JPS6010496B2 - Induction generator control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an induction power generation system which limits the excitation inrush current to the minimum when connecting a concessional generator to the grid, and minimizes grid voltage fluctuations due to the connection of an induction generator. This relates to the control device of the machine.

When connecting an induction generator to the grid, if the capacity is small, connect it directly with a three-pole contactor, and the inrush current should be several times the rated current, including not only the excitation inrush current but also the starting current. It has even reached a certain extent.

Figure 1 is an example, where IG is an induction generator, AN, BN, C
N is the stator winding of the induction generator, N is the neutral point, and S is the three-pole contactor. In this case, only the contactor S is turned on.
As the capacity of the induction generator increases, the inrush current becomes enormous, the system voltage fluctuations affecting the connected system also become large, and the adverse effects on the loads connected to the system cannot be ignored.

In the case of a large-capacity machine, in order to limit the starting current (accelerating current), before turning on the contactor S, the rotor of the induction generator is rotated up to the synchronous speed, and the synchronous speed rotation is maintained. By inputting , the starting current (acceleration current) length can be omitted.

However, most of the remaining excitation inrush currents still reach several times the rated current, and the negative impact on the system cannot be ignored. As a countermeasure to this problem, a method has been considered in which the highest value of the system voltage is detected and a thyristor switch is used instead of the contactor S to connect to the system at the time when the maximum value is reached.

However, the thyristor switch is also somewhat expensive, and a low-cost system using this is required. The present invention aims to provide an inexpensive induction generator control device that eliminates excitation inrush current by connecting thyristor switches only to two phases without using thyristor switches for each of the three phases. purpose. An embodiment of the present invention is shown in FIG.

IG is the induction generator, AN, BN, CN are the stator windings of the induction generator, N is the neutral point, SCR,, SCR2, SCR
3. SCR4 is a thyristor that constitutes a thyristor switch. In the embodiment shown in FIG. 2, the rotor of the induction generator is considered to be cage-shaped.

The rotor is rotated at a synchronous speed to eliminate accelerating current. First, the line voltage between the R phase and the T phase is detected, and at this maximum value, a control device (not shown) gives an ignition signal to the R phase thyristor switches SCR and SCR2, making them conductive. Next, the point in time when the phase voltage of the S phase reaches its maximum value is detected, and similarly, a control device (not shown) applies an ignition signal to the S phase thyristor switches SCR3 and SCR4 to bring them into the conductive state. By controlling in this way, the excitation inrush current can be controlled to zero. In this way, R in the three phases,
Thyristor switches are installed only in the two phases of the S phase,
The fact that the excitation inrush current can be completely eliminated in the same manner as when a thyristor switch is provided in three phases allows the number of expensive thyristors to be reduced by two-thirds, and the objective can be achieved at low cost.
If the stator winding of the induction generator in the above embodiment is considered to be the primary winding of the transformer, a completely similar phenomenon can be considered in the case of the transformer.

That is, if the control device of the present invention is adopted even when a transformer is connected to a power system, the excitation inrush current can be completely controlled, the number of thyristors can be reduced to 2/3, and an inexpensive control device can be provided. I can do it.

Further, as shown in FIG. 3, if contactors K, K2 are provided and the thyristor is short-circuited after being made conductive, the thyristor capacity can be reduced and a more inexpensive control device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram of a conventional device, FIG. 2 is a connection diagram showing one embodiment of the present invention, and FIG. 3 is a connection diagram showing another embodiment of the present invention. IG...concession generator, S...triode contactor, SCR, ~4
...Thyristor switch, K,,K2...
・Contactor. *1 Evil hatred 2 Evil No. 38

Claims (1)

[Claims] 1 When connecting a three-phase induction generator to a grid, detect the highest line voltage of two phases in the grid, connect the two phases at the time of the highest value, and then connect the other one phase to that phase voltage. A control device for an induction generator characterized by connecting to the grid at the point of maximum value.