A rectifier and low voltage inverter array power supply system

Abstract

The rectifier and low-voltage inverter array power supply system provided by the present invention provides the required electric energy for the entire system by adopting a phase-shifting transformer and a shared bus, which can simplify the structure of the system. In addition, the structural form in which each rectifier is connected to multiple inverter groups can also simplify the hardware configuration of the entire system, thereby reducing the production cost of the system and improving the reliability of the system.

Description

Technical Field

[0001] The invention relates to the technical field of variable frequency power supply, and in particular to a rectifier and a low voltage inverter array power supply system. Background Art

[0002] With the rapid development of science and technology and industrialization in my country, my country's industrial energy consumption has remained at around 70%, of which the power consumption of motor systems accounts for more than 60% of my country's industrial power consumption, which is significantly higher than the energy consumption structure of foreign countries. How to meet the continuous and rapid growth of energy demand and achieve clean and efficient use of energy is a severe challenge currently facing my country. Energy conservation and consumption reduction is the strategic thinking of my country's energy development; energy efficiency improvement is the fundamental way to solve my country's energy and environmental problems. Improving the overall energy efficiency of load systems, especially high-energy-consuming load systems, has become the first choice and must-have for various industrial enterprises to achieve energy conservation and efficiency improvement.

[0003] At present, my country's oilfields mainly use mechanical oil production methods, among which beam pumping units (abbreviated as pumping units) account for the highest proportion. Pumping units play an irreplaceable role in crude oil production and are an important part of the "three pumping" of oilfields. Pumping units are the equipment that consumes the most energy in oilfields, accounting for about 40% of the total electricity load in oilfields. The load parameters of pumping units vary greatly, with low load rate, low working efficiency and high energy consumption, resulting in a huge waste of electricity.

[0004] With the exploitation of oil in oil fields, the oil storage capacity of oil wells in different oil fields varies greatly, the liquid level in the well gradually decreases, the filling degree of the pump becomes less and less, and the pump often pumps out empty pumping when the liquid is insufficient. In order to solve the problem of low-yield wells in oil fields and insufficient filling of oil pumps, oil fields often use low-voltage (380V) inverter speed control, such as Figure 1 As shown, it is used to improve pump efficiency and reduce the mechanical impact of frequent start and stop of the oil pump due to insufficient night flow. It has a certain effect of saving energy and extending the life of the oil pump and its accessories.

[0005] The structure of the low-voltage frequency converter in the variable frequency speed regulation energy-saving system of the oil pump used in the prior art is as follows: Figure 2 As shown in the figure, the rectifier circuit of the low-voltage inverter is a six-pulse uncontrolled rectifier, and the current contains high-order harmonic current. When it flows through the power grid, it will cause the grid voltage waveform to be distorted, affecting the current and the load connected in parallel with it, such as causing the AC asynchronous motor torque to decrease, the temperature rise to increase, the protection relay to malfunction, and the measurement instrument error to increase. In order to reduce the impact of the inverter on the power grid, a three-phase reactor needs to be added to the power input end of each inverter to suppress the impact of high-order harmonic current on the power grid. The addition of reactors not only increases the system investment cost, introduces fault points and reduces system reliability, but also increases system losses and reduces system efficiency.

[0006] When the pumping unit is working, it performs a fixed-cycle up-and-down reciprocating motion to continuously pump the crude oil from the well to the ground. In one stroke, as the oil rod rises and falls, the motor periodically switches between the two operating states of electric and power generation. When the oil rod rises, the motor is in the electric state and absorbs electric energy from the power grid; when the oil rod falls, the motor is in the power generation state and needs to convert and consume potential energy. In view of the working characteristics of the pumping unit, a brake circuit is added to the speed control system (see Figure 2 ). It is used to consume the energy generated by the power generation when the pumping unit is lowered, avoiding the fault shutdown caused by overvoltage in the DC circuit of the inverter. The use of resistance energy consumption braking also not only increases the system investment cost, introduces a fault point and reduces the system reliability, but also wastes the electricity generated when the pumping rod is lowered and the pumping unit is in the power generation state.

[0007] In order to reduce energy consumption, it is particularly important to carry out speed regulation and energy-saving transformation of the pumping unit. The oil field pumping units have the characteristics of small power, large number, intermittent motor operation and power generation, and high control performance requirements. Combined with the functional characteristics of the oil field pumping units, it is particularly necessary to simplify the system power supply configuration and comprehensively improve the energy utilization efficiency. Summary of the invention

[0008] The object of the present invention is to provide a rectifier and low voltage inverter array power supply system, which has the characteristics of simple structure and low production cost.

