JPS6359732A - Parallel entry of busbars into induction generator - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for connecting parallel busbars to an induction generator.

(Conventional technology) Recently, as one direction for energy saving measures, large-scale production plants have started to use waste gas from blast furnaces and other gas turbines that were previously discarded, and to use surplus steam from process evaporation systems. The use of steam turbine power generation equipment is becoming a reality.

The purpose of these facilities is to save energy; for example, an induction generator, which does not require an exciter and is extremely inexpensive, is used as a power generating material. Although this induction generator does not require an exciter, it must be operated in parallel with a power system that includes a synchronous machine during power generation in order to obtain reactive power that lags behind an external power bus and use it as an excitation source.

Also, when connected to the bus bar, an inrush current of 5 to 10 times the rated current flows, unlike a synchronous generator, which cannot generate its own voltage.

Figure 2 is a power system diagram showing an example of the method for paralleling the induction generator to the bus bar as shown in d% Publication No. 60-56381. The receiving transformer receives the staining force, 3 is the load, 4 is the synchronous generator,
5 is a reactor, 6 is a short circuit breaker for reactor 5,
7 is a bus line.

Next, the operation will be explained.

In this power system, power is received by power receiving transformer 2, and load 3
When power is being supplied to the receiving transformer 2, synchronous generator 4
are operated in parallel to supply power to the load 3. However, when the induction generator 1 is connected to the bus 7 in parallel, an inrush current flows and causes a drop in the bus voltage.
Connect to bus bar 7. Therefore, in the method of parallel connection to the busbars shown in Fig. 2, the inrush current when the induction generator L is connected in parallel is suppressed by the reactor 5, and after the inrush current has attenuated, the reactor 5 is short-circuited by the short-circuit breaker 6 to restore normal operation. I'm trying to get him to drive.

In addition, Fig. 3 is a power system diagram showing another example of the method of connecting induction generators in parallel to the bus bar. In the figure, 8 is a synchronous generator operated in parallel with induction generator 1, and 9 is an induction generator. This is a system isolation breaker for separating the machine side bus bar 10 and the load side bus bar 7, and the same components in FIG. 3 as in FIG.

Next, the operation will be explained.

The system isolation breaker 9 between the load side bus 7 and the induction generator side bus 10 is opened so that the bus voltage drop due to the rush current when the induction generator 1 is connected in parallel to the bus does not affect the load 3. After charging the induction generator side bus 10 by the synchronous generator 8, the induction generator 1 is inserted into the induction generator side bus. After the inrush current has attenuated, the system isolation breaker 9 is synchronously turned on.

(Problems to be Solved by the Invention) Since the conventional method for arranging induction generators in parallel with busbars is configured as described above, it is possible to arrange induction generators in parallel with busbars using the nine power system diagram shown in Figure 2. In the case of parallel installation, there was a problem in that a reactor 5 and a short-circuit breaker 6 had to be provided, which are not used at all after the parallel installation. Furthermore, when installing an induction generator in parallel to the bus using the power system diagram shown in Fig. 3, a system isolation breaker 9 and a synchronous generator 8 are required for parallel installation, so the synchronous generator 8 and Each of the induction generators 1 requires a prime mover, which poses a problem in that an excessive investment must be made.

This invention has been made to solve the above-mentioned problems, and it is an object of the present invention to obtain a method for parallel connection of an induction generator to a bus bar, which can prevent rush current when the bus line of an induction generator is connected without excessive investment. With the goal.

(Means for Solving the Problems) A method for connecting an induction generator in parallel with a busbar according to the present invention is a method for generating the induction generator electrically connected to a synchronous generator used for supplying excitation current to the induction generator. After the induction generator reaches a predetermined rotational speed, the field current of the synchronous generator is increased, and the output voltage of the synchronous generator is increased to excite the induction generator. After completion, a breaker installed between the busbar and the induction generator is turned on synchronously to prevent inrush current when the induction generator is connected to the busbar to which the synchronous machine and load are connected.

