阅读说明：本技术 一种变压器一体化多电平电池储能功率变流装置 (Transformer integrated multi-level battery energy storage power converter ) 是由 张卓凡 于 2020-12-26 设计创作，主要内容包括：本发明属于电气自动化设备领域,尤其涉及一种变压器一体化多电平电池储能功率变流装置。包括一台三绕组变压器、六台单相电压源逆变桥、一台六相交流电抗器、六台滤波电容器、两台三相取能变压器、两台三相整流桥和两台直流滤波电抗器。本装置中逆变桥输出的相电压为三电平,但省去了NPC三电平逆变器的钳位二极管,因此整体成本更低,变换效率更高。其中的六相交流电抗器可以更好的实现两台三点电压源逆变桥交流侧电流的均衡,也可以采用两台三相交流电抗器实现。三绕组变压器的原边和副边可以采用三角接或星型接线,三绕组变压器的副边也可以增加绕组数以便接入更多的逆变器及滤波电路,以实现装置容量的扩大。(The invention belongs to the field of electric automation equipment, and particularly relates to a transformer integrated multi-level battery energy storage power converter. The three-phase direct current power supply system comprises a three-winding transformer, six single-phase voltage source inverter bridges, a six-phase alternating current reactor, six filter capacitors, two three-phase energy-taking transformers, two three-phase rectifier bridges and two direct current filter reactors. The phase voltage output by the inverter bridge in the device is three-level, but a clamping diode of the NPC three-level inverter is omitted, so that the overall cost is lower, and the conversion efficiency is higher. The six-phase alternating current reactors can better realize the balance of the alternating current side currents of the two three-point voltage source inverter bridges, and can also be realized by adopting two three-phase alternating current reactors. The primary side and the secondary side of the three-winding transformer can be connected in a triangular connection or star connection mode, and the number of windings of the secondary side of the three-winding transformer can be increased so as to be connected with more inverters and filter circuits, so that the capacity of the device is expanded.)

1. A transformer integrated multi-level battery energy storage power converter is characterized by comprising a three-winding transformer T, a first single-phase voltage source inverter bridge, a second single-phase voltage source inverter bridge, a third single-phase voltage source inverter bridge, a fourth single-phase voltage source inverter bridge, a fifth single-phase voltage source inverter bridge, a sixth single-phase voltage source inverter bridge, a six-phase alternating current reactor L1, a first filter capacitor CA1, a second filter capacitor CB1, a third filter capacitor CC1, a fourth filter capacitor CA2, a fifth filter capacitor CB2, a sixth filter capacitor CC2, a first three-phase energy-taking transformer T1, a second three-phase energy-taking transformer T2, a first three-phase rectifier bridge B1, a second three-phase rectifier bridge B2, a first direct current filter reactor L2 and a second direct current filter transformer L3;

the direct current positive ends of the first single-phase voltage source inverter bridge, the second single-phase voltage source inverter bridge and the third single-phase voltage source inverter bridge are connected in parallel, the direct current positive end of the first single-phase voltage source inverter bridge is connected to the direct current positive output end of the transformer integrated multi-level battery energy storage power converter, the direct current negative ends of the first single-phase voltage source inverter bridge, the second single-phase voltage source inverter bridge and the third single-phase voltage source inverter bridge are respectively connected in parallel, and the direct current negative end of the third single-phase voltage source inverter bridge is connected to the direct current positive end of the fourth single-phase voltage source inverter bridge; the direct current negative ends of the fourth single-phase voltage source inverter bridge, the fifth single-phase voltage source inverter bridge and the sixth single-phase voltage source inverter bridge are connected in parallel, and the direct current negative end of the sixth single-phase voltage source inverter bridge is connected to the direct current negative output end of the transformer integrated multi-level battery energy storage power converter;

first alternating current output ends of the first single-phase voltage source inverter bridge, the second single-phase voltage source inverter bridge and the third single-phase voltage source inverter bridge are respectively connected to a first group of three-phase current intersection ends on the input side of a six-phase alternating current reactor L1, first alternating current output ends of the fourth single-phase voltage source inverter bridge, the fifth single-phase voltage source inverter bridge and the sixth single-phase voltage source inverter bridge are respectively connected to a second group of three-phase current intersection ends on the input side of the six-phase alternating current reactor L1, a first group of three-phase alternating current ends on the output side of the six-phase alternating current reactor L1 are respectively connected to one ends of a first filter capacitor CA1, a second filter capacitor CB1 and a third filter capacitor CC1, and a second group of three-phase alternating current ends on the output side of the six-phase alternating current reactor L1 are respectively connected to one ends of a fourth filter capacitor CA2, a fifth filter capacitor CB 68;

