A compatible feedback power grid type energy storage energy saving method

Abstract

The application discloses a compatible feedback power grid type energy storage type energy-saving method, and realizes compatible adaptation of all feedback power grid type energy-saving projects by configuring a closed-loop control strategy for a main control unit on the basis of an energy storage type energy-saving project; meanwhile, the main control unit controls charging current and discharging power of an energy storage unit through a bidirectional conversion unit, ensures that regenerated energy does not flow into a power grid and a braking resistor in the whole process during device operation, completely avoids harmonic pollution caused by regenerated energy flowing into the power grid, simultaneously reduces waste and heat pollution caused by energy consumption through the braking resistor, realizes efficient recovery, storage and reuse of regenerated energy, improves energy-saving efficiency, reduces influence on the power grid, and enhances stability and universality of equipment operation.

Description

Technical Field

[0001] This invention belongs to the technical field of renewable energy conservation, specifically relating to a grid-compatible energy storage method for energy conservation. Background Technology

[0002] In industrial production and transportation, a large amount of equipment (such as elevators lowering heavy objects and crane lifting mechanisms lowering) generates regenerative energy during operation. Currently, there are three main technical approaches for processing this type of regenerative energy: grid-feedback energy-saving technology, energy storage energy-saving technology, and energy consumption braking technology. However, all three types of technologies have significant drawbacks, and the first two are difficult to work in harmony.

[0003] Feedback grid energy-saving technology uses active inverter units to convert regenerated energy into AC power with the same frequency and phase as the grid, which is then fed back into the grid to achieve energy recovery and utilization. However, it has the following shortcomings: 1. It has high requirements for grid quality. When regenerated energy is injected into the grid, it is prone to harmonic pollution, affecting the grid voltage stability, especially in scenarios with low grid load or large voltage fluctuations, which can easily trigger grid protection actions; 2. It has poor compatibility, only adapting to grids of specific voltage levels and frequencies, making it difficult to apply to different specifications of feedback grid energy-saving projects; 3. When the grid experiences faults or maintenance, the regenerated energy cannot be fed back normally, requiring a switch to braking resistor consumption mode, resulting in energy waste and thermal pollution.

[0004] Energy storage technology stores regenerative energy using energy storage components such as supercapacitors and batteries, releasing it for use when equipment needs energy. However, it has the following shortcomings: 1. It has a single function and cannot be compatible with the retrofit requirements of existing grid-feedback energy-saving projects; 2. Some energy storage systems still rely on braking resistors to consume excess regenerative energy when the energy storage components are fully charged or malfunction, which cannot completely avoid energy waste.

[0005] Energy-efficient braking technology involves connecting a braking resistor in parallel with the DC bus. When the motor generates electricity, current flows through the resistor, converting electrical energy into heat and dissipating it. Advantages: simple structure, low cost, and mature technology. Disadvantages: Strictly speaking, this is not "recycling" but rather "controlled waste."

[0006] Therefore, developing an energy storage energy-saving device and method that is compatible with grid-feedback energy-saving projects and ensures that the regenerated energy does not flow into the grid or braking resistors throughout the entire process has become an urgent technical problem to be solved in this field. Summary of the Invention

[0007] The main objective of this invention is to overcome the shortcomings of existing technologies, such as poor compatibility and easy grid pollution of regenerative energy-saving technologies, limited functionality and inability to completely avoid energy waste, and the incompatibility between the two types of technologies. This invention provides a method compatible with regenerative grid-feedback energy storage, achieving compatibility and adaptation for all regenerative grid-feedback energy-saving projects based on energy storage. Simultaneously, it ensures that regenerated energy does not flow into the grid or braking resistor during device operation, achieving efficient recovery, storage, and reuse of regenerated energy, improving energy efficiency, reducing the impact on the grid, and enhancing the stability and versatility of equipment operation.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] One aspect of the present invention provides a grid-compatible energy storage method for energy saving, comprising the following steps:

[0010] The system comprises a main control unit, a busbar acquisition unit, an energy storage unit, a bidirectional converter unit, and an energy storage monitoring unit. The input terminal of the bidirectional converter unit is connected to the DC busbar, and the output terminal is connected to the energy storage unit. The output terminal of the energy storage unit is connected to the reverse input terminal of the bidirectional converter unit. The main control unit is electrically connected to the busbar acquisition unit, the bidirectional converter unit, the energy storage unit, and the energy storage monitoring unit, respectively.

