Long distance power supply system

Abstract

The utility model relates to the technical field of power supply, concretely relates to a long distance power supply system, and the system includes AC / DC module, DC / AC module, lithium super energy storage module and control system, each module is connected with control system, AC / DC module is connected with power grid side, and DC / AC module is set between AC / DC module and load, lithium super energy storage module is connected in parallel between AC / DC module and DC / AC module, and control system includes control algorithm module, and control algorithm module integrates PWM rectification algorithm module, PWM inversion algorithm module, voltage outer ring + current inner ring double -closed -loop control algorithm module, low pass filter algorithm module and voltage equalization control algorithm module. Adopt the long distance power supply system provided by the utility model, solved the problem that long distance power supply voltage pressure drop is big, through lithium super energy storage module smooth output power and emergency power supply, improve long distance power supply stability.

Description

Technical Field

[0001] This utility model relates to the field of power supply technology, specifically to a long-distance power supply system. Background Technology

[0002] With the development of coal mining, underwater production systems, underground operations, and the transportation industry, the distance between power supply equipment and load equipment is constantly increasing, leading to a series of long-distance power supply problems. (See also...) Figure 1 Traditional long-distance power supply systems use long cables for transmission, which has problems such as large voltage drop, power fluctuations, and safety hazards caused by sudden power outages. In the case of long-distance power supply, the voltage drop of the cable caused by the reactive and active current of the motor during operation results in low voltage at the end of the power supply cable, and the load equipment cannot start normally.

[0003] Currently, improvements are being made through the following methods: (1) Increasing the voltage at the power supply start point. This method aims to ensure that power can reach the end equipment more effectively during transmission by increasing the voltage level at the power supply start point. However, when the equipment is in a shutdown or no-load operation state, excessively high end voltage may put additional pressure on the insulation materials of the cable and equipment, and may even exceed its design withstand voltage range, thereby increasing the risk of damage. In addition, if the voltage rise is not properly controlled, it may also lead to unnecessary energy consumption. (2) Reducing the length of the power supply cable between the load equipment and the power supply. This can significantly reduce the voltage drop caused by line impedance, thereby improving the overall power supply quality. However, there are many challenges in implementing this. First, for many large-scale industrial facilities with fixed installations, it is often unrealistic to rearrange or adjust the existing layout to adapt to the new scheme. Second, frequent relocation of the substation location not only requires a large amount of manpower and material resources for construction work, but also affects normal production activities and causes inconvenience to enterprises.

[0004] In summary, there is an urgent need to provide a long-distance power supply system to solve the technical problems existing in the current technology. Utility Model Content

[0005] The purpose of this utility model is to provide a long-distance power supply system to solve the technical problems existing in the prior art. The specific technical solution is as follows:

[0006] A long-distance power supply system is installed between the power grid and the load, including an AC / DC module, a DC / AC module, a lithium super energy storage module, and a control system, wherein the AC / DC module, DC / AC module, and lithium super energy storage module are respectively connected to the control system;

[0007] The AC / DC module is connected to the power grid side and is used to convert three-phase alternating current into direct current. The AC / DC module includes a PWM rectifier and an inductor-capacitor filter connected in sequence, and the PWM rectifier is connected to the control system.

[0008] The DC / AC module is located between the AC / DC module and the load, and is used to convert DC power into three-phase AC power; the DC / AC module includes a PWM inverter, which is connected to the control system;

[0009] The lithium super energy storage module is connected in parallel between the AC / DC module and the DC / AC module to smooth the output power of the AC / DC module and provide emergency power supply.

[0010] The control system includes a control algorithm module, which integrates a PWM rectification algorithm module, a PWM inverter algorithm module, a voltage outer loop + current inner loop dual closed-loop control algorithm module, a low-pass filter algorithm module, and a voltage equalization control algorithm module. The PWM rectification algorithm module is connected to the AC / DC module, and the PWM inverter algorithm module is connected to the DC / AC module. The PWM rectification algorithm module and the PWM inverter algorithm module are used to dynamically adjust the power conversion. The low-pass filter algorithm module is used to filter out noise and prevent signal interference. The voltage equalization control algorithm module is used to equalize the voltage of the lithium super energy storage module. The voltage outer loop + current inner loop dual closed-loop control algorithm module is used to maintain the stability of the DC voltage.