second alternating current output ends of the first single-phase voltage source inverter bridge, the second single-phase voltage source inverter bridge and the third single-phase voltage source inverter bridge are respectively connected to the other ends of the first filter capacitor CA1, the second filter capacitor CB1 and the third filter capacitor CC1, and second alternating current output ends of the fourth single-phase voltage source inverter bridge, the fifth single-phase voltage source inverter bridge and the sixth single-phase voltage source inverter bridge are respectively connected to the other ends of the fourth filter capacitor CA2, the fifth filter capacitor CB2 and the sixth filter capacitor CC 2; two ends of a first filter capacitor CA1, a second filter capacitor CB1 and a third filter capacitor CC1 are respectively connected to six leading-out ends of a first secondary side three-phase winding of a three-winding transformer T, two ends of a fourth filter capacitor CA2, a fifth filter capacitor CB2 and a sixth filter capacitor CC2 are respectively connected to six leading-out ends of a second secondary side three-phase winding of the three-winding transformer T, and a primary side three-phase winding leading-out end of the three-winding transformer T is connected to a power grid;

six leading-out ends of a primary side three-phase winding of the first three-phase energy-taking transformer T1 are respectively connected to first and second alternating current output ends of a first single-phase voltage source inverter bridge, a second single-phase voltage source inverter bridge and a third single-phase voltage source inverter bridge, a secondary side three-phase alternating current end of the first three-phase energy-taking transformer T1 is respectively connected to three alternating current ends of a first three-phase rectifier bridge B1, a direct current positive end of the first three-phase rectifier bridge B1 is connected to a direct current positive end of a fourth single-phase voltage source inverter bridge, a direct current negative end of the first three-phase rectifier bridge B1 is connected to one end of a first direct current filter reactor L2, and the other end of the first direct current filter reactor L2 is connected to a direct current negative end of a sixth single-phase voltage;

six leading-out ends of a primary side three-phase winding of the second three-phase energy-taking transformer T2 are respectively connected to first and second alternating-current output ends of a fourth single-phase voltage source inverter bridge, a fifth single-phase voltage source inverter bridge and a sixth single-phase voltage source inverter bridge, a secondary side three-phase alternating-current end of the second three-phase energy-taking transformer T2 is respectively connected to three alternating-current ends of a second three-phase rectifier bridge B2, a direct-current positive end of the second three-phase rectifier bridge B2 is connected to one end of a second direct-current filter reactor L3, the other end of the second direct-current filter reactor L3 is connected to the direct-current positive end of the first single-phase voltage source inverter bridge, and a direct-current negative end of the second three-phase rectifier bridge B2 is connected to the direct-current negative end;

the direct-current voltages of the first single-phase voltage source inverter bridge, the second single-phase voltage source inverter bridge and the third single-phase voltage source inverter bridge are respectively sampled by the power converter controller, and form feedback control to adjust active power at the alternating-current side of each inverter bridge, so that the direct-current voltages of the two inverter bridges are kept balanced, and the safe operation of power devices of the inverter bridges is ensured.

Technical Field

The invention belongs to the field of electric automation equipment, and particularly relates to a transformer integrated multi-level battery energy storage power converter.

Background

For a battery energy storage device with a direct-current voltage of 1500V, a 1200V IGBT device and a neutral-point voltage clamp (NPC) three-level inverter are generally adopted for realizing the switching frequency of a power device of about 5 kHz. For a high-capacity (more than 1 MW) battery energy storage device, as a power grid of more than 10kV needs to be accessed, one half of the battery energy storage power conversion device is connected to the power grid through a transformer in a boosting mode. The NPC three-level inverter adopts the clamping diode or the clamping IGBT branch circuit to realize three-level phase voltage output, so that the cost and the loss of the inverter are increased. When the transformer is adopted to boost voltage and is connected to a power grid, the three-level phase voltage output of the inverter can be realized by utilizing the wiring mode of the transformer winding. Therefore, the transformer integrated multi-level battery energy storage power converter with lower cost and higher efficiency has important economic significance.

