Grid-connected online low-energy-consumption voltage-stabilizing and current-stabilizing converter

Abstract

The invention relates to the technical field of electric power energy conservation and voltage and current stabilization, in particular to a grid-connected online low-energy-consumption voltage and current stabilization converter and a grid-connected online low-energy-consumption voltage and current stabilization converter, and relates to the field of electric power energy conservation and voltage and current stabilization. When the power grid is powered off, the standby grid-connected non-anti-islanding function and the anti-countercurrent switch jointly ensure that the electricity utilization of the user side is uninterrupted, and the standby grid-connected non-anti-islanding anti-countercurrent switch has the effects of voltage stabilization, current stabilization, energy reduction and consumption reduction and is applied to alternating current (power grid) voltage stabilization, current stabilization, low-energy-consumption uninterrupted power supply, power grid frequency conversion grid connection, power grid frequency conversion capacity increase, peak regulation and frequency modulation, power dispatching and the like.

Description

Technical Field

[0001] This invention relates to the technical field of power energy saving and voltage and current stabilization, and in particular to a grid-connected online low-energy-consumption voltage and current stabilization converter. Background Technology

[0002] When existing grid-connected converters (inverters) are used in conjunction with our company's patented inventions "AC Anti-Reverse Current Method (Application No. CN202510590992.6)" and "AC Anti-Reverse Current Intelligent Switch (Application No. CN202510921356.7)," the existing converters operate with the grid as a reference and stable source after grid connection. Our company's anti-reverse current device possesses ideal (almost perfect) anti-reverse current protection, causing the existing grid-connected converters to malfunction when connected to the backend of our invention's anti-reverse current device. On the other hand... Existing grid-connected converters have anti-islanding effects when the grid is shut down, while our invented anti-reverse current device has ideal anti-reverse current function. When the back-end of our invented anti-reverse current device is connected to the grid, anti-islanding effect is not required. Existing grid-connected converters cannot achieve non-islanding effect. On the other hand, the inverters integrated inside existing online uninterruptible power supplies (UPS) are always online under load, which has high energy consumption and heat generation. If ideal anti-reverse current is combined with grid-connected inverter standby mode, the energy-saving effect of UPS can be realized. However, existing inverters cannot realize the application of this grid-connected inverter standby mode scenario.

[0003] To address the aforementioned issues, this invention proposes a "grid-connected online low-energy-consumption voltage and current stabilizer," which solves these problems and features a simple structure, energy reduction, and suitability for various application scenarios. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a grid-connected online low-energy-consumption voltage and current stabilizer that combines ideal anti-reverse current and grid-connected inverter standby mode to achieve the energy-saving function of UPS.

[0005] The grid-connected online low-energy-consumption voltage and current stabilizer of the present invention includes an AC anti-reverse current switch, an AC-DC conversion unit, a grid-connected converter inverter unit, an energy storage battery, an outer loop voltage acquisition unit, an outer loop current acquisition unit, a setting unit, and a display unit.

[0006] The grid-connected online low-energy-consumption voltage and current stabilizer of this invention has an AC anti-reverse current switch whose input terminal is electrically connected to the power grid and whose output terminal is electrically connected to the user. This prevents AC power from flowing back into the power grid from the user side and provides ideal anti-reverse current functionality, ensuring safe operation under grid-connected conditions without islanding. It also features a protection function that prevents closing the circuit due to phase, voltage, and frequency inconsistencies between the power grid and the user. The AC / DC conversion unit's input terminal is connected to the power grid, converting AC power to DC power. The output DC power is connected to the grid-connected inverter unit to supply power. The grid-connected inverter unit outputs AC power to the user side, requiring grid-connected operation without islanding. The energy storage battery is electrically connected to the DC power supply output from the AC / DC conversion unit.

[0007] The grid-connected online low-energy-consumption voltage and current stabilizer of this invention features an outer-loop voltage acquisition system that collects grid voltage information and an outer-loop current acquisition system that collects current information between the grid and the user. The outer-loop current acquisition point can be located either before or after the AC anti-reverse current switch to meet the acquisition requirements of this invention. The voltage and current information signals collected from the outer loop are connected to the grid-connected converter inverter unit for adjusting and controlling the grid-connected output. The settings and display systems are connected to the grid-connected converter inverter unit for setting parameters and displaying parameters and function menus. The signal connection methods include wires, coaxial cables, and wireless connections.

