JPH1189092A - Power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid a voltage unbalance between phases which is caused by the fluctuations in loads, in a small scale private generator. SOLUTION: Some (1), (2), (3),... of loads L1, L2, (1), (2),... which are connected to the respective phases of a power supply 1 are divided into a plurality of loads L3, L4,... which are connected to the respective phases of the power supply 1 via switches S1, S2,.... The switches are controlled by a centralized control unit 2, which monitors the used electric energies of the respective loads L1, L2,... so as to switch the connections of the loads between the phases, when a power difference between the phases exceeds a certain value. With this constitution, the balance between the respective phases can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inter-phase load switching device for a small-scale power supply such as cogeneration.

[0002]

2. Description of the Related Art In a small-scale regular private power generator such as a cogeneration system, which is not connected in parallel to a commercial power supply, if the load of each phase of the generator is fixed, the balance between the phases due to load fluctuations. If this occurs, there is a problem of imbalance in voltage or a decrease in output.Conventionally, only a stable load is selected and connected to a private generator, and a load or inrush that frequently starts and stops A load with a large current was connected to a commercial power supply.

[0003]

Generally, when a customer who has a relatively large demand for a boiler or hot water supply in a hospital, a restaurant, a small factory, or the like, introduces a cogeneration system, only a load with little fluctuation as in the conventional case. If there is a possibility that the generator output may be excessive, it is necessary to connect the load that is turned on and off as needed or a load with a large inrush current to the generator side to improve the power usage efficiency of cogeneration. There is. However, in order to connect such a fluctuating load to a small-capacity generator or transformer, measures must be taken to ensure that the phases of the single-phase three-wire system, three-phase three-wire system, or three-phase four-wire system are not lost. is necessary.
Accordingly, an object of the present invention is to provide a power supply device of this kind that can maintain a balance between phases even when a load that is easily changed is connected.

[0004]

As shown in FIG. 1, the power supply according to the present invention divides a part of the load (L1, L2,...) Connected to each phase of the power supply 1 into a plurality of parts, Are connected to the respective phases (U, V) of the power supply 1 via the switches (S1, S2,...), And the power consumption of the loads (L1, L2,...) By controlling the switch by the central control unit 2 for monitoring the amount and switching the divided load between the phases when the power difference between the phases exceeds a certain value, the balance between the phases is maintained. According to this configuration, each load (L
1, L2,...) Can be switched while observing the actual power consumption, thereby preventing voltage imbalance and output reduction. Even if a load could not be connected due to the above, the load can be connected to the private generator side with confidence.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment in which the present invention is applied to a single-phase three-wire type private generator, and each phase (U, V) of the generator 1 is fixed to each of the generators. Load (L1, L2
), The load (L3, L4) divided into a plurality of
,...) Are connected via switches (S1, S2,...), And the power consumption of all these loads (L1, L2, L3,. It is constantly monitored via the device CT. If the central control unit 2 detects that the power difference between the phases (for example, U> V) exceeds a certain value, the power consumption of the loads (L3, L4,...) Connected to the U phase. Is selected to be closest to half the power difference of the power difference, and this is switched to the V phase so that the balance between the phases is maintained. In the figure, 3 is a fuse, and CT is a current transformer for detecting a current.

In the present invention, the load connected to each phase (U, V) of the power supply device 1 is not only a stable load such as lighting equipment, but also a refrigerator, a freezer or a ventilation fan. Although it is a steady load, it is repeatedly turned on and off automatically by the temperature control device, and when it is turned on once, such as those with a large inrush current at that time, or air conditioning indoor units, personal computers, televisions, videos, etc. A random load that is used and has a relatively small rush current of each connected device, or a load with a large rush current such as an air-conditioning outdoor unit, a washing machine, a dryer, etc. Various loads are included, such as facsimile machines, microwave ovens, vacuum cleaners, etc., which are used continuously for only a few minutes at a time. If loads with different variations are treated uniformly as described above, for example, short-term fluctuations such as inrush current will cause the load to be switched one by one, causing unstable operation or relay contacts. Or cause wear.

