JP3781403B2 - Power generation device and control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for controlling a power generator. More specifically, a control method for suitably controlling a power generator of a power generator associated with a grid connection that is a power generator combined with a stationary internal combustion engine and is electrically connected to a commercial power system About.
[0002]
[Prior art]
As a power generation device used in a cogeneration system or the like, an internal combustion engine power generation device (for example, a gas engine power generation device) combined with an internal combustion engine (for example, a gas engine using city gas as fuel) is well known.
[0003]
In a power generation device combined with an internal combustion engine and electrically connected to a commercial power system, as a control method for controlling the generated power or output, the generated power is controlled to be constant. (Mode 1) and “received power constant control” (mode 2) for controlling the received power from the commercial power system to be constant are known.
[0004]
For example, as shown in FIG. 7, in “mode 1”, the control target of the power generation output (corresponding to the engine output of the internal combustion engine) is the rated output, and the control target is always constant. No significant output fluctuations are required. On the other hand, in “Mode 2”, since the power generation output needs to be controlled in accordance with the load, such as when starting or stopping (regions at both the left and right sides in FIG. 7), it always fluctuates and is highly accurate. (Power generation) Output control is required.
[0005]
In order to perform highly accurate control as required in “Mode 2”, in the case of an internal combustion engine, such as a gas engine, conventionally used in such a power generator, the opening of the throttle (butterfly valve) is set. In general, output control is performed by controlling the supply amount of the air-fuel mixture. The larger the differential pressure before and after the throttle (upstream and downstream of the throttle), the greater the fluctuations in the gas engine output with respect to minute changes in the opening of the throttle, resulting in improved responsiveness and better controllability. Become. Therefore, when performing operation control of a conventional gas engine, a design or adjustment is performed so that the differential pressure is set to a large value, so that a margin is provided for control response.
[0006]
However, if there is a large differential pressure before and after the throttle, or between the upstream side and the downstream side of the throttle, a pumping loss occurs, which adversely affects the thermal efficiency of the engine. Therefore, it has been difficult to achieve high efficiency with a conventional engine that performs output control using a throttle.
[0007]
[Problems to be solved by the invention]
The present invention has been proposed in view of the problems of the prior art as described above, and is a power generation apparatus configured in combination with an internal combustion engine and a control method therefor, including constant control of received power ("mode" in FIG. Power generation that enables high-accuracy output control required for the internal combustion engine to be achieved in 2), and that the internal combustion engine can achieve high-efficiency operation efficiency. It aims at providing the control method of an apparatus.
[0008]
[Means for Solving the Problems]
According to the present invention, the exhaust gas supercharger that performs supercharging using the exhaust gas is provided, the exhaust system and the intake system have the bypass lines that bypass the turbocharger and the exhaust turbine, respectively, and these bypass lines Each of which is configured in combination with an internal combustion engine in which a bypass valve is interposed, and in a method for controlling a power generation apparatus related to a grid interconnection that is electrically connected to a commercial power grid, a constant generated power control operation is performed. If it is necessary to perform a controlled operation of generated power, the throttle provided in the intake system is fixed to the fully open state, and the opening degree of the bypass valve of the exhaust-side bypass line is controlled. The output control of the internal combustion engine is performed, and it is determined whether or not the operation for constant control of the received power is to be performed. When the control operation of the constant reception power is to be performed, the bypass valve is fixed in the fully closed state. And controlling the internal combustion engine by controlling the opening of the throttle to determine whether or not it is an excessive period in which the operation is controlled from the constant received power control operation to the constant generated power control operation. Includes an initial step in which the throttle is fixed in a fully opened state, an exhaust side bypass valve is fixed in a fully closed state, and the opening degree of the intake side bypass valve is controlled to control the output of the internal combustion engine, and the initial step Subsequently, the throttle is fixed in the fully open state, the intake side bypass valve is fixed in the fully closed state, and the opening degree of the exhaust side bypass valve is controlled to control the output of the internal combustion engine.
