Energy storage converter control method and energy storage converter

Abstract

The invention discloses an energy storage converter which comprises a plurality of bridge arms, a capacity capacitor C1 and a capacity capacitor C2, each of the bridge arms comprises an upper half bridge arm and a lower half bridge arm, and each of the upper half bridge arm and the lower half bridge arm comprises N power units and an electric reactor, and each of the N power units comprises a full-control type power semiconductor device Q1, a full-control type power semiconductor device Q2, a full-control type power semiconductor device Q3, a full-control type power semiconductor device Q4 and a capacity capacitor C. According to the energy storage converter control method and the energy storage converter, through a technical structure arranged in the energy storage converter and the disclosed control method of the energy storage converter, an extremely wide voltage of direct current 0-1500V and alternating current 0-1000V can be realized under the architecture of a single-stage power converter and no transformer; therefore, direct access of low-voltage alternating-current systems with different voltage levels can be met, and favorable conditions for solving various abnormal conditions such as fault ride-through and the like are provided at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical energy storage, and particularly to a control method for an energy storage converter and an energy storage converter. Background Art

[0002] As one of the devices that can control the charging and discharging processes of storage batteries and perform AC-DC conversion, an energy storage converter can directly supply power to AC loads without a power grid. At present, in order to meet the application requirements of different electrochemical energy storage batteries, the energy storage converter of an electrochemical energy storage system needs to ensure a very wide DC voltage range. At the same time, in order to meet the direct access of low-voltage AC systems with different voltage levels and provide solutions for abnormal situations such as various fault ride-throughs, it also needs to have an extremely wide AC voltage range.

[0003] In the prior art, to meet the above requirements, a two-stage power converter architecture or a transformer is usually used. Although the basic usage requirements can be met, due to the increase in the number of devices and the extension of the specific conversion process, not only the usage cost is increased but also the conversion efficiency is reduced in the actual application process, resulting in an obvious imbalance between the benefits and the efforts. Therefore, to solve the defects existing in the above prior art, the applicant will provide a control method for an energy storage converter and an energy storage converter. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a control method for an energy storage converter and an energy storage converter, which solves the problems raised in the above background art.

[0005] To achieve the above object, the present invention provides the following technical solution: An energy storage converter, the energy storage converter includes a plurality of bridge arms, a capacitive capacitor C1, a capacitive capacitor C2, and each of the plurality of bridge arms includes an upper half-bridge arm and a lower half-bridge arm, and the upper half-bridge arm and the lower half-bridge arm each include N power units and a reactor; The N power units each include a fully controlled power semiconductor device Q1, a fully controlled power semiconductor device Q2, a fully controlled power semiconductor device Q3, a fully controlled power semiconductor device Q4, and a capacitive capacitor C.

[0006] Preferably, the number of the plurality of bridge arms is three, and a phase line A, a phase line B, and a phase line C are respectively connected between the three bridge arms and the corresponding power grid.

[0007] Preferably, the upper half-bridge arm is connected between the DC positive and the AC phase line, and the lower half-bridge arm is connected between the DC negative and the AC phase line.

[0008] Preferably, N is a natural number and N is not less than 2.

[0009] Preferably, the connection point of the fully-controlled power semiconductor device Q1 and the fully-controlled power semiconductor device Q3 is the external connection point T1 of the power unit; The connection point of the fully-controlled power semiconductor device Q2 and the fully-controlled power semiconductor device Q4 is the external connection point T2 of the power unit; The fully-controlled power semiconductor device Q1 is connected between the positive electrode of the capacitor and T1, and the fully-controlled power semiconductor device Q2 is connected between the positive electrode of the capacitor and T2; The fully-controlled power semiconductor device Q3 is connected between the negative electrode of the capacitor and T1, and the fully-controlled power semiconductor device Q4 is connected between the negative electrode of the capacitor and T2.

[0010] Preferably, the working voltage across the capacitors of the N power units is Uc, the DC voltage range of the energy storage converter is 0 to N•Uc, and the AC voltage range is .

[0011] Preferably, the energy storage converter is connected to a three-phase four-wire power grid and a neutral line D is led out at the connection point of the capacitance capacitor C1 and the capacitance capacitor C2.

[0012] Preferably, the energy storage converter is connected to a three-phase three-wire power grid, and there is no need to lead out a neutral line D at the connection point of the capacitance capacitor C1 and the capacitance capacitor C2.