[0011] Furthermore, the control system also includes a voltage sensor, a current sensor, and a DSP main control board. The voltage sensor and the current sensor are respectively installed on the output terminal of the PWM rectifier, the output terminal of the PWM inverter, and the lithium super energy storage module and connected to the DSP main control board, for real-time acquisition of output voltage and output current and feedback to the DSP main control board; the control algorithm module is located on the DSP main control board.

[0012] Furthermore, the lithium super energy storage module is asymmetrically composed of a lithium-ion battery and a supercapacitor, including a capacitor-type positive electrode, a separator, a battery-type negative electrode, an electrolyte, and a shell; the capacitor-type positive electrode and the battery-type negative electrode are disposed opposite each other at both ends inside the shell; the separator is disposed inside the shell, located between the capacitor-type positive electrode and the battery-type negative electrode; and the electrolyte fills the inside of the shell.

[0013] Furthermore, the capacitive positive electrode is a composite electrode made of activated carbon or manganese dioxide; the battery-type negative electrode is made of a pre-lithium-intercalated material.

[0014] Furthermore, the battery-type negative electrode undergoes nano-sizing treatment, and the capacitive positive electrode adopts a hierarchical porous structure.

[0015] Furthermore, the diaphragm is a ceramic-coated polyethylene film.

[0016] The application of the technical solution of this utility model has the following beneficial effects:

[0017] (1) This utility model provides a long-distance power supply system, which is set between the grid side and the load, including an AC / DC module, a DC / AC module, a lithium super-energy storage module and a control system. The AC / DC module, DC / AC module and lithium super-energy storage module are respectively connected to the control system. The AC / DC module is connected to the grid side and is used to convert three-phase AC power into DC power. The AC / DC module includes a PWM rectifier and an inductor-capacitor filter connected in sequence. The PWM rectifier is connected to the control system. The DC / AC module is set between the AC / DC module and the load and is used to convert DC power into three-phase AC power. The DC / AC module includes a PWM inverter. The PWM inverter is connected to the control system. The control system adjusts the PWM duty cycle to match the load demand through real-time feedback of voltage and current. The lithium super-energy storage module... The energy storage module is connected in parallel between the AC / DC module and the DC / AC module to smooth the output power of the AC / DC module and provide emergency power supply. The control system includes a control algorithm module, which integrates a PWM rectification algorithm module, a PWM inverter algorithm module, a voltage outer loop + current inner loop dual closed-loop control algorithm module, a low-pass filter algorithm module, and a voltage equalization control algorithm module. The PWM rectification algorithm module is connected to the AC / DC module, and the PWM inverter algorithm module is connected to the DC / AC module. The PWM rectification algorithm module and the PWM inverter algorithm module are used to dynamically adjust the power conversion. The low-pass filter algorithm module is used to filter out noise and prevent signal interference. The voltage equalization control algorithm module is used to equalize the voltage of the lithium super energy storage module. The voltage outer loop + current inner loop dual closed-loop control algorithm module is used to maintain the stability of the DC voltage. The long-distance power supply system provided by this utility model can convert three-phase AC power into DC power for long-distance transmission through the AC / DC module, and then convert the DC power back into three-phase AC power for use in large load equipment through the DC / AC module, thus solving the problem of large voltage drop in long-distance power supply; and improve the stability of long-distance power supply by smoothing the output power and emergency power supply through the lithium super energy storage module.

[0018] (2) In this utility model, high-frequency harmonics in the entire power transmission process are suppressed or filtered out by the filter and low-pass filter algorithm module, and pure AC or DC power is output to achieve the provision of high-quality power supply and improve the stability of power supply.

[0019] (3) In this utility model, the power conversion is dynamically adjusted by the PWM rectifier and PWM inverter, as well as the PWM rectifier algorithm module and the PWM inverter algorithm module, to reduce energy loss and improve the power utilization rate of the system.

[0020] In addition to the objectives, features, and advantages described above, this utility model has other objectives, features, and advantages. The present utility model will now be described in further detail with reference to the figures. Attached Figure Description

[0021] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings:

[0022] Figure 1 This is a schematic diagram of a traditional long-distance power supply system;

[0023] Figure 2 This is a schematic diagram of the medium-to-long-distance power supply system of this utility model;

[0024] Figure 3 This is a schematic diagram of an AC / DC module;

[0025] Figure 4 This is a schematic diagram of a DC / AC module. Detailed Implementation

[0026] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered.

