of a PWM pulse width modulation unit and a DC / DC isolation conversion unit connected in sequence. The utility model can be used and operated in any place with AC power, and can be installed indoors or on a pole. The power supply is arbitrary and random, and is not strictly restricted, so that one local terminal can drag multiple remote terminals to power multiple loads. However, it can only output a fixed DC voltage of DC400V or DC800V, and it does not support AC380V AC voltage input.

[0009] The utility model with application number 202122119540.X discloses a highway DC remote power supply system, which is used to power various load devices in the highway. The DC remote power supply system includes a local terminal device and at least one remote system. Each remote system is arranged in sequence along the highway. Each remote system is connected to at least one load device respectively. Each remote system includes a remote machine, and the remote machine includes a power converter for providing voltage conversion. Each remote system also includes a distributed photovoltaic device for dynamic expansion and stable power supply, and a remote energy storage device to power each load device. The utility model solves the problem in the prior art that when the power grid fails or the local terminal device fails, the stable DC power cannot be output and the load will not work. At the same time, the power supply system is expanded, the transmission capacity of the power grid is effectively improved, the power grid failure problem is dealt with, and the stability of the power supply voltage is ensured. However, in the system disclosed in the new type, a DC / DC needs to be separately set outside the remote machine to connect the photovoltaic device and the battery, and it is impossible to realize the automatic control of the connection and disconnection of the photovoltaic device and the battery, and the charging and discharging of the battery. Summary of the invention

[0010] In order to solve at least one of the above technical problems, the present invention provides a DC remote power supply system with multiple backups suitable for high-speed electromechanical equipment.

[0011] A DC remote power supply system with multiple backups for high-speed electromechanical equipment includes at least one remote unit, wherein the remote unit includes:

[0012] Front-end circuit unit: used to assist in controlling the working mode of the remote unit and stabilize the DC voltage transmitted by the local unit;

[0013] Controller: used to connect with the front-end circuit unit and control the working mode of the remote machine;

[0014] Off-grid inverter unit: used to invert the stabilized DC voltage of the front-end circuit unit into stable AC power to supply power to the load.

[0015] Preferably, the front-end circuit unit includes a first MOS tube Q1, a second MOS tube Q2, a third MOS tube Q3 and a fourth MOS tube Q4; the drain of the first MOS tube Q1 is connected to the positive electrode of the DC input, and the source thereof is connected to the drain of the second MOS tube Q2, and the source of the second MOS tube Q2 is connected to the negative electrode of the DC input; the drain of the third MOS tube Q3 is connected to the positive electrode of the DC input, and the source thereof is connected to the drain of the fourth MOS tube Q4, and the source of the fourth MOS tube Q4 is connected to the negative electrode of the DC input.

[0016] Preferably, in any of the above schemes, the gate of the first MOS tube Q1, the gate of the second MOS tube Q2, the gate of the third MOS tube Q3 and the gate of the fourth MOS tube Q4 are all connected to the controller to receive the corresponding driving waveform output by the controller according to the working mode.

[0017] Preferably, any of the above schemes is that the front-end circuit unit further includes a first inductor L1, a second inductor L2 and a third inductor L3, and a first switch K1, a second switch K2 and a third switch K3; the first inductor L1 is connected in series with the first switch L1 and is arranged between the source of the first MOS tube Q1 and the positive electrode of the battery; the second inductor L2 is connected in series with the second switch K2 and is arranged between the source of the first MOS tube Q1 and the source of the third MOS tube Q3; the third inductor L3 and the third switch K3 are connected in series and are arranged between the source of the third MOS tube Q3 and the positive electrode of the photovoltaic panel.

[0018] Preferably, in any of the above schemes, the negative pole of the battery is connected to the negative pole of the DC input, and the negative pole of the photovoltaic panel is connected to the negative pole of the DC input.

[0019] Preferably, in any of the above solutions, the front-end circuit unit further includes a fifth switch K5 , and the fifth switch K5 is arranged on a DC input positive line between the drain of the first MOS transistor Q1 and the drain of the third MOS transistor Q3 .

[0020] Preferably, the first solution described above is that the front-end circuit unit is connected to the DC bus output by the local terminal through a fourth switch K4.

[0021] Preferably, any of the above schemes is that the off-grid inverter unit includes a single-phase inverter full-bridge circuit and an LCL filter, and after the output end of the front-end circuit unit is connected to the input end of the single-phase inverter full-bridge circuit, single-phase 220V AC power is provided to the load through LCL filtering.

