Feed type photovoltaic power generation compensation system based on super capacitor

Abstract

A feed type photovoltaic power generation compensation system based on a super capacitor comprises a DC bus interface, a PCS connected with the DC bus interface, and a three-phase power grid connected with the PCS. The main control system is used for sending a control signal; the one-way diversion system and the parallel relay are arranged between the direct current bus interface and the PCS, can receive control signals of the main control system and are used for controlling connection and disconnection between the direct current bus interface and the PCS; the super capacitor energy storage device is connected with the one-way diversion system and the doubling relay, and supplies energy to the PCS for compensation after being started according to the received control signal; and the super capacitor management system receives the control signal of the main control system and controls the super capacitor to store energy.

Description

Technical Field

[0001] The utility model relates to the field of photovoltaic power generation and new energy, in particular to a photovoltaic power generation compensation technology based on supercapacitors, and further to a feeding type energy management method for optimizing supercapacitor utilization. Background Art

[0002] With the continuous development of the new energy field, photovoltaic power generation has made rapid progress in the global scope in recent years. Photovoltaic power generation projects of all sizes have increased significantly in various places, and have even been installed in a large number of households.

[0003] Because photovoltaic power generation is particularly affected by weather changes, both large-scale three-phase power generation and small-scale household single-phase power generation currently use traditional batteries as DC buffer storage. Different batteries have the following inevitable disadvantages and safety hazards.

[0004] Lead-acid batteries: They have a short lifespan and need to be replaced almost every year. The used batteries will cause serious pollution.

[0005] Ternary lithium battery: Poor safety. Currently, many safety accidents such as burning and explosion have occurred in the application fields of energy storage, power tools, electric vehicles, communication equipment, etc. And the life span is also poor among lithium battery types.

[0006] Lithium iron phosphate battery: It also has disadvantages such as poor safety and flammability and explosion.

[0007] Lithium titanate battery: high cost, flammable and explosive.

[0008] The discharge rate of all batteries is relatively low. In order to meet the output power of the grid-connected inverter at the rear stage of the photovoltaic power generation system, batteries with a capacity greater than N times the output current must be equipped. Due to the above defects of the battery itself, a vicious cycle is created, which increases the long-term cost of power generation, which is equivalent to greatly reducing the efficiency and energy utilization of photovoltaic power generation.

[0009] However, if the photovoltaic power generation system is not equipped with an energy storage unit, the instability of photovoltaic energy will cause the DC link of the system to fluctuate too much, or even cause irregular power outages. The consequence is that the entire photovoltaic system will be paralyzed, and some or all components will freeze or shut down, which will bring great difficulties to power generation management.

[0010] Under the current trend of energy resource shortage, the rapid increase of photovoltaic power generation projects at all levels, and the policy of national encouragement and promotion of energy conservation and environmental protection. Whether the above problems in the current photovoltaic power generation industry can be improved or even solved is a topic worthy of our in-depth study. Utility Model Content

[0011] In order to solve the above problems, the present technical solution provides a supercapacitor-based feed-type photovoltaic power generation compensation system.

[0012] To achieve the above purpose, the technical solution is as follows:

[0013] A supercapacitor-based feed-type photovoltaic power generation compensation system comprises a DC bus interface, a PCS connected to the DC bus interface, and a three-phase power grid connected to the PCS;

[0014] Also included is a main control system for sending control signals;

[0015] The unidirectional guide system and the parallel relay are arranged between the DC bus interface and the PCS, and can receive the control signal of the main control system, and are used to control the on-off between the DC bus interface and the PCS;

[0016] Supercapacitor energy storage, which is connected to the one-way flow guide system and the parallel relay, and is turned on according to the received control signal to supply energy to the PCS for compensation;

[0017] The supercapacitor management system receives the control signal of the main control system and controls the supercapacitor energy storage operation.

[0018] In some embodiments, a discharge resistor is also included, which is connected to the main control system and is used to discharge the energy stored in the supercapacitor after receiving a signal.

[0019] In some embodiments, an ACDC charger is also included, which is connected to the supercapacitor energy storage, PCS and main control system respectively.

[0020] In some embodiments, the control module in the unidirectional guide system and the parallel relay is one of a relay, a contactor, an IGBT, a MOS tube, and a mechanical switch.