[0009]
Further, according to the present invention, the exhaust gas supercharger that performs supercharging using the exhaust gas is provided, the exhaust system and the intake system have the bypass lines that bypass the turbocharger and the exhaust turbine, respectively, In the control method of the power generation apparatus related to the grid connection, which is configured in combination with an internal combustion engine in which a bypass valve is interposed in each line and is electrically connected to the commercial power system, the generated power constant control operation is performed. It is determined whether or not it should be performed, and when a constant control of generated power is to be performed, the throttle provided in the intake system is fixed to the fully open state, and the opening degree of the bypass valve of the exhaust-side bypass line is controlled. To control the output of the internal combustion engine and to determine whether or not the control operation for constant received power is to be performed. When the control operation for constant received power is to be performed, the bypass valve is fully closed. And controlling the internal combustion engine by controlling the opening of the throttle to determine whether or not it is an excessive period for shifting from a constant generated power control operation to a constant received power control operation. The throttle is fixed in a fully open state, the exhaust side bypass valve is fixed in a fully closed state, and the opening degree of the intake side bypass valve is controlled to control the output of the internal combustion engine; and Subsequent to the initial step, the intake side and exhaust side bypass valves are fixed in a fully closed state, and the output of the internal combustion engine is controlled by controlling the opening of the throttle.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 6 of the accompanying drawings. In the figure, the same reference numerals are assigned to the same members, and duplicate descriptions are omitted. In FIG. 1, a gas engine generally indicated by reference numeral 10 is integrally formed with a power generator (not shown). For example, a cogeneration system provided with a stationary gas engine power generator using a fuel gas such as city gas. Is configured. Although not clearly shown in the figure, it is electrically connected to a commercial power system and is linked to the system.
[0019]
The intake line 12 and the exhaust line 14 of the gas engine 10 are provided with a turbocharger generally indicated by a symbol TC. More specifically, the turbocharger TC supercharger S is interposed in the intake line 12 for supplying the air-fuel mixture to the gas engine 10 via the intake manifold 16, and the gas engine 10 is connected via the exhaust manifold 18. An exhaust turbine T of the turbocharger TC is interposed in the exhaust line 14 connected to the exhaust line 14.
[0020]
A throttle 20 is interposed in the intake line 12. By controlling and adjusting the opening of the throttle 20, the output of the gas engine 10 can be controlled.
[0021]
On the other hand, a bypass line 22 </ b> B that bypasses the turbine T branches off from an upstream side (engine 10 side) of the exhaust turbine T in the exhaust line 14. The bypass line 22B joins the exhaust line 14 on the downstream side (not shown) of the turbine T, and a bypass valve VB is interposed in the middle thereof.
[0022]
In the intake line 12, reference numerals 24 and 26 indicate fuel gas supply lines.
[0023]
In FIG. 1, reference numeral 30 is a gas engine output sensor (means for detecting the output of the internal combustion engine) for detecting the output of the gas engine 10 (physical quantity corresponding to the power generation amount of the cogeneration system), and reference numeral 32 is a commercial Is a sensor (means for detecting the received power from the commercial power system) for detecting received power from the power system, and reference numeral 34 denotes a timer (various control timings) for measuring timings necessary for various controls described later. Means for measuring the time to determine. The sensor 30, the sensor 32, and the timer 34 send their detection signals to the control unit 40 through the control lines CL1, CL2, and CL3 indicated by the one-dot chain line in FIG. The control unit 40 sends control signals (signals for controlling the valve opening) to the throttle 20 and the bypass valve VB via control lines CL4 and CL5, respectively.
[0024]
Although not clearly shown in FIG. 1, the intake line pressure, boost pressure / temperature, intake air temperature / humidity, and fuel gas temperature / pressure necessary for operation control of the gas engine 10 are measured by a measuring means (not shown) and controlled. Necessary processing is performed in the unit, and operation control is performed.
[0025]
The operation of the embodiment shown in FIG. 1 will be described mainly with reference to FIG.
[0026]
First, the output of the gas engine 10 which is a physical quantity corresponding to the power generation amount of the cogeneration system is measured by the sensor 30, the received power from the commercial power system (not shown) is measured by the sensor 32, and the time interval is set by the timer 34. Measure (Step S1).
[0027]
Then, the engine output corresponding to the generated power exceeding the rated value (engine output exceeding the predetermined value) is measured by the sensor 30, and the state where the received power from the commercial power system is above the predetermined value by the sensor 32 is predetermined. It is judged in the control unit 40 whether or not it has continued for a time or more (timer 34) (step S2). The rated value, the predetermined value, and the predetermined time mentioned here vary depending on various hardware conditions of each system, various environments of installation locations, usage purposes, design matters, and others, so-called “case-by-case”. This is the numerical value that should be obtained in “Case”.
[0028]
If the state where the engine output is equal to or greater than the predetermined value and the received power from the commercial power system is equal to or greater than the predetermined value continues for a predetermined time or longer (Yes in step S2), the operation state at that time is shown in FIG. It is determined that the mode is “mode 1” (step S3).
