An artificial zero-crossing emergency power static switch device and a control method thereof

Abstract

The application discloses an artificial zero-crossing emergency power static switch device and a control method thereof, relates to the technical field of dual-power supply, and solves the problem that market static switches cannot guarantee main and standby power switching within 10 ms, and comprises a control unit, a signal acquisition unit, a main power thyristor switch and a standby power thyristor switch, the control unit is connected with the signal acquisition unit, the main power thyristor switch and the standby power thyristor switch are both connected with the control unit, the application provides an artificial zero-crossing emergency power static switch device design and a control scheme, the static switch device is an independent device, does not need to track the phase control of the main power as a standby power by using an emergency power, the static switch device performs coarse synchronization and accurate synchronization switching according to the main and standby power states, and the LC artificial zero-crossing is used to realize fast switching within 10 ms during coarse synchronization switching.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dual power supply, in particular to an emergency power static switch device with artificial zero-crossing and a control method thereof. BACKGROUND

[0002] Important loads, sensitive loads such as chemical industry, metallurgy, hospital, fire fighting, civil aviation, etc. need to be configured with dual power supply. When the main power supply is abnormal, it is required to switch to the backup power supply through the dual power supply switching device. For important loads, uninterrupted power supply is required to ensure that important loads do not restart after power failure. Therefore, the switching time of the dual power supply switching device is required to be controlled within 10 ms. The usual practice is to use UPS and EPS for backup power supply, and at the same time, the UPS and EPS lock the phase of the power supply. When the main power supply has voltage sag, voltage failure and other faults, the main power supply switch is turned off, and the backup power supply is switched through the thyristor. The premise of this method is that the backup power supply uses the UPS and EPS power supply with phase-locked synchronization technology. When the backup power supply is a grid power supply or an inverter power supply without phase-locked synchronization technology, considering the load characteristics and the current zero-crossing turn-off characteristics of the thyristor, it cannot guarantee that the static switching switch switches the main and backup power supplies within 10 ms.

[0003] At present, there is no effective solution to the problems in the related art. SUMMARY

[0004] In view of the problems in the related art, the present application provides an emergency power static switch device with artificial zero-crossing and a control method thereof to overcome the above technical problems existing in the prior art.

[0005] The technical scheme of the present application is as follows:

[0006] According to one aspect of the present application, an emergency power static switch device with artificial zero-crossing is provided.

[0007] The emergency power static switch device with artificial zero-crossing includes a control unit, a signal acquisition unit, a main power supply thyristor switch and a backup power supply thyristor switch. The control unit is connected to the signal acquisition unit. The main power supply thyristor switch and the backup power supply thyristor switch are both connected to the control unit. The main power supply thyristor switch is provided with a main circuit LC artificial forced zero-crossing circuit. The control unit includes a main power supply thyristor drive unit, a backup power supply thyristor drive unit and a main circuit LC artificial forced zero-crossing circuit drive unit.

[0008] Further, the signal acquisition unit is used to acquire the main power supply voltage and current signals, the backup power supply voltage and current signals and the output voltage and current signals of the static switch device.

[0009] Further, the output terminals of the main power source thyristor switch and the standby power source thyristor switch are connected together to connect a load.

[0010] According to another aspect of the present application, a control method of an artificial zero-crossing emergency power static switch device is provided.

[0011] The use of the artificial zero-crossing emergency power static switch device includes the following steps:

[0012] S101, the static switch device phase-locks the main power source and the standby power source, and through the collected main power source voltage signal and standby power source voltage signal, an improved double second-order generalized integral is used for software phase-locking;

[0013] S102, main power source rapid fault judgment, the main power source voltage is subjected to CLARK and PARK transformation, and the root mean square of the square sum of the d-axis and q-axis components is calculated under the dq coordinate system. The value is the phase voltage peak value. The root mean square is judged, and different modes are switched to the standby power source according to the relationship between the value and the rated value;