[0027] In the description of this utility model, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "front", "back", "lateral", "longitudinal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0028] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0029] Example:

[0030] See Figure 1Traditional long-distance power supply systems use long cables for transmission, which has problems such as large voltage drop, power fluctuations, and safety hazards caused by sudden power outages. In the case of long-distance power supply, the voltage drop of the cable caused by the reactive and active current of the motor during operation results in low voltage at the end of the power supply cable, and the load equipment cannot start normally.

[0031] To solve the above-mentioned technical problems, this utility model provides a long-distance power supply system.

[0032] See Figure 2 The long-distance power supply system is set between the grid side and the load (large load equipment), including AC / DC module, DC / AC module, lithium super energy storage module and control system. The AC / DC module, DC / AC module and lithium super energy storage module are respectively connected to the control system.

[0033] The control system includes a control algorithm module, which integrates a PWM rectification algorithm module, a PWM inverter algorithm module, a voltage outer loop + current inner loop dual closed-loop control algorithm module, a low-pass filter algorithm module, and a voltage equalization control algorithm module. The PWM rectification algorithm module is connected to the AC / DC module, and the PWM inverter algorithm module is connected to the DC / AC module. The PWM rectification algorithm module and the PWM inverter algorithm module are used to dynamically adjust the power conversion. The low-pass filter algorithm module is used to filter out noise and prevent signal interference. The voltage equalization control algorithm module is used to equalize the voltage of the lithium super energy storage module. The voltage outer loop + current inner loop dual closed-loop control algorithm module is used to maintain the stability of the DC voltage.

[0034] The control system also includes a voltage sensor, a current sensor, and a DSP main control board. The voltage sensor and current sensor are respectively installed on the output end of the PWM rectifier, the output end of the PWM inverter, and the lithium super energy storage module, and are connected to the DSP main control board (the control algorithm module is installed on the main control board via a chip) to collect the output voltage and output current in real time and feed them back to the DSP main control board.

[0035] See Figure 3 The AC / DC module is connected to the power grid side and is used to convert three-phase AC power into DC power. The AC / DC module includes a PWM rectifier and an inductor-capacitor filter connected in sequence. The output terminal of the PWM rectifier is connected to a voltage sensor and a current sensor to collect the output voltage and output current in real time and feed them back to the DSP main control board. The DSP main control board changes the duty cycle of the PWM signal to adjust the output voltage and frequency to match the load requirements and ensure that the output parameters meet the requirements.

[0036] A PWM rectifier consists of six diodes and six power switching devices. It can convert three-phase alternating current into pulsating direct current and also enables bidirectional energy flow, allowing energy to flow from the AC grid side to the DC side and vice versa. After the three-phase AC power is input, the power switching devices in the bridge circuit are controlled by the PWM rectification algorithm to adjust the rectifier's input current waveform so that it remains in phase with the input voltage waveform, achieving unity power factor.

[0037] The rectified pulsating DC power passes through an inductor-capacitor filter to remove high-frequency harmonic components, resulting in a more stable DC power. The model of the inductor-capacitor filter is adjusted according to the actual application.

[0038] The advantages of using PWM rectifiers and inductor-capacitor filtering are:

[0039] ① High efficiency: PWM rectifiers reduce harmonic content and improve power conversion efficiency by precisely controlling the on and off times of the switching transistors;

[0040] ② High power factor: It can make the input current and input voltage in phase, so that the power factor is close to 1, reducing harmonic pollution to the power grid;

[0041] ③ Fast dynamic response: PWM rectifiers have a fast dynamic response capability, which can quickly adjust the output voltage and current according to load changes;

[0042] ④ Energy can flow in both directions: It has the ability to flow energy in both directions, and can realize regenerative braking and energy recovery;

[0043] ⑤ Good stability: The filter can significantly improve the stability of DC power and provide high-quality DC power for subsequent circuits.

[0044] See Figure 2 and Figure 4 The DC / AC module is positioned between the AC / DC module and the load to convert direct current (DC) into three-phase alternating current (AC). The DC / AC module includes a PWM inverter, which converts DC to AC. The output of the PWM inverter is connected to voltage and current sensors to collect output voltage and current data in real time and feed them back to the DSP main control board. The DSP main control board adjusts the PWM duty cycle based on the real-time feedback voltage and current to match load requirements. A filter is also included. After DC is input to the PWM inverter, the high-frequency switching devices of the PWM inverter generate high-frequency pulse voltage, which is then smoothed by the filter to obtain stable three-phase AC.

