JP2009085182A - Combined cycle power generation plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a load follow-up delay when an output increasing device is started corresponding to the increase of a load demanding command. <P>SOLUTION: When an output increasing device is stopped, a prediction value of a load demanding command for a next period or plural periods after the next period is determined using a load demanding command inputted periodically of every setting period as an actual value, and it is judged whether the prediction value of the load demanding command for each period exceeds a rated power generation of a power generation plant or not. When the prediction value of at least one period exceeds the rated power generation, a starting command is outputted to an output increasing device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a combined cycle power plant, and more particularly to start / stop control of an output increasing device that increases the output of a gas turbine and a steam turbine that constitute the combined cycle power plant.

  A combined cycle power plant is known as a power plant that generates power with high efficiency. In the combined cycle power plant, steam is generated using the heat of exhaust gas discharged from the gas turbine, the steam turbine is driven by the generated steam, and the generator is driven by the gas turbine and the steam turbine. It is configured. Thus, the combined cycle power plant can achieve high-efficiency power generation by effectively using the thermal energy of the exhaust gas of the gas turbine.

  Furthermore, in order to increase the output of the combined cycle power plant, an auxiliary combustion device that heats the exhaust gas of the gas turbine to raise the temperature, or a power increase device such as a cooler that cools the combustion air of the gas turbine may be used. is there.

  The auxiliary combustion device sprays fuel on the exhaust gas of the gas turbine and burns the fuel to raise the temperature of the exhaust gas, thereby increasing the amount of steam generated, increasing the output of the steam turbine, and increasing the power generation output Let

  The cooler that cools the combustion air of the gas turbine cools the air that flows into the compressor and increases the mass of the air that flows into the compressor, thereby increasing the fuel that can be burned in the combustor of the gas turbine. Increase the output of the gas turbine. At the same time, as the flow rate of the gas turbine exhaust gas increases, the amount of steam generated increases and the output of the steam turbine increases. Thus, by providing the cooler for the combustion air of the gas turbine, the gas turbine output and the steam turbine output are increased, so that the power generation output of the combined cycle power plant can be increased.

  As an example of the activation control of the output increasing device, Patent Document 1 proposes starting the activation when the load request command increases and the output is insufficient unless the output increasing device increases the output.

JP 2006-57580 A

  However, since the output increasing device has a certain time delay from when it is activated until the output actually increases, according to the method of Patent Document 1, it is not possible to quickly respond to an increase in the load request command. There is a problem.

  That is, when starting the auxiliary combustion device, a certain start-up time is required from the preparation for starting the fuel supply system, such as fuel purge, to the completion of ignition. A few minutes) can not be avoided. Even in the case of a gas turbine combustion air cooler, a certain start-up time is required from when the refrigerator is started until the air is actually cooled by the cooler, thus avoiding load follow-up delay. I can't.

  In order to avoid such a load follow-up delay, it is conceivable to wait in a state where the output increasing device is activated even when it is not necessary. However, when the output increasing device is always operated, there is a problem that wasteful fuel is consumed, chiller power is wasted, and the power generation efficiency of the power plant is reduced.

  The problem to be solved by the present invention is to reduce the load follow-up delay when starting the output increasing device in response to an increase in the load request command.

  In order to solve the above-described problem, the present invention provides a power generation amount control device that controls a power generation amount based on a load request command that is input every set cycle. A predicted means for obtaining a predicted value of the load request command for the next cycle or a plurality of cycles after the next cycle using the load request command to be a performance value, and the predicted value of the load request command for each cycle as a result Determining means for determining whether or not to exceed, and a start control means for outputting a start command to the output increasing device when the predicted value for at least one cycle by the means exceeds the rated power generation amount. Features.

  That is, according to the present invention, a predicted value of a future load request command is obtained for each set cycle, and when it is determined that the predicted value exceeds the rated power generation amount of the power plant, the output increasing device is started in advance. It is. Therefore, since the output increasing device is started before the load request command actually increases, the load follow-up delay can be reduced by the time for starting in advance. Therefore, according to this invention, since it is not necessary to always start an output increase apparatus, the fall of power generation efficiency can be suppressed.

