One-driving-five-power frequency conversion undisturbed switching device of cascaded high-voltage frequency converter

Abstract

The utility model relates to a cascade type high-voltage frequency converter one-driving-five-power frequency conversion undisturbed switching device, which comprises an alternating current bus, six high-voltage switch cabinets, frequency converters, motors M1-M5 and contactors, and circuit breakers QF01 and 1QF-5QF are arranged in the six high-voltage switch cabinets; the output end of the QF01 is connected to the input end of the frequency converter through the KM1, and the output end of the frequency converter is connected to the power input end of the M1 through the KM0 and the KM2 in sequence. Power supplies of the motors M1-M5 are respectively connected to an alternating current power grid through 1QF-5QF; and the power supplies of the motors M2-M5 are respectively connected to a connecting line between the normally open contact of the KM0 and the normally open contact of the relay KM2 through the contactors KM3-KM6. The one-driving-five-power frequency conversion undisturbed switching device not only can realize frequency conversion control of the motors, but also can realize conversion from frequency conversion to power frequency, and five motors use one frequency converter, so that the utilization efficiency of the frequency converter is improved, and the cost of a multi-motor frequency conversion control device is reduced.

Description

Technical Field

[0001] The utility model relates to an industrial frequency conversion disturbance-free switching device, and more specifically, to a cascade type one-to-five industrial frequency conversion disturbance-free switching device. Background Art

[0002] At present, the conventional models in the high-voltage inverter market are one-to-one or one-to-two models, or ordinary variable frequency soft start models. However, there are often situations on site where multiple motors need to be operated. It is necessary not only to control the motor variable frequency starting, but also to control the motor to stop or slow down under the variable frequency state to ensure system stability. In addition, there is currently a lack of relevant one-to-multiple variable frequency control methods, and inverter resources cannot be fully utilized.

[0003] It can be seen that the existing high-voltage inverter models are often limited in their applicability to field applications. They are unable to handle the frequency conversion operation of multiple motors, and the motor driving sequence is strictly restricted. They are also unable to quickly and effectively handle special field situations, resulting in a waste of inverter resources. To address these issues and ensure stable operation of field equipment, this paper proposes a cascaded high-voltage inverter with one-to-five motors, non-disruptive frequency conversion switching device. Summary of the Invention

[0004] In order to overcome the disadvantages of the above technical problems, the utility model provides a cascade-type high-voltage frequency converter one-to-five-worker frequency conversion disturbance-free switching device.

[0005] The utility model discloses a cascaded high-voltage frequency converter with one-to-five working frequency conversion and disturbance-free switching device, comprising an AC bus, a high-voltage switchgear, a frequency converter, a motor, and a contactor. The input terminal of the high-voltage switchgear is connected to the AC bus, and a circuit breaker is provided in the high-voltage switchgear. The utility model is characterized in that: the number of the motors is 5, the number of the high-voltage switchgear is 6, the five motors are M1, M2, M3, M4, and M5, and the six high-voltage switchgears are respectively provided with circuit breakers QF01, 1QF, 2QF, 3QF, 4QF, and 5QF; the output terminal of the circuit breaker QF01 is connected to the input terminal of the frequency converter via the normally open point of the contactor KM1, and the output terminal of the frequency converter is connected to the power input terminal of the motor M1 via the normally open point of the contactor KM0 and the normally open point of KM2 in sequence;

[0006] The power input terminals of motors M1, M2, M3, M4 and M5 are connected to the AC power grid via circuit breakers 1QF, 2QF, 3QF, 4QF and 5QF respectively; the power input terminals of motors M2, M3, M4 and M5 are connected to the line between the normally open point of relay KM0 and the normally open point of relay KM2 via the normally open points of contactors KM3, KM4, KM5 and KM6 respectively.