[0014] S103, after judging the fault type according to the main power source voltage, it is decided whether to perform coarse synchronization switching or quasi-synchronization switching. If coarse synchronization switching is performed, it is first judged whether artificial zero-crossing is needed according to the phase of the main power source voltage. If artificial zero-crossing is needed, the on-off switch of the LC resonance circuit is decided according to the direction of the main power source current, and the resonance current of the LC resonance circuit is used to realize artificial zero-crossing of the main power source thyristor, so as to meet the switching time less than 10ms. If quasi-synchronization switching is performed, the phase difference between the main power source and the standby power source is used to judge. When the phase difference is less than 3°, the main power source thyristor drive signal is turned off, and the standby power source thyristor drive signal is enabled, and the main power source and the standby power source are switched;

[0015] S104, main power source recovery work, in the working process of the static switch device, the main power source voltage signal is collected in real time, and the main power source is judged whether it is restored to normal through the three-phase voltage of the main power source. When the main power source is restored to normal, the phase difference between the main power source and the standby power source is used to judge. When the phase difference is less than 3°, the standby power source thyristor drive signal is turned off, and the main power source thyristor drive signal is enabled, and the standby power source is switched to the main power source to work, which is quasi-synchronization switching;

[0016] S105, the static switch device sets manual and automatic working modes. When the automatic mode works, the device automatically collects the main power source voltage and current signal and the standby power source voltage and current signal and performs corresponding processing, automatically judges the main power source fault or normal state, and performs coarse synchronization and quasi-synchronization switching of the main power source and the standby power source. When the manual mode works, the main power source is switched to the standby power source according to the main power source voltage state.

[0017] Further, when the main and standby power sources are phase-locked, first, the phase of the main and standby power sources is judged, for three-phase equipment, the CLARK and PARK transformation is directly performed, and the software phase-locked loop is performed in the dq coordinate system, for single-phase equipment, the virtual three-phase coordinate is used to perform the CLARK and PARK transformation, the software phase-locked loop is first performed in the dq coordinate system, and then the software phase-locked loop is performed.

[0018] Compared with the prior art, the application has the following beneficial effects: the application provides an emergency power static switch device design and control scheme with artificial zero-crossing, the static switch device is an independent device, does not need to track the phase control of the main power source as the standby power source, and performs coarse synchronization and accurate synchronization switching according to the state of the main and standby power sources, the LC artificial zero-crossing is used to realize fast switching within 10ms during the coarse synchronization and accurate synchronization switching, the problem that the market static switch cannot guarantee the switching of the main and standby power sources within 10ms is solved, and the control scheme of the emergency power is simplified. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description only constitute some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative effort.

[0020] Figure 1 It is a structure block diagram of an emergency power static switch device with artificial zero-crossing according to the application;

[0021] Figure 2 It is a principle diagram of the LC artificial zero-crossing of the emergency power static switch device with artificial zero-crossing in the application;

[0022] Figure 3 It is a CLARK and PARK transformation coordinate axis schematic diagram applied in the application;

[0023] Figure 4 It is a principle diagram of the improved double-second-order generalized integral software phase-locked loop control.

[0024] Corresponding symbols:

[0025] 1, control unit; 101, main power thyristor drive unit; 102, standby power thyristor drive unit; 103, main circuit LC artificial forced zero circuit drive unit; 2, signal acquisition unit; 3, main power thyristor switch; 301, main circuit LC artificial forced zero circuit; 4, standby power thyristor switch. DETAILED DESCRIPTION

[0026] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present application.

[0027] Embodiments

[0028] According to an aspect of the present application, an artificial zero-crossing emergency power static switch device is provided.

[0029] Please refer to Figure 1 The artificial zero-crossing emergency power static switch device comprises a signal acquisition unit 2, a control unit 1, a main power thyristor switch 3, and a backup power thyristor switch 4. The main power thyristor switch comprises a main circuit LC artificial forced zero-crossing circuit 301. The control unit 1 comprises a main power thyristor drive unit 101, a backup power thyristor drive unit 102, and a main circuit LC artificial forced zero-crossing circuit drive unit 103. The dual power supply is input by the main power thyristor switch 3 and the backup power thyristor switch 4, and the output ends of the main power thyristor switch 3 and the backup power thyristor switch 4 are connected together to connect the load. The signal acquisition unit 2 is used to acquire the main power voltage and current signals, the backup power voltage and current signals, and the output voltage and current signals of the static switch device.

