Optical storage direct current flexible power distribution and utilization system

Abstract

The invention, which relates to the power distribution and utilization field, discloses an optical storage DC flexible power distribution and utilization system comprising a photovoltaic power generation module, a current and voltage monitoring module, a commercial power interface module, an energy storage module, a DC load power supply module, a standby power supply module, and a DC bus and power distribution module. The photovoltaic power generation module directly converts solar energy into direct-current electric energy through a photovoltaic assembly and a converter and accesses the direct-current electric energy to a direct-current bus, traditional boosting, inversion and rectification links are reduced, and efficient utilization of distributed energy is achieved. The energy storage module stores and releases redundant electric energy through energy storage equipment, and dynamic adjustment of load requirements is met; the electric energy quality optimization module realizes harmonic suppression, voltage fluctuation compensation and system state monitoring through an active filter, a dynamic voltage recovery unit and an electric energy quality monitoring unit, and guarantees the stability of system operation and the electric energy quality.

Description

Technical Field

[0001] The present invention relates to the field of power distribution technology, and more specifically, to a photovoltaic energy storage direct current flexible power distribution system. Background Art

[0002] With the popularization of distributed energy, low-voltage DC distribution systems have gradually become a hot topic in research and application. Existing technologies have conducted a lot of exploration in the field of low-voltage DC systems, such as the development of DC ecological housing in Japan, the research on low-voltage DC systems without central control units in the United States, and the promotion and application of domestic DC distribution networks. DC systems are widely used in office buildings, residences, industrial plants and other scenarios due to their high power supply efficiency, low reactive power loss, and strong equipment compatibility. However, when traditional DC distribution systems are used for distributed energy applications, they usually require multiple energy conversion links, resulting in reduced energy utilization efficiency. At the same time, due to load diversity and power supply fluctuations, harmonic interference and voltage fluctuations are prone to occur during system operation, which seriously affects power supply quality and equipment safety.

[0003] In the existing low-voltage DC distribution system, the most significant defect is the efficiency loss caused by multiple energy conversions and the lack of effective control of harmonics and voltage problems. Specifically, the traditional DC system usually needs to adapt to different load requirements through complex conversion links (such as boosting, inversion, and rectification), which not only increases equipment costs and energy consumption, but also easily introduces high-order harmonics due to nonlinear loads, resulting in deterioration of current quality. Summary of the invention

[0004] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a photovoltaic-storage-direct-current flexible power distribution system, which directly connects the photovoltaic components to the DC bus by optimizing the photovoltaic power generation module, the energy storage module and the DC power supply architecture, thereby reducing the multiple energy conversion links in the traditional DC distribution system, improving the utilization efficiency of distributed energy, and reducing system losses and operational complexity, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a photovoltaic storage direct current flexible power distribution system, comprising a photovoltaic power generation module, a current and voltage monitoring module, a mains interface module, an energy storage module, a DC load power supply module, a backup power supply module, a DC bus and a power distribution module;

[0006] The photovoltaic power generation module includes a photovoltaic module and a converter; the photovoltaic module includes a No. 1 photovoltaic module, a No. 2 photovoltaic module, and a No. 3 photovoltaic module; the converter includes a No. 1 DC / DC converter, a No. 2 DC / DC converter, and a DC / AC converter;

[0007] The current and voltage monitoring module includes a No. 1 current transformer and a No. 2 current transformer;

[0008] The mains interface module includes mains and AC / DC converter;

[0009] The energy storage module includes an energy storage converter, a primary battery pack or a storage battery pack;

[0010] The DC load power supply module includes a DC charging pile and a lighting distribution box;

[0011] The backup power supply module includes backup equipment;

[0012] The DC bus and power distribution module includes a No. 1 bus, a No. 2 bus, and a No. 3 DC / DC converter.

