JPH02311187A - Starting method for combined cycle generating plant - Google Patents

Abstract

PURPOSE:To save man power by operating one of a plurality of generators as a variable frequency generator and operating other generators as synchronous motors. CONSTITUTION:In a combined cycle generating plant, three sets of turbine generators 2A-2C are connected through a generator interrupter 3 and a booster 4 with a generating bus 1. A starter motor 7 is connected through an interrupter 9 and a VVVF unit 10 with an independent starting bus system 8. One variable frequency generator and other synchronous motors are connected with a main circuit, then the speed of the variable frequency motor is increased gradually thus generating power. Consequently, rotary speed of other synchronous motors increases synchronously with the speed of the variable frequency generator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a combined cycle power plant.

(Prior Art) The conventional technology will be explained with reference to FIGS. 3 and 4.

In conventional combined cycle power plants, at startup,
It is necessary to control the rotation speed at 10% to 70% of the rated rotation speed of the gas turbine. For example, as shown in FIG. Installed to control speed. Since the hydraulic clutch 13 and starting electric motor 7 are attached to the two shafts of each generator, additional settings such as a control device, oil piping, and motor opening/closing device are also increased, which increases the installation space and cost of the combined cycle power generation plant. This causes problems such as complexity of maintenance.

Recently, in order to solve these problems, as shown in Fig. 4, the generator 2D is used as a synchronous motor at startup, and the generator 2D is started as a synchronous motor with variable speed control by the inverter device 12 installed in the main circuit. A method has been devised that allows this to occur, and this method is called the static star evening method.

Even in this static starter system, harmonic components are generated by the inverter, so it is necessary to take countermeasures against harmonics, such as installing a full-length damper on the generator rotor. This requires drawing out the circuit, which complicates the circuit and causes an increase in cost. Also, if you use a method of starting multiple generator shafts with one inverter starting device, 1
Since other axes cannot be started until one axis has been completely started, this places significant restrictions on operation and eliminates the greatest advantage of a combined cycle power plant, which is the ability to start up in a short time and operate at rated load.

As a result, an inverter starting device had to be provided for each axis, resulting in an increase in installation space.

(Problem to be Solved by the Invention) As described above, the conventional combined cycle power generation plant requires a lot of ancillary equipment such as a hydraulic clutch and a starting electric motor, and has drawbacks such as increased cost and complicated maintenance. In addition, even in the conventional static starter system, there is a need for an inverter starting device for each shaft and harmonic countermeasures for all generators, making the device complex, increasing costs and reducing reliability. This results in a decline in

The present invention was made in view of the above-mentioned drawbacks, and takes advantage of the inherent merits of a combined cycle power generation plant that it can be started up and operated at rated load in a short time, while simultaneously starting up and controlling speed at the same time to simplify the equipment. The purpose of this invention is to provide a method for starting a combined cycle power plant that can perform the following steps.

- [Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, in the present invention, in a combined cycle power generation plant equipped with a plurality of generators, one of the generators is controlled by a variable frequency generator. By connecting a starting motor driven by a power source and operating it as a variable frequency generator, the other generator is operated as a synchronous motor,
By controlling the speed of the generator connected to the starting motor, the other generators are raised to the ignition speed of the gas turbine, the gas turbine is ignited, and each generator is controlled to the same speed to increase its rotation, thereby operating as a synchronous generator. Perform simultaneous startup.

(Function) The present invention is configured as described above, and for example, one variable frequency generator and another synchronous motor are connected through a main circuit to generate electricity while gradually increasing the speed of the variable frequency generator. As a result, the other synchronous motors increase their rotation in synchronization with the variable frequency generator, so by controlling the speed of one generator, it is possible to control the speed of the other shafts as well, and the speed can be increased to the ignition speed of the gas turbine. It is now possible to start.

(Example) An example of the method for starting up a combined cycle power plant according to the present invention will be described with reference to the drawings.

In Fig. 1, three turbine generators 2 are installed on a power generation bus 1.
A, 2B, and 2G are connected via a generator breaker 3 and a step-up transformer 4, respectively. Turbine generator 2
The gas turbine 5A and the starting electric motor 7 are directly connected to the shaft, and the gas turbine 5 and the steam turbine 6 are directly connected to the turbine generator 28.2G.