  Here, the rated power generation amount of the power plant refers to the power generation amount that can be generated by the gas turbine and the steam turbine in a state where the output increasing device is not operated. By the way, since the gas turbine uses ambient air as combustion air, the mass of the intake air varies depending on the temperature of the ambient air, and thus the output of the gas turbine also varies. Therefore, it is preferable to correct the rated power generation amount, for example, according to the temperature for each set cycle.

  Further, the purpose of obtaining the predicted value of the load request command for a plurality of future cycles based on the actual value of the load request command for a plurality of cycles is to supply the power generation output of the power plant of the present invention to the load by power consignment. It considers the same amount of constraints. For example, the simultaneous equal amount condition is a condition that the average power amount for a predetermined reference time (for example, 30 minutes) is kept within the contract power amount. In order to satisfy this condition, the penalty time is generally avoided by dividing the reference time into multiple sections, adjusting the power generation amount of each section, and keeping the average power amount within the contracted power amount. Control is being performed. The present invention calculates the predicted value of the load request command at the next reference time (for example, 30 minutes) at every set period (for example, 5 minutes) at the current reference time, assuming this simultaneous operation of the same amount. In order to satisfy the same amount of power at the next reference time, when the power generation amount in a specific set cycle exceeds the rated power generation amount, the simultaneous operation of the same amount can be satisfied by starting the output increasing device early. It becomes easy.

  In the case of simultaneous same amount operation, the predicted value of the next cycle by the prediction means is a value obtained by adding the upper limit value of the load request command that can be operated at the same amount to the actual value of the load request command in the current set cycle. It is possible to provide a determination means for determining whether or not the value exceeds the value, and to include a start control means for outputting a start command to the output increasing device when the determination is affirmative. Here, the increase width (upper limit) of the load request command that can be operated at the same time can be confirmed in advance by simulation and set in the database. For example, when the output is xMW, it is set so that it can be increased to yMW. In addition, experience values can be made into a database after the start of actual operation.

  ADVANTAGE OF THE INVENTION According to this invention, the load follow-up delay at the time of starting an output increase apparatus corresponding to the increase in load request | requirement instruction | command can be reduced.

  Hereinafter, an embodiment of a combined cycle power plant (hereinafter referred to as a power plant) of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram of a start / stop control device for an output increasing device, which is a characteristic part of a power plant according to the present invention. FIG. 2 is a block diagram showing an outline of the configuration of the power plant according to the present invention. FIG. 3 is a flowchart illustrating an embodiment of a startup control procedure of the output increasing device. 4 and 5 are timing charts for explaining the operation of starting control of the output increasing device. FIG. 6 is a flowchart showing an embodiment of a stop control procedure of the output increasing device.

  As shown in FIG. 2, a generator (G) 2 and an air compressor (AC) 3 are connected to a gas turbine (GT) 1, and the gas turbine 1 burns fuel with high-pressure air discharged from the air compressor 3. Driven by the combustion gas supplied from the combustor 4, the generator 2 is driven to generate power. The exhaust gas that has driven the gas turbine 1 is guided to an exhaust heat recovery boiler (HRSG) 5, which generates steam by heating the feed water supplied from a water supply source (not shown), and the exhaust gas that has circulated through the exhaust heat recovery boiler 5. Is discharged to the atmosphere through an exhaust gas treatment device (not shown). Steam generated in the exhaust heat recovery boiler 5 is guided to a steam turbine (ST) 6, and a generator (G) 7 connected to the steam turbine 6 is driven to be returned to the condenser. In the illustrated example, the two-shaft type in which the generators 2 and 7 are connected to the gas turbine 1 and the steam turbine 6 respectively is shown, but a single-shaft type in which they are connected in one shaft can be applied.