[0008] The present invention relates to a grid-connected online low-energy-consumption voltage and current regulated converter, wherein the grid-connected converter inverter unit comprises a DC-DC auxiliary power supply, DC voltage acquisition, DC current acquisition, inner loop voltage acquisition, inner loop current acquisition, AD conversion (including the built-in microcontroller), microcontroller, gate standing still, and inverter main topology.

[0009] The grid-connected online low-energy-consumption voltage and current stabilized converter of the present invention uses a DC-DC auxiliary power supply, which is drawn from the main DC power supply and converted to supply power to each chip in the entire grid-connected inverter unit, ensuring its normal operation. The AD conversion (including the built-in microcontroller) converts the analog signals of DC voltage acquisition, DC current acquisition, inner loop voltage acquisition, inner loop current acquisition and the above-mentioned external loop acquisition into digital signals, which are easy for the microcontroller to identify and process. The microcontroller generates an SPWM wave based on the signal processing of the external sensors, outputs it to the gate oscillator, drives the switching transistor in the main topology of the inverter, and completes the grid-connected output.

[0010] The grid-connected online low-energy-consumption voltage and current stabilized converter of the present invention includes the following microcontroller control program flow in the grid-connected converter inverter unit: start → initialization → phase-locked loop → SPWM wave → inverter.

[0011] The grid-connected online low-energy-consumption voltage and current stabilized converter of the present invention has a phase-locked loop (PLL) whose loop includes the following six corresponding acquisition signals and controls: The first path involves acquiring the outer loop voltage of the power grid (in three-phase applications, this includes the ABC acquisition of the three-phase power grid) to control the output AC current of the grid-connected converter inverter unit to synchronize with the power grid, and to control the output voltage to synchronize with the power grid voltage. This allows the inverter's output frequency and voltage to follow the changes in the power grid. When no external signal triggers relevant commands, the inverter's output voltage is equal to the power grid voltage, and it is in an online grid-connected standby state. The inverter has no power output or very low power output to the outside world. The second path involves the outer loop current acquisition of the power grid (in three-phase applications, this includes the ABC acquisition of the three-phase power). This current acquisition signal is used to compare two adjustable threshold values ​​(the first value is less than the second value or the two values ​​are equal). When the first value is not reached, the grid-connected converter inverter unit is in online grid-connected standby state or has very little power output. When the first threshold value is reached, the grid-connected converter inverter unit starts to output power, which plays a role in current stabilization and power supplementation for the user side. This value is adjustable and is used to compensate for insufficient power supply from the power grid. The output power varies with the load changes on the user side. When the second value is reached, the inverter maintains a constant maximum power output.

[0012] The third path is the inner loop voltage acquisition (which includes the ABC acquisition of three-phase power when applied in three-phase power). This voltage acquisition is used to adjust the locked grid-connected converter inverter unit so that it still has AC voltage output and stable upper and lower limit voltage control in the offline state (power grid loss).

[0013] The fourth channel, the inner-loop current acquisition (which includes ABC acquisition in three-phase applications), is mainly used to adjust the power factor of the grid-connected converter inverter unit output and compensate for inductive and capacitive loads. The control functions of this acquisition signal also include dynamically adjusting the total power and limiting protection when the total power exceeds a set value. The fifth channel includes DC voltage acquisition, which is used for protection control when the total DC voltage is lower or higher than a specified set value. The sixth channel includes DC current acquisition for dynamically adjusting the total power of the grid-connected converter inverter unit and limiting protection when the total power exceeds a set value.

[0014] The aforementioned grid-connected online low-energy-consumption voltage and current stabilizer converter, based on the described working principle, can have its topology further expanded, including... Figure 3 , Figure 4 , Figure 5 The extended topology structure.

