JPS6248271A - No-break power supply system - Google Patents

Abstract

PURPOSE:To remove transient variation on load transfer by controlling an output from an inverter so that the effective and reactive power of the inverter or a bypass power supply on the side detached from load under the state of synchronous control are brought to zero. CONSTITUTION:A switch 23 is turned to the terminal B side and a thyristor switch 2 is turned ON for load transfer to a commercial power supply 1 from an inverter 5. Consequently, the parallel operation of the commercial power supply 1 and the inverter 5 is started, the conditions of an AND circuit 21 hold by the presence of both currents in current transformers 22 and 14, and a switch 19 is brought to the state shown in the diagram and a switch 20 is turned ON. As a result, control in which the reactive and effective power of the inverter 5 are brought to zero is started, and share is transferred to the commercial power supply 1 side from the inverter 5. Accordingly, transient variation on load transfer is removed, and load can be transferred positively while output capacitance from the inverter is brought to approximately load capacitance.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an uninterruptible power supply system using an inverter and a bypass voltage Δ1;

13 Summary of the Invention The present invention synchronizes the inverter and the bypass power supply by using an uninterruptible power supply system that supplies power to the load by switching between the inverter and the bypass power supply! By controlling the output of the inverter to zero the effective/reactive 1u force of the inverter or bypass power supply from the 112-row state, transient fluctuations at the time of load transition are eliminated and reliable power supply switching is achieved.

C Conventional technology (1) As a power outage system, an inverter with a spare battery and a bypass power source such as a commercial power source are used to supply the load uninterruptedly by transferring the load between the inverter and the bypass power source. There is something.

D Problems to be Solved by the Invention In load transfer control between an inverter and a bypass power supply, conventionally the load was transferred by instantaneous parallel control of an electromagnetic contactor or Zyristor switch. There is a problem in that voltage transient fluctuations become large due to changes in the voltage. In order to avoid malfunctions of the load circuit due to this voltage fluctuation, the device capacity of the inverter must be increased and the internal impedance must be lowered, but the problem remains that this increases the cost of the inverter.

E3 Means for Solving the Problems The present invention has been made in view of the above-mentioned problems, so there is no need to install a switch that can open and close between the bypass power supply, the inverter output, and the bypass power supply output to connect the load to the load. a power supply switching contactor connected to the bypass power supply, a means for controlling synchronized operation with the bypass power supply, and a control means for controlling the output frequency and output voltage of the inverter so as to reduce the active power and reactive power of the inverter and the bypass power supply to zero. and a control circuit for the inverter having a control circuit for the inverter, and after turning on the switch in a state where the bypass power supply is synchronously controlled to the inverter side power supply, the contactor is switched to the inverter side to enable the bypass power supply. ++1 The output of the inverter is controlled so that the full effective power is used, and the inverter is controlled to transfer the load from the inverter to the bypass power supply. Controlling the output of the inverter so that the active/reactive power becomes zero, and controlling the inverter output so that the active/reactive power of the power supply or inverter on the side that is disconnected from the load when switching from the synchronous control state becomes zero, When the load transfer is complete, disconnect the inverter or bypass power supply from the load.

F. Example The drawing is a circuit diagram showing an embodiment of the present invention.

The commercial power source l serving as a bypass power source is connected to the load 3 via the Zyristor switch 2, and is also enabled to supply power to the load 3 via the power switching contactor 4. The inverter 5 is enabled to supply power to the load 3 via the contactor 1. The inverter 5 should include a control circuit consisting of 6 to 23.

This control circuit consists of a phase shifter ([1 comparator circuit 6, frequency 1 regulator 7, and voltage controlled oscillator]; 8 and a phase shifter 9 including a gate circuit.
It is equipped with a frequency control system of a Karanaro PLL circuit, and enables the output voltage of the commercial power supply l to follow the detection frequency from the detection transformer 10, and to perform synchronous control. The control circuit also includes a voltage control system consisting of a voltage setter 11 and a voltage control amplifier 12, and detects the output voltage of the inverter 5 i,l =j
- The detected voltage from the transformer 13 is used as a feedback signal to control the phase of the phase shifter 9. The setting devices 7 and 12 are adjusted to the output frequency and voltage of the commercial power supply 1.

In addition to the control system described above, the control circuit includes a load sharing control system. This control system includes a current transformer 14 that detects the detection output and output current of a transformer 13 that detects the output voltage of the inverter 5, or a current transformer 1 that detects the output current of the commercial power supply 1.
an active/reactive power detection circuit 16 that detects active power P and non-public power Q from the detection output of 5; an effective sharing adjustment circuit 17 that obtains
Obtain a feedback signal to the voltage control system by performing signal processing to make the sharing ratio for the reactive power Q zero.11) (Effective sharing, L!+Provide a rectifying circuit I8.