[0009] To achieve the above object, the present invention provides the following solutions:

[0010] A rectifier comprises: a plurality of rectifier modules and a phase-shifting transformer sharing a DC bus;

[0011] The secondary windings of the phase-shifting transformer are respectively connected to the plurality of rectifier modules, and the phase-shifting transformer is used to adjust the voltage input to the rectifier module, and the rectifier module is used to form a pulse current.

[0012] Optionally, the rectification module includes: a filtering circuit and a rectification circuit;

[0013] The filter circuit is connected to the rectifier circuit, and the filter circuit is used to filter out the peak of the current in the rectifier circuit; the rectifier circuit is used to convert three-phase alternating current into direct current.

[0014] Optionally, the rectifier module further includes: an input power supply;

[0015] The input power source is connected to the secondary winding of the phase-shifting transformer, and the input power source is used to input the current output by the phase-shifting transformer.

[0016] A power supply system for a low-voltage inverter array, the power supply system comprising the above-mentioned rectifier and a plurality of inverter groups;

[0017] Each of the rectifiers is connected to a plurality of the inverter groups; the rectifier is used to convert three-phase alternating current into direct current; and the inverter is used to convert direct current into alternating current.

[0018] Optionally, the power supply system further includes: a control center group;

[0019] The control center group is connected to the rectifier and the inverter group respectively; the control center group is used to adjust the working state of the inverter group.

[0020] Optionally, the control center group includes a plurality of control center modules, and the number of the control center modules is the same as the number of the rectifiers;

[0021] The control central module is connected to the rectifier in a one-to-one correspondence.

[0022] Optionally, the control center module includes: a main controller and a PLC;

[0023] The main controller is connected to the PLC, and the main controller is used to adjust the running speed of the motor in the inverter group and the spatial position of the motor; the PLC is used to adjust the closing and opening of the switch between the inverter and the rectifier according to the working status of the inverter and the motor.

[0024] Optionally, the inverter group includes: a plurality of inverter modules;

[0025] The inverter module includes a sub-controller;

[0026] The sub-controller is connected to the main controller and the motor in the inverter group respectively; the sub-controller is used to transmit the detected motor running speed and the spatial position of the motor to the main controller;

[0027] The main controller generates a control instruction according to the detected running speed of the motor and the spatial position of the motor, thereby controlling the running speed and the spatial position of the motor.

[0028] Optionally, the inverter module further includes: a vacuum contactor and an inverter;

[0029] The vacuum contactor is connected to the inverter; the vacuum contactor is used to connect or disconnect the working current of the system to control the start or stop of the motor in the inverter group.

[0030] Optionally, the inverter is an IGBT inverter.

[0031] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: the rectifier and low-voltage inverter array power supply system provided by the present invention provides the required electric energy for the entire system by adopting a phase-shifting transformer and a shared bus, which can simplify the structure of the system, and adopt a structural form in which each rectifier is connected to multiple inverter groups, which can also simplify the hardware configuration of the entire system, thereby reducing the production cost of the system and improving the reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0033] Figure 1 It is a structural schematic diagram of a variable frequency speed regulation energy-saving system for an oil pump in the prior art;

[0034] Figure 2 It is a structural schematic diagram of a low-voltage frequency converter used in a variable frequency speed regulation energy-saving system for an oil pumping unit in the prior art;

[0035] Figure 3 A schematic diagram of the structure of a phase-shifting transformer provided in an embodiment of the present invention;

[0036] Figure 4 A schematic diagram of the structure of a rectifier module provided in an embodiment of the present invention;

[0037] Figure 5 A schematic diagram of the structure of a power supply system of a low-voltage inverter array provided in an embodiment of the present invention;

[0038] Figure 6 A schematic diagram of the structure of an inverter group provided in an embodiment of the present invention;

[0039] Figure 7 This is a diagram of the inverter working principle of the power supply system of the low-voltage inverter array provided in an embodiment of the present invention.

[0040] Reference numerals:

[0041] 1 high-voltage incoming line cabinet, 2 rectifier, 2-1 phase-shifting transformer, 2-2 rectifier module, 2-2-1 input power supply, 2-2-2 protection circuit, 2-2-3 rectifier circuit, 2-2-4 buffer circuit, 2-2-5 filter circuit, 2-2-6 braking circuit, 4 control center group, 3-1 main controller, 3-2 PLC, 4 inverter group, 4-1 sub-controller, 4-2 vacuum contactor, 4-3 inverter, 4-4 motor. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The object of the present invention is to provide a rectifier and low voltage inverter array power supply system, which has the characteristics of simple structure and low production cost.