[0013] In a preferred embodiment, the No. 1 photovoltaic module is connected to the No. 1 bus through the No. 1 DC / DC converter, the No. 2 photovoltaic module is connected to the No. 1 bus through the No. 2 DC / DC converter, and the No. 3 photovoltaic module is connected to the No. 1 bus through the DC / AC converter and the No. 1 current transformer;

[0014] An AC / DC converter is connected between the first current transformer and the first busbar;

[0015] The first current transformer is connected to the mains, and the second current transformer is connected between the first current transformer and the mains;

[0016] The first busbar is connected to a primary battery pack or a storage battery pack through an energy storage converter; the first busbar is connected to a DC charging pile;

[0017] The No. 1 bus is connected to the lighting distribution box and the No. 2 bus through the No. 3 DC / DC converter, and the No. 2 bus is connected to the backup equipment.

[0018] In a preferred embodiment, the photovoltaic power generation module converts solar energy into electrical energy through photovoltaic modules and converters, and connects to the DC bus No. 1 after voltage regulation;

[0019] The current and voltage monitoring module is used to monitor the current and voltage changes in the system through the No. 1 current transformer and the No. 2 current transformer, providing data support for the system scheduling;

[0020] When the photovoltaic power generation is insufficient or the energy storage module cannot meet the load demand, the mains interface module provides auxiliary power supply to the system through the mains and AC / DC converter to ensure the continuity of power supply;

[0021] The energy storage module is connected to the primary battery group or the storage battery group through the energy storage converter to store the excess electric energy generated by photovoltaic power generation;

[0022] The DC load power supply module supplies power to the DC load through the DC charging pile and the lighting distribution box. The DC load power supply includes charging electric vehicles or supporting the operation of the lighting system.

[0023] The backup power supply module provides emergency power supply through backup equipment when the power supply source fails or is interrupted. The power supply source includes photovoltaic modules, mains interface modules or energy storage modules;

[0024] The DC bus and distribution module connect each module through bus No. 1 and bus No. 2, which are used to transmit electric energy and distribute electric energy between different modules, and adjust the voltage through DC / DC converter No. 3.

[0025] In a preferred embodiment, it also includes a power quality optimization module; the power quality optimization module includes an active filter unit, a dynamic voltage recovery unit, and a power quality monitoring unit;

[0026] The active filter unit includes a power electronic inverter, a current sensor, a control unit, a filter inductor, and a filter capacitor; the power electronic inverter is used to generate a compensation current opposite to the harmonic current; the current sensor is used to monitor the bus current harmonic component in real time; the control unit is used to execute the harmonic detection and compensation control algorithm; the filter inductor and the filter capacitor are used to smooth the compensation current signal;

[0027] The dynamic voltage recovery unit includes a three-phase inverter, an energy storage unit, a voltage sensor, a control unit, and a step-up transformer; the three-phase inverter is used to generate a dynamic voltage compensation signal; the energy storage unit is used to provide instantaneous power support; the voltage sensor is used to monitor the actual voltage deviation of the bus; the control unit is used to execute the voltage recovery algorithm; and the step-up transformer is used to inject the compensation voltage into the bus;

[0028] The power quality monitoring unit includes a digital power quality monitor, a microprocessor, a communication module, a display panel and a remote monitoring terminal; the digital power quality monitor includes real-time acquisition of harmonic distortion rate and voltage deviation; the microprocessor is used to comprehensively calculate power quality indicators and coordinate control of filters and voltage recovery devices; the communication module is used to transmit monitoring data and optimization instructions; the display panel and remote monitoring terminal are used to present system status and power quality indicators in real time.

[0029] In a preferred embodiment, a harmonic suppression model is established based on an active filter unit;

[0030] The source of harmonics is the photovoltaic components of the photovoltaic power generation module connected to the No. 1 bus through the converter. The DC charging pile and lighting distribution box as non-linear loads generate high-order harmonic currents when they are in operation.

[0031] In harmonic compensation, the bus harmonic components are extracted in real time through the active filter unit, and a compensation current opposite to the harmonic is generated to make the total harmonic current approach zero;

[0032]

[0033] The compensation current i generated by the above formula is comp (t) is used to offset the harmonic components in the bus; k is the harmonic order; N is the upper limit of the harmonic order to be compensated; I k,harm is the amplitude of the kth harmonic, measured by bus current sensors No. 1 and No. 2; f base is the bus fundamental frequency; t is time; k is the initial phase angle of the kth harmonic.