[0045] Using a PWM inverter has the following advantages:

[0046] ① High flexibility: PWM inverters can flexibly adjust the output voltage and frequency to adapt to the power needs of different devices;

[0047] ② High efficiency: The inverter has high efficiency, which reduces energy loss and improves the system's power utilization rate.

[0048] The lithium super energy storage module is connected in parallel between the AC / DC module and the DC / AC module to smooth the output power of the AC / DC module and provide emergency power supply.

[0049] Lithium-ion superchargers (LISS) offer advantages such as high power density, fast charging speed, long cycle life, wide operating temperature range, strong high-current discharge capability, and zero pollution. These characteristics make LISSs particularly suitable for applications requiring short-duration high-power output.

[0050] Charging process: During periods of low load, the AC / DC module stores excess electrical energy into the lithium super energy storage module.

[0051] Discharge process: During peak load periods or when the main power supply fails, the lithium super energy storage module releases electrical energy, which is then converted into AC power by the DC / AC module to supply large load equipment.

[0052] In this embodiment, the lithium super energy storage module is composed of an asymmetric composite of a lithium-ion battery and a supercapacitor, including a capacitor-type positive electrode, a separator, a battery-type negative electrode, an electrolyte, and a shell; the capacitor-type positive electrode and the battery-type negative electrode are disposed opposite each other at both ends inside the shell; the separator is disposed inside the shell, located between the capacitor-type positive electrode and the battery-type negative electrode; and the electrolyte fills the inside of the shell.

[0053] The capacitive positive electrode uses activated carbon or composite materials (such as manganese dioxide composite electrodes) to achieve rapid charging and discharging; the battery-type negative electrode uses pre-lithium-intercalated materials to provide high capacity; the above materials are preferred, but can also be replaced with other materials that can achieve the same function. The capacity of the negative electrode needs to be slightly higher than that of the positive electrode to prevent overload of the positive electrode.

[0054] Preferably, the battery-type negative electrode is nano-sized to alleviate volume expansion; the capacitive positive electrode adopts a hierarchical porous structure, such as a graphene / carbon nanotube composite; the above materials are preferred materials, but can also be replaced with other materials that can achieve the same function.

[0055] The electrolyte is preferably an EC / DMC solution containing LiPF6 (lithium hexafluorophosphate); the separator is preferably a ceramic-coated polyethylene membrane, which can improve safety. These materials are preferred, but can be replaced with other materials that achieve the same function.

[0056] Advantages of using lithium super energy storage:

[0057] ① High power density: Lithium-ion batteries have high energy density, capable of storing large amounts of electrical energy; while supercapacitors have extremely high power density, allowing for rapid charging and discharging in a short time. Combining the two provides powerful power support for applications requiring high power output, meeting emergency power supply needs.

[0058] ② Fast response: Lithium supercharging is fast, and can complete charging and discharging operations in a short time, adapting to frequent charging and discharging needs.

[0059] ③ Long lifespan: Compared to traditional lithium-ion batteries, lithium supercapacitors have a longer cycle life. The charging and discharging process of supercapacitors is mainly a physical reaction with strong reversibility. The structure of the electrode materials is relatively stable and does not undergo a large number of chemical changes during charging and discharging like lithium-ion batteries. Therefore, their cycle life can reach tens of thousands or even hundreds of thousands of times, which makes lithium supercapacitors more reliable in long-term use and reduces maintenance costs.

[0060] ④ High safety: Lithium-ion batteries may experience safety issues such as thermal runaway under overcharge, over-discharge, or high-temperature conditions, while supercapacitors have relatively high safety. The combination of lithium and supercapacitors can reduce the safety risks of the battery system through reasonable design and control strategies; for example, in a battery management system, lithium-ion batteries and supercapacitors can be managed and monitored separately to ensure they operate within safe limits.

[0061] ⑤ Good environmental performance: Both lithium-ion batteries and supercapacitors in the lithium-supercapacitor combination are relatively environmentally friendly energy storage technologies. Lithium-ion batteries do not contain harmful heavy metals such as lead and cadmium; the materials of supercapacitors also have good recyclability and reusability.