(Function) The method of paralleling the induction generator to the busbar in this invention controls the field current of the synchronous generator, and supplies the excitation current of the induction generator to the synchronous generator, thereby eliminating inrush current. It becomes possible to excite the induction generator with Since the induction generator is connected in parallel to the bus bar, the synchronous generator and the bus bar are connected in parallel, so there is no voltage drop on the bus bar, and the induction generator can be easily supplied.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a power system diagram for explaining one embodiment of the present invention, and the same parts in FIG. In FIG. 1, reference numeral 20 denotes a synchronous generator, which is used to supply exciting current to the induction generator 1. 21 is a transmission mechanism such as a clutch that directly connects the induction generator 1 and the synchronous generator 20, and this transmission mechanism 21 is not directly connected until the induction generator 1 is connected to the bus bar 7. They are controlled so that they are separated after being inserted. 22 is an excitation device for the synchronous generator 20, and 23 is a breaker provided between the bus bar 7 and the induction generator l.

Next, the operation will be explained.

When the induction generator 1 and the synchronous generator 20 are started by directly connecting the transmission 21, the excitation device 21 of the synchronous generator 20 is stopped or kept at a constant minute output. Then, the induction generator 1 is started while electrically connected to the synchronous generator 20, and after the rotational speed of the induction generator 1 reaches a specified value, the output of the excitation device 22 is gradually increased. In particular, the output voltage of the synchronous generator 20 increases, and the induction generator 1 is excited as the output voltage of the synchronous generator 20 increases, so no inrush current flows. Since the induction generator 1 and the synchronous generator 20 are directly connected, their rotational speed is the same, and the frequency generated by the synchronous generator 20 is equal to the rated frequency because it supplies only the excitation current of the induction generator 1. However, it is small.

After completing the excitation of the induction generator 1, synchronization is verified between the bus 7 and the output of the synchronous generator 20, and a breaker 23 between the induction generator 1 and the bus 7 is connected and connected in parallel. At the time of parallel entry, the induction generator 1 has been completely excited, so there is no inrush current from the bus 7, so there is no voltage drop on the bus 7.

After the parallel connection, the transmission mechanism 21 is disconnected, and the synchronous generator 20 is operated as a synchronous motor to supply excitation current (delay) to the induction generator 1. Excitation current (delay) is also unnecessary.

In the above embodiment, the induction generator 1 and the synchronous generator 20 are directly connected to the transmission mechanism 21, but the transmission mechanism 2
1 may be removed and the synchronous generator 20 may be driven by an electric motor, and the same effect as in the above embodiment can be obtained.

(Effects of the Invention) As described above, according to the present invention, the induction generator is excited by the synchronous generator before it is connected to the bus bar, so that an inrush current does not flow when the induction generator is connected to the bus bar. There is no drop in bus voltage, and an inexpensive induction generator can be used even for small-scale capacity buses.

[Brief explanation of drawings]

FIG. 1 is a power system diagram for explaining a method for paralleling an induction generator to a bus line according to an embodiment of the present invention, and FIG. 2 is a power system diagram for explaining an example of a method for paralleling a conventional induction generator to a bus line. The system diagram and FIG. 3 are power system diagrams for explaining another conventional example. 1 is an induction generator, 3 is a load, 4 is a synchronous generator, 7 is a bus bar, 20 is a synchronous generator, and 23 is a breaker. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] In a method for connecting an induction generator in parallel to a bus bar connected to a synchronous machine and a load to prevent inrush current that occurs when an induction generator is connected in parallel to a bus bar connected to a synchronous machine and a load, a synchronous generator used for supplying excitation current to the induction generator and an electric The induction generator is started with the induction generator connected to the synchronous generator, and after the induction generator reaches a predetermined rotational speed, the field current of the synchronous generator is increased, and the output voltage of the synchronous generator is increased. Excite the above induction generator,
A method for connecting an induction generator in parallel with a busbar, characterized by synchronously closing a breakout switch provided between the busbar and the induction generator after excitation is completed.