JPS6032526A - Reactive power controller of composite generating plant - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a reactive power control device for a combined cycle power plant (hereinafter referred to as a combined cycle) formed by combining a plurality of gas turbines and steam turbines.

[Technical background of the invention and its problems] One method of improving the efficiency of the power generation system as a whole is to generate steam using gas turbine U1 air, drive a steam turbine with the steam, and drive the gas turbine and the steam turbine. Combined cycle systems have recently come into use, in which the combined driving forces of two motors rotate a generator to generate electricity.

FIG. 1 shows an example of the configuration of the above-mentioned combined cycle.

Gas turbine 1. The steam turbine 22 and the generator 3 are coupled on one shaft, and the output of the generator 3 is boosted by the main transformer 4 and then connected to the grid 6 via the breaker 5.

The output of the generator 3 used is one with a small to medium capacity of about 100 MII, and a plurality of the above systems (about 5 to 6) are connected in parallel to form one power generation plant.

When a plant is configured with multiple generators in this way, there is an advantage that even if the -shaft breaks down, it does not have a major impact on the generated wind as a whole, but the increased number of generators means that all operators Since it is not possible to increase the number of units, a control device is required to control multiple units together as one system.

FIG. 2 shows a schematic control block diagram of a reactive power control device as one of the two control devices. A reactive power command value is generated by an integrator 9 via a change rate limiter 8 in response to a reactive power increase/decrease command 7 from a central power supply station or a manual switch of an operator. After being limited by the upper and lower limit controller 10 determined by the number of operating units, the reactive power 12 of each axis is input to the comparator 11.
are added together by the adder 13 and compared. The comparator 1 compares the command value and the actual value of reactive power, and only the difference is input to the distributor 14 to distribute the target reactive power to each axis. - The reactive power target value indicated in F is input to each axis control section J5, and the rate of change limiter 16. After setting the upper and lower limit limiter 17, the comparator 18 compares it with the actual reactive power 19 of the axis being controlled, and the difference between the two is used as a reactive power increase/decrease command to set the excitation amount of the generator [ 20, and the voltage setting device 22 of the automatic power regulator (hereinafter referred to as AVR) 21 is inputted to the reactive power increase/decrease command.

AVR is a device that controls the excitation current of the generator to adjust the voltage of the generator, but it is connected to the generator input power system Mt, and when the system voltage remains constant, If you increase the excitation current, the reactive power <S>, and if you decrease the excitation current, the reactive power will decrease. In other words, controlling the increase/decrease of reactive power in AVR is basically a waste of time.

FIG. 3 shows an example of a configuration diagram of an excitation device. This figure shows a typical example of the wood-isiri-hasu-r lister direct excitation method. Thyristor direct excitation and I'j: Figure 3 [The output voltage of the iron generator 23 is reduced to an appropriate voltage level by the excitation transformer 24], and then rectified by the thyristor stub 1 node 25. The excitation method is to supply the field winding 27 via the field breaker 26, and since the output is used as the excitation source for the power generator 4 and 23, no other excitation source is required. It is an excitation method. Conventionally, as an excitation device, AVR is used to adjust the output voltage of the generator to the set value of the generator.
21, and a constant excitation regulator (hereinafter referred to as AEC) 28, which performs control to adjust the field current to a certain set value when the AVIt 21 fails or to adjust the field current to a certain set value.

When the control is performed by the AVR 21, the output voltage of the generator 23 is transferred to the AVR 2 via the M1 power transformer 29.
1, and a pulse signal is sent to the gate 1- of each thyristor bridge 25 to control the excitation current so as to match the set value of the voltage setting device 22 of the AVR 21. The output voltage and current of the generator is over-excited via the voltage transformer 29 or current transformer 30.

A signal is sent to the AVR 21 from each limiter 31 for low excitation, etc., and the amount of excitation is limited so as not to exceed the stable operation limit.

When control is performed by the MEC 28, the field voltage or field current is input to the MEC 2g, and a pulse signal is sent to the gate of each thyristor of the thyristor bridge 25 so that this value matches the setting value of the voltage setting device 32. is sent to control the excitation current.

The difference between the control by the AVR 21 and the control by the port C28 is whether the voltage setting value 22.32 is compared with the generator terminal voltage or the field voltage and current. When the generator is connected to the grid, if the grid voltage fluctuates, the generator voltage will also fluctuate. At this time, when the AVR is used for control, the excitation current is controlled in a direction that suppresses voltage fluctuations, thereby improving the stability of the entire system.

On the other hand, when the MEC is used for control, the amount of excitation is not changed even if the system fluctuates, so no improvement in the stability of the system can be expected.

For this reason, conventionally, the AVR performs control during normal operation, and the NlEC performs control only when the AVR fails or starts up. That is, A
During MBC control due to a VR failure, the operator monitors conditions such as the state of the system for 6t when there is an intermediate supply command, and if the NEC voltage setting device is manually changed, 5t operation is performed.