[0029]
The operation state of mode 1 is an operation in which the generated power is controlled to be constant, and rapid control of the output of the gas engine 10 and quick response are not required. Accordingly, quick control by the throttle 20 is not essential. Therefore, according to the illustrated embodiment, the throttle 20 is fixed in the fully open state (step S4), and the supercharging pressure is controlled by controlling the bypass valve VB and adjusting the exhaust flow rate flowing through the bypass line 22B. Accordingly, output control of the gas engine 10 is performed (step S4).
[0030]
In the operating state of mode 1, prompt response control is not required, and control by the throttle 20 is not essential. Therefore, the throttle 20 is fully opened to reduce the resistance in the intake line 12, and this is a problem in the prior art. Pumping loss can be eliminated. Therefore, highly efficient operation is possible.
[0031]
On the other hand, if the state where the engine output is equal to or greater than the predetermined value and the received power from the commercial power system is equal to or greater than the predetermined value does not continue for a predetermined time or longer (No in step S2), the operation state at that time is “ It is determined that the mode is “2” (step S5).
[0032]
The operation state of mode 2 is an operation in which the electric power received from the commercial power system is controlled to be constant, and the power generation output or the gas engine 10 must be controlled in accordance with the load, so that rapid control and quick response are possible. Is required. Therefore, in the operation state of mode 2, it is desirable to perform quick control by opening degree control of the throttle 20. Therefore, according to the illustrated embodiment, the bypass valve VB is fully closed, and the output control of the gas engine 10 is performed by the throttle 20 (step S6).
[0033]
After step S4 and step S6, if the operation is continued (No in step S7), the process returns to step S1, and if the operation is terminated (Yes in step S7), the process is terminated according to a predetermined procedure.
[0034]
FIG. 3 shows a second embodiment of the present invention.
[0035]
In the first embodiment of FIG. 1, the bypass line 22B and the bypass valve VB are provided on the exhaust line 14 side (or on the exhaust turbine T side). In contrast, in the second embodiment of FIG. 3, the bypass line 22A and the bypass valve VA are provided on the intake line 12 side (supercharger S side).
[0036]
In the second embodiment of FIG. 3, in the operation state of mode 1 (the state in which the output control of the gas engine 10 is controlled by the opening degree control of the bypass valve VA), the throttle 20 is fixed to the fully open state, and the bypass valve VA is opened. The output of the gas engine 10 is controlled by controlling the flow rate of the air-fuel mixture flowing through the bypass line 22A (the air-fuel mixture compressed by the supercharger S). Compared with the first embodiment shown in FIG. 1, the second embodiment shown in FIG. 3 is slightly less efficient but has improved responsiveness. Since the second embodiment in FIG. 3 is the same as the first embodiment described in FIGS. 1 and 2 with respect to other configurations and operations, the description thereof will be omitted.
[0037]
FIG. 4 shows a third embodiment of the present invention. In the first embodiment of FIG. 1 and the second embodiment of FIG. 3, the bypass line (22B, 22A) and the bypass valve (VB, VA) are on the exhaust line 14 side (exhaust turbine T side) or the intake line 12 side. It is provided only on either one (supercharger S side). On the other hand, in the third embodiment shown in FIG. 4, the bypass lines (22B, 22A) and the bypass are provided on both the exhaust line 14 side (exhaust turbine T side) and the intake line 12 side (supercharger S side). Valves (VB, VA) are provided. The bypass valve VB on the exhaust line 14 side is configured to receive a control signal from the control unit 40 via the control line CL5B, and the bypass valve VA on the intake line 12 side is controlled by the control line CL5A. The unit 40 is connected.
[0038]
Other configurations in the embodiment of FIG. 4 are substantially the same as those shown in FIG. 1 or FIG.
[0039]
Next, the operation of the embodiment of FIG. 4 will be described. In this embodiment, when high efficiency is to be pursued in the operation state of the mode 1 described above, the throttle 20 is fixed in the fully open state, the bypass valve VA is fixed in the fully closed state, and the bypass valve VB. The output of the gas engine 10 may be controlled by controlling the opening degree or the exhaust flow rate flowing through the bypass line 22B.
[0040]
On the other hand, when it is desired to achieve quick response in the operation state of the mode 1 described above, the throttle 20 is fixed in a fully opened state, the bypass valve VB is fixed in a fully closed state, and the bypass valve VA is opened. The output of the gas engine 10 is controlled by controlling the flow rate of the air-fuel mixture flowing through the bypass line 22A. Details of the operation of the embodiment shown in FIG. 4 will be described below mainly with reference to FIG.
[0041]
First, the output of the gas engine 10 which is a physical quantity corresponding to the power generation amount of the cogeneration system is measured by the sensor 30, the received power from the commercial power system (not shown) is measured by the sensor 32, and the time interval is set by the timer 34. Measure (Step S10).