[0062] In this embodiment, the PWM rectification algorithm module is connected to the AC / DC module, and the PWM inverter algorithm module is connected to the DC / AC module.

[0063] The PWM rectification algorithm in the PWM rectification algorithm module calculates a suitable switching duty cycle based on the instantaneous value of the AC input voltage, the current command value, and the grid voltage vector to achieve efficient AC-to-DC conversion. Simultaneously, it controls the waveform and phase of the input current to approximate a sine wave and be in phase with the grid voltage, thereby achieving unity power factor operation and reducing reactive power pollution to the grid. The PWM rectification algorithm significantly reduces switching and conduction losses, improving power conversion efficiency; furthermore, by precisely controlling the duty cycle and phase of the PWM waveform, it can achieve high-quality power output and reduce harmonic content.

[0064] The PWM inverter algorithm in the PWM inverter algorithm module is used to achieve DC-to-AC (DC / AC) power conversion, transforming direct current into alternating current. To obtain a near-sinusoidal AC output, the PWM inverter algorithm typically uses a sine wave as the modulation wave, comparing it with a high-frequency triangular wave (or sawtooth wave) to generate an SPWM (Sinusoidal Pulse Width Modulation) signal. By precisely controlling the on and off times of the power switching devices, the PWM inverter algorithm achieves high-efficiency power conversion and generates a near-sinusoidal AC output, which helps reduce harmonic distortion and improve power quality. Adjusting parameters such as the width, frequency, and phase of the PWM pulse allows for flexible control of the output waveform characteristics to meet the needs of different application scenarios.

[0065] The low-pass filtering algorithm in the low-pass filtering module is applied to the AC / DC and DC / AC conversion processes. During these conversions, a large number of high-frequency harmonic components are generated, which can interfere with the power grid and other electronic equipment. The low-pass filtering algorithm allows signals below a certain cutoff frequency to pass through, while signals above that cutoff frequency are attenuated or suppressed. It processes the signal in the frequency domain, suppressing or filtering out high-frequency harmonics, thereby smoothing and denoising the signal, resulting in a cleaner output AC or DC power.

[0066] Using low-pass filtering algorithms has the following advantages:

[0067] ①Smoothing signals: By removing high-frequency noise, low-pass filtering algorithms can make signals smoother and reduce abrupt changes and fluctuations in the signal;

[0068] ②Preserve key features: While filtering out high-frequency noise, the low-pass filtering algorithm can preserve the key features of the signal, ensuring that the basic shape and trend of the signal are not affected;

[0069] ③ Improve signal-to-noise ratio: By filtering out high-frequency noise, low-pass filtering algorithms can improve the signal-to-noise ratio of a signal, making the signal clearer and more distinguishable;

[0070] ④ High flexibility: The parameters of the low-pass filter algorithm (such as the cutoff frequency) can be adjusted according to actual needs, so as to adapt to different application scenarios and performance requirements;

[0071] ⑤ High computational efficiency: The low-pass filtering algorithm has high computational efficiency and can process signals in real-time or near real-time conditions.

[0072] The dual closed-loop control algorithm module, consisting of an outer voltage loop and an inner current loop, is connected to the DC side to maintain DC voltage stability. The dual closed-loop control includes an inner current loop and an outer voltage loop. The inner current loop detects and adjusts the converter's output current to control power flow and improve dynamic performance. The outer voltage loop regulates the output voltage to ensure stability and reduce the impact of load changes on the system.

[0073] The main function of the outer voltage loop is to ensure the stability and accuracy of the system output voltage. It obtains the voltage error signal by monitoring the output voltage in real time and comparing it with the set reference voltage. Then, the voltage error signal is processed by the PI / PID controller to generate the reference signal for the inner current loop.

[0074] The inner current loop focuses on the dynamic response and stability of the control system. It receives the current reference signal output from the outer voltage loop and compares it with the actual current to obtain the current error signal. This error signal is also processed by the PI / PID controller to finally generate a control signal to drive the actuator.

[0075] In the dual-loop control algorithm module, the voltage outer loop and the current inner loop cooperate and interact with each other. The voltage outer loop adjusts the reference signal of the current inner loop according to the change of the output voltage, while the current inner loop responds quickly to the change of this reference signal and changes the current output of the system by adjusting the actuator. While maintaining the stability of the system, fast and accurate voltage and current control is achieved.