[0022] Preferably, any of the above schemes is that the off-grid inverter unit includes a three-phase inverter full-bridge circuit and an LCL filter, and after the output end of the front-end circuit unit is connected to the input end of the three-phase inverter full-bridge circuit, three-phase 380V AC power is provided to the load through LCL filtering.

[0023] Preferably, in any of the above solutions, the controller controls the working mode of the remote device to include:

[0024] Step 1: Detect whether the value of the remote DC input voltage is within the set threshold range. If so, execute step 2; if not, execute step 5;

[0025] Step 2: Control the second switch K2 to close and detect whether the battery needs to be charged. If not, execute step 3; if yes, execute step 4;

[0026] Step 3: The first MOS tube Q1, the second MOS tube Q2, the third MOS tube Q3, the fourth MOS tube Q4 and the second inductor L2 form a BUCK / BOOST circuit to stabilize the remote DC input voltage to a fixed voltage value and then input it into the off-grid inverter unit;

[0027] Step 4: Control the first switch K1 to close, the first MOS tube Q1, the second MOS tube Q2 and the first inductor L1 form a BUCK circuit to charge the battery; the third MOS tube Q3, the fourth MOS tube Q4 and the second inductor L2 form a BOOST circuit to stabilize the remote DC input voltage to a fixed voltage value and then input it into the off-grid inverter unit;

[0028] Step 5: Check whether the photovoltaic panel can output normally. If yes, go to step 6; if not, go to step 9;

[0029] Step 6: Control the third switch K3 to close, and detect whether the battery needs to be charged. If not, execute step 7; if yes, execute step 8;

[0030] Step 7: The third MOS tube Q3, the fourth MOS tube Q4 and the second inductor L2 form a BOOST circuit, which stabilizes the output voltage of the photovoltaic panel to a fixed voltage value and then inputs it into the off-grid inverter unit;

[0031] Step 8: Control the first switch K1 and the fifth switch K5 to be closed, the third MOS tube Q3, the fourth MOS tube Q4 and the second inductor L2 form a BOOST circuit, stabilize the output voltage of the photovoltaic panel to a fixed voltage value and then input it into the off-grid inverter unit; the first MOS tube Q1, the second MOS tube Q2 and the first inductor L1 form a BUCK circuit to charge the battery;

[0032] Step 9: Detect whether the battery can provide power. If yes, execute step 10. If no, issue a power failure alarm.

[0033] Step 10: Control the first switch K1 and the second switch K2 to close, and the third MOS tube Q3, the fourth MOS tube Q4, the first inductor L1 and the second inductor L2 form a BOOST circuit to stabilize the output voltage of the battery to a fixed voltage value and then input it into the off-grid inverter unit.

[0034] Preferably, in any of the above solutions, the set threshold value range is DC300V to DC1000V.

[0035] Preferably, in any of the above schemes, the fixed voltage value is DC350V.

[0036] Preferably, in any of the above schemes, during the process in which the controller controls the working mode of the remote device, the fourth switch K4 is in a closed state except when it is in an open state due to a fault.

[0037] Preferably, any of the above schemes is that the DC remote power supply system also includes at least one local terminal, and the local terminal is provided with an AC input terminal and a DC output terminal, wherein the AC input terminal inputs AC220V or AC380V AC power, and the DC output terminal outputs DC300V~DC1000V DC power, and the DC output terminal is connected to at least one of the remote terminals via a cable to provide the remote DC input voltage therefor.

[0038] Preferably, in any of the above schemes, two local terminals located in two adjacent power supply locations are arranged to serve as backup for each other.

[0039] The DC remote power supply system with multiple backups applicable to high-speed electromechanical equipment of the present invention has the following beneficial effects:

[0040] 1. High reliability. It is equipped with photovoltaic panels, batteries, and nearby central office machines for backup. It can provide uninterrupted power supply to the load when the central office machine fails or the power supply connected to the central office machine is cut off, thus improving the reliability of power supply.

[0041] 2. The existing photovoltaic panels and batteries can be used as backup, and there is no need to set up separate DC / DC converters for the photovoltaic panels and batteries to boost the voltage;

[0042] 3. The remote machine can automatically control the working mode, realize automatic control of the local machine power supply, photovoltaic power supply, and battery charging and discharging, with a high degree of automation. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a partial structural schematic diagram of a preferred embodiment of a DC remote power supply system with multiple backups suitable for high-speed electromechanical equipment according to the present invention.