[0044] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] For ease of understanding, it is first necessary to explain the English abbreviations used in the entire technical solution of the present invention:

[0046] The English definitions of abbreviations, terms and key terms are as follows:

[0047] IGBT: Insulated Gate Bipolar Transistor, is a composite fully controlled voltage-driven power semiconductor device composed of BJT (bipolar transistor) and MOS (insulated gate field effect transistor), which has the advantages of both high input impedance of MOSFET and low on-state voltage drop of GTR;

[0048] KM: Vacuum contactor, which uses vacuum interrupter to extinguish arc, is used to frequently connect and disconnect normal working current, usually used to connect and disconnect 6kV, 380V AC motors with medium and low voltages that are frequently started and stopped at long distances;

[0049] HMI: HMI is the abbreviation of Human Machine Interface, also known as human-machine interface;

[0050] PLC: PLC control system, Programmable Logic Controller, a digital computing electronic device designed for industrial production. It uses a type of programmable memory to store programs internally, execute user-oriented instructions such as logic operations, sequential control, timing, counting and arithmetic operations, and control various types of machinery or production processes through digital or analog input / output;

[0051] PWM: PWM is pulse width modulation, which is a pulse waveform with a variable duty cycle;

[0052] TCP / IP: TCP / IP (Transmission Control Protocol / Internet Protocol) is not a simple protocol, but a group of special protocols, including TCP, IP, UDP, ARP, etc., which are called sub-protocols. Among these protocols, the most important and famous are TCP and IP.

[0053] The specific technical solutions provided by the present invention are as follows:

[0054] A rectifier, comprising: a plurality of rectifier modules 2-2 and a phase-shifting transformer 2-1 sharing a DC bus;

[0055] The secondary windings of the phase-shifting transformer 2-1 are respectively connected to the plurality of rectifier modules 2-2, and the phase-shifting transformer 2-1 is used to adjust the voltage input to the rectifier module 2-2. Figure 3 shown.

[0056] Figure 4 A structural diagram of a rectifier module provided in an embodiment of the present invention is shown in FIG. Figure 4 As shown, the rectifier module 2-2 includes: a filter circuit 2-2-5 and a rectifier circuit 2-2-3;

[0057] The filter circuit 2-2-5 is connected to the rectifier circuit 2-2-3, and the filter circuit 2-2-5 is used to filter out the peak of the current in the rectifier circuit 2-2-3.

[0058] The rectifier 2 is the core part of the entire design of the present invention, which specifically includes 3n groups of common DC bus rectifier modules 2-2. Each group of rectifier modules 2-2 is connected to the secondary winding of the mobile transformer through a vacuum contactor 4-2. If any group of rectifier modules 2-2 has an overload or overcurrent fault, the faulty group can be cut off by the vacuum contactor 4-2 configured in the group to ensure the normal operation of other devices in the common DC bus low-voltage inverter array.

[0059] In the present invention, the oil pumps within a certain range (generally a range with a radius of 500 meters) at the oil field site can share a set of rectifiers 2, and the several rectifier modules 2-2 in each rectifier 2 mainly include: an input power supply 2-2-1, a protection circuit 2-2-2, a rectifier circuit 2-2-3, a buffer circuit 2-2-4, a filter circuit 2-2-5 and a braking circuit 2-2-6.

[0060] The input power supply 2-2-1 is connected to the secondary winding of the phase-shifting transformer 2-1 to provide a suitable power supply for the rectifier 2 through the dry-type phase-shifting transformer 2-1 with extended triangle phase shifting.

[0061] The protection circuit 2-2-2 includes a contactor and a fuse. When the common DC bus rectifier 2, or the inverter 4-3 or the motor 4-4 it carries, etc., is overloaded (125%, 1 minute, 180%, 3 seconds), the contactor can cut off the faulty part after a delay determined by software; when the common DC bus rectifier 2, or the inverter 4-3 or the motor 4-4 it carries, etc., has a phase-to-phase or relative short circuit fault, the fuse can quickly cut off the faulty part to ensure that other common DC bus rectifiers 2 and the inverters 4-3 they carry can operate normally.