[0030] Figure 2 The LC artificial zero-crossing principle diagram of the emergency power static switch device is described by taking the A-phase power supply as an example for convenience of description. The B-phase and C-phase power supplies are the same. The circuit comprises a main power switch, a backup power switch, and a main power LC forced zero-crossing circuit. T Z1 , T Z2 is the main power thyristor switch 3, B1 , T B2 is the backup power thyristor, LC1 , T LC2 , T LC31 , T LC4 comprises the main power LC forced zero-crossing circuit, and T LC1 , T LC2 , T LC31 , T LC4The LC resonance current is artificially reversed to force the main power thyristor to turn off according to the selective conduction of the main power current direction; whether the main power thyristor switch 3 is turned off is judged through main power current detection, and after the turning off is determined, a closing instruction of the standby power thyristor switch 4 is issued, and the standby power is put into operation; in the whole switching process, the principle of first separation and then combination should be followed; in order to avoid the impact of the main power on the load during the switching process, when the main power is abnormal, there are two cases of switching to the standby power, the main power voltage signal and the standby power voltage signal are calculated in real time, CLARKE and PARK transformation are carried out, phase voltage peak value calculation and software phase locking are carried out in the DQ coordinate system, whether quasi-synchronous switching or rough switching is adopted is judged according to the real-time phase voltage peak value, when the main power voltage is 80%-90% of the rated value, quasi-synchronous switching is carried out, that is, when the phase difference between the main power and the standby power is within 3°, the standby power is first combined and then the main power is turned off; when the main power voltage is less than 80% of the rated value, forced switching is carried out through artificial zero-crossing, that is, rough switching.

[0031] Figure 3 The CLARKE and PARK transformation coordinate axis schematic diagram applied in the application is shown in the figure, and the definitions of various coordinate transformation arrays required by the application are as follows:

[0032] CLARK3 transformation:

[0033] Counterclockwise PARK transformation:

[0034] Counterclockwise PARK inverse transformation:

[0035] Figure 4 In order to improve the principle diagram of the improved double second-order generalized integral software phase-locked loop, the bypass voltage is phase-locked in the alpha-beta coordinate system, and the real-time angular frequency ω and the real-time A-phase phase θ=θ+ωΔt can be obtained. The purpose of using the improved double second-order generalized integral (DSOGI) phase-locked loop is to avoid the influence of the harmonic and negative sequence components of the bypass voltage on the phase-locked loop accuracy.

[0036] According to another aspect of the application, a control method of an artificial zero-crossing emergency power static switch device is also provided.

[0037] The control method of the artificial zero-crossing emergency power static switch device comprises the following steps:

[0038] S101, assuming that the initial angular frequency of the main power voltage is ω0=100π, the corresponding frequency is 50Hz, the real-time angular frequency is ω1, the A-phase voltage phase of the main power is θ1, the sampling period is Δt, then the real-time phase is θ1=θ1+ω1Δt, and the main power voltage U Za , U Zb , U ZcThe CLARK3 and PARK transformation are performed to obtain:

[0039] The value in alpha-beta coordinate system:

[0040] The value in dq coordinate system:

[0041] Reference Figure 4 In order to improve the double second-order generalized integral software phase-locked control, the bypass voltage is phase-locked in the alpha-beta coordinate system, and the real-time angular frequency ω1 and the real-time A-phase phase θ1=θ1+ω1Δt can be obtained. Similarly, the standby power is transformed and phase-locked, and the standby power real-time angular frequency ω2 and the real-time A-phase phase θ2=θ2+ω2Δt can be obtained. The purpose of the improved double second-order generalized integral (DSOGI) phase-locked loop is to avoid the influence of the bypass voltage harmonic and negative sequence component on the phase-locked accuracy.

