Three-phase voltage equalization treatment circuit

Abstract

The utility model discloses a three-phase voltage balance treatment circuit, which belongs to the field of power transmission and comprises an ACDC (alternating current direct current) module, a DCAC (direct current alternating current) module, a bypass unit and a coupling transformer which are arranged between a power grid and a load, and a circuit main path and a circuit bypass are arranged between the power grid and the load; the circuit main circuit is electrically connected with an ACDC module, a DCAC module, a bypass unit and a coupling transformer in sequence, the ACDC module is used for rectifying unbalanced alternating current into direct current, the DCAC module is used for outputting required compensation voltage, the coupling transformer is used for adjusting an output voltage value, and the bypass unit is used for keeping equipment in a standby state when the voltage of a power grid is normal. The ACDC module and the DCAC module carry out flexible control and bidirectional adjustment on voltage needing to be compensated, output voltage is flexibly set, the adjustment range is large, inversion output voltage is coupled to a system side through the coupling transformer, and after the inversion output voltage is superposed with system voltage, the purpose of voltage compensation is achieved, and three-phase voltage balance is achieved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to electric power transportation technical field, concretely relates to a three -phase voltage equalization management circuit. BACKGROUND

[0002] Three -phase voltage, as the core element in polyphase alternating -current circuit, refers to the voltage difference between the phase conductor and the system neutral conductor at a specific point. However, in actual operation, three -phase voltage often appears unbalanced phenomenon, this is mainly the result of the interweaving action of multiple complex factors. The uneven distribution of power system load leads to significant differences in each phase current; the mismatch of equipment parameters makes the response of each phase voltage inconsistent; the fluctuation of power supply voltage further aggravates the instability of voltage; in addition to the sudden conditions such as wire structure fault, power equipment aging or damage, broken wire and grounding fault, all of which can cause three -phase voltage imbalance. In addition, the resonance phenomenon, unreasonable three -phase load distribution and the dynamic change of power load are also important factors leading to voltage imbalance.

[0003] The harm caused by three -phase voltage imbalance cannot be underestimated. It will first directly affect the normal operation of electrical equipment, shorten the service life of equipment, because the electrical equipment subjected to unbalanced voltage for a long time is more vulnerable. At the same time, unbalanced voltage distribution will lead to the decrease of power factor, the increase of power consumption, causing unnecessary energy waste. More seriously, voltage imbalance may cause equipment overload and overheating, increase the risk of equipment failure, and even cause equipment damage. In addition, the increase of voltage fluctuation and line loss will not only reduce the overall efficiency of power system, but also affect the power supply quality, make the load distribution more unbalanced, and the system performance becomes unstable. CONTENT OF THE UTILITY MODEL

[0004] The utility model aims at providing a three -phase voltage equalization management circuit to solve the problem of three -phase voltage imbalance.

[0005] In order to achieve the above purpose, the utility model provides the following technical scheme: a three -phase voltage equalization management circuit, including the ACDC module, DCAC module, bypass unit and coupling transformer arranged between the power grid and load, circuit main road and circuit bypass are arranged between the power grid and load;

[0006] The ACDC module, DCAC module, bypass unit and coupling transformer are electrically connected in sequence on the circuit main road, the ACDC module is used for rectifying unbalanced alternating current into direct current, the DCAC is used for outputting required compensation voltage, the coupling transformer adjusts the output voltage value, and the bypass unit is used for keeping the equipment in standby state when the power grid voltage is normal.

[0007] Further, an AC contactor KM1 is arranged on the circuit bypass.

[0008] Further, the circuit main road and ACDC module are provided with a circuit breaker QF2, and the DCAC module and the circuit bypass are provided with an AC contactor KM2.

[0009] Further, the ACDC module comprises three groups of IGBT tube groups and capacitor groups, and the three groups of IGBT tube groups and capacitor groups are connected in parallel.

[0010] Further, each group of IGBT tube groups is sequentially connected in series from top to bottom by a first IGBT tube, a second IGBT tube, a third IGBT tube and a fourth IGBT tube, and the first IGBT tube and the second IGBT tube and the third IGBT tube and the fourth IGBT tube are connected by a diode N1 line, and the capacitor group comprises two first capacitors, and the two first capacitors are connected by a N1 line.

[0011] Further, the second IGBT tube and the third IGBT tube in the three groups of IGBT tube groups are respectively connected by two inductors A1, B1, C1 lines, and the second capacitor is connected with the N1 line in the middle of the two inductors on the A1, B1, C1 line.