The starting motor 7 is connected to a starting bus 8 that is separate from the power generation bus 1.
9. It is connected via the VVVF device IO.

The operation of the next embodiment will be explained.

Turn on each generator breaker 3 before starting.

Next, the starting motor 7 is set to Q rpm by the VVVF device IO.
Gradually increase the speed.

The turbine generator 2A generates electricity at a frequency according to the rotation speed,
When a field current is applied to the turbine generator 28.2C, the turbine generator 28.2C rotates as a synchronous motor synchronized with the power frequency of the turbine generator 2A.

The starting motor 7 is further accelerated by the variable frequency power supply (VVVF) 10 to reach the ignition speed of the gas turbine 5A. At this time, the gas turbine 5 directly connected to the turbine generators 2B and 2C also changes the ignition speed at the same time. i can be ignited at once.

After the gas turbines 5 and 5A are ignited, they are controlled to the same speed and their rotations are increased, and when the output of the gas turbine exceeds the power related to shaft rotation, the turbine generators 2B and 2C are switched from synchronous motors to synchronous motors that are synchronized with the turbine generator 2A. It becomes a generator.

The startup of the combined power generation plant is completed by synchronously joining the power generation bus 1 to the grid.

In this way, in the method for starting a combined cycle power plant according to the present invention, the hydraulic clutch that was conventionally installed on each generator shaft can be removed, and the starting motor can also be installed on one arbitrary generator shaft. Furthermore, compared to the method of starting the generator with a static starter, no countermeasures against harmonics of the generator are required, and the starting device only requires one arbitrary generator shaft, making it possible to start multiple shafts at the same time and ignite the gas turbine.

In addition, since each generator starts up in synchronization, it only needs to be connected to the grid once, further shortening the start-up time.

Next, other embodiments of the present invention will be described with reference to the drawings.

In the above embodiment, an induction motor was used as the starting motor, and a variable frequency power supply was used to control its speed. The speed may be controlled by the device, and in this case, after the gas turbine is ignited, it can also be used as a synchronous generator. Furthermore, a case in which auxiliary steam is supplied to a steam turbine waiting to be started and a plurality of steam turbines are simultaneously started by controlling the rotation speed of the steam turbine also corresponds to the gist of the present invention.

In the above embodiments, a single-shaft combined cycle power plant has been described in which the steam turbine, gas turbine, and generator are on one shaft, but the gas turbine and the steam turbine are on separate shafts.

〔Effect of the invention〕

As explained above, according to the present invention, the cost of the starting device can be significantly reduced without sacrificing the advantages of short startup time and rated load operation of the combined cycle power generation plant, and a low cost combined power generation plant can be provided.
In addition, maintenance can be simplified by reducing the number of mechanical parts and equipment, making it possible to save labor and improve reliability.

[Brief explanation of the drawing]

FIG. 1 is a single line diagram for explaining an embodiment of the method for starting up a combined cycle power plant of the present invention, and FIG.
The figure is a single line diagram showing another embodiment of the present invention, Figure 3 is a single line diagram of a conventional combined cycle power generation plant using a hydraulic clutch, and Figure 4 is a conventional combined cycle diagram using a static starter. A single line diagram of a power plant is shown. 1... Power generation bus 2, 2A, 2B, 2G... Turbine generator 3.
... Generator breaker 4 ... Step-up transformer 5.5A.
... Gas turbine 6 ... Steam turbine 7 ... Starting electric motor 8 ... Starting bus bar 9 ... Breaker
10...VVVF device Figure 1

Claims (1)

[Claims] In a combined cycle power generation plant equipped with a plurality of generators, one of the generators is operated as a variable frequency generator by connecting a starting motor driven by a variable frequency power source, and using the generated power of the generator. The other generator is operated as a synchronous motor, and by controlling the speed of the generator connected to the starting motor, the other generator is increased to the ignition speed of the gas turbine to ignite the gas turbine, and each generator is controlled to the same speed. 1. A method for starting a combined cycle power generation plant characterized by increasing the rotation speed and operating as a synchronous generator for simultaneous startup.