Disclosure of Invention

The invention aims to provide a transformer integrated multi-level battery energy storage power converter, which overcomes the defects of the prior art, reduces the cost of the power converter and improves the power conversion efficiency.

The invention provides a transformer integrated multi-level battery energy storage power converter, which comprises a three-winding transformer T, a first single-phase voltage source inverter bridge, a second single-phase voltage source inverter bridge, a third single-phase voltage source inverter bridge, a fourth single-phase voltage source inverter bridge, a fifth single-phase voltage source inverter bridge, a sixth single-phase voltage source inverter bridge, a six-phase alternating current reactor L1, a first filter capacitor CA1, a second filter capacitor CB1, a third filter capacitor CC1, a fourth filter capacitor CA2, a fifth filter capacitor CB2, a sixth filter capacitor CC2, a first three-phase energy-taking transformer T1, a second three-phase energy-taking transformer T2, a first three-phase rectifier bridge B1, a second three-phase rectifier bridge B2, a first direct current filter reactor L2 and a second direct current filter L3;

the direct current positive ends of the first single-phase voltage source inverter bridge, the second single-phase voltage source inverter bridge and the third single-phase voltage source inverter bridge are connected in parallel, the direct current positive end of the first single-phase voltage source inverter bridge is connected to the direct current positive output end of the transformer integrated multi-level battery energy storage power converter, the direct current negative ends of the first single-phase voltage source inverter bridge, the second single-phase voltage source inverter bridge and the third single-phase voltage source inverter bridge are respectively connected in parallel, and the direct current negative end of the third single-phase voltage source inverter bridge is connected to the direct current positive end of the fourth single-phase voltage source inverter bridge; the direct current negative ends of the fourth single-phase voltage source inverter bridge, the fifth single-phase voltage source inverter bridge and the sixth single-phase voltage source inverter bridge are connected in parallel, and the direct current negative end of the sixth single-phase voltage source inverter bridge is connected to the direct current negative output end of the transformer integrated multi-level battery energy storage power converter;

first alternating current output ends of the first single-phase voltage source inverter bridge, the second single-phase voltage source inverter bridge and the third single-phase voltage source inverter bridge are respectively connected to a first group of three-phase current intersection ends on the input side of a six-phase alternating current reactor L1, first alternating current output ends of the fourth single-phase voltage source inverter bridge, the fifth single-phase voltage source inverter bridge and the sixth single-phase voltage source inverter bridge are respectively connected to a second group of three-phase current intersection ends on the input side of the six-phase alternating current reactor L1, a first group of three-phase alternating current ends on the output side of the six-phase alternating current reactor L1 are respectively connected to one ends of a first filter capacitor CA1, a second filter capacitor CB1 and a third filter capacitor CC1, and a second group of three-phase alternating current ends on the output side of the six-phase alternating current reactor L1 are respectively connected to one ends of a fourth filter capacitor CA2, a fifth filter capacitor CB 68;

second alternating current output ends of the first single-phase voltage source inverter bridge, the second single-phase voltage source inverter bridge and the third single-phase voltage source inverter bridge are respectively connected to the other ends of the first filter capacitor CA1, the second filter capacitor CB1 and the third filter capacitor CC1, and second alternating current output ends of the fourth single-phase voltage source inverter bridge, the fifth single-phase voltage source inverter bridge and the sixth single-phase voltage source inverter bridge are respectively connected to the other ends of the fourth filter capacitor CA2, the fifth filter capacitor CB2 and the sixth filter capacitor CC 2; two ends of a first filter capacitor CA1, a second filter capacitor CB1 and a third filter capacitor CC1 are respectively connected to six leading-out ends of a first secondary side three-phase winding of a three-winding transformer T, two ends of a fourth filter capacitor CA2, a fifth filter capacitor CB2 and a sixth filter capacitor CC2 are respectively connected to six leading-out ends of a second secondary side three-phase winding of the three-winding transformer T, and a primary side three-phase winding leading-out end of the three-winding transformer T is connected to a power grid;