[0076] Using dual-loop control improves system performance and stability. The inner current loop provides a fast dynamic response, quickly tracking changes in the outer voltage loop's reference signal, thus enhancing the overall system response speed. The outer voltage loop, through a PI / PID controller, precisely controls the output voltage, reducing steady-state error and improving control accuracy. The cooperation between the outer and inner current loops makes the system more stable. When the load or input voltage changes, the inner current loop adjusts rapidly to maintain system stability, while the outer voltage loop fine-tunes the output voltage as needed. The dual-loop structure effectively suppresses interference factors in the loops, improving the system's anti-interference capability.

[0077] The voltage balancing control algorithm in the voltage balancing control module is applied to the lithium super energy storage module to ensure that the voltage of each capacitor remains balanced, thus avoiding overvoltage or undervoltage of individual capacitors from affecting system performance and lifespan. When an inconsistency in the voltage of individual cells in the battery pack is detected, the switching system controls the capacitors to connect to the cells with higher and lower voltages, exchanging energy between the higher-voltage and lower-voltage capacitors to bring the voltages closer together. For the higher-voltage cell, the switch closes, allowing it to discharge to the lower-voltage cell through the capacitor until the voltage reaches equilibrium.

[0078] Voltage balancing algorithms can improve battery pack lifespan, prevent overcharging and over-discharging, reduce battery degradation rate, improve battery pack performance, increase battery pack capacity, enhance battery pack output power, improve safety, and reduce the risk of thermal runaway.

[0079] The power supply system provided by this utility model has the following beneficial effects:

[0080] ① Strong voltage stability: The addition of the lithium supermodule significantly improves the voltage stability of the system. In traditional AC transmission systems, voltage fluctuation is a common problem, especially under conditions of large load changes. However, in the power supply system provided by this invention, the lithium supermodule can quickly release or absorb energy when needed based on the feedback of the PWM signal, thereby smoothing power fluctuations. This dynamic adjustment capability not only improves voltage stability but also reduces the impact on the power grid and extends the service life of the equipment.

[0081] ② High energy transmission efficiency: Direct current (DC) has a natural advantage in long-distance transmission. Compared with alternating current (AC), DC does not have phase issues, so there is no additional energy loss due to capacitance and inductance during transmission. This means that under the same transmission conditions, DC can achieve higher energy transmission efficiency. Furthermore, DC transmission can reduce transmission line losses, further lowering operating costs.

[0082] ③ Emergency power supply capability: The lithium super energy storage module is not only an energy buffer device, but also provides critical power support in emergencies. When the main power supply fails or is under maintenance, the lithium super energy storage module can quickly take over the power supply task, ensuring the continuous operation of large load equipment.

[0083] ④ Flexibility and scalability: The long-distance power supply system of this utility model has high flexibility and scalability. It can adjust the distance between the grid side and the load, and through modular design, it can adjust the energy storage capacity and power output according to actual needs to adapt to different application scenarios.

[0084] ⑤ Green and environmentally friendly: Because direct current has less energy loss during transmission, lower energy loss reduces fossil fuel consumption and greenhouse gas emissions. Therefore, the long-distance power supply system of this invention is more environmentally friendly. Furthermore, the lithium supermodule's raw material composition, production, use, storage, and dismantling processes are all pollution-free, making it an ideal green and environmentally friendly power source.

[0085] The power supply system described above is used to provide power, and includes the following steps:

[0086] 1) The three-phase AC power from the grid side is converted into DC power through the AC / DC module, and the unity power factor operation is achieved by using a PWM rectifier and PWM rectifier algorithm module;

[0087] 2) The DC voltage stability is maintained through a dual closed-loop control algorithm module consisting of an outer voltage loop and an inner current loop;

[0088] 3) Connect a lithium super energy storage module in parallel on the DC side to dynamically adjust charging and discharging according to load demand: store energy when the load is low and release energy when the load is high or there is a grid fault;

[0089] 4) The voltage of each cell in the lithium super energy storage module is balanced through a voltage balancing control algorithm module;

[0090] 5) The DC / AC module converts the DC power into the three-phase AC power required by the load. The PWM inverter algorithm module and PWM inverter achieve stable output of AC power. The control system adjusts the PWM duty cycle to match the power demand of the load.