[0015] The beneficial effects of this invention are as follows: As can be seen from the structure and working process of the above-mentioned grid-connected online low-energy-consumption voltage and current stabilizer, since the power supply to the user side is directly connected from the power grid through the AC anti-reverse current switch, the switching power transistor in the AC anti-reverse current switch performs switching at the zero crossing of the power frequency, and there is no electronic switch action during the entire positive and negative half-cycle, thus having very low energy consumption (existing technology); the grid-connected inverter unit is in standby grid connection except when operating in capacity expansion mode, and has no power output (or very low power output). When the power grid fails, the standby grid connection non-islanding function plus the anti-reverse current switch together ensure uninterrupted power supply to the user side. Therefore, the "grid-connected online low-energy-consumption voltage and current stabilizer" of this invention can meet the functions of uninterruptible power supply, voltage stabilization, and current stabilization. It also has the function of reducing energy consumption during operation. Combined with the above-mentioned extended applications, it can meet the characteristics of multi-scenario applications. Attached Figure Description

[0016] Figure 1 Schematic diagram of a grid-connected online low-energy-consumption voltage and current stabilizer; Figure 2 Flowchart of a grid-connected online low-energy-consumption voltage and current stabilizer; Figure 3 Diagram of heterogeneous power converter grid connection application; Figure 4 Solar power generation application diagram; Figure 5 Diagram of multi-network converter grid connection application; The labels in the attached diagram are: 1-AC anti-reverse current switch, 2-AC-DC conversion unit, 3-grid-connected converter inverter unit, 4-energy storage battery, 5-outer loop voltage acquisition, 6-outer loop current acquisition, 7-setting, 8-display. Detailed Implementation

[0017] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0018] Example 1: Implementation method of using a grid-connected online low-energy-consumption voltage and current stabilizer in an "uninterruptible power supply" (UPS). The specific implementation method is as follows: The implementation method of using a grid-connected online low-energy-consumption voltage and current stabilizer in an "uninterruptible power supply" is as follows: Grid-connected online low-energy-consumption voltage and current stabilizer, see Figure 1 Its structure comprises: an AC anti-reverse current switch 1, an AC / DC conversion unit 2, a grid-connected converter inverter unit 3, an energy storage battery (optional) 4, an outer loop voltage acquisition unit 5, an outer loop current acquisition unit 6, a setting unit 7, and a display unit 8. Its characteristic is that: The AC anti-reverse current switch 1 is electrically connected to the power grid at its input and to the user at its output. It prevents AC power from flowing back into the power grid from the user side and has an ideal anti-reverse current function. It can ensure the safe operation of the user side under grid-connected non-islanding conditions and also has a protection function that prohibits closing the switch due to inconsistencies in phase, voltage, and frequency between the power grid and the user. The AC-DC converter unit 2 is connected to the power grid at its input and converts the AC power from the power grid into DC power. The DC power output is connected to the grid-connected inverter unit 3 to supply power to it. The AC power output of the grid-connected inverter unit 3 is connected to the user side, requiring grid-connected non-islanding conditions. The energy storage battery 4 is electrically connected to the DC power supply output of the AC-DC converter unit 2.

[0019] The outer loop voltage acquisition 5 collects grid voltage information, and the outer loop current acquisition 6 collects current information between the grid and the user. The outer loop current acquisition point can be set before or after the AC anti-reverse current switch to meet the acquisition requirements of this invention. The voltage 5 and current 6 information signals collected by the outer loop are connected to the grid-connected converter inverter unit 3 for adjusting and controlling the grid-connected output. The setting 7 and display 8 are connected to the grid-connected converter inverter unit 3 for setting parameters and displaying parameters and function menus. The above signal connection methods include wires, coaxial cables, and wireless connections.

[0020] The grid-connected online low-energy-consumption voltage and current stabilized converter, wherein the grid-connected inverter unit 3 consists of a DC-DC auxiliary power supply, DC voltage acquisition, DC current acquisition, inner loop voltage acquisition, inner loop current acquisition, AD conversion (including built-in microcontroller), microcontroller, gate standing still, and inverter main topology, characterized in that: The auxiliary power supply draws power from the main DC power supply and then supplies power to each chip in the entire grid-connected converter inverter unit to ensure its normal operation. The AD conversion (including the built-in microcontroller) converts the analog signals from DC voltage acquisition, DC current acquisition, inner loop voltage acquisition, inner loop current acquisition, and the above-mentioned external loop acquisition into digital signals, which are easy for the microcontroller to identify and process. The microcontroller generates an SPWM wave based on the signal processing of the external sensors and outputs it to the gate oscillator to drive the switching transistors in the main topology of the inverter to complete the grid-connected output.

