JPH02303327A - Device for selecting number of parallel units in uninterrupted power supply system - Google Patents

Abstract

PURPOSE:To elevate efficiency in system operation by dissolving the parallel operation of an uninterruptive power supply device, which is performing parallel operation, or by making parallel operation, with the increase or reduction of load capacity. CONSTITUTION:If AC input should be lost, a high-speed current limiting breaker 10 inside an inverter device 1 is closed, and the DC power from a storage battery 3 is converted into AC power by an inverter 8 through a DC-DC chopper 7, and AC power is supplied from a parallel output panel 4 to load 14. In this parallel redundant operation system, the load currents on the secondary side of an AC breaker 12 in the parallel output panel 4 are detected with a current transformer 14, and this is converted into actual load capacity with a device 15 for selecting the number of units, and the parallel dissolution or parallel making is done within the range of not loosing parallel redundancy by the opening/closing operation of a switch 11 in the parallel output panel 4.

Description

[Detailed description of the invention] [Purpose of the invention] related.

(Prior Art) A conventional parallel system of uninterruptible power supplies includes an inverter device, a charger board, a storage battery, and a parallel output board.

In an inverter device, the AC input is set to an appropriate voltage by a transformer, and! A single current converter converts this into direct current, supplies the direct current power to the DC-DC chopper, and then converts it back to alternating current with an inverter, and then insulates it with a transformer to obtain alternating current voltage. The inverter device constitutes a parallel operation system with a parallel output panel, and the parallel output panel is composed of a switch for parallel inspection and an AC breaker for a feeder supplying to the load. The parallel operation system is operated as a parallel redundant operation system by providing one or several spare inverter devices for the total load capacity.

(Problems to be Solved by the Invention) The present invention provides a system for unparalleling or paralleling inverter devices without losing the redundancy of parallel system operation as the total load capacity increases or decreases. Provided is a device for selecting the number of parallel power supply devices during power outage.

[The beginning of the invention]

(Means for Solving the Problems) The present invention detects the load current on the secondary side of the AC circuit breaker in the parallel output panel using a current transformer, converts this into an actual load capacity using a number selection device, and converts it into an inverter device. This is a parallel unit selection device for an uninterruptible power supply system that selects the number of parallel units.

(Function) In a parallel system consisting of n uninterruptible power supplies, the uninterruptible power supplies operating in parallel are disconnected from parallel or connected in parallel as the load capacity increases or decreases.

(Example) Next, one embodiment of the present invention will be described.

Figure 1 shows an inverter system that converts DC power to AC power!
! 1, a parallel output board 4 that discloses a parallel circuit between the inverter device 1 and other inverter devices, and a current transformer 14 that is installed in the AC side circuit of each of the plurality of inverter devices 1 and measures the alternating current. It is connected to each secondary circuit of the current transformer 14, calculates the total load current, calculates the optimal number of inverters to operate, and outputs a switching signal to the parallel output panel 14. A device for selecting the number of parallel uninterruptible power supplies is shown.

In other words, each inverter unit w1 making up the parallel redundant operation system shown in Fig. 1 normally supplies one-fifth of the total capacity of the loads 13 with AC power, but in the unlikely event that one unit breaks down. In this case, the failed inverter device 1 is immediately parallel-disconnected from the parallel redundant operation system to supply continuous AC power to the load 13. After the failure is recovered, parallel power is applied and the parallel redundant operation system continues.

In addition, in the event that AC input is lost, inverter device 1
The high-speed current limiting circuit breaker 10 inside is closed, and the DC power from the storage battery 3 is converted to AC power by the inverter 8 via the OC-OC chopper 7.

Each inverter device 1 illustrated in FIG.
Parallel control is performed to divide the load by one-fifth of the total capacity of 3. Therefore, each inverter device 1
The efficiency draws a decreasing curve depending on the load factor.

That is, the present invention includes an inverter device 1 that converts AC power into DC power with a rectifier 6, supplies it to a DC-DC chopper 7, and converts it into AC power with an inverter 8, and a parallel redundant operation system. It consists of a parallel output board 4.

In the event that AC input is lost, the high-speed current limiting circuit breaker 10 inside the inverter device 1 is closed, and the DC power from the storage battery 3 is converted to AC power by the inverter 8 via the DC-DC chopper. death.

AC power is supplied from the parallel output board 4 to the load 13.

In this parallel redundant operation system, the load current on the secondary side of the AC circuit breaker 12 of the parallel output board 14 is detected by the current transformer 14, and this is converted into the actual load capacity by the number selection device 15,
Opening/closing of the parallel output panel 14 within the range without losing parallel redundancy
Inverter installation by opening/closing operation of ll! ! ② Perform parallel uncoupling or parallel input.

Note that 2 is a charger board and 9 is a transformer.

FIG. 2 is a configuration diagram showing another embodiment in which the number selection device 15 stops or starts the inverter devices 1.

〔Effect of the invention〕

According to the present invention, in a parallel redundant system of inverter devices, by limiting the number of parallel redundant inverter devices according to the total load capacity without losing parallel redundancy, the inverter device The system can be operated without reducing efficiency.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a parallel redundant operation system for an uninterruptible power supply device showing one embodiment of the present invention, and FIG. 2 is a configuration diagram of a parallel redundant operation system showing another embodiment. 4...Parallel output panel 7...DC-DC chopper 10...High speed current limiting circuit breaker 11...Switch 12
...AC breaker 14...Current transformer 15...
Number selection device

Claims (1)

[Claims] An inverter device that converts DC power into AC power, a parallel output panel that opens and closes a parallel circuit between this inverter device and another inverter device, and a parallel output board that is provided in the AC side circuit of each of the plurality of inverter devices and converts the AC current. It is connected to the current transformer to be measured and the secondary circuits of these multiple current transformers, calculates the total load current, calculates the optimal number of inverters to operate, and outputs a switching signal to the parallel output panel. A parallel unit number selection device for an uninterruptible power supply system, comprising a number selection device.