However, in a combined cycle, multiple generators are controlled as if they were one unit, so if the AVR of a certain axis fails, the operator can control the MBC of that axis.
voltage setting device; manual control is difficult.

Therefore, in the conventional reactive power control device for the combined cycle, control was performed to trip the failed shaft due to the AV or R failure. However, according to this conventional method, since a combined cycle has multiple axes forming one plant, even if one axis is 1-ripped, the effect on the whole is smaller than in a plant other than the combine 1-cycle. However, there was a problem in that even if the L axis was tripped, it would cause considerable disturbance to the grid.

[Object of the Invention] The present invention enables MEC
The object of the present invention is to provide a reactive power control device for a combined power generation plant that allows continuous operation.

[Summary of the Invention] Therefore, the present invention performs MIEC operation on the failed axis of the AVH at a preset value, subtracts the reactive power from the reactive power command value, and applies the subtracted 9 command value to each AVH. This feature is characterized in that the variation in reactive power is adjusted by the normal AVR by distributing it to the AVR.

[Embodiments of the invention] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 shows a control block diagram of a reactive power control device showing an embodiment of the present invention, and in the figure, the same reference numerals as in FIG. 2 indicate the same or Ainuma parts. The difference in the configuration of the diagram from that in FIG. The difference is that the total value is subtracted and the output thereof is input to the change rate limiter 8.

In other words, the idea is that the reactive power of the axes that are not in AVR automatic operation is subtracted in advance and then used as the reactive power command value.

Next, the output of the upper and lower limit limiter 10 is compared in a comparator 11 with a value obtained by adding AVI+reactive power 37 of the shaft during automatic operation in an adder 13. This is because the reactive power of the non-AVR automatic operation axis has already been subtracted, so reactive power feedback is considered only for the AVR automatic operation axis. Next, the distributor 14 distributes the target value of reactive power to each axis during AVR automatic operation and sends a signal to each axis control section 15.

Hereinafter, the same control as described above with reference to FIG. 2 is performed for the axes during AVR automatic operation.

On the other hand, the AVlt failed and the operation of the excitation system [20 was t・lE].
The axis that has transitioned to control by C28 manually inputs the reactive power setter 38 at the time of AVR failure and the actual reactive power 19 of the axis being controlled to the comparator 39, and is closed when it transitions to NEC control due to AVR failure. The voltage setter 32 of the MEC 2B is controlled via the contact 4o.

At this time, the setting value of the reactive power setting device 38 can be selected arbitrarily, but the load that the generator can stably bear is the maximum when the reactive power is zero, that is, the power factor is "1". Therefore, the set value should be set to zero.

In this way, if the AVR malfunctions, the AVR control
For the axes that have transitioned to EC control and then NEC control, set the reactive power to zero or an arbitrary value.

By subtracting the reactive power of the non-AVR automatic axes from the command value in advance and controlling the reactive power only with the AVR automatic axis, even if the AVR malfunctions, the operator does not have to constantly monitor and control it. It becomes possible to continue driving.

In the above embodiment, the excitation system was explained using the Zyristor direct system, but it goes without saying that other systems can provide the same effects.

Further, it is also possible to use a reactive power relay in place of the reactive power setter 38 and comparator 39 in the above embodiment.

[Effects of the Invention] As described above, according to the present invention, even when the AVR breaks down, it is possible to continue automatic operation using the MEC without placing a burden on the operator.

[Brief explanation of the drawing]

Figure 1 shows the groove diagram of a typical combined cycle, Figure 2
The figure is a control block diagram of a conventional reactive power control device applied to the combined cycle, Figure 3 is a configuration diagram of a general excitation device using the Zyristor direct excitation method, and Figure 4 is applied to the combined cycle of Figure 1. 1 is a control block diagram of a reactive power control device according to an embodiment of the present invention; FIG. 7 ・Increase/decrease command, 8 ・Change rate limiter, 9.33 °
・Integrator, 10・ Upper and lower limit controller, 1.1, 18.39
Comparator, 13, 3 (i Adder, 14 Distributor, 1
5. Each axis control section, 16. Variable 1 hit rate limiter, 17.
Upper and lower limit limiter, 19...Actual reactive power, 20...Exciter, 21...=AVR122, 32-Voltage setting 1B,
28...NEC, 34...Subtractor, 35.37...
Reactive power, 38 Reactive power setting device, /IO... Contact.

Claims (1)

[Claims] In a combined power generation plant consisting of multiple gas turbines, steam turbines, and generators connected on a single shaft, the generators on each shaft are controlled by an automatic voltage regulator or constant excitation regulator, thereby eliminating the power of the entire plant. In a reactive power control device for a combined power generation plant that controls electric power, there is provided a means for subtracting a total H1 value of reactive powers of axes whose excitation is controlled by a constant excitation regulator from a reactive power command value; 1. A reactive power control device for a combined power generation plant, comprising means for distributing the reactive power command value to the shafts undergoing excitation control using an automatic voltage regulator.