[0062] The rectifier circuit 2-2-3 uses a three-phase uncontrolled rectifier bridge to convert the three-phase AC into DC to provide power for the rectifier 2;

[0063] The buffer circuit 2-2-4 includes a contactor and a current limiting resistor to prevent the power-on shock from damaging the rectifier bridge. During operation, the contactor is disconnected, and the resistor is connected in series to the circuit to limit the current. The delay is 10s. After the power is on, the contactor is closed to short-circuit the power-on resistor.

[0064] The filter circuit 2-2-5, including an electrolytic capacitor and a voltage-equalizing resistor, is used to filter out the peaks in the DC circuit after rectification by the three-phase rectifier bridge in the rectifier circuit 2-2-3.

[0065] The braking circuit 2-2-6, including a resistor and a contactor, is used to absorb the unconsumed electric energy generated by the descending power generation of all motors 4-4 supported by the common DC bus rectifier 2.

[0066] The capacity of the entire rectifier 2 can be determined according to the number of pumping units and power that need to be regulated on site and after calculation. Specifically, if the number of pumping units in the area is large enough, the DC output bus of the rectifier 2 can supply power to several inverter circuits, forming a bus power supply mode in which multiple inverter circuits share the bus. By coordinating and controlling the up and down strokes of the pumping units carried by the rectifier 2, the power of the pumping units in the electric state and the power generation state is basically balanced to improve energy efficiency and reduce energy consumption. If the number of pumping units in the area is insufficient, or the oil field oil reserves change, and the number of operating pumping units is insufficient, the DC output bus of the rectifier 2 in the area can also be connected to another set of DC output bus of the rectifier 2 nearby to form multiple sets of rectifiers 2 to share the DC bus, so as to supply the pumping units in multiple areas to improve energy efficiency and reduce energy consumption.

[0067] Figure 5 A schematic diagram of the structure of a power supply system of a low voltage inverter array provided in an embodiment of the present invention is shown in FIG. Figure 5 As shown, a power supply system of a low-voltage inverter 4-3 array includes the above-mentioned rectifier 2 and multiple inverter groups 4.

[0068] Each of the rectifiers 2 is connected to a plurality of the inverter groups 4; the rectifier is used to convert three-phase alternating current into direct current, and the inverter is used to convert direct current into alternating current.

[0069] The power supply system further includes: a control center group 3;

[0070] The control center group 3 is connected to the rectifier 2 and the inverter group 4 respectively; the control center group 3 is used to adjust the working state of the inverter group 4.

[0071] The control center group 3 is the brain of the common DC bus low-voltage inverter array, and includes the same number of control center modules as the rectifier 2 , and the control center modules are connected to the rectifier 2 in a one-to-one correspondence.

[0072] Each control center module includes a touch screen, a PLC 3-2 and a main controller 3-1.

[0073] Among them, PLC3-2 uses Siemens Smart series PLC3-2, which is used to collect and control the status of the contactors in the entire system and complete the system logic control. PLC3-2 has 18 input / 12 output switch quantities. When the switch quantity input and output points are insufficient, the switch quantity module (EMDE08 (8 inputs), EMDR08 (8 outputs) or EMDR16 (8 inputs + 8 outputs)) can be expanded to obtain the on and off status of the DC input contactor of the inverter group 4 in the jurisdiction and control the on and off of the contactor according to the protection instructions of the main controller 3-1.

[0074] The touch screen serves as a human-computer interaction window, which can display in real time the fault alarms and real-time operating status of all inverter groups 4 driven by the rectifier module 2-2 it serves, complete the function adjustment and parameter setting of each inverter group 4, and is a window for the rectifier module 2-2 and all the inverter groups 4 it drives to communicate with the operator.

[0075] The main controller 3-1, as the core of the control center, mainly adopts a high-performance BKD05 controller, including DSP2812, FPGA and digital logic circuits. The main controller 3-1 quickly calculates and generates an operation model based on the operating speed, current size, etc. of each motor 4-4, and transmits it to the sub-controller 4-1 of each inverter group 4 through parallel (FPGA) for execution (the technology relied on by the controller is the conventional technology of controlling the motor operating speed in the prior art). The main controller 3-1 calculates and controls the on and off of each inverter 4-3 IGBT in real time by FPGA according to the operating data and alarm data of each inverter 4-3 transmitted by each sub-controller 4-1, so as to realize the speed-oriented rotor vector control of each pumping unit; the operating speed and spatial position of each motor are adjusted in real time according to the current and direction of the motor 4-4 carried by each inverter group 4, so as to make full use of the power supply energy of the pumping unit driven by the rectifier 2 (such as Figure 6 The control center and each inverter 4-3 sub-controller 4-1 and the control center all use optical fiber (TCP / IP) to communicate in real time and quickly.