  The power plant configured in this manner performs load follow-up control by controlling the output of the gas turbine 1 in accordance with a load request command given from a higher-level control device by a power generation amount control device (not shown). is doing. However, in a state where the output from the gas turbine 1 has reached the upper limit rated power generation amount, it is necessary to cope with the increase in the load request command by the output increasing device 8 (or 11).

  Here, the output increasing device 8 that increases the output by cooling the intake air of the gas turbine 1 includes a cooler 10 that cools the suction air of the air compressor 3 by heat exchange, and a refrigerator that circulates the refrigerant to the cooler 10. 9. The amount of combustion gas generated in the combustor 4 of the gas turbine 1 increases in proportion to the amount of combustion air supplied from the air compressor 3. Since the amount of combustion air supplied to the combustor 4 correlates with the compression pressure and the mass flow rate, the mass flow rate can be increased by cooling the suction air of the air compressor 3. As a result, the amount of combustion gas flowing into the gas turbine 1 can be increased, and the amount of power generation that is the output of the gas turbine 1 can be increased. Further, the flow rate of the gas turbine exhaust gas flowing into the exhaust heat recovery boiler 5 increases, the amount of steam generated increases, and the power generation amount that is the output of the steam turbine 6 can be increased.

  On the other hand, the power increasing device 11 that raises the temperature of the exhaust gas of the gas turbine 1 injects the supplied fuel into the exhaust gas from the auxiliary burner provided at the inlet of the exhaust heat recovery boiler 5, and burns with the residual oxygen in the exhaust gas. To increase the temperature of the exhaust gas. As a result, the temperature and flow rate of the gas turbine exhaust gas flowing into the exhaust heat recovery boiler 5 increases, so the amount of steam generated in the exhaust heat recovery boiler 5 is increased and the power generation amount that is the output of the steam turbine 6 is increased. be able to. The power increasing device 11 is not limited to this, and fuel is injected from the auxiliary burner into the exhaust gas from the gas turbine 1 to the exhaust heat recovery boiler 5 and burned by the residual oxygen in the exhaust gas to raise the temperature of the exhaust gas. You can also. Moreover, in this embodiment, although the power plant provided with the two output increase apparatuses 8 and 11 is shown, it can be comprised including either one of the output increase apparatuses.

  The output increasing device 8 (or 11) is controlled to be started and stopped by the start / stop control device 15 of the output increasing device which is a characteristic part of the present embodiment. As shown in FIG. 1, the start / stop control device 15 includes a load request command prediction unit 16 and a start / stop determination / monitoring unit 17. The load request command prediction unit 16 sets the load request command MWD given from the host controller at every set cycle (for example, 5 minutes), the power generation plan value MWP created on the previous day, and the time t. It is taken in every cycle, and a predicted value MWD * of a future load request command is obtained and output to the start / stop determination / monitoring unit 17. The start / stop determination / monitoring unit 17 takes in the load request command MWD given from the host control device and the predicted value MWD * output from the load request command prediction unit 16 at the set cycle T, and outputs the output increasing device 8 (or 11). ) Is determined whether or not it is necessary to start or stop, and a start / stop command signal is output to the output increasing device 8 (or 11).

  Here, along with the flowchart shown in FIG. 3, the configurations of the load request command prediction unit 16 and the start / stop determination / monitoring unit 17 related to the start control of the start / stop control device 15 will be described together with operations. As shown in FIG. 3, the load request command predicting unit 16 and the start / stop determination / monitoring unit 17 are started every predetermined set period T (for example, 5 min). This set cycle can be synchronized with the cycle of the input load request command MWD. In step 101, it is determined whether or not the output increasing device 8 (or 11) is being activated. This determination is made based on a memory flag indicating that the start / stop determination / monitoring unit 17 is outputting a start command to the output increasing device 8 (or 11). When this determination is affirmative (YES), the start control is terminated. If the determination in step 101 is negative, the process proceeds to step 102.