[0012] Further, the DCAC module circuit is connected with the ACDC module circuit by a symmetrical circuit A2, B2, C2, N1 line.

[0013] Further, the bypass unit comprises three groups of thyristors, and the left ends of the three groups of thyristors are respectively connected with A2, B2, C2 lines, and the right ends of the three groups of thyristors are connected with N1 lines.

[0014] Further, the bypass unit further comprises three short-circuit switches for short-circuiting the three groups of thyristors.

[0015] Compared with the prior art, the utility model has the advantages of:

[0016] The three-phase voltage equalization treatment circuit flexibly controls the voltage to be compensated by the ACDC module and the DCAC module, bidirectionally adjusts, flexibly sets the output voltage, has a large adjustment range, and the inverter output voltage is coupled to the system side through a coupling transformer, is superposed with the system voltage, and reaches the purpose of compensating the voltage; that is, only the difference part needs to be compensated, the minimum compensation power is realized, and the three-phase voltage is balanced.

[0017] The three-phase voltage equalization treatment circuit has two working modes of main road operation and bypass operation, automatically switches to bypass operation when the grid voltage is normal, the ACDC module and the DCAC module stop running, and enters a standby state, at this time, the grid voltage directly supplies the load through the coupling transformer, and at this time, the minimum overall working loss is realized. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Figure is a three-phase voltage equalization management circuit system diagram;

[0019] Figure 2 Figure is a three-phase voltage equalization management circuit diagram;

[0020] Figure 3 Figure is Figure 2 Figure is an ACDC module circuit diagram;

[0021] Figure 4 Figure is Figure 2 Figure is a bypass unit circuit diagram.

[0022] In the figure: 10, ACDC module;110, first IGBT tube;120, second IGBT tube;130, third IGBT tube;140, fourth IGBT tube;150, diode;160, inductance;170, second capacitor;180, first capacitor;20, DCAC module;30, bypass unit;310, thyristor;320, short-circuit switch;40, coupling transformer;510, circuit main road;520, circuit bypass. DETAILED DESCRIPTION

[0023] The utility model will be further described below in combination with examples.

[0024] The following examples are used to illustrate the utility model, but cannot be used to limit the protection scope of the utility model. The conditions in the examples can be further adjusted according to specific conditions, and simple improvement of the method of the utility model under the concept of the utility model belongs to the range of the utility model required to protect.

[0025] Please refer to Figure 1 The utility model provides a three-phase voltage equalization management circuit, including ACDC module 10, DCAC module 20, bypass unit 30 and coupling transformer 40, and circuit main road 510 and circuit bypass 520 are arranged between power grid and load.

[0026] The alternating current contactor KM1 is arranged on the circuit bypass 520;When A, B, C three-phase voltage is equal, by alternating current contactor KM1 intercommunication, so that power grid is powered for load through circuit bypass 520.

[0027] ACDC module 10, DCAC module 20, bypass unit 30 and coupling transformer 40 are sequentially electrically connected on the circuit main road 510 circuit, and the circuit breaker QF2 is arranged between the circuit main road 510 and ACDC module 10, and the alternating current contactor KM2 is arranged between DCAC module 20 and circuit bypass 520.

[0028] In the three-phase voltage equalization management circuit, when the three-phase voltage of the power grid A, B and C is unbalanced, the circuit starts. First, the ACDC module 10 rectifies the unbalanced alternating current into direct current, and ensures the stability of the direct current voltage through the stable direct current bus capacitor. Then, the DCAC module 20 as the inverter side outputs the required compensation voltage according to the real-time deviation of the three-phase voltage, realizes the accurate control of the voltage. The adjusted voltage is further adjusted through the coupling transformer 40 to output the voltage value, so as to achieve the purpose of partial power compensation and ensure the stable transmission of the voltage. When the grid voltage is in a normal balanced state, the bypass unit 30 plays a role, and the main circuit 510 (including ACDC, DCAC and coupling transformer) of the circuit remains in standby state, so as to improve the overall efficiency and reliability of the circuit.

[0029] The ACDC module 10 includes three groups of IGBT tube groups and capacitor groups, and the three groups of IGBT tube groups and capacitor groups are arranged in parallel. Each group of IGBT tube groups is sequentially arranged from top to bottom by the first IGBT tube 110, the second IGBT tube 120, the third IGBT tube 130 and the fourth IGBT tube 140. The first IGBT tube 110 and the second IGBT tube 120 are electrically connected to the N1 line through the diode 150, and the capacitor group includes two first capacitors 180, and the two first capacitors 180 are electrically connected to the N1 line.