[0021] The flow chart of the microcontroller control program in the grid-connected online low-energy voltage and current stabilizing converter unit is shown below. Figure 2 .

[0022] The program flow includes: Start → (representing the execution of the next task) Initialization → Phase-locked loop → SPWM wave → Inverter.

[0023] The program's phase-locked loop (PLL) includes the following six channels of acquired signals and control: The first path involves acquiring the outer loop voltage of the power grid (in three-phase applications, this includes the ABC acquisition of the three-phase power grid) to control the output AC current of the grid-connected converter inverter unit to synchronize with the power grid, and to control the output voltage to synchronize with the power grid voltage. This allows the inverter's output frequency and voltage to follow the changes in the power grid. When no external signal triggers relevant commands, the inverter's output voltage is equal to the power grid voltage, and it is in an online grid-connected standby state. The inverter has no power output or very low power output to the outside world. The second path involves the outer loop current acquisition of the power grid (in three-phase applications, this includes the ABC acquisition of the three-phase power). This current acquisition signal is used to compare two adjustable threshold values ​​(the first value is less than the second value or the two values ​​are equal). When the first value is not reached, the grid-connected converter inverter unit is in online grid-connected standby state or has very little power output. When the first threshold value is reached, the grid-connected converter inverter unit starts to output power, which plays a role in current stabilization and power supplementation for the user side. This value is adjustable and is used to compensate for insufficient power supply from the power grid. The output power varies with the load changes on the user side. When the second value is reached, the inverter maintains a constant maximum power output.

[0024] The third path is the inner loop voltage acquisition (which includes the ABC acquisition of three-phase power when applied in three-phase power). This voltage acquisition is used to adjust the locked grid-connected converter inverter unit so that it still has AC voltage output and stable upper and lower limit voltage control in the offline state (power grid loss).

[0025] The fourth channel, the inner-loop current acquisition (which includes ABC acquisition in three-phase applications), is mainly used to adjust the power factor of the grid-connected converter inverter unit output and compensate for inductive and capacitive loads. The control functions of this acquisition signal also include dynamically adjusting the total power and limiting protection when the total power exceeds a set value. The fifth channel includes DC voltage acquisition, which is used for protection control when the total DC voltage is lower or higher than a specified set value. The sixth channel includes DC current acquisition for dynamically adjusting the total power of the grid-connected converter inverter unit and limiting protection when the total power exceeds a set value.

[0026] The above implements the functions of a grid-connected online low-energy-consumption voltage and current stabilizer, based on the principle. Figure 1As can be seen from the structure and working process, since the power supply to the user side is directly connected to the grid through the AC anti-reverse current switch, the switching power tube in the AC anti-reverse current switch performs switching at the zero crossing of the power frequency. There is no electronic switch action during the entire positive and negative half-cycle, so it has very low energy consumption (existing technology). Except when operating in the capacity expansion mode, the grid-connected converter inverter unit is in standby grid connection in other situations, with no power output (or very low power output). When the grid fails, the standby grid connection non-islanding function plus the anti-reverse current switch together ensure uninterrupted power supply to the user side. Therefore, the "grid-connected online low-energy-consumption voltage and current stabilizer" of this invention can meet the functions of uninterruptible power supply, voltage stabilization, and current stabilization, and also has the function of reducing energy consumption during operation.

[0027] The aforementioned grid-connected online low-energy-consumption voltage and current stabilizer can be further expanded in its connection combinations, and its features include: Figure 3 , Figure 4 , Figure 5 Applications of extended topology structures.