[0034] In a preferred embodiment, a dynamic voltage recovery model is established based on the dynamic voltage recovery unit;

[0035] The source of voltage fluctuation is the dynamic power output of the mains interface module and the energy storage module, which causes the voltage of bus No. 1 to drop or fluctuate temporarily. The three-phase inverter of the dynamic voltage recovery unit injects the compensation voltage v in real time. comp (t), restore the bus voltage to the reference value preset by the system;

[0036]

[0037] where v comp (t) is the compensation voltage; v ref is the reference voltage; v bus (t) is the actual bus voltage, which is measured by the voltage sensor of the dynamic voltage recovery unit; K p is the proportional gain coefficient; K i is the integral gain coefficient, which is used to adjust the contribution of the accumulated deviation to the compensation voltage; t is the time; τ is the integral time variable.

[0038] In a preferred embodiment, a comprehensive power quality control model is established based on the power quality monitoring unit;

[0039] The comprehensive power quality control model quantifies the comprehensive impact of harmonic distortion and voltage deviation on the system power quality; combines the total amount of harmonics and voltage deviation to construct a comprehensive power quality index Q quality ;

[0040]

[0041] Where Q quality W is the comprehensive indicator of power quality; THD is the harmonic distortion weight coefficient; W Vdev is the voltage deviation weight coefficient; Indicates the amplitude of the nth harmonic current; Indicates the fundamental current amplitude; v ref is the reference voltage; v bus (t) is the actual bus voltage; Used to indicate the impact of harmonic distortion on power quality; Used to indicate the impact of voltage deviation on power quality.

[0042] Technical effects and advantages of the present invention:

[0043] 1. Through the optimization of photovoltaic power generation modules and DC power supply architecture, multiple power conversion losses in the traditional "boost-inverter-rectifier" mode are avoided; photovoltaic modules are directly connected to the DC bus, the energy storage module effectively utilizes excess power, and the DC load module realizes localized DC power supply, which improves the efficiency of distributed energy use;

[0044] 2. The active filter unit in the power quality optimization module detects the high-order harmonic components in the bus current in real time and generates a compensation current opposite to it, suppressing harmonic interference and improving current quality;

[0045] 3. The dynamic voltage recovery unit uses a three-phase inverter and an energy storage unit to quickly inject compensation voltage based on the bus voltage deviation monitored in real time by the voltage sensor, and restores the system voltage to the designed reference value, thus ensuring the continuity and stability of the load power supply;

[0046] 4. The power quality monitoring unit collects the system's harmonic distortion rate and voltage deviation in real time through a digital power quality monitor and a remote terminal, and coordinates the operation of the filter and voltage recovery unit based on the calculation results of the microprocessor. The monitoring and optimization control functions not only improve the system's operating efficiency, but also facilitate the visualization of key states and remote maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the system structure of the present invention.

[0048] The reference numerals are: photovoltaic module No. 1 (1), DC / DC converter No. 1 (2), photovoltaic module No. 2 (3), DC / DC converter No. 2 (4), photovoltaic module No. 3 (5), DC / AC converter (6), current transformer No. 1 (7), AC / DC converter (8), current transformer No. 2 (9), mains (10), energy storage converter (11), primary battery pack or storage battery pack (12), DC charging pile (13), DC / DC converter No. 3 (14), lighting distribution box (15), backup equipment (16), bus No. 1 (17), bus No. 2 (18). DETAILED DESCRIPTION

[0049] 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.

[0050] Refer to the instruction manual Figure 1 , a photovoltaic storage direct current flexible power distribution system according to an embodiment of the present invention comprises a photovoltaic power generation module, a current and voltage monitoring module, a mains interface module, an energy storage module, a DC load power supply module, a backup power supply module, a DC bus and a power distribution module;

[0051] The photovoltaic power generation module includes a photovoltaic assembly and a converter; the photovoltaic assembly includes a first photovoltaic assembly 1, a second photovoltaic assembly 3, and a third photovoltaic assembly 5; the converter includes a first DC / DC converter 2, a second DC / DC converter 4, and a DC / AC converter 6;

[0052] The current and voltage monitoring module includes a No. 1 current transformer 7 and a No. 2 current transformer 9;

[0053] The mains interface module includes a mains 10 and an AC / DC converter 8;

[0054] The energy storage module includes an energy storage converter 11 and a primary battery pack or a storage battery pack 12;

[0055] The DC load power supply module includes a DC charging pile 13 and a lighting distribution box 15;

[0056] The backup power supply module includes a backup device 16;

[0057] The DC bus and power distribution module includes a No. 1 bus 17 , a No. 2 bus 18 , and a No. 3 DC / DC converter 14 .