[0030] The second IGBT tube 120 and the third IGBT tube 130 in the three groups of IGBT tube groups are respectively electrically connected to the A1, B1 and C1 lines through two inductors 160, and the two inductors 160 are respectively connected to the N1 line through the second capacitor 170. The existence of the inductor 160 can smooth the current waveform and reduce the generation of harmonics, and also limits the current variation rate to a certain extent, thereby protecting the IGBT tube. The second capacitor 170 is used to filter high-frequency noise on the power line and maintain the stability of the power line. At the same time, together with the inductor 160, it forms a filter circuit to further smooth the current waveform.

[0031] The DCAC module 20 circuit is symmetrically connected to the A2, B2, C2 and N1 lines with the ACDC module 10 circuit.

[0032] The bypass unit 30 includes three groups of thyristors 310, and the left ends of the three groups of thyristors 310 are respectively electrically connected to the A2, B2 and C2 lines. The right ends of the three groups of thyristors 310 are all electrically connected to the N1 line. The bypass unit 30 further includes three short-circuit switches 320 for short-circuiting the three groups of thyristors 310.

[0033] The use principle of the present application: in the three-phase voltage balance management circuit, when the three-phase voltage of the power grid A, B and C is unbalanced, the circuit starts, first, the ACDC module 10 rectifies the unbalanced alternating current into direct current, and ensures the stability of the direct current voltage through the stable direct current bus capacitor. Then, the DCAC module 20 as the inverter side, according to the real-time deviation of the three-phase voltage, outputs the required compensation voltage, realizes the accurate control of the voltage. The adjusted voltage is further adjusted through the coupling transformer to output the voltage value, so as to achieve the purpose of partial power compensation and ensure the stable transmission of the voltage.

[0034] Suppose that the three-phase voltages A, B and C are 90V, 100V and 110V respectively, the three-phase voltage balance is 100V, the A-phase outputs the positive compensation voltage, the C-phase outputs the negative compensation voltage, and the three-phase voltage is finally balanced to 100V through the accurate adjustment of the coupling transformer, so as to guarantee the stable and safe operation of the power grid.

[0035] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and modifications can be made to these embodiments without departing from the principles and spirits of the present application, the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A three-phase voltage equalization governing circuit, characterized by: The application relates to an AC-DC module, a DC-AC module, a bypass unit and a coupling transformer arranged between an AC power grid and a load, and a main circuit and a bypass circuit arranged between the AC power grid and the load. The AC-DC module is used for rectifying unbalanced AC power into DC power, the DC-AC module is used for outputting required compensation voltage, the coupling transformer is used for adjusting the output voltage value, and the bypass unit is used for keeping the device in a standby state when the AC power grid voltage is normal. The AC-DC module comprises three groups of IGBT tubes and a capacitor group, the three groups of IGBT tubes and the capacitor group are arranged in parallel, the DC-AC module circuit is symmetrically connected with the A2, B2, C2 and N1 lines of the AC-DC module circuit, the bypass unit comprises three groups of thyristors, the left ends of the three groups of thyristors are respectively connected with the A2, B2 and C2 lines, the right ends of the three groups of thyristors are all connected with the N1 line, and the bypass unit further comprises three short-circuit switches used for respectively short-circuiting the three groups of thyristors. An AC contactor KM1 is arranged on the bypass circuit.

2. A three-phase voltage equalization governing circuit according to claim 1, characterized in that: A circuit breaker QF2 is arranged between the main circuit and the AC-DC module, and an AC contactor KM2 is arranged between the DC-AC module and the bypass circuit.

3. A three-phase voltage equalization governing circuit according to claim 1, characterized in that: Each group of IGBT tubes comprises a first IGBT tube, a second IGBT tube, a third IGBT tube and a fourth IGBT tube arranged in series from top to bottom, the first IGBT tube and the second IGBT tube and the third IGBT tube and the fourth IGBT tube are all connected with the N1 line through diodes, and the capacitor group comprises two first capacitors connected with the N1 line.

4. A three-phase voltage equalization governing circuit according to claim 3, characterized in that: The second IGBT tube and the third IGBT tube of each group of IGBT tubes are respectively connected with the A1, B1 and C1 lines through two inductors, and the two inductors are respectively connected with the N1 line through second capacitors.

5. A three-phase voltage equalization governing circuit according to claim 4, characterized in that: ​

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