A second aspect of the present invention solves the above-mentioned problems, and the loads (L 3, L 4,
..) Are divided into a plurality of stages (levels 1, 2,...) According to the inrush current of the equipment included in each load, the frequency of starting and stopping, and the like. For example, level 1: ΔT = 5 seconds, level 2: ΔT
= 20 seconds, level 3: ΔT = 10 minutes, and an appropriate dead time ΔT is associated with each other, and the duration T of the change in the power consumption of each load exceeds the dead time (T> Δ).
T) At this time, the change in the amount of power is included in the power difference between the phases. The setting of the dead time ΔT may be performed by providing a timer in the control circuit 4 in each switch (see FIG. 3), or may be performed by software on the central control unit 2 side. In addition, the dead time fluctuation width ΔW which is not regarded as a significant power fluctuation width instead of the dead time
May be set at a plurality of levels, or ΔT and ΔW may be individually determined for each load, and more precise control may be performed.

Next, an embodiment shown in FIG. 2 shows an embodiment in which the present invention is applied to a three-phase generator, and has substantially the same configuration except that each pair of three-pole switches is used as a switch. is there. FIG. 3 shows an embodiment of the third aspect of the present invention, wherein a semiconductor switch 6 such as a thyristor is connected in parallel to a mechanical relay contact 5 as the switch (S1, S2,...). Yes, the current is bypassed by the semiconductor switch 6 for a very short time until the mechanical contact 5 responds. According to this configuration, it is possible to manufacture a high-speed switch relatively inexpensively, and by using this to subdivide the load, a very low-cost instantaneous interruption switch compared to all semiconductor switches can be manufactured. Can be configured.

[0009]

According to the present invention, as described above, switching can be performed while always watching the actual power consumption of each load (L1, L2,...), Thereby preventing voltage imbalance and output reduction. Since the load can be prevented, a load that could not be connected due to an operation rate or an inrush current can be connected to the private power generator side with ease without any problem. Even if the load recovers within a few seconds or a load recovers within a few minutes, the dead time ΔT is set in a plurality of stages, so that the load can be unnecessarily dealt with in response to temporary fluctuations. There is an advantage that it is possible to prevent the switching from being performed and prevent the wear and operation of the relay contact from becoming unstable, and further, as a switching device that requires frequent switching as in claim 3,
By using a mechanical relay contact with a semiconductor switch connected in parallel, it is possible to produce a high-speed switch relatively inexpensively, and by using this to subdivide the load, compared to all semiconductor switches. However, there is an advantage that an extremely low-cost instantaneous interruption type switch can be configured.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention.

FIG. 2 is a circuit diagram of another embodiment of the above.

FIG. 3 is a circuit diagram of a high-speed switching device used in the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single-phase three-wire or three-phase generator 2 Central control unit 3 Fuse 4 Control circuit 5 Mechanical contact 6 Semiconductor switch L1, L2, ... Load S1, S2, ... Switch

Claims (3)

[Claims] 1. A part of a load connected to each phase of a single-phase three-wire power supply or a three-phase power supply is divided into a plurality of parts, and the divided loads are connected to each phase via a switch. By controlling the switch by a centralized control unit that monitors the amount of power used, when the power difference between the phases exceeds a certain value, the divided loads are switched to maintain the balance between the phases. A power supply device, characterized in that: 2. The divided loads are divided into a plurality of types according to the inrush current of equipment included in each load, the frequency of starting and stopping, and the like, and an appropriate dead time is assigned to each type. 2. The power supply according to claim 1, wherein when a change in the amount of power used by the load exceeds a fixed value longer than the dead time, the change in the amount of power is included in the power difference between the phases. apparatus. 3. The power supply device according to claim 1, wherein a high-speed switch in which a semiconductor switch is connected in parallel to a mechanical relay contact is used as the switch.