[0011] The power grid or feeder current on the DC bus is monitored through the bus acquisition unit;

[0012] The energy storage monitoring unit monitors in real time the power generated by regenerative energy, the charging and discharging power of the energy storage unit, the power consumed by the load drive unit, and the voltage, current, and temperature of each unit.

[0013] Based on the monitoring data from the busbar acquisition unit and the energy storage monitoring unit, the closed-loop control strategy of the main control unit is configured as follows:

[0014] When the main control unit detects that the renewable energy device is generating electricity and feeding current back to the grid, it controls the bidirectional converter to increase the charging current of the energy storage unit and reduce the current fed back to the grid.

[0015] When the regenerative energy device is detected to be in an electric state, the main control unit controls the bidirectional converter to release the electrical energy of the energy storage unit to the DC bus, and sets the power to be less than or equal to the power consumed by the load drive unit.

[0016] As a preferred technical solution, the monitoring of the grid or feeder current on the DC bus specifically includes:

[0017] The DC bus current magnitude and direction are monitored in real time, and the DC bus current value is set to 0A. When the monitored current is positive, it is determined to be the current supplied by the mains power to the load drive unit, and when it is negative, it is determined to be the current fed back to the grid by the regenerative energy equipment.

[0018] As a preferred technical solution, parameters are reconfigured through the main control unit to adapt to different types of grid-feedback energy-saving projects.

[0019] As a preferred technical solution, when a fault is detected, the main control unit controls the regenerative energy equipment to operate in a downgraded manner or shut down.

[0020] Another aspect of the present invention provides a grid-compatible energy storage system, characterized in that it includes a main control unit, a bus acquisition unit, an energy storage unit, a bidirectional converter unit, and an energy storage monitoring unit;

[0021] The bidirectional converter unit is used to realize bidirectional conversion of DC power and adjust voltage and current parameters; the input end of the bidirectional converter unit is connected to the DC bus, and the output end is connected to the energy storage unit.

[0022] The output terminal of the energy storage unit is connected to the reverse input terminal of the bidirectional converter unit, which is used to store regenerative energy and release the stored electrical energy when energy is needed.

[0023] The energy storage monitoring unit is used to monitor in real time the power generated by regenerative energy, the charging and discharging power of the energy storage unit, the power consumed by the load drive unit, and the voltage, current, and temperature parameters of each unit, and transmit the monitoring data to the main control unit.

[0024] The main control unit is electrically connected to the bus acquisition unit, the bidirectional converter unit, the energy storage unit, and the energy monitoring unit, respectively. It is used to receive monitoring data from the energy storage monitoring unit, control the bidirectional converter unit to perform energy flow control according to the operating conditions of the regenerative energy equipment and the SOC state of the energy storage unit, and at the same time receive monitoring data from the bus acquisition unit to prevent regenerative energy from flowing into the power grid.

[0025] As a preferred technical solution, the main control unit, bus acquisition unit, bidirectional converter unit, and energy storage monitoring unit are connected via communication.

[0026] As a preferred technical solution, the energy storage unit includes an energy storage element group, an energy storage management module, and a charge / discharge protection module; the energy storage management module is used to monitor the SOC, voltage, and temperature parameters of the energy storage element group in real time; the charge / discharge protection module is used to prevent the energy storage element group from being overcharged, over-discharged, over-temperatured, or short-circuited.

[0027] As a preferred technical solution, the energy storage element group adopts a hybrid energy storage structure of supercapacitor and battery.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] (1) Strong compatibility: Through the configurable design of the grid adaptation unit and the compatible control strategy of the main control unit, it can be compatible with all different specifications and types of feedback grid energy-saving projects on the basis of energy storage energy saving, without the need to add an independent feedback device, reducing the cost of transformation and application and expanding the scope of application;

[0030] (2) High energy efficiency and environmental protection: Through the precise energy distribution of the bidirectional converter unit and the hybrid energy storage design of the energy storage unit, all the regenerated energy is used for load driving or energy storage reuse, which completely avoids the harmonic pollution caused by the regenerated energy flowing into the grid, and at the same time reduces the waste and thermal pollution caused by the energy consumed through the braking resistor.

[0031] (3) Stable and reliable operation: The grid isolation module adopts a dual isolation structure to ensure that the regenerated energy is completely isolated from the grid and is not affected by grid voltage fluctuations, faults and other factors; at the same time, it is equipped with a fault diagnosis unit and a complete protection mechanism to avoid energy accumulation during faults and improve the stability and safety of equipment operation.