[0021] In some embodiments, the supercapacitor energy storage is a supercapacitor monomer with a capacity of 5-500F and a voltage of 600-1200V.

[0022] In some embodiments, the supercapacitor energy storage is one of a wet supercapacitor, a dry supercapacitor, and a lithium-ion supercapacitor.

[0023] In some embodiments, a communication module connected to the main control system is also included.

[0024] In some embodiments, a display module connected to the main control system is also included.

[0025] The beneficial effects of this application are:

[0026] 1. It can reduce the overall cost and long-term cost of traditional photovoltaic power generation systems. 2. The utility model adopts supercapacitors as energy storage buffers, which have a long life and can be maintenance-free for a long period of time. 3. The utility model can better stabilize the DC bus voltage of the photovoltaic power generation system. 4. The utility model provides higher peak power for photovoltaic power generation and grid connection. 5. The utility model can maintain the normal operation of the system when the photovoltaic energy is very weak. 6. The utility model can keep the photovoltaic power generation system in standby mode at night. 7. The utility model can achieve energy saving and environmental protection due to the long life and low internal resistance of supercapacitors. 8. Compared with the traditional system using battery energy storage, the utility model is safer and does not burn or explode because of the use of supercapacitor components. 9. The utility model adopts the mains feedback method, which can greatly reduce the capacity of the energy storage unit, thereby reducing costs. 10. The utility model adopts a one-way controllable parallel connection method, which cooperates with the host computer and makes energy management more flexible. 11. The utility model can ensure that MTTP and DCAC will not crash and stop due to unstable power supply all day. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following briefly introduces the drawings required for describing the embodiments.

[0028] Figure 1 It is a structural schematic diagram of an embodiment of the utility model. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects solved by the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0030] Please refer to Figure 1 As shown, the purpose of the utility model is to address the above practical problems in the current photovoltaic power generation industry, and to solve the disadvantages brought to the power generation system by the instability of photovoltaic energy, as well as the defects of poor lifespan, flammability and explosion of various batteries. Supercapacitors are used as buffers, in conjunction with power grid feedback of electric energy, and reasonable energy management software algorithms. The purposes of achieving stable DC link of photovoltaic power generation, no power failure, maintenance-free energy storage, safety and reliability, energy saving and environmental protection, no crash or shutdown of photovoltaic power generation, and even automatic energy management are achieved.

[0031] In order to achieve the above purpose, the comprehensive technical solution adopted by the utility model is: a feed-type photovoltaic power generation compensation system based on supercapacitors. It includes a DC bus interface, PCS, a three-phase grid interface, a unidirectional conduction and parallel control module, a supercapacitor ACDC dedicated charger, a supercapacitor energy storage buffer unit, a supercapacitor management system (CMS), a system maintenance discharge unit, a detection unit, a main control system, an external communication module, a display and a touch screen. Its main feature is that the utility model adopts a new type of supercapacitor energy storage device with a service life of up to 50 years and no combustion or explosion as a photovoltaic power generation DC link buffer unit, realizes current compensation and power stability during high-power output of the photovoltaic power generation system, realizes energy saving and environmental protection, maintenance-free, no combustion, no explosion, and reduces the overall cost and long-term cost of the photovoltaic power generation system. By borrowing the previous power generation of the system or the grid energy in combination with advanced software algorithms, the basic energy consumption guarantee of each node of the photovoltaic power generation system is achieved, and dynamic photovoltaic energy compensation is achieved to improve the utilization rate of photovoltaic energy.