In step 102, the load request command MWD, the power generation plan value MWP, and the time t are taken in, and the predicted value MWD * of the load request command after the next cycle is obtained. The predicted value MWD * is obtained as a difference (ΔMWD _i = MWD _i −MWD _i ) between the power generation planned value MWP _i and the actual value MWD _i of the load request command MWD in the current cycle i (i: natural number). _i is added to the power generation plan value MWP _{i + 1} in the next cycle i + 1 to predict the predicted value MWD * _{i + 1} of the load request command.

  Next, the start / stop determination / monitoring unit 17 executes the determination of the following equation.

Predicted value MWD * _{i + 1} > actual value MWD _i + A _{i + 1} (1)
Here, A _{i + 1} is the upper limit of the increase width of the load request command MWD that can be operated simultaneously at the same amount. For example, in the case of simultaneous operation with the same amount of power demand and power generation for 30 minutes, simultaneous operation with the same amount of power is realized even with the rated power generation amount G ₀ when the output increasing device 8 (or 11) is stopped by simulation or actual device data. The upper limit value A _{i + 1} of the increase range of the load request command that cannot be obtained is grasped in advance. Then, when the predicted value MWD * _{i + 1 of the} load request command exceeding G ₀ + A _{i + 1} is predicted, the output requesting device 8 (or 11) is activated in advance, so that the load request can be made with a margin without following delay. It can cope with the increase in directives.

In this way, the start / stop determination / monitoring unit 17 outputs a start command to the output increasing device 8 (or 11) when the determination result of Expression (1) is affirmative (YES). The start command is output at an appropriate time from t _{i to} t _{i + 1} .

On the other hand, when the determination result of the expression (1) in the start / stop determination / monitoring unit 17 is negative (NO), the process proceeds to step 104 and the actual value MWD _{i + 1} of the load request command is monitored. In step 105, the start / stop determination / monitoring unit 17 executes the following determination.

Actual value MWD _{i + 1} > Rated power generation amount G ₀ (2)
When the determination of Expression (1) is affirmative (YES), the start / stop determination / monitoring unit 17 outputs a start command to the output increasing device 8 (or 11). The output timing of this activation command is assumed to be ti _{+ 1} .

  On the other hand, when the determination result of the expression (2) in the start / stop determination / monitoring unit 17 is negative (NO), the process returns to step 102 and the process is repeated.

As described above, according to the start / stop control device 15 of the output increasing device of the present embodiment, the predicted value MWD * _{i + 1} of the load request command of the next cycle is predicted every set cycle T, and based on this prediction result. Thus, since the output increasing device 8 (or 11) can be activated in advance, quick load following can be realized even when the load request command changes.
(Embodiment 2)
The flowchart which shows one Embodiment of the stop control procedure of the starting stop control apparatus 15 of the power increase apparatus which is the characterizing part of the power plant of this invention in FIG. 6 is shown.

As shown in the figure, it is determined at a setting cycle whether the output increasing device 8 (or 11) is activated in step 201. If this determination is negative (NO) and not activated, the process ends there. On the other hand, if the determination is affirmative (YES) and activated, the process proceeds to step 202 and the actual value MWD _{i + 1} of the load request command is monitored. Then, the process proceeds to step 203, and the start / stop control device 15 returns to step 202 and repeats the process if the actual value MWD _{i + 1} is a value that causes insufficient output unless the output increasing device is used. On the other hand, if the determination in step 203 is the actual value MWD _{i + 1} of the load request command that does not cause insufficient output even if the output increasing device 8 (or 11) is not used, the process proceeds to step 204.

  In step 204, it is determined whether or not the current time is a set time zone such as noon (12:00 to 13:00). If the determination is affirmative (YES), the process returns to step 202 and the process is repeated. If the determination in step 204 is negative and not during the daytime, the output increasing device 8 (or 11) is stopped.

  That is, in the stop control of this embodiment, the tendency of the daily power demand change can be roughly grasped as shown in FIG. 7, for example, and even in the daytime when the power demand is large, 13:00) generally limits the stoppage of the output increasing device 8 (or 11) in view of a decrease in power demand.