[0013] Preferably, the control method of the energy storage converter includes the following steps: S1. By calculating the capacitor voltages of all power units in each arm, the command value of the sum of the currents of the upper and lower half arms of each arm is obtained. The more specific operations are as follows: (1) Measure the voltage of the capacitor of each power unit; (2) Sum the capacitor voltages of all power units in each arm respectively; (3) Subtract the sum of the capacitor voltages of all power units in each arm from the set value of the sum of the capacitor voltages of the power units in each arm, and perform a proportional-integral regulator on this difference to obtain the command value of the sum of the currents of the upper and lower half arms of each arm; S2. Divide the active power and reactive power commands of each phase issued by the upper-level control unit by the corresponding phase AC voltage, and then obtain the active current command and reactive current command of each phase. After the active current command and reactive current command are respectively subjected to rotational coordinate transformation and added, the instantaneous value of the output current command of each phase is obtained, that is, the command value of the current difference between the upper and lower half arms of each arm; S3. By calculating the currents of the upper and lower half arms of each arm, the command value of the sum of the output voltages of the upper and lower half arms of each arm and the command value of the difference between the output voltages of the upper and lower half arms of each arm are obtained. The more specific operations are as follows: (1) Measure the currents of the upper and lower half-bridges of each arm. (2) Calculate the measured value of the sum of the currents of the upper and lower half-bridges of each arm. (3) Calculate the measured value of the difference between the currents of the upper and lower half-bridges of each arm. (4) Subtract the measured value from the command value of the sum of the currents of the upper and lower half-bridges of each arm, and perform a proportional-integral regulator on this difference to obtain the command value of the sum of the output voltages of the upper and lower half-bridges of each arm. (5) Subtract the measured value from the command value of the difference between the currents of the upper and lower half-bridges of each arm, and perform a proportional second-order generalized integral regulator on this difference to obtain the command value of the difference between the output voltages of the upper and lower half-bridges of each arm. S4. Add the command value of the sum of the output voltages of the upper and lower half-bridges of each arm and the command value of the difference between the output voltages of the upper and lower half-bridges of each arm, and then divide by two to obtain the command value of the output voltage of the upper half-bridge of each arm. S5. Subtract the command value of the difference between the output voltages of the upper and lower half-bridges of each arm from the command value of the sum of the output voltages of the upper and lower half-bridges of each arm, and then divide by two to obtain the command value of the output voltage of the lower half-bridge of each arm. S6. Divide the output voltage of each half-bridge by the number N of power units included in each half-bridge to obtain the command value of the output voltage of each power unit. S7. Divide the output voltage of each power unit by the DC voltage of each power unit to obtain the duty cycle command value of each power unit. S8. Subtract the voltage of the capacitor of each power unit from the average value of the capacitor voltages of each power unit in the same arm, and after passing through a proportional regulator, obtain the current command for the required capacitor voltage balance. Then divide it by the measured value of the current flowing through the power unit to obtain the correction value of the duty cycle command of each power unit. S9. Add the duty cycle command value of each power unit and the correction value of the duty cycle command of each power unit to obtain the modulation wave value of the pulse width modulation of the power unit Q1. Take the negative value to obtain the modulation wave value of the pulse width modulation of Q2. Compare with the carrier value to obtain the action signals of Q1 and Q2. Invert the action signal of Q1 and add a dead zone as the action signal of Q3. Invert the action signal of Q2 and add a dead zone as the action signal of Q4. S10. The carrier phases of the power units in the same arm differ by π / 2N, forming carrier phase-shifted multilevel modulation.

[0014] The present invention provides a control method and an energy storage converter, having the following beneficial effects: (1) The energy storage converter control method and the energy storage converter can achieve an extremely wide voltage range of DC 0 to 1500 volts and AC 0 to 1000 volts in a single-stage power converter and transformerless architecture through the technical structure set in the energy storage converter and the disclosed control method of the energy storage converter. Thus, it can meet the direct access of low-voltage AC systems with different voltage levels and provide favorable conditions for solving various abnormal situations such as fault ride-through, and further adapt to the application requirements of different electrochemical energy storage batteries, where the electrochemical energy storage batteries include lithium-ion batteries, sodium-ion batteries, flow batteries, and supercapacitors.

[0015] (2) For the energy storage converter control method and the energy storage converter, after the configured energy storage converter is used in combination with a suitable three-phase four-wire power grid, the three-phase four-wire power grid provides the phase voltage between the phase line and the neutral line D, usually 220V, and the introduction of the neutral line D provides power for single-phase loads. A complete circuit is formed between each phase line and the neutral line D, which makes the three-phase four-wire power grid particularly suitable for the energy storage converter circuit system and can efficiently output power to both three-phase and single-phase loads simultaneously.