[0032] The DC bus interface realizes the connection between the compensation system and the original photovoltaic power generation system or the DC link of the traditional photovoltaic power generation system. The PCS mainly includes the grid-connected inverter of the photovoltaic power generation system. This unit can be a functional module of the traditional system, or it can be designed with integrated functions by this system. The three-phase grid interface realizes the connection between the system and the power grid. The unidirectional conduction and parallel control module realizes the unidirectional current protection of the compensation system and the photovoltaic power generation DC link, as well as the incorporation and exit control of the supercapacitor energy storage buffer unit. The supercapacitor ACDC dedicated charger realizes the borrowing of grid power and can achieve 0V starting charging power for the supercapacitor. Its dedicated charger is adjusted by the main controller of the compensation system according to the current, voltage, temperature and other conditions collected at each point. The supercapacitor energy storage buffer unit adopts supercapacitor energy storage devices with large current power characteristics, and is connected in parallel to form a high-voltage energy storage buffer module that matches the photovoltaic power generation target system. The main function of the supercapacitor management system (CMS) is to collect information such as the voltage and temperature of the supercapacitor cell, and to realize the performance estimation of the supercapacitor cell through the internal software algorithm, control the realization of the supercapacitor cell voltage balancing function, the group balancing function, and provide useful information to the upper control circuit through its own communication interface. The system maintenance discharge unit is mainly composed of a discharge resistor and a discharge switch. When the system is overhauled, the supercapacitor currently stored electric energy is first released through this unit to ensure the safety of equipment and personnel during maintenance. The detection unit realizes the voltage and current detection of the supercapacitor energy storage unit, the DC bus voltage detection of the photovoltaic system, the charging power detection, etc., and sends the collected analog signal to the compensation system control unit for data processing. The main control system adopts a single-chip microcomputer with a software algorithm to realize system data analysis and control output. The external communication module mainly realizes the data communication between the compensation system and the outside. The utility model prototype adopts RS485 and CAN communication. The display and touch screen realize the human-computer interaction of the compensation system. On the one hand, it displays various data of the compensation system, and on the other hand, it receives human-computer operations to realize parameter setting.

[0033] Display and touch screen

[0034] Preferably, the unidirectional conduction and parallel connection control module adopts a method of connecting a high-current diode and a high-voltage DC relay in series. The high-current diode realizes unidirectional current flow, and the high-voltage DC relay realizes the parallel connection of the supercapacitor energy storage unit and the photovoltaic DC bus.

[0035] Preferably, the supercapacitor ACDC dedicated charger adopts a digital program-controlled supercapacitor dedicated charger, which can easily achieve the 0V charging requirement and communication control of the supercapacitor.

[0036] Preferably, the supercapacitor energy storage buffer unit adopts a low internal resistance supercapacitor monomer, which is matched with the DC bus of the target photovoltaic power generation system in a series manner.

[0037] Preferably, the supercapacitor management system (CMS) realizes supercapacitor performance inspection and estimation such as supercapacitor cell voltage detection, cell voltage balancing, group balancing, module voltage detection, and module SOC calculation.

[0038] Preferably, the system maintenance discharge unit adopts a high-power ripple resistor for discharge, and its discharge control adopts DC circuit breaker control.

[0039] Preferably, the detection unit mainly detects the voltage and current of each node. For voltage acquisition, a resistor series voltage division method is used for detection, and for current acquisition, a Hall current sensor is used for detection.

[0040] Preferably, the main control system adopts a control circuit with a single-chip microcomputer as the core to implement system analysis and algorithms for digital signal processing.

[0041] Preferably, the external communication module is designed as RS48+CAN communication mode, which can adapt to more industrial applications.

[0042] Preferably, the display and touch screen adopts a 15-inch touch LCD display screen, which has a larger display range and is convenient for human-computer interaction.

[0043] This application works as follows:

[0044] A supercapacitor-based feed-type photovoltaic power generation compensation system, including a DC bus interface, PCS, a three-phase grid interface, a unidirectional conduction and parallel control module, a supercapacitor ACDC dedicated charger, a supercapacitor energy storage buffer unit, a supercapacitor management system (CMS), a system maintenance discharge unit, a detection unit, a main control system, an external communication module, and a display and touch screen.

[0045] The three-phase grid interface is used as an AC bidirectional input and output interface. After the three-phase AC voltage of the grid passes through the rectification and filtering inside the supercapacitor ACDC dedicated charger and high-frequency power conversion, the supercapacitor energy buffer unit is charged in a voltage-limited and current-limited manner. The charging voltage and current are detected by the main control system according to the voltage and current of each node, and the supercapacitor ACDC dedicated charger is correctly analyzed and judged. The supercapacitor energy storage buffer unit is charged to the target voltage through digital communication control. Through the control of the main control system, the parallel relay can be controlled to be attracted, and the DC bus of the photovoltaic power generation system can be paralleled through a large current diode connected in series with it. After paralleling, when the photovoltaic energy suddenly decreases, the supercapacitor energy storage energy can provide transition energy to the DC bus at the maximum power to ensure that the power of the photovoltaic power generation system does not undergo a power mutation. When the weather gets dark for a long time and the photovoltaic panel converts electrical energy, the supercapacitor energy storage buffer unit can continue to provide continuous energy for the photovoltaic power generation system. At the same time, the supercapacitor ACDC dedicated charger accepts the adjustment of the main control system and continues to provide power to the supercapacitor energy storage buffer unit to achieve the purpose of voltage maintenance.