[0091] 6) Low-pass filtering algorithm modules are used throughout the power transmission process to suppress or filter out high-frequency harmonics, outputting pure AC or DC power.

[0092] In this embodiment, the voltage balancing control algorithm module balances the voltage of each cell in the lithium super energy storage module as follows: each cell in the lithium super energy storage module is connected to a voltage sensor, which detects the voltage of each cell in the lithium super energy storage module; the voltages of each cell are compared; energy is transferred from the high-voltage cell to the low-voltage cell; and the cycle continues until the voltage of each cell is balanced.

[0093] In this embodiment, a microgrid power supply in a remote area (such as an island or mountainous area) is taken as an example. Remote areas are far from the main power grid, require stable power supply, and rely on renewable energy sources (such as wind power and photovoltaics). The long-distance power supply system of this utility model can achieve stable power supply. Specifically, the fluctuating AC power generated by wind power / photovoltaic power is converted into DC power for transmission through an AC / DC module, and then inverted into AC power for the load through a DC / AC module. A lithium super energy storage module connected in parallel between the AC / DC module and the DC / AC module provides instantaneous power support and can dynamically adjust charging and discharging to cope with voltage fluctuations during load changes or faults. Combined with the synergistic effect of the control system, long-distance power supply is achieved.

[0094] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A long distance power supply system, which is provided between a power grid side and a load, characterized by, It includes an AC / DC module, a DC / AC module, a lithium super energy storage module, and a control system, wherein the AC / DC module, DC / AC module, and lithium super energy storage module are respectively connected to the control system; The AC / DC module is connected to the power grid side and is used to convert three-phase alternating current into direct current. The AC / DC module includes a PWM rectifier and an inductor-capacitor filter connected in sequence, and the PWM rectifier is connected to the control system. The DC / AC module is located between the AC / DC module and the load, and is used to convert DC power into three-phase AC power; the DC / AC module includes a PWM inverter, which is connected to the control system; The lithium super energy storage module is connected in parallel between the AC / DC module and the DC / AC module to smooth the output power of the AC / DC module and provide emergency power supply. The control system includes a control algorithm module, which integrates a PWM rectification algorithm module, a PWM inverter algorithm module, a voltage outer loop + current inner loop dual closed-loop control algorithm module, a low-pass filter algorithm module, and a voltage equalization control algorithm module. The PWM rectification algorithm module is connected to the AC / DC module, and the PWM inverter algorithm module is connected to the DC / AC module. The PWM rectification algorithm module and the PWM inverter algorithm module are used to dynamically adjust the power conversion. The low-pass filter algorithm module is used to filter out noise and prevent signal interference. The voltage equalization control algorithm module is used to equalize the voltage of the lithium super energy storage module. The voltage outer loop + current inner loop dual closed-loop control algorithm module is used to maintain the stability of the DC voltage.

2. The long-distance power supply system according to claim 1, characterized in that, The control system also includes a voltage sensor, a current sensor, and a DSP main control board. The voltage sensor and the current sensor are respectively installed on the output end of the PWM rectifier, the output end of the PWM inverter, and the lithium super energy storage module and are connected to the DSP main control board. They are used to collect the output voltage and output current in real time and feed them back to the DSP main control board. The control algorithm module is located on the DSP main control board.

3. A long-distance power supply system according to claim 1, characterized in that, The lithium super energy storage module is an asymmetric composite of a lithium-ion battery and a supercapacitor, including a capacitor-type positive electrode, a separator, a battery-type negative electrode, an electrolyte, and a shell. The capacitor-type positive electrode and the battery-type negative electrode are disposed opposite each other at both ends inside the shell. The separator is disposed inside the shell, between the capacitor-type positive electrode and the battery-type negative electrode. The electrolyte fills the inside of the shell.

4. A long-distance power supply system according to claim 3, characterized in that, The capacitive positive electrode is made of activated carbon or manganese dioxide composite electrode; the battery-type negative electrode is made of pre-lithium-intercalated material.

5. A long-distance power supply system according to claim 4, characterized in that, The battery-type negative electrode is nano-sized, and the capacitive positive electrode adopts a hierarchical porous structure.

6. A long-distance power supply system according to claim 5, characterized in that, The diaphragm is made of ceramic-coated polyethylene film.

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