[0058] The first photovoltaic module 1 is connected to the first bus 17 through the first DC / DC converter 2, the second photovoltaic module 3 is connected to the first bus 17 through the second DC / DC converter 4, and the third photovoltaic module 5 is connected to the first bus 17 through the DC / AC converter 6 and the first current transformer 7;

[0059] An AC / DC converter 8 is connected between the No. 1 current transformer 7 and the No. 1 busbar 17;

[0060] The first current transformer 7 is connected to the mains 10, and the second current transformer 9 is connected between the first current transformer 7 and the mains 10;

[0061] The first busbar 17 is connected to the primary battery pack or the storage battery pack 12 through the energy storage converter 11; the first busbar 17 is connected to the DC charging pile 13;

[0062] The No. 1 bus 17 is connected to the lighting distribution box 15 and the No. 2 bus 18 through the No. 3 DC / DC converter 14 , and the No. 2 bus 18 is connected to the backup equipment 16 .

[0063] The photovoltaic power generation module converts solar energy into electrical energy through photovoltaic modules and converters, and is connected to the DC bus No. 1 17 after voltage regulation;

[0064] The current and voltage monitoring module is used to monitor the current and voltage changes in the system through the No. 1 current transformer 7 and the No. 2 current transformer 9, to ensure the safety and stability of the system operation, and to provide data support for the protection and scheduling of the system;

[0065] When the photovoltaic power generation is insufficient or the energy storage module cannot meet the load demand, the mains interface module provides auxiliary power supply to the system through the mains 10 and the AC / DC converter 8 to ensure the continuity of power supply;

[0066] The energy storage module is connected to the primary battery group or the storage battery group 12 through the energy storage converter 11 to store the excess electricity generated by photovoltaic power generation, and releases the electricity when the system load demand increases or the photovoltaic power generation is insufficient, so as to balance the energy supply and demand;

[0067] The DC load power supply module supplies power to the DC load through the DC charging pile 13 and the lighting distribution box 15. The DC load power supply includes charging electric vehicles or supporting the operation of the lighting system to improve the efficiency of DC power utilization;

[0068] The backup power supply module provides emergency power supply through the backup device 16 when the power supply source fails or is interrupted. The power supply source includes a photovoltaic module, a mains interface module or an energy storage module to ensure reliable operation of the system;

[0069] The DC bus and distribution module are connected to each module through bus No. 1 17 and bus No. 2 18 for transmitting electric energy and distributing electric energy between different modules. At the same time, the voltage is adjusted through DC / DC converter No. 3 14 to support the operation of diversified equipment.

[0070] It also includes a power quality optimization module; the power quality optimization module includes an active filter unit, a dynamic voltage recovery unit, and a power quality monitoring unit;

[0071] The active filter unit includes a power electronic inverter, a current sensor, a control unit, a filter inductor, and a filter capacitor; the power electronic inverter is used to generate a compensation current opposite to the harmonic current; the current sensor is used to monitor the bus current harmonic component in real time; the control unit is used to execute the harmonic detection and compensation control algorithm; the filter inductor and the filter capacitor are used to smooth the compensation current signal; the current sensor includes a Hall sensor; the control unit includes a DSP or an FPGA;

[0072] The dynamic voltage recovery unit includes a three-phase inverter, an energy storage unit, a voltage sensor, a control unit, and a step-up transformer; the three-phase inverter is used to generate a dynamic voltage compensation signal; the energy storage unit is used to provide instantaneous power support; the voltage sensor is used to monitor the actual voltage deviation of the bus; the control unit is used to execute the voltage recovery algorithm; the step-up transformer is used to inject the compensation voltage into the bus; the energy storage unit includes a supercapacitor or a lithium battery pack; the voltage sensor includes a voltage divider circuit or a voltage transformer; the control unit includes an embedded MCU;

[0073] The power quality monitoring unit includes a digital power quality monitor, a microprocessor, a communication module, a display panel and a remote monitoring terminal; the digital power quality monitor includes real-time acquisition of harmonic distortion rate THD and voltage deviation; the microprocessor is used to comprehensively calculate power quality indicators and coordinate control of filters and voltage recovery devices; the communication module is used to transmit monitoring data and optimization instructions; the display panel and the remote monitoring terminal are used to present system status and power quality indicators in real time; the microprocessor includes DSP or FPGA; the communication module includes RS485 or Ethernet interface.