The iron and frequency control system is the output of the phase comparator circuit 6.

The voltage control system has one switch so that a feedback signal can be obtained by switching between the output of the f-effect division adjustment circuit 17 and
It has a switch 20 so that it can be turned off. These switches 19 and 20 are on/off controlled by an AND circuit 2I that determines the simultaneous establishment of the inverter output signal from the current transformer 14 and the output signal from the commercial power source 1 through the sirisk switch 2 from the current transformer 22. Be it. Further, the detection outputs of the current transformers I4 and 15 are switched by the switch 23, and this switching signal is sent to the active/reactive power detection circuit 1G.

In such a configuration, during power supply by the commercial power source 1, the contactor 4. The switch 23 is set to the terminal B side. At this time,
When the condition is not satisfied, the AND circuit 21 switches the switch I9 in the opposite direction to that shown in the figure, and turns off the switch 20. Therefore, the inverter 5 is controlled in synchronization with the power supply I, and the voltage is adjusted by the setter II.

From this state, in order to transfer the load from the commercial power source to the inverter 5, turn on the Cyrisk switch 2, as well as the contactor 1. Switch switch 23 to terminal I side. As a result, the power supply from the commercial power source 1 is continued through the thyrisk switch 2, and the inverter 5. Current begins to flow, and when the AND circuit 21 satisfies the conditions, the switch 19 is placed in the illustrated position, the switch 20 is closed, and the commercial type IF and the inverter 5 are in a shared control state. At this time, the detection circuit I6 detects the r1 effect and reactive power on the commercial power supply l side, and the frequency and voltage of the inverter 5 are controlled in the direction of this detection or zero, and the load is transferred from the commercial power supply l to the inverter 5.・It is done. After that, when the load line 43 is completed, the sirisk switch 2 is turned off, the current in the current transformer 22 becomes zero, the switches 19 and 20 are reset, and the inverter 5 (to Maedoku Unhan) is turned off. -Ro starts power supply 4゛Ro.

Next, to transfer the load from the inverter 5 to the commercial power supply 1, set the switch 23 to the terminal 13 side and turn on the SIRISK switch 2. 1; Parallel operation of the commercial power supply 1 and the inverter 5 is started, and the condition of the ant circuit 21 is satisfied with both the current lights of the current transformers 22 and 14, and the switch 19 is in the state shown in the figure, and the switch 20 is turned on. Measure to. As a result, control to reduce the active power of the inverter 5 to zero is started], and the share is transferred from the inverter 5 to the commercial power source 1 side. After the load transfer is completed, connect contactor 4 to terminal ■3.
side, and turn off the SIRISK switch 2 to complete the transition.

In addition, when power is being supplied by the inverter, the Cyrisk switch 2
is accidentally turned on, and since the inverter is always in a synchronous control state, no stem down will occur.

G1 Effects of the Invention As shown in L, the present invention provides a system in which the active/reactive power of the inverter or bypass power supply on the side that is disconnected from the load becomes zero in a synchronous control state during load transfer between the bypass power supply and the inverter. In order to control the inverter output so that
Transient fluctuation during load transition jH(<: l;, output capacity;
': 4M from fS ('J,: negative a:: r + ρ
I can go.

[Brief Description of the Drawings] The drawings are circuit diagrams showing one implementation of the present invention. l ・Commercial telephony (, 2... Cyrisk switch, 3...
Load, 4 Electrical switching contactor, 5... Inverter, 6 Phase comparator circuit, 7... Frequency setter, 8... Voltage: l' control oscillator, 9... Position I'll unit, 11... Voltage setting device,
12 voltage control amplifier, 16 active/reactive power detection circuit,
I7... Effective portion sharing adjustment circuit, 18... Reactive portion sharing adjusting circuit.

Claims (1)

[Claims] A bypass power supply having a switch that can be opened and closed between the power supply and the load, a power supply switching contactor that switches between an inverter output and the bypass power supply output and connects the output to the load, a means for controlling synchronized operation with the bypass power supply, and the inverter and the bypass power supply. and a control circuit for the inverter having a control means for controlling the output frequency and output voltage of the inverter so as to make active power and reactive power of After turning on the switch under synchronous control, the contactor is switched to the inverter side, and the output of the inverter is controlled so as to reduce the active and reactive power of the bypass power source to zero, and the load is transferred from the inverter to the bypass power source. An uninterruptible power supply system characterized in that the output of the inverter is controlled so that the active and reactive power of the inverter is reduced to zero when the switch is turned on while the inverter is controlled in synchronization with a bypass power supply.