[0044] Figure 2 The present invention is a schematic diagram of the structure of the front-end circuit unit of a preferred embodiment of a remote device with a multiple backup DC remote power supply system suitable for high-speed electromechanical equipment according to the present invention.

[0045] Figure 3 According to the present invention, a remote device of a DC remote power supply system with multiple backups for high-speed electromechanical equipment is provided. Figure 2 A schematic structural diagram of an off-grid inverter unit of the illustrated embodiment.

[0046] Figure 4 According to the present invention, a remote device of a DC remote power supply system with multiple backups for high-speed electromechanical equipment is provided. Figure 2 A schematic diagram of the controller working process of the illustrated embodiment.

[0047] Figure 5 The present invention is a schematic structural diagram of an off-grid inverter unit of another embodiment of a remote device of a DC remote power supply system with multiple backups applicable to high-speed electromechanical equipment according to the present invention.

[0048] Figure 6 According to the present invention, a remote device of a DC remote power supply system with multiple backups for high-speed electromechanical equipment is provided. Figure 5 A schematic diagram of the appearance of the embodiment shown.

[0049] Figure 7 The present invention is a schematic structural diagram of a preferred embodiment of a local terminal of a DC remote power supply system suitable for high-speed electromechanical equipment with multiple backups. DETAILED DESCRIPTION

[0050] In order to better understand the present invention, the present invention is described in detail below in conjunction with specific embodiments.

[0051] Example 1

[0052] A DC remote power supply system with multiple backup functions suitable for high-speed electromechanical equipment includes at least one local terminal and at least one remote terminal. The local terminal is provided with an AC input terminal and a DC output terminal. The AC input terminal inputs AC220V or AC380V AC power, and the DC output terminal outputs DC300V to DC1000V DC power. The DC output terminal is connected to at least one of the remote terminals via a cable.

[0053] Figure 1 The figure shows a partial structural schematic diagram of a DC remote power supply system with multiple backups suitable for high-speed electromechanical equipment. In the DC remote power supply system, local terminals JDJ11 and JDJ12 are arranged in the first power-taking location, local terminals JDJ21 and JDJ22 are arranged in the second power-taking location, and local terminals JDJ31 and JDJ32 are arranged in the third power-taking location. Each local terminal leads out a DC bus, and a number of cable T-junction boxes are arranged on the DC bus led out by the local terminal. Cables led out from each cable T-junction box are connected to one of the remote terminals, and each remote terminal supplies power to at least one load, namely, electromechanical equipment on a highway.

[0054] It should be noted that the two local terminals located in two adjacent power supply locations are set to be mutually backed up. The DC busbars drawn from the two local terminals that are mutually backed up are the same DC busbar. Specifically, local terminal JDJ12 and local terminal JDJ21 are mutually backed up, local terminal JDJ22 and local terminal JDJ31 are mutually backed up, local terminal JDJ11 and a local terminal in the adjacent substation in front of it are mutually backed up, and local terminal JDJ32 and a local terminal in the adjacent substation in the rear are mutually backed up. The following is a detailed explanation of the case where the local machine JDJ12 and the local machine JDJ21 serve as backup for each other. Assuming that there are N loads connected to the DC bus between the local machine JDJ12 and the local machine JDJ21, (1) the local machine JDJ12 can be set to power the N loads. When the local machine JDJ12 fails or loses power, the backup local machine JDJ21 is put into use and starts to power the N loads. (2) the local machine JDJ12 can also be set to power the M loads on the DC bus between the local machine JDJ12 and the local machine JDJ21, and the local machine JDJ21 powers the remaining NM loads. When the local machine JDJ12 fails or loses power, the local machine JDJ21 automatically starts to power all the N loads. When the local machine JDJ21 fails or loses power, the local machine JDJ12 performs the same operation.

[0055] The remote machine comprises:

[0056] Front-end circuit unit: used to assist in controlling the working mode of the remote unit and stabilize the DC voltage transmitted by the local unit;

[0057] Controller: used to connect with the front-end circuit unit and control the working mode of the remote machine;

[0058] Off-grid inverter unit: used to invert the DC voltage stabilized by the front-end circuit unit into AC power to supply power to the load.