[0028] The following is combined with Figure 3 , Figure 4 , Figure 5 The extension is explained as follows: Example 2, the implementation method of "heterogeneous grid converter grid connection" application, is as follows: Grid-connected online low-energy-consumption voltage and current stabilizer, see Figure 3 Its structure includes: an AC anti-reverse current switch 1, an AC / DC conversion unit 2, a grid-connected converter inverter unit 4, an outer loop voltage acquisition unit 5, and an outer loop current acquisition unit. Its characteristic is that: The input terminal of the AC anti-backflow switch 1 is electrically connected to the power grid, and the output terminal is electrically connected to the user. The input terminal of the AC-DC conversion unit 2 is connected in parallel to other power grids, and the DC output is connected to the grid-connected converter inverter unit 3 to supply power to it. The output AC power of the grid-connected converter inverter unit 3 is connected to the user side.

[0029] The above principle, combined with the first example, can satisfy the merging of two power grids, including merging when the frequencies of the two power grids (including but not limited to 50Hz and 60Hz) are inconsistent.

[0030] Therefore, the structure and principle of this embodiment can be applied to places where dual power supplies are combined, such as dual power supplies for fire protection, dual power supplies for important computer centers, hospitals that require high-reliability power supply, etc., and can also be applied to frequency conversion substations.

[0031] The grid-connected online low-energy-consumption voltage and current stabilizer converter described in Example 1 states: "The second path is the outer loop current acquisition of the power grid (in three-phase applications, it includes the ABC acquisition of three-phase power). After the current acquisition signal reaches a set value, the grid-connected converter inverter unit starts to output power." If this value is set to "zero-power start" and combined with the structure of Example 2, the two power grids can be merged and the capacity increased.

[0032] Example 3: The implementation method of "solar power generation" application is as follows: The grid-connected online low-energy-consumption voltage and current stabilizer converter described above, combined with the principles of Examples 1 and 2, can be used in new energy applications, such as solar power generation. Figure 4 , Figure 4 The implementation of this system allows photovoltaic power generation and grid power to supply electricity to users simultaneously, solving the problem of uninterrupted power supply during grid outages.

[0033] Example 4: Implementation method of "multi-network converter grid connection" application, the specific implementation method is as follows: The grid-connected online low-energy-consumption voltage and current stabilizer converter described above, combined with the principles of Examples 1 and 2, can be used to construct multi-grid converter interconnection. (See...) Figure 5 , Figure 5 The implementation of this technology satisfies the merging of multiple power grids and can be applied to the capacity merging of wind power generation and scattered photovoltaic power generation. It can solve the problem of power merging between various power generation systems and the problem of mutual reverse flow between subsystem power grids. Therefore, it can merge power grids of different standards.

[0034] Examples one, two, three, and four above demonstrate grid-connected online low-energy-consumption voltage and current stabilizers, which can reduce energy consumption and meet the needs of various application scenarios.

[0035] The above are merely preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A grid-connected online low-energy-consumption voltage and current stabilizer, characterized in that, It includes an AC anti-reverse current switch, an AC / DC conversion unit, a grid-connected converter inverter unit, an energy storage battery, an outer loop voltage acquisition unit, an outer loop current acquisition unit, and settings and displays.

2. The grid-connected online low-energy-consumption voltage and current stabilizer converter as described in claim 1, characterized in that, The AC anti-reverse current switch is electrically connected to the power grid at its input and to the user at its output. It prevents AC power from flowing back into the power grid from the user side and has an ideal anti-reverse current function. It can ensure the safe operation of the user side under grid-connected non-islanding conditions and also has a protection function that prohibits closing the switch due to inconsistencies in phase, voltage, and frequency between the power grid and the user. The AC-DC converter unit is connected to the power grid at its input to convert the AC power from the grid to DC power. The DC power output is connected to the grid-connected inverter unit to supply power to it. The AC power output of the grid-connected inverter unit is connected to the user side, requiring grid-connected non-islanding conditions. The energy storage battery is electrically connected to the DC power supply output of the AC-DC converter unit.