[0076] The inverter group 4 further includes: a sub-controller 4-1;

[0077] The sub-controller 4-1 is connected to the main controller 3-1 and the motor 4-4 in the inverter group 4 respectively; the sub-controller 4-1 is used to transmit the detected running speed of the motor 4-4 and the spatial position of the motor 4-4 to the main controller 3-1, and control the running speed and spatial position of the motor 4-4 according to the control instructions issued by the main controller 3-1.

[0078] The inverter group 4 includes a plurality of inverter modules, each of which includes: a vacuum contactor 4-2, an inverter 4-3, drive hardware and a sub-controller 4-1;

[0079] The vacuum contactor 4 - 2 is connected to the inverter 4 - 3 ; the vacuum contactor 4 - 2 is used to connect or disconnect the working current of the system to control the start and stop of the motor 4 - 4 in the inverter group 4 .

[0080] The controllable inverter is the power inversion part of the inverter 4-3, which consists of a three-phase controllable rectifier circuit composed of IGBT, a switch, and a fuse. Among them, the switch is used to power on the inverter module separately, forming an obvious breakpoint in case of failure. The fuse is used for short-circuit protection of the inverter module and its back end. In case of failure, the faulty part is promptly removed from the system to improve system reliability.

[0081] The driving hardware completes the driving of each IGBT PWM waveform and the IGBT current driving protection;

[0082] In addition, Figure 5 The rectifier module 1 and rectifier module n in the figure are to reflect that there are n rectifier modules, and the 1 and n of the inverter and the motor have the same meaning.

[0083] like Figure 7 As shown, the sub-controller 4-1 is composed of a control module, a PWM output, a TCP / IP interface, a current sensor interface, an encoder interface, an operator interface, an I / O interface, etc.; the sub-controller 4-1 receives the coordination control signal from the upper-level centralized control center through the TCP / IP interface and generates PWM, which is transmitted to the PWM drive hardware through the PWM output;

[0084] Each motor 4-4 is independently equipped with a current sensor and an encoder. The current sensor interface is used to detect the running current of the motor 4-4 nearby, and the encoder interface is used to detect the speed of the motor 4-4 nearby, and transmit the signal to the central controller group for coordinated control;

[0085] The operator interface of the entire power supply system is equipped with start, stop, reset, emergency stop and other buttons to facilitate customer-side control.

[0086] In addition, the power supply system provided by the present invention also includes a high-voltage switch cabinet 1. The high-voltage power supply 10kV or 06kV of the user's home is used to supply power to the phase-shifting transformer 2-1 of the common DC bus low-voltage inverter array through the high-voltage switch cabinet 1; the comprehensive protection configured in the high-voltage switch cabinet 1 is mainly used to detect whether the grid network voltage and the total load of all driven pumping units are within the normal range, and is used to protect the normal operation of the equipment.

[0087] The present invention adopts a multi-tap dry-type transformer with a phase-shifting Yanbian triangle on the secondary side to power the system. Each group of taps is accompanied by a set of rectifiers to form an energy pool, and a shared DC bus is used to provide energy for multiple groups of IGBT inverters. The rectifier incoming power supply no longer needs to provide an incoming line reactor separately to reduce the pollution of harmonics to the power grid. Multiple inverter parts share a common DC bus and its accessories, which reduces the number of hardware of each pumping unit inverter, simplifies the hardware configuration, improves system reliability and reduces the primary cost investment. In addition, by controlling the central coordination of the power generation and motoring states of all pumping units driven by the rectifier, the inverter group driven by the common DC bus under the rectifier works in the best matching state, which greatly improves the energy utilization rate while increasing the life of the resistance braking circuit.

[0088] Compared with the prior art, the present invention also has the following outstanding features:

[0089] 1. The present invention adopts a multi-tap dry-type rectifier transformer with a phase-shifted secondary side to replace the traditional power transformer for low-voltage rectifier circuit array for the first time. Each group of taps is accompanied by a group of rectifier modules to form a DC power supply energy pool. The rectifier incoming power supply does not need to provide a separate incoming line reactor to reduce harmonic pollution to the power grid.