[0032] (4) Flexible adaptability: The energy storage unit adopts a hybrid structure of supercapacitor and battery, which can quickly respond to the absorption of instantaneous high-power regenerative energy and achieve long-term stable energy storage, adapting to the regenerative energy characteristics under different working conditions; when switching to adapt to different feedback grid type projects, only parameter configuration is required, and the operation is simple. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of a grid-compatible energy storage system according to an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the electric state current of the regenerative energy device according to an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the power generation state current of the regenerative energy device according to an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the closed-loop control strategy of the main control unit in an embodiment of the present invention. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative effort are within the scope of protection of the present application.

[0038] Example 1:

[0039] like Figure 1 As shown, this embodiment provides a grid-compatible energy storage system for energy conservation, applied to equipment that generates renewable energy (hereinafter referred to as renewable energy equipment), including a main control unit, a bus acquisition unit, an energy storage unit, a bidirectional converter unit, and an energy storage monitoring unit;

[0040] The bidirectional converter unit is used to realize bidirectional conversion of DC power and adjust voltage and current parameters; the input end of the bidirectional converter unit is connected to the DC bus, and the output end is connected to the energy storage unit.

[0041] The output terminal of the energy storage unit is connected to the reverse input terminal of the bidirectional converter unit, which is used to store regenerative energy and release the stored electrical energy when energy is needed.

[0042] The energy storage monitoring unit is used to monitor in real time the power generated by regenerative energy, the charging and discharging power of the energy storage unit, the power consumed by the load drive unit, and the voltage, current, and temperature parameters of each unit, and transmit the monitoring data to the main control unit.

[0043] The main control unit is electrically connected to the bus acquisition unit, the bidirectional converter unit, the energy storage unit, and the energy monitoring unit, respectively. It is used to receive monitoring data from the energy storage monitoring unit, control the bidirectional converter unit to perform energy flow control according to the operating conditions of the regenerative energy equipment and the SOC state of the energy storage unit, and at the same time receive monitoring data from the bus acquisition unit to prevent regenerative energy from flowing into the power grid.

[0044] In one or more preferred embodiments, the bidirectional converter main control unit, the bus acquisition unit, the bidirectional converter unit, and the energy storage monitoring unit are connected via communication (such as Ethernet, CAN, etc.).

[0045] In one or more preferred embodiments, the energy storage unit includes an energy storage element group, an energy storage management module, and a charge / discharge protection module; the energy storage element group adopts a hybrid energy storage structure of supercapacitor and battery, the energy storage management module is used to monitor parameters such as SOC (State of Charge), voltage, and temperature of the energy storage element group in real time, and the charge / discharge protection module is used to prevent the energy storage element group from being overcharged, over-discharged, over-temperatured, or short-circuited.

[0046] In one or more preferred embodiments, the main control unit has a built-in compatible control strategy that can be adapted to different types of grid-feedback energy-saving projects through parameter configuration.

[0047] It should be noted that the system provided in the above embodiments is only an example of the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure can be divided into different functional modules to complete all or part of the functions described above. The system can be applied to a grid-compatible energy storage energy-saving method in the following embodiments.

[0048] Example 2:

[0049] This embodiment provides a grid-compatible energy storage energy-saving method, including the following steps:

[0050] S1. Arrange a grid-compatible energy storage system as described in Example 1;

[0051] S2. Monitor the grid or feeder current on the DC bus through the bus acquisition unit;

[0052] S3. The energy storage monitoring unit monitors in real time the power generated by regenerative energy, the charging and discharging power of the energy storage unit, the power consumed by the load drive unit, and the voltage, current, and temperature of each unit.

[0053] S4. Based on the monitoring data from the bus acquisition unit and the energy storage monitoring unit, configure the closed-loop control strategy of the main control unit as follows:

[0054] When the main control unit detects that the renewable energy device is generating electricity and feeding current back to the grid, it controls the bidirectional converter to increase the charging current of the energy storage unit and reduce the current fed back to the grid.

[0055] When the regenerative energy device is detected to be in an electric state, the main control unit controls the bidirectional converter to release the electrical energy of the energy storage unit to the DC bus, and sets the power to be less than or equal to the power consumed by the load drive unit.