[0007] The utility model discloses a cascaded high-voltage frequency converter with one-to-five working frequency conversion disturbance-free switching device. A manual isolating knife QS1 is connected in series between the output end of the circuit breaker QF01 and the normally open point of the contactor KM1. Manual isolating knives QS2, QS3, QS4, QS5 and QS6 are connected in series between the normally open point of the contactor KM0 and the normally open points of the contactors KM2, KM3, KM4, KM5 and KM6, respectively.

[0008] The utility model discloses a cascade type high voltage frequency converter one-to-five-worker frequency conversion disturbance-free switching device, which comprises a reactor connected in parallel with the normally open point of the contactor KM0.

[0009] The utility model discloses a cascaded high-voltage frequency converter with one-to-five working frequency conversion and disturbance-free switching device. The frequency converter is composed of a phase-shifting transformer and a power unit. The input end of the phase-shifting transformer forms the input end of the frequency converter, the output end of the phase-shifting transformer is connected to the input end of the power unit, and the output end of the power unit forms the output end of the frequency converter.

[0010] The utility model discloses a cascaded high-voltage frequency converter with one-to-five frequency conversion and disturbance-free switching device. The input end of the phase-shifting transformer is provided with a current transformer TA1, and the output end of the power unit is provided with current transformers TA2 and TA3.

[0011] The beneficial effects of the present invention are as follows: the cascaded high-voltage frequency converter one-to-five industrial frequency conversion disturbance-free switching device of the present invention is provided with an AC bus, a frequency converter, five motors (M1-M5) and six high-voltage switch cabinets, each of which is provided with a circuit breaker (QF01, 1QF-5QF). The AC bus supplies power to the five motors via contactor KM1, the frequency converter, and contactor KM0, and contactors KM2-KM6 are respectively provided on the power input terminals of the five motors. In this way, after the frequency converter draws power from the AC power grid, it can control the corresponding motor to perform variable-frequency starting, variable-frequency deceleration or variable-frequency shutdown by closing the contactor on the power input terminal of a motor. At the same time, the power input terminals of the five motors are also connected to the AC power grid via the five circuit breakers 1QF-5QF. After the motor variable-frequency starting is completed, phase locking is performed to switch the motor to industrial frequency operation. It can be seen that the cascaded high-voltage inverter one-to-five industrial frequency conversion disturbance-free switching device of the utility model can not only realize the variable frequency starting, deceleration or shutdown of the motor, but also realize the conversion from variable frequency to industrial frequency. Moreover, since five motors use one inverter, the utilization efficiency of the inverter is improved and the cost of the multi-motor frequency conversion control device is reduced.

[0012] Furthermore, a manual isolating knife QS1 is provided between the circuit breaker QF01 and the contactor KM1 bracket, and manual isolating knives QS2, QS3, QS4, QS5, and QS6 are respectively provided between the contactor KM0 and the contactors KM2, KM3, KM4, KM5, and KM6. In this way, by disconnecting the corresponding manual isolating knife, the inverter and the motor can be cut off from the power supply circuit, so as to facilitate the inspection, repair and maintenance of the inverter and the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a circuit schematic diagram of a cascaded high-voltage inverter one-to-five-worker frequency conversion disturbance-free switching device of the utility model.

[0014] In the figure: 1 AC bus, 2 inverter, 3 motor, 4 high-voltage switchgear, 5 phase-shifting transformer, 6 power unit, 7 reactor; KM0, KM1, KM2, KM3, KM4, KM5, KM6 are all contactors, QS1, QS2, QS3, QS4, QS5, QS6 are all manual isolating switches, QF01, 1QF, 2QF, 3QF, 4QF, 5QF are all circuit breakers, M1, M2, M3, M4, M5 are all motors. Implementation Method

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] like Figure 1 As shown, a circuit schematic diagram of a cascaded high-voltage inverter one-to-five-worker frequency conversion disturbance-free switching device of the present invention is given, which consists of an AC bus 1, an inverter, 6 high-voltage switchgear 4, 5 motors, 7 contactors, and 6 manual isolating knives. The 5 motors are M1, M2, M3, M4, and M5, the 7 contactors are KM0, KM1, KM2, KM3, KM3, KM4, KM5, and KM6, the 6 manual isolating knives are QS1, QS2, QS3, QS4, QS5, and QS6, and the 6 high-voltage switchgears are all provided with circuit breakers. The circuit breakers provided in the 6 high-voltage switchgears are QS1, QS2, QS3, QS4, QS5, and QS6, and the input ends of the 6 high-voltage switchgears are all connected to the AC bus 1.