six leading-out ends of a primary side three-phase winding of the first three-phase energy-taking transformer T1 are respectively connected to first and second alternating current output ends of a first single-phase voltage source inverter bridge, a second single-phase voltage source inverter bridge and a third single-phase voltage source inverter bridge, a secondary side three-phase alternating current end of the first three-phase energy-taking transformer T1 is respectively connected to three alternating current ends of a first three-phase rectifier bridge B1, a direct current positive end of the first three-phase rectifier bridge B1 is connected to a direct current positive end of a fourth single-phase voltage source inverter bridge, a direct current negative end of the first three-phase rectifier bridge B1 is connected to one end of a first direct current filter reactor L2, and the other end of the first direct current filter reactor L2 is connected to a direct current negative end of a sixth single-phase voltage;

six leading-out ends of a primary side three-phase winding of the second three-phase energy-taking transformer T2 are respectively connected to first and second alternating-current output ends of a fourth single-phase voltage source inverter bridge, a fifth single-phase voltage source inverter bridge and a sixth single-phase voltage source inverter bridge, a secondary side three-phase alternating-current end of the second three-phase energy-taking transformer T2 is respectively connected to three alternating-current ends of a second three-phase rectifier bridge B2, a direct-current positive end of the second three-phase rectifier bridge B2 is connected to one end of a second direct-current filter reactor L3, the other end of the second direct-current filter reactor L3 is connected to the direct-current positive end of the first single-phase voltage source inverter bridge, and a direct-current negative end of the second three-phase rectifier bridge B2 is connected to the direct-current negative end;

the direct-current voltages of the first single-phase voltage source inverter bridge, the second single-phase voltage source inverter bridge and the third single-phase voltage source inverter bridge are respectively sampled by the power converter controller, and form feedback control to adjust active power at the alternating-current side of each inverter bridge, so that the direct-current voltages of the two inverter bridges are kept balanced, and the safe operation of power devices of the inverter bridges is ensured.

The invention provides a transformer integrated multilevel battery energy storage power converter, which has the advantages that:

compared with the existing power converter device based on the parallel connection of a three-phase two-level or NPC three-level inverter, the transformer integrated multi-level battery energy storage power converter device has the advantages that the phase voltage output by the inverter bridge is also three-level, but a clamping diode of the NPC three-level inverter is omitted, so that the overall cost of the battery energy storage power converter device is lower, and the conversion efficiency is higher. The six-phase alternating current reactor can better realize the balance of the alternating current side currents of the two three-point voltage source inverter bridges, and the six-phase alternating current reactor can also be realized by adopting two three-phase alternating current reactors. The primary side and the secondary side of the three-winding transformer can be connected in a triangular connection or star connection mode, and the number of windings of the secondary side of the three-winding transformer can be increased so as to be connected with more inverters and filter circuits, so that the capacity of the device is expanded.

Drawings

Fig. 1 is a schematic circuit diagram of a transformer-integrated multilevel battery energy storage power converter device according to the present invention.

Fig. 2 is a schematic circuit diagram of a single-phase voltage source inverter bridge in the transformer integrated multilevel battery energy storage power converter.

Detailed Description

The transformer integrated multi-level battery energy storage power converter provided by the invention is shown in a circuit schematic diagram of fig. 1 and comprises a three-winding transformer T, a first single-phase voltage source inverter bridge, a second single-phase voltage source inverter bridge, a third single-phase voltage source inverter bridge, a fourth single-phase voltage source inverter bridge, a fifth single-phase voltage source inverter bridge, a sixth single-phase voltage source inverter bridge, a six-phase alternating current reactor L1, a first filter capacitor CA1, a second filter capacitor CB1, a third filter capacitor CC1, a fourth filter capacitor CA2, a fifth filter capacitor CB2, a sixth filter capacitor CC2, a first three-phase energy-taking transformer T1, a second three-phase energy-taking transformer T2, a first three-phase rectifier bridge B1, a second three-phase rectifier bridge B2, a first direct current filter L2 and a second direct current filter reactor L3;