[0056] In one or more preferred embodiments, the monitoring of the grid or feeder current on the DC bus specifically includes:

[0057] The DC bus current magnitude and direction are monitored in real time, and the DC bus current value is set to 0A. When the monitored current is positive, it is determined to be the current supplied by the mains power to the load drive unit. When it is negative, it is determined to be the current fed back to the grid by the regenerative energy equipment.

[0058] In one or more preferred embodiments, parameters are reconfigured by the main control unit to adapt to different types of grid-feedback energy-saving projects.

[0059] In one or more preferred embodiments, when a fault is detected, the main control unit controls the regenerative energy equipment to degrade or shut down.

[0060] Example 3:

[0061] This embodiment illustrates the principle of a grid-compatible energy storage method for energy saving provided in Embodiment 2, so that those skilled in the art can better understand the technical solution of this application.

[0062] 1. When the regenerative energy equipment is in electric mode, such as Figure 2 When the energy-saving device is not activated, the entire load of the regenerative energy equipment is powered by mains electricity. At this time:

[0063] I 负载 = I 市电 ;

[0064] When the energy-saving device enters discharge mode, and its power is less than the load's operating power, the load's energy consumption is partly obtained from the mains power and partly from the energy storage unit. At this time:

[0065] I 负载 = I 市电 + I 释放 ;

[0066] When the energy-saving device is turned on and its output power exceeds the load's operating power, part of the electrical energy released by the energy-saving device supplies the load, and part is fed back to the grid through the grid feedback unit. At this time:

[0067] I 释放 = I 馈网 + I 负载 ;

[0068] II. When the regenerative energy equipment is in power generation mode, such as Figure 3 When the energy-saving device is not activated, a small portion of the regenerated electrical energy flows into the braking unit, where it is converted into heat by the braking resistor and consumed. Most of the energy is fed back to the grid through the grid feedback unit. At this time:

[0069] I 再生 = I馈网 + I 制动 ;

[0070] When the energy-saving device activates charging mode, and its power is less than the device's regenerative power, a small portion of the device's regenerative energy flows into the braking unit, where it is converted into heat by the braking resistor, consuming this portion of the regenerative energy. The majority of the energy flows into the grid feedback unit and the energy storage unit. The distribution between these two units is determined by the power of the energy storage device. At this time:

[0071] I 再生 = I 馈网 + I 制动 + I 回收 ;

[0072] When the energy-saving device starts charging mode, and its starting power exceeds the device's regenerative power, most of the device's regenerative energy will flow into the energy storage unit. However, the energy storage unit will also absorb mains power at this time.

[0073] I 回收 = I 再生 + I 市电 ;

[0074] Third, when energy storage devices and grid feedback devices coexist, they compete with each other; if one absorbs more energy, the other absorbs less. Therefore, this invention provides a high-precision closed-loop control strategy. By installing a data acquisition unit on the DC bus to collect grid or feeder current, the main control unit reads this data and adjusts the charging and discharging current of the energy storage unit through a closed-loop control algorithm, controlling the current fed back to the grid to approximately 0A. Figure 4 The implementation process is as follows:

[0075] Regenerative energy equipment power generation status: When the set DC bus current value (when this current is positive, it is the mains power supply current to the load; when this current is negative, it is the regenerative energy supply current to the grid) is 0A, the main control unit reads the bus acquisition unit current as I. 母线 When the value is negative, it indicates that the system is feeding current back to the grid. The main control unit controls the bidirectional converter to increase the charging current. When the charging current increases, the current fed back to the grid will decrease. Under the cyclical control of the control unit of "measurement-comparison-calculation-adjustment", the whole system can achieve the maximum recovery of regenerated energy.

[0076] Electric state of regenerative energy equipment: The main control unit determines whether the regenerative energy equipment is in electric state by reading parameters such as DC bus current and voltage collected by the bus acquisition unit and the bidirectional converter unit. It controls the bidirectional converter unit to release the electrical energy of the energy storage unit to the DC bus, reducing the load's reliance on mains power. If the current released by the energy storage unit to the DC bus is too small, most of the energy consumed by the load is taken from the grid, resulting in a low energy saving rate. If the current released by the energy storage unit to the DC bus is too large, its power may even exceed the load's power. The excess power is transmitted to the grid through the grid feedback unit and flows into the braking unit, where it is converted into heat by the braking resistor and consumed. Although the energy saving rate is high, there is a significant waste. Therefore, the main control unit must control the output power of the energy storage unit. Under the cyclical control of "measurement-comparison-calculation-adjustment" by the control unit, the entire system can maximize the energy saving rate while protecting the safety of the entire equipment.