[0017] The output end of the circuit breaker QF01 is connected to the input end of the inverter 2 through the manual isolation knife QS1 and the normally open point of the contactor KM1. The output end of the inverter 2 is connected to the power input end of the motor M1 through the normally open point of the contactor KM0, the manual isolation knife QS2, and the normally open point of the contactor KM2. The power input of motor M2 is connected to the line between contactors KM0 and QS2 via the normally open point of contactor KM3 and the manual isolating knife QS3. Correspondingly, the power input of motor M3 is connected to the line between contactors KM0 and QS2 via the normally open point of contactor KM4 and the manual isolating knife QS4. The power input of motor M4 is connected to the line between contactors KM0 and QS2 via the normally open point of contactor KM5 and the manual isolating knife QS5. The power input of motor M5 is connected to the line between contactors KM0 and QS2 via the normally open point of contactor KM6 and the manual isolating knife QS6. In this way, under the control of inverter 2, by closing the contactor on the power input of the corresponding motor 3, the corresponding motor 3 can be controlled to start, change speed, or stop with variable frequency.

[0018] To enable motor 3 to operate at commercial frequency (50Hz) while disconnected from inverter 2's control, the power input of motor M1 is connected to AC bus 1 via circuit breaker 1QF. Correspondingly, the power inputs of motors M2, M3, M4, and M5 are connected to AC bus 1 via circuit breakers 2QF, 3QF, 4QF, and 5QF, respectively. Thus, after inverter 2 completes the variable-frequency start of the corresponding motor 3, motor 3 can be switched to commercial frequency operation by disconnecting it from inverter 2's output and connecting it to AC bus 1 via the circuit breaker. This, in turn, allows inverter 2 to perform variable-frequency control over the other motors 3.

[0019] The illustrated inverter 2 consists of a phase-shifting transformer 5 and a power unit 6. The input of the phase-shifting transformer 5 forms the input of the inverter 2 and is connected to the normally open terminal of contactor KM1. The output of the phase-shifting transformer 5 is connected to the input of the power unit 6. The output of the power unit 6 forms the output of the inverter 2 and is connected to the normally open terminal of contactor KM0. The power unit 6, through rectification and inversion, outputs frequency-controlled AC power, thereby achieving variable-frequency control of the motor 3.

[0020] The input of the phase-shifting transformer 5 is provided with a current transformer TA1, and the output of the power unit 6 is provided with current transformers TA2 and TA3. Thus, the current signals at the input and output of the inverter 2 can be measured through the current transformers TA1, TA2, and TA3. A reactor 7 is connected in parallel to the normally open point of the contactor KM0.

[0021] The working principle of the cascaded high-voltage inverter one-to-five-worker frequency conversion disturbance-free switching device of the utility model is as follows:

[0022] Frequency conversion control: When frequency conversion control is applied to motor M1, circuit breaker QF01 in high-voltage switchgear 4 is closed and sends a high-voltage ready signal. At this point, manual disconnect switches QS1 and QS2 are ensured to be closed. Contactor KM1 is then closed, followed by contactor KM2 after a 1.5-second delay. Finally, contactor KM0 is closed, and the frequency converter is operational. This allows motor M1 to be started, decelerated, or stopped using frequency conversion. Motors M2, M3, M4, and M5 are controlled in the same manner.