[0042] S102, according to the A-phase phase θ of the main power supply voltage obtained by phase-locked in step S101, the value in dq coordinate system obtained by PARK transformation The following formula is used for calculation:

[0043]

[0044] The calculated U Zrms_dq is the peak value of the main power supply voltage. Even if the angle θ1 obtained by phase-locked has deviation from the actual phase, the final result is only The value contains a sine component But the physical meaning is unchanged, which is the peak value of the bypass phase voltage. According to the value of U Zrms_dq , the abnormality of the bypass voltage can be determined. In order to determine reliably, 5 continuous sampling periods are used to determine U Zrms_dq , which can accurately determine whether the bypass voltage is abnormal. It can ensure that the determination is completed within 1ms, which is of great significance for the fast switching of the main and standby power supplies, and can be applied in STS switches.

[0045] S103, according to the U Zrms_dq calculated in step S102, the main and standby power switching modes are determined. For example, if U Zrms_dq is greater than 90% of the rated value, the main and standby power switching is not performed; if U Zrms_dq is within 80%-90% of the rated value, the quasi-synchronous switching is performed; if U Zrms_dq is less than 80% of the rated value, the rough switching is performed.

[0046] Quasi-synchronous switching: when U Zrms_dqWithin 80%-90% of the rated value, the switching time is determined based on the phase difference between the main and backup power phases θ1 and θ2 obtained by phase locking the main and backup power in step one. When the absolute value of the difference between the two is abs(θ1-θ2) < 3°, the backup power drive is turned on first, the backup power thyristor is closed, the backup power is put into operation, and then the main power thyristor is turned off to perform seamless switching between the main and backup power.

[0047] Coarse synchronization switching: When U Zrms_dq If the value is less than 80% of the rated value, perform a coarse synchronization switch between the main and backup power supplies, stop supplying trigger signals to the main power supply thyristors, and perform LC forced zero-crossing switching according to the direction of the main power supply current. Figure 2 As shown, phase A will be used for explanation, such as i Za exist Figure 2 In the direction shown, then T Z1 When the circuit is turned on, T in the LC forced zero-crossing circuit is triggered. LC1 T LC4 The LC circuit performs resonant discharge, and the discharge current direction is opposite to i. Za Conversely, for T Z1 Force shutdown; such as i Za and Figure 2 If the directions shown are opposite, then T Z2 When the circuit is turned on, T in the LC forced zero-crossing circuit is triggered. LC2 T LC3 The LC circuit performs resonant discharge, and the discharge current direction is opposite to i. Za Conversely, for T Z2 Forced shutdown; after manually forcing the main power supply to zero-crossing shutdown, the main power supply current i is then monitored in real time. Za When it reaches zero, the backup power thyristor is triggered to switch on the backup power supply, thus completing the coarse synchronization switch between the main and backup power supplies.

[0048] S104. Main power restored. According to step S102, U is collected and calculated in real time. Zrms_dq , when U Zrms_dq When the value is greater than 90% of the rated value, the main power supply is considered to have returned to normal. At this time, the power switching device should be restored to the main power supply mode and switch from the backup power supply to the main power supply. At this time, the quasi-synchronous switching mode is adopted. The switching time is determined according to the phase difference of the main and backup power phases θ1 and θ2 obtained by phase locking of the main and backup power supplies in step S101. When the absolute value of the difference between the two is abs(θ1-θ2) < 3°, the main power drive is turned on first, the main power thyristor is closed, the main power supply is put into operation, and then the backup power thyristor is turned off, so that the seamless switching from the backup power supply to the main power supply is performed.

[0049] S105, the static switching device sets manual and automatic working modes, in the automatic mode, the device automatically collects and processes the voltage and current signals of the main and standby power supply, automatically judges the main power supply fault or normal state, and performs coarse synchronization and fine synchronization switching of the main and standby power supply; in the manual mode, the device is switched from the main power supply to the standby power supply according to the voltage state of the main and standby power supply.

[0050] Compared with the prior art, the application has the following beneficial effects: the application provides an emergency power static switch device design and control scheme of artificial zero-crossing, the static switch device is an independent device, does not need to track the phase control of the main power supply as the standby power supply, and performs coarse synchronization and fine synchronization switching according to the state of the main and standby power supply; the coarse synchronization switching is realized by LC artificial zero-crossing to achieve fast switching within 10ms, solves the problem that the market static switch cannot guarantee the switching of the main and standby power supply within 10ms, and simplifies the control scheme of the emergency power supply.