[0042]
Then, the engine output corresponding to the generated power exceeding the rated value (engine output exceeding the predetermined value) is measured by the sensor 30, and the state where the received power from the commercial power system is above the predetermined value by the sensor 32 is predetermined. It is judged in the control unit 40 whether or not it has continued for a time or more (timer 34) (step S12).
[0043]
If the state where the engine output is equal to or greater than the predetermined value and the received power from the commercial power system is equal to or greater than the predetermined value continues for a predetermined time or longer (step S11 is Yes), the operation state at that time is shown in FIG. It is determined that the mode is “mode 1” (step S12). Then, it is determined whether or not the previous cycle (one series of control from step S10 to step S17) was "mode 2" (step S13).
[0044]
Here, if the operation state is “mode 1” even in the previous cycle (Yes in step S13), the operation of mode 1 is continuously performed, so the output control of the gas engine 10 is also suitable for mode 1. Control in various forms. That is, the operation state of mode 1 is an operation in which the generated power is controlled to be constant, and rapid control of the output of the gas engine 10 and quick response are not required. Absent. Therefore, the throttle 20 is fixed in the fully open state. At the same time, since control with good response by the bypass valve VA is not essential, the bypass valve VA is also fixed in the fully closed state. Then, the supercharging pressure is controlled by controlling the bypass valve VB and adjusting the flow rate of the exhaust gas flowing through the bypass line 22B, thereby controlling the output of the gas engine 10 (step S14). In other words, in the mode 1 state, the control intended to increase the efficiency is optimal.
[0045]
On the other hand, if step S13 is “No”, that is, if the operating state is “mode 2” in the previous cycle, it is a transition period from mode 2 to mode 1. As described above, the operation state in mode 2 is an operation in which the received power from the commercial power system is controlled to be constant, and the gas engine 10 must be controlled in accordance with the load, so that rapid control and quick response are achieved. Is required. Therefore, it is desirable that the output of the gas engine 10 be controlled quickly even during the transition from mode 2 to mode 1. On the other hand, output control by the throttle 20 is not performed in the mode 1 operation state.
[0046]
Therefore, when step S13 is “No”, control with good response by the bypass valve VA is performed. More specifically, the throttle 20 is fixed in the fully open state, the bypass valve VB is fixed in the fully closed state, and the gas engine 10 is controlled by controlling the opening of the bypass valve VA or the flow rate of the air-fuel mixture flowing through the bypass line 22A. Is controlled (step S15).
[0047]
In this state, control is performed until the time corresponding to the transition period from mode 2 to mode 1 elapses (step S16 is “No” loop), and if the transition period elapses (step S16 is “Yes”), Performs optimal control for mode 1. That is, the output of the gas engine 10 is controlled by controlling the opening degree of the bypass valve VB, thereby improving the efficiency (step S14).
[0048]
Here, since the throttle 20 is fully opened in the mode 1 operation state, the resistance in the intake line 12 can be reduced. At the same time, the pumping loss that has been a problem in the prior art can be solved. Therefore, highly efficient operation is possible.
[0049]
In step S11, if the state where the engine output is equal to or greater than a predetermined value and the received power from the commercial power system is equal to or greater than the predetermined value does not continue for a predetermined time or longer, the operation state at that time is “mode 2” in FIG. It is determined that there is (step S19). Then, it is determined whether or not the previous cycle was “mode 1” (step S20).
[0050]
Here, if the operation state is “mode 2” even in the previous cycle (Yes in step S20), the operation of mode 2 is continuously performed, so the output control of the gas engine 10 is also suitable for mode 2. Control in various forms. As described above, in the operation state of mode 2, the power generation output or the gas engine 10 must be controlled according to the load, and rapid control and quick response are required. Rapid control is desirable. Therefore, according to the illustrated embodiment, the bypass valves VA and VB are fully closed, and the output control of the gas engine 10 is performed only by the throttle 20 (step S21).
[0051]
On the other hand, if step S20 is “No”, that is, if the operating state is “mode 1” in the previous cycle, it is a transition period from mode 1 to mode 2. In the control shown in FIG. 5, in this transition period, the mode 2 is not immediately shifted to the operation, but first, the operation is the mode 1 (the throttle 20 is fixed fully open), and the control response is high. Do good driving. That is, the bypass valve VB is fixed fully closed, the opening degree of the bypass valve VA is controlled, and the flow rate control of the air-fuel mixture flowing through the bypass line 22A is performed (step S22).