[0090] 2. The DC power output end of each set of rectifier modules can provide energy for multiple sets of IGBT inverters at the same time. Multiple inverter modules are connected to the output end of the rectifier module, sharing the common DC bus and its accessories to form a common DC bus form, which reduces the number of inverter hardware for each pumping unit, simplifies the hardware configuration, improves system reliability and reduces the primary investment.

[0091] 3. The control part of the present invention adopts a distributed control mode of control center + sub-controller. It is convenient for the control center to centrally regulate the speed, power generation, and motor state of all the pumping units driven by a certain rectifier module, so that all the inverters carried by the rectifier module work in the best matching state, which not only improves the life of the resistance braking circuit, but also greatly improves the energy utilization rate. At the same time, it is convenient for the sub-controller to quickly collect the operating data and fault alarm information of each inverter module to ensure the reliable and safe operation of the fault-free part in the system.

[0092] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0093] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A power supply system for a low voltage inverter array, characterized in that: The power supply system includes a plurality of rectifiers and a plurality of inverter groups; Each of the rectifiers is connected to a plurality of the inverter groups; the rectifier is used to convert three-phase alternating current into direct current; the inverter is used to convert direct current into alternating current; The rectifier comprises: a plurality of rectifier modules and a phase-shifting transformer sharing a DC bus; The secondary winding of the phase-shifting transformer is respectively connected to the plurality of rectifier modules through vacuum contactors, and the phase-shifting transformer is used to adjust the voltage input to the rectifier module, and the rectifier module is used to form a pulse current; The system is powered by a multi-tap dry-type transformer with a Yanbian triangle phase shift on the secondary side. Each set of taps is equipped with a set of rectifiers to form an energy pool. If the number of oil pumps reaches the set number, the rectifier DC output bus will supply power to several inverter circuits, forming a bus power supply mode in which multiple inverter circuits share the bus; by coordinating and controlling the up and down strokes of the oil pumps carried by the rectifier, the power of the oil pumps in the electric state and the power generation state is kept balanced; if the number of oil pumps is insufficient or the oil storage capacity of the oil field changes, the rectifier DC output bus is connected to another set of rectifier DC output bus to form multiple sets of rectifiers sharing the DC bus to supply the oil pumps in multiple areas.

2. A power supply system for a low voltage inverter array according to claim 1, characterized in that: The power supply system further includes: a control center group; The control center group is connected to the rectifier and the inverter group respectively; the control center group is used to adjust the working state of the inverter group.

3. A power supply system for a low voltage inverter array according to claim 2, characterized in that: The control center group includes a plurality of control center modules, and the number of the control center modules is the same as the number of the rectifiers; The control central module is connected to the rectifier in a one-to-one correspondence.

4. A power supply system for a low voltage inverter array according to claim 3, characterized in that: The control center module includes: a main controller and a PLC; The main controller is connected to the PLC, and the main controller is used to adjust the running speed of the motor in the inverter group and the spatial position of the motor; the PLC is used to adjust the closing and opening of the switch between the inverter and the rectifier according to the working status of the inverter and the motor.

5. A power supply system for a low voltage inverter array according to claim 4, characterized in that: The inverter group includes: a plurality of inverter modules; The inverter module includes a sub-controller; The sub-controller is connected to the main controller and the motor in the inverter group respectively; the sub-controller is used to transmit the detected motor running speed and the spatial position of the motor to the main controller; The main controller generates a control instruction according to the detected running speed of the motor and the spatial position of the motor, thereby controlling the running speed and the spatial position of the motor.

6. A power supply system for a low voltage inverter array according to claim 5, characterized in that: The inverter module also includes: a vacuum contactor and an inverter; The vacuum contactor is connected to the inverter; the vacuum contactor is used to connect or disconnect the working current of the system to control the start or stop of the motor in the inverter group.

7. A power supply system for a low voltage inverter array according to claim 6, characterized in that: The inverter is an IGBT inverter.

8. A power supply system for a low voltage inverter array according to claim 1, characterized in that: The rectifier module includes: a filter circuit and a rectifier circuit; The filter circuit is connected to the rectifier circuit, and the filter circuit is used to filter out the peak of the current in the rectifier circuit; the rectifier circuit is used to convert three-phase alternating current into direct current.

9. A power supply system for a low voltage inverter array according to claim 1, characterized in that: The rectifier module also includes: an input power supply; The input power source is connected to the secondary winding of the phase-shifting transformer, and the input power source is used to input the current output by the phase-shifting transformer.

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