[0016] (3) For the energy storage converter control method and the energy storage converter, after the configured energy storage converter is used in combination with a suitable three-phase four-wire power grid, the three-phase three-wire power grid can not lead out the neutral line D, and its three transmission lines are spaced 120 degrees apart in phase angle, enabling the load current to remain balanced even without a neutral point. Moreover, if the load is completely balanced, theoretically the current at the neutral point is zero, so there is even less need for the neutral line D. Thus, it can create favorable conditions for optimizing the usage cost of the energy storage converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic circuit diagram of Embodiment 1 of the structure of the present invention; Figure 2 is a schematic circuit diagram of Embodiment 2 of the structure of the present invention; Figure 3 is a schematic circuit diagram of the power unit of the structure of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0019] Embodiment 1 Please refer to Figure 1 , an energy storage converter, the energy storage converter includes a plurality of bridge arms, a capacitance capacitor C1, a capacitance capacitor C2, and each of the plurality of bridge arms includes an upper half bridge arm and a lower half bridge arm, and the upper half bridge arm and the lower half bridge arm each include N power units and reactors; Each of the N power units includes a fully controlled power semiconductor device Q1, a fully controlled power semiconductor device Q2, a fully controlled power semiconductor device Q3, a fully controlled power semiconductor device Q4, and a capacitance capacitor C. The operating voltage across the capacitors of the N power units is Uc. The DC voltage range of this energy storage converter is 0 to N•Uc, and the AC voltage range is , where N is a natural number and N is not less than 2.

[0020] The connection point of the fully controlled power semiconductor device Q1 and the fully controlled power semiconductor device Q3 is the external connection point T1 of the power unit. The connection point of the fully controlled power semiconductor device Q2 and the fully controlled power semiconductor device Q4 is the external connection point T2 of the power unit. The fully controlled power semiconductor device Q1 is connected between the positive electrode of the capacitor and T1. The fully controlled power semiconductor device Q2 is connected between the positive electrode of the capacitor and T2. The fully controlled power semiconductor device Q3 is connected between the negative electrode of the capacitor and T1. The fully controlled power semiconductor device Q4 is connected between the negative electrode of the capacitor and T2; The number of the several bridge arms is three, and phase lines A, B, and C are respectively connected between the three bridge arms and the corresponding power grid. The upper half bridge arm is connected between the DC positive and the AC phase line, and the lower half bridge arm is connected between the DC negative and the AC phase line. This energy storage converter is connected to a three-phase four-wire power grid and a neutral line D is led out at the connection point of the capacitance capacitor C1 and the capacitance capacitor C2.

[0021] In use, the three-phase four-wire power grid specifically used by the energy storage converter includes four wires, namely three phase lines (L1, L2, L3) and a neutral line D. In addition to the line voltage between the phase lines (usually 380V), the three-phase four-wire power grid also provides the phase voltage between the phase line and the neutral line D, usually 220V. And the introduction of the neutral line D provides power for single-phase loads. A complete circuit is formed between each phase line and the neutral line D. This makes the three-phase four-wire power grid particularly suitable for the energy storage converter circuit system and can efficiently output power to three-phase and single-phase loads simultaneously.

[0022] Please refer to Figure 2 , this energy storage converter is connected to a three-phase three-wire power grid and does not need to lead out a neutral line D at the connection point of the capacitance capacitor C1 and the capacitance capacitor C2.

[0023] During use, the three-phase three-wire power grid specifically used by the energy storage converter is mainly composed of three conductors. The voltage between the three phase lines is called the line voltage, usually 380V or within other standard ranges in industrial applications. The three-phase three-wire power grid does not lead out the neutral line D, and the three transmission lines are spaced 120 degrees apart in phase angle from each other, enabling the load current to remain balanced even without a neutral point. Moreover, if the load is completely balanced, theoretically the current at the neutral point is zero, so there is even less need for the neutral line D. As a result, it can create favorable conditions for optimizing the usage cost of the energy storage converter.