[0051] Although the embodiments of the application have been shown and described, it is to be understood that the application is not limited to these embodiments. It will be obvious to a person skilled in the art that various changes, modifications, replacements and modifications can be made to these embodiments without departing from the principles and spirit of the application, and the scope of the application is defined by the appended claims and their equivalents.

Claims

1. A control method of an artificial zero-crossing emergency power static switch device, characterized by, An emergency power static switch device for artificial zero-crossing, comprising the following steps: S101, the static switch device phase-locks the main and backup power sources, and uses an improved double second-order generalized integral to perform software phase-locking through the collected main and backup power voltage signals; S102, main power fast fault judgment, the main power voltage is subjected to CLARK and PARK transformation, and the root mean square of the square sum of the d-axis and q-axis components is calculated in the dq coordinate system. This value is the phase voltage peak value. The root mean square is judged, and different modes are switched to the backup power source according to the relationship between this value and the rated value; S103, after judging the fault type according to the main power voltage, it is decided whether to perform coarse synchronization switching or quasi-synchronization switching. If coarse synchronization switching is performed, it is first judged whether artificial zero-crossing is needed according to the main power voltage phase, and if artificial zero-crossing is needed, the switching of the LC resonance circuit is decided according to the main power current direction, and the resonance current of the LC resonance circuit is used to realize artificial zero-crossing of the main power thyristor, so as to meet the requirement that the switching time is less than 10 ms; if quasi-synchronization switching is performed, the phase difference between the phase-locked main and backup power sources is used to judge, and when the phase difference is less than 3°, the main power thyristor drive signal is turned off, and the backup power thyristor drive signal is enabled, so as to switch the main and backup power sources; The emergency power static switch device for artificial zero-crossing comprises a control unit, a signal acquisition unit, a main power thyristor switch and a backup power thyristor switch. The control unit is connected with the signal acquisition unit. The main power thyristor switch and the backup power thyristor switch are connected with the control unit. The main power thyristor switch is provided with a main circuit LC artificial forced zero-crossing circuit. The control unit comprises a main power thyristor drive unit, a backup power thyristor drive unit and a main circuit LC artificial forced zero-crossing circuit drive unit. The signal acquisition unit is used to acquire the main power voltage and current signals, the backup power voltage and current signals and the output voltage and current signals of the static switch device. The output ends of the main power thyristor switch and the backup power thyristor switch are connected together to connect a load.

2. The control method of an emergency power static switchgear with artificial zero according to claim 1, characterized in that, Further comprising the following steps: S104, main power recovery, in the working process of the static switch device, the main power voltage signal is acquired in real time, and it is judged whether the main power is restored to normal through the main power three-phase voltage. When the main power is restored to normal, it is judged according to the phase difference between the main and backup power sources. When the phase difference is less than 3°, the backup power thyristor drive signal is turned off, and the main power thyristor drive signal is enabled, so as to switch from the backup power to the main power for working, which is quasi-synchronization switching.

3. The control method of an emergency power static switchgear with artificial zero according to claim 2, characterized in that, Further comprising the following steps: S105, the static switch device is provided with a manual and automatic working mode. When the automatic mode works, the device automatically acquires the main and backup power voltage and current signals and performs corresponding processing, automatically judges the main power fault or normal state, and performs main and backup power coarse synchronization and quasi-synchronization switching. When the manual working mode works, the main and backup power coarse synchronization or quasi-synchronization switching is performed according to the main and backup power voltage state.

4. The control method of an emergency power static switchgear with artificial zero according to claim 1, characterized in that, When the main and standby power sources are phase-locked, first, the phase of the main and standby power sources is judged, for three-phase equipment, the CLARK and PARK transformations are directly used to perform software phase-locked in the dq coordinate system, for single-phase equipment, the CLARK and PARK transformations are used in virtual three-phase coordinates, first, software phase-locked is performed in the dq coordinate system, and then, software phase-locked is performed.

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