[0023] Motor frequency conversion to industrial frequency control: With motor M1 running, a signal is given to convert M1 to industrial frequency. Upon receiving this signal, inverter 2 automatically increases the frequency to industrial frequency. When the operating frequency of motor M1 exceeds a certain limit, contactor KM0 is disconnected, the reactor is activated, and phase lock operation begins, waiting for phase lock to complete. After phase lock is completed, circuit breaker 1QF closes, KM2 and KM1 open, and a signal indicating the completion of the conversion to industrial frequency is output, completing the disturbance-free conversion of motor M1 to industrial frequency. Motors M2, M3, M4, and M5 are controlled in the same manner.

[0024] Motor power frequency to frequency conversion control: Verify that circuit breakers QS1 and QS2 are in the closed position and that inverter 2 itself is fault-free. Apply an external frequency conversion signal. Contactor KM1 closes, and inverter 2 enters the voltage stabilization process. Once voltage stabilization is complete, inverter 2 starts and performs phase lock. After phase lock is complete, contactor KM2 closes, and manual disconnect switch 1QF opens. After inverter 2 stabilizes, contactor KM0 closes, removing reactor 7 and ensuring grid stability. This completes the undisturbed power frequency to frequency conversion of motor M1. Motors M2, M3, M4, and M5 are controlled in the same manner.

Claims

1. A cascaded high-voltage inverter one-to-five-input frequency conversion disturbance-free switching device, comprising an AC busbar (1), a high-voltage switch cabinet (4), an inverter (2), a motor (3) and a contactor, wherein the input terminal of the high-voltage switch cabinet is connected to the AC busbar, and a circuit breaker is arranged in the high-voltage switch cabinet; the characteristics are: The number of the motors is 5, the number of the high-voltage switch cabinets is 6, the 5 motors are M1, M2, M3, M4, M5, and the 6 high-voltage switch cabinets are respectively provided with circuit breakers QF01, 1QF, 2QF, 3QF, 4QF, 5QF; the output end of the circuit breaker QF01 is connected to the input end of the frequency converter via the normally open point of the contactor KM1, and the output end of the frequency converter is connected to the power input end of the motor M1 via the normally open point of the contactor KM0 and the normally open point of KM2 in sequence; The power input terminals of motors M1, M2, M3, M4 and M5 are connected to the AC power grid via circuit breakers 1QF, 2QF, 3QF, 4QF and 5QF respectively; the power input terminals of motors M2, M3, M4 and M5 are connected to the connecting line between the normally open point of relay KM0 and the normally open point of relay KM2 via the normally open points of contactors KM3, KM4, KM5 and KM6 respectively.

2. The cascaded high-voltage inverter one-to-five-input frequency conversion disturbance-free switching device according to claim 1 is characterized in that: A manual isolating knife QS1 is connected in series between the output end of the circuit breaker QF01 and the normally open point of the contactor KM1, and manual isolating knives QS2, QS3, QS4, QS5, QS6 are connected in series between the normally open point of the contactor KM0 and the normally open points of the contactors KM2, KM3, KM4, KM5, KM6, respectively.

3. The cascaded high-voltage inverter one-to-five-input frequency conversion disturbance-free switching device according to claim 1 or 2, characterized in that: It includes a reactor (7) connected in parallel with the normally open point of the contactor KM0.

4. The cascaded high-voltage inverter one-to-five-input frequency conversion disturbance-free switching device according to claim 1 or 2, characterized in that: The frequency converter (2) is composed of a phase-shifting transformer (5) and a power unit (6), the input end of the phase-shifting transformer forms the input end of the frequency converter, the output end of the phase-shifting transformer is connected to the input end of the power unit, and the output end of the power unit forms the output end of the frequency converter.

5. The cascaded high-voltage inverter one-to-five-input frequency conversion disturbance-free switching device according to claim 4 is characterized in that: A current transformer TA1 is provided at the input end of the phase-shifting transformer (5), and a current transformer TA2 and a current transformer TA3 are provided at the output end of the power unit (6).

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