[0074] Establish a harmonic suppression model based on active filter units;

[0075] The source of harmonics is the photovoltaic components of the photovoltaic power generation module connected to the No. 1 bus 17 through the converter, and the DC charging pile 13 and the lighting distribution box 15 as non-linear loads generate high-order harmonic currents when they are running;

[0076] In harmonic compensation, the bus harmonic components are extracted in real time through the active filter unit, and a compensation current opposite to the harmonic is generated to make the total harmonic current approach zero;

[0077]

[0078] The compensation current i generated by the above formula is comp (t) used to offset the harmonic components in the bus; i comp (t) is the compensation current, that is, the current generated by the filter; k is the harmonic order, starting from the second harmonic (k = 2, 3, ..., N); N is the upper limit of the harmonic order to be compensated, which is determined by the system design; I k,harmis the amplitude of the kth harmonic, measured by bus current sensors No. 1 current transformer 7 and No. 2 current transformer 9; f base is the bus base frequency, which is determined by the system operating frequency; t is the time; k is the initial phase angle of the kth harmonic; I k,harm sin(2πkf base t+ k ) is used to describe the dynamic characteristics of the kth harmonic component, including amplitude, frequency, time and phase information; the negative sign indicates that the compensation current is in the opposite direction to the harmonic current and is used to eliminate harmonics.

[0079] A dynamic voltage recovery model is established based on a dynamic voltage recovery unit;

[0080] The voltage fluctuation source is the dynamic power output of the mains interface module and the energy storage module, which causes the voltage of bus No. 1 17 to drop or fluctuate temporarily; the three-phase inverter of the dynamic voltage recovery unit injects the compensation voltage v in real time. comp (t), restore the bus voltage to the reference value preset by the system;

[0081]

[0082] where v comp (t) is the compensation voltage; v ref is the reference voltage, which is the ideal bus voltage designed for the system; v bus (t) is the actual bus voltage, which is measured by the voltage sensor of the dynamic voltage recovery unit; K p is the proportional gain coefficient, which is used to adjust the contribution of instantaneous deviation to the compensation voltage; K i is the integral gain coefficient, which is used to adjust the contribution of the accumulated deviation to the compensation voltage; t is the time; τ is the integral time variable; v ref -v bus (t) is used to describe the instantaneous deviation of bus voltage; Used to describe the contribution of the voltage deviation change rate to the compensation voltage and enhance the transient response capability of the system; It is used to describe the contribution of the accumulated voltage deviation to the compensation voltage and eliminate the steady-state error.

[0083] Establish a comprehensive power quality control model based on the power quality monitoring unit;

[0084] The comprehensive power quality control model quantifies the comprehensive impact of harmonic distortion and voltage deviation on the system power quality; combines the total amount of harmonics and voltage deviation to construct a comprehensive power quality index Q quality ;

[0085]

[0086] Where Q quality W is the comprehensive indicator of power quality; THD is the harmonic distortion weight coefficient; W Vdev is the voltage deviation weight coefficient; I h n arm Indicates the amplitude of the nth harmonic current; I f 1 und Indicates the fundamental current amplitude; v ref is the reference voltage; v bus (t) is the actual bus voltage; Used to indicate the impact of harmonic distortion on power quality; Used to indicate the impact of voltage deviation on power quality;