[0059] like Figure 2As shown, the front-end circuit unit includes a first MOS tube Q1, a second MOS tube Q2, a third MOS tube Q3 and a fourth MOS tube Q4; the drain of the first MOS tube Q1 is connected to the positive electrode of the DC input, and the source thereof is connected to the drain of the second MOS tube Q2, and the source of the second MOS tube Q2 is connected to the negative electrode of the DC input; the drain of the third MOS tube Q3 is connected to the positive electrode of the DC input, and the source thereof is connected to the drain of the fourth MOS tube Q4, and the source of the fourth MOS tube Q4 is connected to the negative electrode of the DC input. The front-end circuit unit also includes a first inductor L1, a second inductor L2 and a third inductor L3, and a first switch K1, a second switch K2 and a third switch K3; the first inductor L1 is connected in series with the first switch L1 and is arranged between the source of the first MOS tube Q1 and the positive electrode of the battery; the second inductor L2 is connected in series with the second switch K2 and is arranged between the source of the first MOS tube Q1 and the source of the third MOS tube Q3; the third inductor L3 is connected in series with the third switch K3 and is arranged between the source of the third MOS tube Q3 and the positive electrode of the photovoltaic panel. The front-end circuit unit also includes a fifth switch K5, which is arranged on the DC input positive line between the drain of the first MOS tube Q1 and the drain of the third MOS tube Q3. The front-end circuit unit is connected to the DC bus output by the local terminal through the fourth switch K4. The negative electrode of the battery is connected to the negative electrode of the DC input, and the negative electrode of the photovoltaic panel is connected to the negative electrode of the DC input.

[0060] The gate of the first MOS transistor Q1 , the gate of the second MOS transistor Q2 , the gate of the third MOS transistor Q3 and the gate of the fourth MOS transistor Q4 are all connected to the controller to receive corresponding driving waveforms output by the controller according to the working mode.

[0061] like Figure 3 As shown, the off-grid inverter unit includes a single-phase inverter full-bridge circuit and an LCL filter. After the output end of the front-end circuit unit is connected to the input end of the single-phase inverter full-bridge circuit, single-phase 220V AC power is provided to the load through LCL filtering.

[0062] like Figure 4 As shown, the controller controls the working mode of the remote machine to include:

[0063] Step 1: Detect whether the value of the remote DC input voltage is within the set threshold range. If so, execute step 2; if not, execute step 5;

[0064] Step 2: Control the second switch K2 to close and detect whether the battery needs to be charged. If not, execute step 3; if yes, execute step 4;

[0065] Step 3: The first MOS tube Q1, the second MOS tube Q2, the third MOS tube Q3, the fourth MOS tube Q4 and the second inductor L2 form a BUCK / BOOST circuit to stabilize the remote DC input voltage to a fixed voltage value and then input it into the off-grid inverter unit;

[0066] Step 4: Control the first switch K1 to close, the first MOS tube Q1, the second MOS tube Q2 and the first inductor L1 form a BUCK circuit to charge the battery; the third MOS tube Q3, the fourth MOS tube Q4 and the second inductor L2 form a BOOST circuit to stabilize the remote DC input voltage to a fixed voltage value and then input it into the off-grid inverter unit;

[0067] Step 5: Check whether the photovoltaic panel can output normally. If yes, go to step 6; if not, go to step 9;

[0068] Step 6: Control the third switch K3 to close, and detect whether the battery needs to be charged. If not, execute step 7; if yes, execute step 8;

[0069] Step 7: The third MOS tube Q3, the fourth MOS tube Q4 and the second inductor L2 form a BOOST circuit, which stabilizes the output voltage of the photovoltaic panel to a fixed voltage value and then inputs it into the off-grid inverter unit;

[0070] Step 8: Control the first switch K1 and the fifth switch K5 to be closed, the third MOS tube Q3, the fourth MOS tube Q4 and the second inductor L2 form a BOOST circuit, stabilize the output voltage of the photovoltaic panel to a fixed voltage value and then input it into the off-grid inverter unit; the first MOS tube Q1, the second MOS tube Q2 and the first inductor L1 form a BUCK circuit to charge the battery;

[0071] Step 9: Detect whether the battery can provide power. If yes, execute step 10. If no, issue a power failure alarm.