the direct current positive ends of the first single-phase voltage source inverter bridge, the second single-phase voltage source inverter bridge and the third single-phase voltage source inverter bridge are connected in parallel, the direct current positive end of the first single-phase voltage source inverter bridge is connected to the direct current positive output end of the transformer integrated multi-level battery energy storage power converter, the direct current negative ends of the first single-phase voltage source inverter bridge, the second single-phase voltage source inverter bridge and the third single-phase voltage source inverter bridge are respectively connected in parallel, and the direct current negative end of the third single-phase voltage source inverter bridge is connected to the direct current positive end of the fourth single-phase voltage source inverter bridge; the direct current negative ends of the fourth single-phase voltage source inverter bridge, the fifth single-phase voltage source inverter bridge and the sixth single-phase voltage source inverter bridge are connected in parallel, and the direct current negative end of the sixth single-phase voltage source inverter bridge is connected to the direct current negative output end of the transformer integrated multi-level battery energy storage power converter;

first alternating current output ends of the first single-phase voltage source inverter bridge, the second single-phase voltage source inverter bridge and the third single-phase voltage source inverter bridge are respectively connected to a first group of three-phase current intersection ends on the input side of a six-phase alternating current reactor L1, first alternating current output ends of the fourth single-phase voltage source inverter bridge, the fifth single-phase voltage source inverter bridge and the sixth single-phase voltage source inverter bridge are respectively connected to a second group of three-phase current intersection ends on the input side of the six-phase alternating current reactor L1, a first group of three-phase alternating current ends on the output side of the six-phase alternating current reactor L1 are respectively connected to one ends of a first filter capacitor CA1, a second filter capacitor CB1 and a third filter capacitor CC1, and a second group of three-phase alternating current ends on the output side of the six-phase alternating current reactor L1 are respectively connected to one ends of a fourth filter capacitor CA2, a fifth filter capacitor CB 68;

second alternating current output ends of the first single-phase voltage source inverter bridge, the second single-phase voltage source inverter bridge and the third single-phase voltage source inverter bridge are respectively connected to the other ends of the first filter capacitor CA1, the second filter capacitor CB1 and the third filter capacitor CC1, and second alternating current output ends of the fourth single-phase voltage source inverter bridge, the fifth single-phase voltage source inverter bridge and the sixth single-phase voltage source inverter bridge are respectively connected to the other ends of the fourth filter capacitor CA2, the fifth filter capacitor CB2 and the sixth filter capacitor CC 2; two ends of a first filter capacitor CA1, a second filter capacitor CB1 and a third filter capacitor CC1 are respectively connected to six leading-out ends of a first secondary side three-phase winding of a three-winding transformer T, two ends of a fourth filter capacitor CA2, a fifth filter capacitor CB2 and a sixth filter capacitor CC2 are respectively connected to six leading-out ends of a second secondary side three-phase winding of the three-winding transformer T, and a primary side three-phase winding leading-out end of the three-winding transformer T is connected to a power grid;

six leading-out ends of a primary side three-phase winding of the first three-phase energy-taking transformer T1 are respectively connected to first and second alternating current output ends of a first single-phase voltage source inverter bridge, a second single-phase voltage source inverter bridge and a third single-phase voltage source inverter bridge, a secondary side three-phase alternating current end of the first three-phase energy-taking transformer T1 is respectively connected to three alternating current ends of a first three-phase rectifier bridge B1, a direct current positive end of the first three-phase rectifier bridge B1 is connected to a direct current positive end of a fourth single-phase voltage source inverter bridge, a direct current negative end of the first three-phase rectifier bridge B1 is connected to one end of a first direct current filter reactor L2, and the other end of the first direct current filter reactor L2 is connected to a direct current negative end of a sixth single-phase voltage;

six leading-out ends of a primary side three-phase winding of the second three-phase energy-taking transformer T2 are respectively connected to first and second alternating-current output ends of a fourth single-phase voltage source inverter bridge, a fifth single-phase voltage source inverter bridge and a sixth single-phase voltage source inverter bridge, a secondary side three-phase alternating-current end of the second three-phase energy-taking transformer T2 is respectively connected to three alternating-current ends of a second three-phase rectifier bridge B2, a direct-current positive end of the second three-phase rectifier bridge B2 is connected to one end of a second direct-current filter reactor L3, the other end of the second direct-current filter reactor L3 is connected to a direct-current positive end of the first single-phase voltage source inverter bridge, and a direct-current negative end of the second three-phase rectifier bridge B2 is connected to a direct-current negative end.