[0087] It should be noted that the above three models are set up to comprehensively optimize the power quality, and respectively solve and evaluate harmonics, voltage fluctuations and comprehensive performance; the purpose of the harmonic suppression model is to detect the high-order harmonic components in the current and generate a compensation current opposite to it to offset the harmonic current, thereby improving the bus current quality; its working principle is to analyze the current signal in real time, extract the harmonic components and calculate the compensation signal, and finally output the compensation current through the active filter; the purpose of the dynamic voltage recovery model is to restore the actual voltage to the ideal value by dynamically injecting the compensation voltage when the bus voltage fluctuates or temporarily drops; its working principle is to monitor the deviation of the bus voltage in real time, and dynamically adjust the compensation voltage according to the size, change speed and accumulation of the deviation, and inject the inverter into the system to achieve voltage stability; the purpose of the comprehensive power quality control model is to quantitatively evaluate the harmonic distortion and voltage deviation of the system power quality, and provide guidance for optimizing equipment operation; its working principle is to collect harmonic data and voltage deviation in real time, and generate performance indicators through comprehensive weighted calculation, which are used to evaluate and optimize the coordinated work of the filter and the voltage compensation device to ensure that the overall power quality of the system reaches the best level as much as possible.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A photovoltaic storage and direct current flexible power distribution system, comprising a photovoltaic power generation module, a current and voltage monitoring module, a mains interface module, an energy storage module, a DC load power supply module, a backup power supply module, a DC bus and a power distribution module, characterized in that: The photovoltaic power generation module comprises a photovoltaic assembly and a converter; the photovoltaic assembly comprises a first photovoltaic assembly (1), a second photovoltaic assembly (3), and a third photovoltaic assembly (5); the converter comprises a first DC / DC converter (2), a second DC / DC converter (4), and a DC / AC converter (6); The current and voltage monitoring module comprises a No. 1 current transformer (7) and a No. 2 current transformer (9); The mains interface module comprises a mains supply (10) and an AC / DC converter (8); The energy storage module comprises an energy storage converter (11), a primary battery pack or a storage battery pack (12); The DC load power supply module comprises a DC charging pile (13) and a lighting distribution box (15); The backup power supply module includes a backup device (16); The DC bus and power distribution module comprises a No. 1 bus (17), a No. 2 bus (18), and a No. 3 DC / DC converter (14).

2. According to claim 1, the photovoltaic energy storage and direct current flexible power distribution system is characterized by: The first photovoltaic assembly (1) is connected to the first bus (17) via the first DC / DC converter (2), the second photovoltaic assembly (3) is connected to the first bus (17) via the second DC / DC converter (4), and the third photovoltaic assembly (5) is connected to the first bus (17) via the DC / AC converter (6) and the first current transformer (7); An AC / DC converter (8) is connected between the first current transformer (7) and the first busbar (17); The first current transformer (7) is connected to the mains (10), and the second current transformer (9) is connected between the first current transformer (7) and the mains (10); The first busbar (17) is connected to a primary battery pack or a storage battery pack (12) via an energy storage converter (11); the first busbar (17) is connected to a DC charging pile (13); The No. 1 busbar (17) is connected to the lighting distribution box (15) and the No. 2 busbar (18) via the No. 3 DC / DC converter (14), and the No. 2 busbar (18) is connected to the backup equipment (16).

3. The photovoltaic energy storage and direct current flexible power distribution system according to claim 2 is characterized in that: The photovoltaic power generation module converts solar energy into electrical energy through photovoltaic modules and converters, and connects to the DC bus No. 1 (17) after voltage regulation; The current and voltage monitoring module is used to monitor the current and voltage changes in the system through the No. 1 current transformer (7) and the No. 2 current transformer (9), and provides data support for the scheduling of the system; When the photovoltaic power generation is insufficient or the energy storage module cannot meet the load demand, the mains interface module provides auxiliary power supply to the system through the mains (10) and the AC / DC converter (8) to ensure the continuity of power supply; The energy storage module is connected to a primary battery group or a storage battery group (12) via an energy storage converter (11) to store excess electric energy generated by photovoltaic power generation; The DC load power supply module supplies power to the DC load through the DC charging pile (13) and the lighting distribution box (15), and the DC load power supply includes charging the electric vehicle or supporting the operation of the lighting system; The backup power supply module provides emergency power supply through the backup device (16) when a power supply source fails or is interrupted, and the power supply source includes a photovoltaic module, a mains interface module or an energy storage module; The DC bus and the power distribution module are connected to each module via a No. 1 bus (17) and a No. 2 bus (18) for transmitting electric energy and distributing electric energy between different modules, and adjusting the voltage via a No. 3 DC / DC converter (14).