[0072] Step 10: Control the first switch K1 and the second switch K2 to close, and the third MOS tube Q3, the fourth MOS tube Q4, the first inductor L1 and the second inductor L2 form a BOOST circuit to stabilize the output voltage of the battery to a fixed voltage value and then input it into the off-grid inverter unit.

[0073] In this embodiment, preferably, the set threshold range is DC300V-DC1000V, and the fixed voltage value is DC350V. During the process of the controller controlling the working mode of the remote device, the fourth switch K4 is in a closed state except when it is in an open state due to a fault.

[0074] It should be noted that only when both the primary and standby local terminals connected to the remote terminal fail, the photovoltaic panels and storage batteries may be put into use to supply power to the load.

[0075] Example 2

[0076] The difference from Example 1 is that Figure 5 As shown, the off-grid inverter unit of the remote machine includes a three-phase inverter full-bridge circuit and an LCL filter. The output end of the LCL filter is connected to the input end of a TC transformer through an AC main contactor KM1, the output end of the TC transformer is connected to the input end of an AC EMC filter, and the output end of the AC EMC filter is connected to the load through an AC circuit breaker QF1 to provide three-phase 380V AC power to the load.

[0077] In this embodiment, preferably, the input and output ends of the remote machine are also provided with lightning protection units, and the output end is also provided with an overvoltage protection unit, which can quickly cut off the power supply and issue an alarm when the output voltage exceeds 10% of the set value.

[0078] like Figure 6 As shown, the electrical components of the remote machine, such as the lightning protection unit, overvoltage protection unit, off-grid inverter, front-end circuit unit, AC main contactor KM1, TC transformer, AC EMC filter and AC circuit breaker QF1, are all arranged in a housing 10, a display module 30 is arranged on the upper surface of the housing 10, a heat dissipation strip 20 is also arranged on the upper surface of the housing 10, a protruding edge 40 is arranged at the bottom of the housing 10, and a plurality of wiring terminals 50 are arranged on the edge 40 for connecting the remote machine with a battery, a photovoltaic panel, a DC bus, a load, etc.

[0079] Example 3

[0080] like Figure 7 As shown, the local terminal includes two power parts, AC / DC rectification and DC / DC conversion, as well as input and output protection and auxiliary power supply. The AC / DC rectification part includes the front-stage bridge rectification and smoothing filter, which is used to rectify the input AC power into smooth DC power; the DC / DC conversion part includes a DC / DC converter and its control circuit, and a rectification and filtering part, which is used to convert the DC power output by the AC / DC rectification part into a stable voltage value between 300V and 1000V required by the power supply system and then output it. The DC / DC control circuit includes a microprocessor, over-temperature protection, a resonant voltage type dual-loop control loop, over-voltage and over-current short-circuit protection, current sharing control, and feedback sampling. The local terminal also includes an RS-485 communication interface, a digital tube display button, and a dip switch.

[0081] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the above embodiments describe the present invention in detail, those skilled in the art should understand that they may modify the technical solutions recorded in the above embodiments, or replace some or all of the technical features therein with equivalents, and these replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present invention.