The transformer integrated multi-level battery energy storage power converter can adopt a conventional single-phase two-level voltage source inverter bridge, the circuit schematic diagram of which is shown in figure 2, and can also adopt a conventional single-phase NPC three-level voltage source inverter bridge. In practical application, in order to enlarge the capacity of the power converter, the single-phase two-level voltage source inverter bridge or the single-phase NPC three-level voltage source inverter bridge can also operate in a mode that a plurality of direct current sides are directly connected in parallel with alternating current sides and connected in parallel through reactors.

The working principle of the transformer integrated multilevel battery energy storage power converter is as follows: the positive end and the negative end of the energy storage battery pack are respectively connected to a direct current positive output positive end DC + and a direct current negative output end DC-of the transformer integrated multi-level battery energy storage power converter. The direct current sides of the first/second/third single-phase voltage source inverter bridge and the fourth/fifth/sixth single-phase voltage source inverter bridge form a series connection relation to adapt to higher direct current voltage of the energy storage battery, and the alternating current output ends are respectively connected to the secondary low-voltage winding of the three-winding transformer after being filtered by a filter consisting of L1 and CA1/CB1/CC1/CA2/CB2/CC2, so that isolation of the alternating current sides of the two groups of three single-phase voltage source inverter bridges is formed. When the power converter is in a charging operation mode, the first/second/third single-phase voltage source inverter bridge and the fourth/fifth/sixth single-phase voltage source inverter bridge are controlled by the power converter controller, so that active power flows from the source side to the secondary side of the three-winding transformer, is converted into direct current through the first/second/third single-phase voltage source inverter bridge and the fourth/fifth/sixth single-phase voltage source inverter bridge, and flows to two groups of energy storage batteries, and the batteries are charged; when the device is in a discharging operation mode, the first/second/third single-phase voltage source inverter bridge and the fourth/fifth/sixth single-phase voltage source inverter bridge are controlled by the power converter controller, so that active power flows from the two groups of energy storage batteries to the first/second/third single-phase voltage source inverter bridge and the fourth/fifth/sixth single-phase voltage source inverter bridge, is converted into alternating current, flows to the three-winding transformer and finally flows to an alternating current power supply on the source side of the three-winding transformer, and discharging of the batteries is achieved. In order to reduce harmonic current flowing to the transformer power grid side by the first/second/third single-phase voltage source inverter bridge and the fourth/fifth/sixth single-phase voltage source inverter bridge, the carrier phase shift mode can be adopted for PWM control pulses of the first/second/third single-phase voltage source inverter bridge and the fourth/fifth/sixth single-phase voltage source inverter bridge.

The direct-current voltages of the first/second/third single-phase voltage source inverter bridge and the fourth/fifth/sixth single-phase voltage source inverter bridge are respectively sampled by the power converter controller, and form feedback control to adjust the active power of the alternating-current side of each inverter bridge, so that the direct-current voltages of the two inverter bridges are kept balanced, and the safe operation of power devices of the inverter bridges is ensured. The energy-taking transformer T1/T2, the three-phase rectifier bridge B1/B2 and the direct-current filter reactor L2/L3 form a direct-current voltage balance auxiliary control circuit, and the principle is as follows: when the direct-current voltage of the first/second/third single-phase voltage source inverter bridge is higher, the amplitude of the output alternating-current voltage is also higher, the direct-current voltage is isolated by T1 and rectified by B1, and then the direct-current side of the fourth/fifth/sixth single-phase voltage source inverter bridge is charged through L2, so that the direct-current voltage of the fourth/fifth/sixth single-phase voltage source inverter bridge is increased until the direct-current voltage is as high as the direct-current voltage of the first/second/third single-phase voltage source inverter bridge, and then the charging is stopped, and therefore the balance control of the direct-current voltages of the two inverter bridges is realized.

In the transformer integrated multi-level battery energy storage power converter, the six-phase alternating current reactors can better realize the balance of the alternating current side currents of the two three-point voltage source inverter bridges, and the six-phase alternating current reactors can also be realized by adopting two three-phase alternating current reactors. The primary side and the secondary side of the three-winding transformer can be connected in a triangular connection or star connection mode, and the number of windings of the secondary side of the three-winding transformer can be increased so as to be connected with more inverters and filter circuits, so that the capacity of the device is expanded.

Any equivalent transformation circuit based on the circuit of the present invention is within the protection scope of the present invention.