4. The photovoltaic energy storage and direct current flexible power distribution system according to claim 3 is characterized by: It also includes a power quality optimization module; the power quality optimization module includes an active filter unit, a dynamic voltage recovery unit, and a power quality monitoring unit; The active filter unit includes a power electronic inverter, a current sensor, a control unit, a filter inductor, and a filter capacitor; the power electronic inverter is used to generate a compensation current opposite to the harmonic current; the current sensor is used to monitor the bus current harmonic component in real time; the control unit is used to execute the harmonic detection and compensation control algorithm; the filter inductor and the filter capacitor are used to smooth the compensation current signal; The dynamic voltage recovery unit includes a three-phase inverter, an energy storage unit, a voltage sensor, a control unit, and a step-up transformer; the three-phase inverter is used to generate a dynamic voltage compensation signal; the energy storage unit is used to provide instantaneous power support; the voltage sensor is used to monitor the actual voltage deviation of the bus; the control unit is used to execute the voltage recovery algorithm; and the step-up transformer is used to inject the compensation voltage into the bus; The power quality monitoring unit includes a digital power quality monitor, a microprocessor, a communication module, a display panel and a remote monitoring terminal; the digital power quality monitor includes real-time acquisition of harmonic distortion rate and voltage deviation; the microprocessor is used to comprehensively calculate power quality indicators and coordinate control of filters and voltage recovery devices; the communication module is used to transmit monitoring data and optimization instructions; the display panel and remote monitoring terminal are used to present system status and power quality indicators in real time.

5. The photovoltaic energy storage and direct current flexible power distribution system according to claim 4 is characterized in that: Establish a harmonic suppression model based on active filter units; The source of harmonics is the photovoltaic components of the photovoltaic power generation module connected to the No. 1 bus (17) through a converter, and the DC charging pile (13) and the lighting distribution box (15) as nonlinear loads generate high-order harmonic currents when they are in operation; In harmonic compensation, the bus harmonic components are extracted in real time through the active filter unit, and a compensation current opposite to the harmonic is generated to make the total harmonic current approach zero; The compensation current i generated by the above formula is comp (t) is used to offset the harmonic components in the bus; k is the harmonic order; N is the upper limit of the harmonic order to be compensated; I k,harm is the amplitude of the kth harmonic, measured by bus current sensors No. 1 current transformer (7) and No. 2 current transformer (9); f base is the bus fundamental frequency; t is time; k is the initial phase angle of the kth harmonic.

6. The photovoltaic energy storage and direct current flexible power distribution system according to claim 5 is characterized by: A dynamic voltage recovery model is established based on a dynamic voltage recovery unit; The voltage fluctuation source is caused by the dynamic power output of the mains interface module and the energy storage module, which causes the voltage of bus No. 1 (17) to drop or fluctuate temporarily; the three-phase inverter of the dynamic voltage recovery unit injects the compensation voltage v in real time. comp (t), restore the bus voltage to the reference value preset by the system; where v comp (t) is the compensation voltage; v ref is the reference voltage; v bus (t) is the actual bus voltage, which is measured by the voltage sensor of the dynamic voltage recovery unit; K p is the proportional gain coefficient; K i is the integral gain coefficient, which is used to adjust the contribution of the accumulated deviation to the compensation voltage; t is the time; τ is the integral time variable.

7. The photovoltaic energy storage and direct current flexible power distribution system according to claim 6 is characterized by: Establish a comprehensive power quality control model based on the power quality monitoring unit; The comprehensive power quality control model quantifies the comprehensive impact of harmonic distortion and voltage deviation on the system power quality; combines the total amount of harmonics and voltage deviation to construct a comprehensive power quality index Q quality ; Where Q quality is the comprehensive indicator of power quality; W THD is the harmonic distortion weight coefficient; W Vdev is the voltage deviation weight coefficient; Indicates the amplitude of the nth harmonic current; Indicates the fundamental current amplitude; v ref is the reference voltage; v bus (t) is the actual bus voltage; Used to indicate the impact of harmonic distortion on power quality; Used to indicate the impact of voltage deviation on power quality.

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