[0077] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0078] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A grid-compatible energy storage energy-saving method, characterized in that, Includes the following steps: The system comprises a main control unit, a busbar acquisition unit, an energy storage unit, a bidirectional converter unit, and an energy storage monitoring unit. The input terminal of the bidirectional converter unit is connected to the DC busbar, and the output terminal is connected to the energy storage unit. The output terminal of the energy storage unit is connected to the reverse input terminal of the bidirectional converter unit. The main control unit is electrically connected to the busbar acquisition unit, the bidirectional converter unit, the energy storage unit, and the energy storage monitoring unit, respectively. The power grid or feeder current on the DC bus is monitored through the bus acquisition unit; The energy storage monitoring unit monitors in real time the power generated by regenerative energy, the charging and discharging power of the energy storage unit, the power consumed by the load drive unit, and the voltage, current, and temperature of each unit. Based on the monitoring data from the busbar acquisition unit and the energy storage monitoring unit, the closed-loop control strategy of the main control unit is configured as follows: When the main control unit detects that the renewable energy device is generating electricity and feeding current back to the grid, it controls the bidirectional converter to increase the charging current of the energy storage unit and reduce the current fed back to the grid. When the regenerative energy device is detected to be in an electric state, the main control unit controls the bidirectional converter to release the electrical energy of the energy storage unit to the DC bus, and sets the power to be less than or equal to the power consumed by the load drive unit.

2. The energy-saving method for grid-compatible energy storage according to claim 1, characterized in that, The monitoring of the grid or feeder current on the DC bus specifically includes: The DC bus current magnitude and direction are monitored in real time, and the DC bus current value is set to 0A. When the monitored current is positive, it is determined to be the current supplied by the mains power to the load drive unit, and when it is negative, it is determined to be the current fed back to the grid by the regenerative energy equipment.

3. The energy-saving method for grid-compatible energy storage according to claim 1, characterized in that, By reconfiguring parameters through the main control unit, it can be adapted to different types of grid-feedback energy-saving projects.

4. The energy-saving method for grid-compatible energy storage according to claim 1, characterized in that, When a fault is detected, the main control unit controls the regenerative energy equipment to degrade or shut down.

5. A grid-compatible energy storage system, characterized in that, It includes a main control unit, a bus acquisition unit, an energy storage unit, a bidirectional converter unit, and an energy storage monitoring unit; The bidirectional converter unit is used to realize bidirectional conversion of DC power and adjust voltage and current parameters; the input end of the bidirectional converter unit is connected to the DC bus, and the output end is connected to the energy storage unit. The output terminal of the energy storage unit is connected to the reverse input terminal of the bidirectional converter unit, which is used to store regenerative energy and release the stored electrical energy when energy is needed. The energy storage monitoring unit is used to monitor in real time the power generated by regenerative energy, the charging and discharging power of the energy storage unit, the power consumed by the load drive unit, and the voltage, current, and temperature parameters of each unit, and transmit the monitoring data to the main control unit. The main control unit is electrically connected to the bus acquisition unit, the bidirectional converter unit, the energy storage unit, and the energy monitoring unit, respectively. It is used to receive monitoring data from the energy storage monitoring unit, control the bidirectional converter unit to perform energy flow control according to the operating conditions of the regenerative energy equipment and the SOC state of the energy storage unit, and at the same time receive monitoring data from the bus acquisition unit to prevent regenerative energy from flowing into the power grid.

6. The grid-compatible energy storage system according to claim 5, characterized in that, The main control unit, bus acquisition unit, bidirectional converter unit, and energy storage monitoring unit are connected via communication.

7. The grid-compatible energy storage system according to claim 5, characterized in that, The energy storage unit includes an energy storage element group, an energy storage management module, and a charge / discharge protection module; the energy storage management module is used to monitor the SOC, voltage, and temperature parameters of the energy storage element group in real time; the charge / discharge protection module is used to prevent the energy storage element group from being overcharged, over-discharged, over-temperatured, or short-circuited.

8. The grid-compatible energy storage system according to claim 7, characterized in that, The energy storage element group adopts a hybrid energy storage structure of supercapacitors and batteries.

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