  That is, even when the output request device 8 (or 11) is activated, the load request command decreases, and even if the load request command falls within a range that can be handled without using the output increase device 8 (or 11), In a short time period in which the demand decreases, a subsequent increase in load request command is predicted, but in other times, a subsequent decrease in load request command is predicted. Therefore, by predicting the subsequent tendency of the load request command according to the time and determining whether or not to stop the output increasing device 8 (or 11), it is possible to avoid unnecessary start and stop of the output increasing device. it can.

It is a block block diagram of the starting / stopping control device of the output increasing device which is a characteristic part of the power plant of the present invention. It is a block block diagram which shows the structure outline | summary of the power plant of this invention. It is a flowchart which shows one Embodiment of the starting control procedure of an output increase apparatus. It is a timing chart explaining operation of starting control of an output increase device. It is a timing chart explaining operation of starting control of an output increase device. It is a flowchart which shows one Embodiment of the stop control procedure of an output increase apparatus. It is a figure which shows the change of the electric power demand amount on the 1st.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas turbine 2 Generator 4 Combustor 5 Waste heat recovery boiler 6 Steam turbine 7 Generator 8 Output increase device 9 Refrigerator 10 Cooler 11 Output increase device 12 Auxiliary combustion device 15 Start / stop control device

Claims (6)

Gas turbine, steam turbine driven by steam generated by recovering heat of exhaust gas from the gas turbine, generator driven by the gas turbine and the steam turbine, and load request input every set cycle Increase in the output of at least one of a power generation amount control device that controls the power generation amount based on the command, a cooling device that cools the combustion air of the gas turbine, and an auxiliary combustion device that raises the temperature by burning the exhaust gas of the gas turbine In a combined cycle power plant comprising a device,
When the output increasing device is stopped, the power generation amount control device uses the load request command input for each set cycle as a result value and the predicted value of the load request command for the next cycle or a plurality of cycles after the next cycle. Determining means for determining, determining means for determining whether or not the predicted value of the load request command for each cycle exceeds the rated power generation amount of the power plant, and the predicted value for at least one cycle by the means determines the rated power generation amount A combined cycle power plant comprising: a start control means for outputting a start command to the output increasing device when exceeding. Gas turbine, steam turbine driven by steam generated by recovering heat of exhaust gas from the gas turbine, generator driven by the gas turbine and the steam turbine, and load request input every set cycle Increase in the output of at least one of a power generation amount control device that controls the power generation amount based on the command, a cooling device that cools the combustion air of the gas turbine, and an auxiliary combustion device that raises the temperature by burning the exhaust gas of the gas turbine In a combined cycle power plant comprising a device,
The power generation amount control device includes: a prediction unit that obtains a predicted value of the load request command in the next cycle using the load request command input at each set cycle as a result value when the output increasing device is stopped; A determination means for determining whether or not the predicted value of the load request command in the next cycle exceeds a value obtained by adding the upper limit value of the load request command that can be simultaneously operated in the same amount to the actual value of the current set cycle; A combined cycle power plant comprising start control means for outputting a start command to the output increasing device when the determination by the means is affirmative. In the combined cycle power plant according to claim 1,
The combined cycle power plant is characterized in that the rated power generation amount of the power plant is corrected according to the temperature for each of the set cycles. In the combined cycle power plant according to claim 1 or 2,
The predicting means obtains a difference between a power generation plan value created by predicting in advance corresponding to a time of a day and an actual value of the load request command for each cycle, and the difference is calculated for the power generation plan of the cycle. A combined cycle power plant characterized in that a predicted value of a load request command is obtained by adding to a value. In the combined cycle power plant according to any one of claims 1 to 4,
The power generation amount control device compares the load request command with the rated power generation amount for each set period when the output increasing device is in operation, and the load request command is less than the rated power generation amount. A combined cycle power plant comprising stop control means for outputting a stop command to the output increasing device. In the combined cycle power plant according to claim 5,
The combined cycle power plant is characterized in that the stop control means does not output the stop command when a time zone in which the load request command is equal to or less than the rated power generation amount is a predetermined time zone.

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