3. The grid-connected online low-energy-consumption voltage and current stabilizer converter as described in claim 1, characterized in that, The outer loop voltage acquisition collects grid voltage information, and the outer loop current acquisition collects current information between the grid and the user. The outer loop current acquisition point can be set before or after the AC anti-reverse current switch to meet the acquisition requirements of this invention. The voltage and current information signals collected by the outer loop are connected to the grid-connected converter inverter unit for adjusting and controlling the grid-connected output. The setting and display are connected to the grid-connected converter inverter unit for setting parameters and displaying parameters and function menus. The above signal connection methods include wires, coaxial cables, and wireless connections.

4. The grid-connected online low-energy-consumption voltage and current stabilizer converter as described in claim 2, characterized in that, The grid-connected online low-energy-consumption voltage and current stabilizer converter includes a grid-connected inverter unit consisting of a DC-DC auxiliary power supply, DC voltage acquisition, DC current acquisition, inner loop voltage acquisition, inner loop current acquisition, AD conversion (including built-in microcontroller), microcontroller, gate standing still, and inverter main topology.

5. The grid-connected online low-energy-consumption voltage and current stabilizer converter as described in claim 4, characterized in that, The DC-DC auxiliary power supply draws power from the main DC power supply and then supplies power to each chip in the entire grid-connected converter inverter unit, ensuring its normal operation. The AD conversion (including the built-in function of the microcontroller) converts the analog signals from DC voltage acquisition, DC current acquisition, inner loop voltage acquisition, inner loop current acquisition, and the aforementioned external loop acquisitions into digital signals, facilitating microcontroller recognition and processing. The microcontroller processes the signals from the external sensors to generate an SPWM wave, which is then output to the gate to drive the switching transistors in the main topology of the inverter, completing the grid-connected output.

6. The grid-connected online low-energy-consumption voltage and current stabilizer converter as described in claims 3 and 5, characterized in that, The microcontroller control program flow in the grid-connected converter inverter unit includes: Start → Initialization → Phase-locked loop → SPWM wave → Inverter.

7. The grid-connected online low-energy-consumption voltage and current stabilizer converter as described in claim 6, characterized in that, The program's phase-locked loop (PLL) includes the following six channels of acquired signals and control: The first path involves acquiring the outer loop voltage of the power grid (in three-phase applications, this includes the ABC acquisition of the three-phase power grid) to control the output AC current of the grid-connected converter inverter unit to synchronize with the power grid, and to control the output voltage to synchronize with the power grid voltage. This allows the inverter's output frequency and voltage to follow the changes in the power grid. When no external signal triggers relevant commands, the inverter's output voltage is equal to the power grid voltage, and it is in an online grid-connected standby state. The inverter has no power output or very low power output to the outside world. The second path involves acquiring the outer loop current of the power grid (in three-phase applications, this includes the ABC acquisition of the three phases). This current acquisition signal is used to compare two adjustable threshold values ​​(the first value is less than the second value or the two values ​​are equal). When the first value is not reached, the grid-connected converter inverter unit is in online grid-connected standby mode or has very little power output. When the first threshold value is reached, the grid-connected converter inverter unit starts outputting power, which plays a role in current stabilization and power supplementation for the user side. This value is adjustable and is used to compensate for insufficient power supply from the power grid. The output power varies with the load changes on the user side. When the second value is reached, the inverter maintains a constant maximum power output. The third path is the inner loop voltage acquisition (which includes the ABC acquisition of three-phase power when applied in three-phase power). This voltage acquisition is used to adjust the locked grid-connected converter inverter unit so that it still has AC voltage output and stable upper and lower limit voltage control in the offline state (power grid loss). The fourth channel, inner loop current acquisition (which includes ABC acquisition of three-phase power when applied in three-phase power), is mainly used to adjust the power factor of the grid-connected converter inverter unit output and to compensate for inductive and capacitive loads; the control function of this acquisition signal also includes dynamic adjustment of total power and protection when the total power exceeds the set value. The fifth channel includes DC voltage acquisition, which is used for protection control when the total DC voltage is lower or higher than a specified set value. The sixth channel includes DC current acquisition for dynamically adjusting the total power of the grid-connected converter inverter unit and limiting protection when the total power exceeds a set value.

8. The grid-connected online low-energy-consumption voltage and current stabilizer converter as described in claim 1, with its topology extended according to the working principle, including the extended topology structures shown in Figures 3, 4, and 5.

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