[0024] Embodiment Three Please refer to Figure 1 、 Figure 3 , the control method of the energy storage converter includes the following steps: S1. By calculating the capacitor voltages of all power units in each bridge arm, the command value of the sum of the currents of the upper and lower half-bridge arms of each bridge arm is obtained. The more specific operations are as follows: (1) Measure the voltage of the capacitor of each power unit. (2) Sum the capacitor voltages of all power units in each bridge arm respectively. (3) Subtract the sum of the capacitor voltages of all power units in each bridge arm from the set value of the sum of the capacitor voltages of the power units in each bridge arm, and perform a proportional-integral regulator on this difference to obtain the command value of the sum of the currents of the upper and lower half-bridge arms of each bridge arm. S2. Divide the active power and reactive power commands of each phase issued by the upper-level control unit by the corresponding phase AC voltage, and then obtain the active current command and reactive current command of each phase. After the active current command and reactive current command are respectively subjected to rotational coordinate transformation and added together, the instantaneous value of the output current command of each phase is obtained, that is, the command value of the difference between the currents of the upper and lower half-bridge arms of each bridge arm. S3. By calculating the currents of the upper and lower half-bridge arms of each bridge arm, the command value of the sum of the output voltages of the upper and lower half-bridge arms of each bridge arm and the command value of the difference between the output voltages of the upper and lower half-bridge arms of each bridge arm are obtained. The more specific operations are as follows: (1) Measure the currents of the upper and lower half-bridge arms of each bridge arm. (2) Calculate the measured value of the sum of the currents of the upper and lower half-bridge arms of each bridge arm. (3) Calculate the measured value of the difference between the currents of the upper and lower half-bridge arms of each bridge arm. (4) Subtract the measured value from the command value of the sum of the currents of the upper and lower half-bridge arms of each bridge arm, and perform a proportional-integral regulator on this difference to obtain the command value of the sum of the output voltages of the upper and lower half-bridge arms of each bridge arm. (5) Subtract the measured value from the command value of the current difference between the upper and lower half-bridges of each arm, and perform a proportional second-order generalized integral regulator on this difference to obtain the command value of the output voltage difference between the upper and lower half-bridges of each arm; S4. Add the command value of the sum of the output voltages of the upper and lower half-bridges of each arm to the command value of the output voltage difference between the upper and lower half-bridges of each arm and then divide by two to obtain the command value of the output voltage of the upper half-bridge of each arm; S5. Subtract the command value of the output voltage difference between the upper and lower half-bridges of each arm from the command value of the sum of the output voltages of the upper and lower half-bridges of each arm and then divide by two to obtain the command value of the output voltage of the lower half-bridge of each arm; S6. Divide the output voltage of each half-bridge by the number of power units N included in each half-bridge to obtain the command value of the output voltage of each power unit; S7. Divide the output voltage of each power unit by the DC voltage of each power unit to obtain the duty cycle command value of each power unit; S8. Subtract the voltage of each power unit capacitor from the average value of the capacitor voltages of each power unit in the same arm, pass through a proportional regulator to obtain the current command for the required capacitor voltage balance, and then divide by the measured value of the current flowing through the power unit to obtain the correction value of the duty cycle command of each power unit; S9. Add the duty cycle command value of each power unit to the correction value of the duty cycle command of each power unit to obtain the modulation wave value of the pulse width modulation of the power unit Q1, take the negative value to obtain the modulation wave value of the pulse width modulation of Q2, compare with the carrier value to obtain the action signals of Q1 and Q2, invert the Q1 action signal and add a dead zone as the action signal of Q3, and invert the Q2 action signal and add a dead zone as the action signal of Q4; S10. The carrier phases of the power units in the same arm differ by π / 2N to form carrier phase-shifted multilevel modulation.

[0025] In summary, the energy storage converter control method and the energy storage converter, through the above disclosed technical structure and the control method of the energy storage converter, can further achieve an extremely wide voltage of DC 0 to 1500 volts and AC 0 to 1000 volts in a single-stage power converter and transformerless architecture. Therefore, it can meet the direct access of low-voltage AC systems with different voltage levels and provide favorable conditions for various abnormal situations such as fault ride-through, and thus adapt to the application requirements of different electrochemical energy storage batteries, and the electrochemical energy storage batteries include lithium-ion batteries, sodium-ion batteries, flow batteries, and supercapacitors.

[0026] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0027] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A energy storage converter, the energy storage converter includes a plurality of bridge arms, capacitance capacitor C1, capacitance capacitor C2, and each of the plurality of bridge arms includes an upper half bridge arm and a lower half bridge arm, and the upper half bridge arm and the lower half bridge arm both include N power units and reactors; Each of the N power units includes a fully controlled power semiconductor device Q1, a fully controlled power semiconductor device Q2, a fully controlled power semiconductor device Q3, a fully controlled power semiconductor device Q4 and a capacitance capacitor C.