[0046] During normal operation of the system, the data of each module circuit in the entire supercapacitor-fed photovoltaic power generation compensation system can be displayed in real time on the LCD screen. At the same time, a touch screen is attached to the screen to accept manual setting of system parameters by external personnel.

[0047] During normal operation of the system, the system can be connected to a higher-level master control system through the external communication module to design and control the parameters of the system through communication instructions.

[0048] During normal operation of the system, if the upstream photovoltaic DC suddenly loses power, the system can actively send a power emergency processing instruction to the main controller through the communication module. After receiving the instruction, the upper main controller controls the overall output power of the photovoltaic power generation system.

[0049] The utility model adopts a new type of supercapacitor energy storage device with a service life of up to 50 years and no combustion or explosion as a buffer unit of the DC link of photovoltaic power generation, realizing current compensation and power stability when the photovoltaic power generation system has high power output, achieving energy saving and environmental protection, maintenance-free, no combustion, no explosion, and reducing the overall cost and long-term cost of the photovoltaic power generation system. By borrowing the previous power generation of the system or the energy of the power grid in combination with advanced software algorithms, the basic energy consumption of each node of the photovoltaic power generation system is guaranteed, and dynamic photovoltaic energy compensation is realized to improve the utilization rate of photovoltaic energy.

[0050] At the same time, it can solve the disadvantages of photovoltaic energy instability to the power generation system, as well as the defects of poor life of various batteries, flammability and explosion. Using supercapacitors as buffers, combined with power grid feedback, and reasonable energy management software algorithms, it can achieve the goals of photovoltaic power generation DC link stability, no power failure, energy storage maintenance-free, safe and reliable, energy-saving and environmentally friendly, photovoltaic power generation without crashes or shutdowns, and even automatic energy management.

[0051] The above description is only a preferred embodiment of the present application and is not intended to limit the scope of implementation of the present application. Other principles and basic structures that are the same or similar to those of the present application are within the protection scope of the present application.

Claims

1. A supercapacitor-based feed-type photovoltaic power generation compensation system, characterized in that: It includes a DC bus interface, a PCS connected to the DC bus interface, and a three-phase power grid connected to the PCS; Also included is a main control system for sending control signals; The unidirectional guide system and the parallel relay are arranged between the DC bus interface and the PCS, and can receive the control signal of the main control system, and are used to control the on-off between the DC bus interface and the PCS; Supercapacitor energy storage, which is connected to the one-way flow guide system and the parallel relay, and is turned on according to the received control signal to supply energy to the PCS for compensation; The supercapacitor management system receives the control signal of the main control system and controls the supercapacitor energy storage operation.

2. According to claim 1, a supercapacitor-based feed-type photovoltaic power generation compensation system is characterized in that: It also includes a discharge resistor, which is connected to the main control system and is used to discharge the energy stored in the supercapacitor after receiving a signal.

3. According to claim 2, a supercapacitor-based feed-type photovoltaic power generation compensation system is characterized in that: It also includes an ACDC charger, which is connected to the supercapacitor energy storage, PCS and main control system respectively.

4. A supercapacitor-based feed-type photovoltaic power generation compensation system according to claim 3, characterized in that: The control module in the one-way flow guide system and the paralleling relay is one of a relay, a contactor, an IGBT, a MOS tube, and a mechanical switch.

5. A supercapacitor-based feed-type photovoltaic power generation compensation system according to claim 4, characterized in that: The supercapacitor energy storage is a supercapacitor monomer with a capacity of 5-500F and a voltage of 600-1200V.

6. A supercapacitor-based feed-type photovoltaic power generation compensation system according to claim 5, characterized in that: The supercapacitor energy storage is one of a wet supercapacitor, a dry supercapacitor, and a lithium-ion supercapacitor.

7. The supercapacitor-based feed-type photovoltaic power generation compensation system according to claim 1, characterized in that: It also includes a communication module connected to the main control system.

8. The supercapacitor-based feed-type photovoltaic power generation compensation system according to claim 1, characterized in that: Also included is a display module connected to the main control system.

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