Claims

1. A DC remote power supply system with multiple backups for high-speed electromechanical equipment, comprising at least one remote unit, characterized in that: The remote machine comprises: Front-end circuit unit: used to assist in controlling the working mode of the remote unit and stabilize the DC voltage transmitted by the local unit; Controller: used to connect with the front-end circuit unit and control the working mode of the remote machine; Off-grid inverter unit: used to invert the DC voltage stabilized by the front-end circuit unit into stable AC power to supply power to the load; The front-end circuit unit includes a first MOS tube Q1, a second MOS tube Q2, a third MOS tube Q3 and a fourth MOS tube Q4; the drain of the first MOS tube Q1 is connected to the positive electrode of the DC input, the source of the first MOS tube Q1 is connected to the drain of the second MOS tube Q2, and the source of the second MOS tube Q2 is connected to the negative electrode of the DC input; the drain of the third MOS tube Q3 is connected to the positive electrode of the DC input, the source of the third MOS tube Q3 is connected to the drain of the fourth MOS tube Q4, and the source of the fourth MOS tube Q4 is connected to the negative electrode of the DC input; The front-end circuit unit further includes a first inductor L1, a second inductor L2 and a third inductor L3, and a first switch K1, a second switch K2 and a third switch K3; the first inductor L1 is connected in series with the first switch L1 and is arranged between the source of the first MOS tube Q1 and the positive electrode of the battery; the second inductor L2 is connected in series with the second switch K2 and is arranged between the source of the first MOS tube Q1 and the source of the third MOS tube Q3; the third inductor L3 and the third switch K3 are connected in series and are arranged between the source of the third MOS tube Q3 and the positive electrode of the photovoltaic panel; the negative electrode of the battery is connected to the negative electrode of the DC input, and the negative electrode of the photovoltaic panel is connected to the negative electrode of the DC input; The front-end circuit unit further includes a fifth switch K5, and the fifth switch K5 is arranged on a DC input positive line between the drain of the first MOS transistor Q1 and the drain of the third MOS transistor Q3; The controller controls the working mode of the remote device including: Step 1: Detect whether the value of the remote DC input voltage is within the set threshold range. If so, execute step 2; if not, execute step 5; Step 2: Control the second switch K2 to close and detect whether the battery needs to be charged. If not, execute step 3; if yes, execute step 4; Step 3: The first MOS tube Q1, the second MOS tube Q2, the third MOS tube Q3, the fourth MOS tube Q4 and the second inductor L2 form a BUCK / BOOST circuit to stabilize the remote DC input voltage to a fixed voltage value and then input it into the off-grid inverter unit; Step 4: Control the first switch K1 to close, the first MOS tube Q1, the second MOS tube Q2 and the first inductor L1 form a BUCK circuit to charge the battery; the third MOS tube Q3, the fourth MOS tube Q4 and the second inductor L2 form a BOOST circuit to stabilize the remote DC input voltage to a fixed voltage value and then input it into the off-grid inverter unit; Step 5: Check whether the photovoltaic panel can output normally. If yes, go to step 6; if not, go to step 9; Step 6: Control the third switch K3 to close, and detect whether the battery needs to be charged. If not, execute step 7; if yes, execute step 8; Step 7: The third MOS tube Q3, the fourth MOS tube Q4 and the second inductor L2 form a BOOST circuit, which stabilizes the output voltage of the photovoltaic panel to a fixed voltage value and then inputs it into the off-grid inverter unit; Step 8: Control the first switch K1 and the fifth switch K5 to be closed, the third MOS tube Q3, the fourth MOS tube Q4 and the second inductor L2 form a BOOST circuit, stabilize the output voltage of the photovoltaic panel to a fixed voltage value and then input it into the off-grid inverter unit; the first MOS tube Q1, the second MOS tube Q2 and the first inductor L1 form a BUCK circuit to charge the battery; Step 9: Detect whether the battery can provide power. If yes, execute step 10. If no, issue a power failure alarm. Step 10: Control the first switch K1 and the second switch K2 to close, and the third MOS tube Q3, the fourth MOS tube Q4, the first inductor L1 and the second inductor L2 form a BOOST circuit to stabilize the output voltage of the battery to a fixed voltage value and then input it into the off-grid inverter unit.

2. The DC remote power supply system with multiple backups suitable for high-speed electromechanical equipment as claimed in claim 1, characterized in that: The off-grid inverter unit includes a single-phase inverter full-bridge circuit and an LCL filter. After the output end of the front-end circuit unit is connected to the input end of the single-phase inverter full-bridge circuit, single-phase 220V AC power is provided to the load through LCL filtering.

3. The DC remote power supply system with multiple backups suitable for high-speed electromechanical equipment as claimed in claim 1, characterized in that: The off-grid inverter unit includes a three-phase inverter full-bridge circuit and an LCL filter. After the output end of the front-end circuit unit is connected to the input end of the three-phase inverter full-bridge circuit, three-phase 380V AC power is provided to the load through LCL filtering.

4. The DC remote power supply system with multiple backups suitable for high-speed electromechanical equipment as claimed in claim 1, characterized in that: The DC remote power supply system also includes at least one local terminal, which is provided with an AC input terminal and a DC output terminal. The AC input terminal inputs AC220V or AC380V AC power, and the DC output terminal outputs DC300V~DC1000V DC power. The DC output terminal is connected to at least one remote terminal through a cable to provide it with a remote DC input voltage.

5. The DC remote power supply system with multiple backups suitable for high-speed electromechanical equipment as claimed in claim 4, characterized in that: Two local terminals located in two adjacent power supply locations are configured to serve as backup for each other.

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