2. The energy storage converter according to claim 1, wherein: The number of the plurality of bridge arms provided is three, and phase lines A, B, and C are respectively connected between the three bridge arms and the corresponding power grid.

3. The energy storage converter according to claim 1, characterized in that: The upper half bridge arm is connected between the DC positive and the AC phase line, and the lower half bridge arm is connected between the DC negative and the AC phase line.

4. An energy storage converter according to claim 1, characterized in that: The N is a natural number and N is not less than 2.

5. A power storage converter according to claim 1, characterized in that: The connection point of the fully controlled power semiconductor device Q1 and the fully controlled power semiconductor device Q3 is the external connection point T1 of the power unit; The connection point of the fully controlled power semiconductor device Q2 and the fully controlled power semiconductor device Q4 is the external connection point T2 of the power unit; The fully controlled power semiconductor device Q1 is connected between the positive electrode of the capacitor and T1, and the fully controlled power semiconductor device Q2 is connected between the positive electrode of the capacitor and T2; The fully controlled power semiconductor device Q3 is connected between the negative electrode of the capacitor and T1, and the fully controlled power semiconductor device Q4 is connected between the negative electrode of the capacitor and T2.

6. A power storage converter according to claim 1, characterized in that: The operating voltage across the capacitors of the N power units is all Uc. The DC voltage range of this energy storage converter is 0 to N•Uc, and the AC voltage range is .

7. A power storage converter according to claim 1, characterized in that: The energy storage converter is connected to a three-phase four-wire power grid and a neutral line D is led out at the connection point of the capacitance capacitor C1 and the capacitance capacitor C2.

8. A power storage converter according to claim 1, characterized in that: The energy storage converter is connected to a three-phase three-wire power grid, and it is not necessary to lead out a neutral line D at the connection point of the capacitance capacitor C1 and the capacitance capacitor C2.

9. A control method for an energy storage converter as described in any one of claims 1-8, characterized in that, It includes the following operation steps: S1. By calculating the capacitor voltages of all power units of each bridge arm, the command value of the sum of the currents of the upper and lower half bridge arms of each bridge arm is obtained; S2. The active power command and the reactive power command of each phase issued by the upper-level control unit are divided by the corresponding phase AC voltage, and then the active current command and the reactive current command of each phase are obtained. After the active current command and the reactive current command are respectively subjected to rotational coordinate transformation and added, the instantaneous value of the output current command of each phase is obtained, that is, the command value of the current difference between the upper and lower half bridge arms of each bridge arm; S3. By calculating the currents of the upper and lower half bridge arms of each bridge arm, the command value of the sum of the output voltages of the upper and lower half bridge arms of each bridge arm and the command value of the difference between the output voltages of the upper and lower half bridge arms of each bridge arm are obtained; S4. The command value of the sum of the output voltages of the upper and lower half bridge arms of each bridge arm and the command value of the difference between the output voltages of the upper and lower half bridge arms of each bridge arm are added and then divided by two to obtain the output voltage command value of the upper half bridge arm of each bridge arm; S5. The command value of the sum of the output voltages of the upper and lower half bridge arms of each bridge arm and the command value of the difference between the output voltages of the upper and lower half bridge arms of each bridge arm are subtracted and then divided by two to obtain the output voltage command value of the lower half bridge arm of each bridge arm; S6. Divide the output voltage of each half-bridge arm by the number N of power units included in each half-bridge arm to obtain the command value of the output voltage of each power unit; S7. Divide the output voltage of each power unit by the DC voltage of each power unit to obtain the duty cycle command value of each power unit; S8. Subtract the voltage of the capacitor of each power unit from the average value of the capacitor voltages of each power unit in the same arm, and through a proportional regulator, obtain the current command for the required capacitor voltage balance, and then divide it by the measured value of the current flowing through the power unit to obtain the correction value of the duty cycle command of each power unit; S9. Add the duty cycle command value of each power unit to the correction value of the duty cycle command of each power unit to obtain the modulation wave value of the pulse width modulation of Q1 of this power unit, take the negative value to obtain the modulation wave value of the pulse width modulation of Q2, and obtain the action signals of Q1 and Q2 by comparing with the carrier value. The action signal of Q1 is inverted and added with a dead zone as the action signal of Q3, and the action signal of Q2 is inverted and added with a dead zone as the action signal of Q4; S10. The carrier phases of the power units in the same arm differ by π / 2N, forming carrier phase-shifted multi-level modulation.

Images