[0052]
Then, the operation shown in step S22 is continued for the time corresponding to the transition period ("predetermined time" in step S23) (step S23 is a "No" loop), and the operation state is shifted to the mode 2 (step S21). .
[0053]
After step S14 and step S21, if the operation is continued (No in step S17), the process returns to step S10. At this time, the process waits for a predetermined time in step S18 (a loop in which step S18 is No). In other words, the control in FIG. 5 (the same as the control shown in FIGS. 2 and 6) is not performed without a break, but a series of control (cycle) from step S10 to step S17 is performed at a predetermined time interval. It is performed intermittently with a gap. If the operation is to be ended (step S17 is Yes), the operation is ended according to a predetermined procedure.
[0054]
The control shown in FIG. 5 is not only in the case of shifting from mode 2 to mode 1, but also in the reverse case (shifting from mode 1 to mode 2), the operation is shifted in multiple stages during the transition period. ing. However, when changing from mode 1 to mode 2, the driving may be changed immediately.
[0055]
FIG. 6 shows such control, which is roughly the same as the control of FIG. 5, but when it is determined that the operation state is mode 2 (step S19), the bypass valves VB and VA are immediately closed. The output of the gas engine 10 is controlled by the throttle 20 (step S21). Other controls are the same as in FIG.
[0056]
It should be noted that the illustrated embodiment is merely an example, and is not a description to limit the technical scope of the present invention.
[0057]
【The invention's effect】
The effects of the present invention are listed below.
(1) In a grid-connected power generation apparatus using an internal combustion engine (for example, a gas engine), it is possible to achieve significantly higher efficiency as compared with the conventional one while maintaining good controllability.
(2) In the constant power generation control operation (mode 1), it is possible to prevent the occurrence of differential pressure before and after the throttle, eliminate the pumping loss due to the differential pressure, and achieve high efficiency.
(3) In the received power constant control operation (mode 2), it is possible to cope with a rapid output control corresponding to the load fluctuation.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main part of a first embodiment of the present invention.
FIG. 2 is a flowchart showing an example of control in the embodiment of FIG.
FIG. 3 is a block diagram showing a main part of a second embodiment of the present invention.
FIG. 4 is a block diagram showing a main part of a third embodiment of the present invention.
FIG. 5 is a flowchart showing an example of control in the third embodiment.
FIG. 6 is a flowchart showing another control example in the third embodiment.
FIG. 7 is a diagram showing the operation of a grid-connected gas engine power generator.

Claims (2)

  It has an exhaust gas supercharger that performs supercharging using exhaust gas, and has a bypass line that bypasses the turbocharger and the exhaust turbine respectively in the exhaust system and the intake system, and each bypass line has a bypass valve. Whether the power generation device constant control operation should be performed in the control method of the power generation apparatus related to the grid interconnection configured in combination with the internal combustion engine installed and electrically connected to the commercial power grid If the constant power generation control operation is to be performed, the throttle provided in the intake system is fixed fully open, and the opening degree of the bypass valve on the exhaust side bypass line is controlled to control the output of the internal combustion engine. In addition, it is determined whether or not there is a situation in which the received power constant control operation is to be performed. When the received power constant control operation is to be performed, the bypass valve is fixed in a fully closed state, and the slot The internal combustion engine is controlled by controlling the opening of the torr, and it is determined whether or not it is an excessive period when the control is performed from the constant received power control operation to the constant power generation control operation. Is fixed in the fully open state, the exhaust side bypass valve is fixed in the fully closed state, the opening degree of the intake side bypass valve is controlled to control the output of the internal combustion engine, and the throttle following the initial step Is controlled in the fully open state, the intake side bypass valve is fixed in the fully closed state, and the opening degree of the exhaust side bypass valve is controlled to control the output of the internal combustion engine.   It has an exhaust gas supercharger that performs supercharging using exhaust gas, and has a bypass line that bypasses the turbocharger and the exhaust turbine respectively in the exhaust system and the intake system, and each bypass line has a bypass valve. Whether the power generation device constant control operation should be performed in the control method of the power generation apparatus related to the grid interconnection configured in combination with the internal combustion engine installed and electrically connected to the commercial power grid If the constant power generation control operation is to be performed, the throttle provided in the intake system is fixed fully open, and the opening degree of the bypass valve of the exhaust side bypass line is controlled to control the output of the internal combustion engine. In addition, it is determined whether or not there is a situation in which the received power constant control operation is to be performed. When the received power constant control operation is to be performed, the bypass valve is fixed in a fully closed state, and the slot The internal combustion engine is controlled by controlling the opening of the tor, and it is determined whether or not it is an excessive period in which the generated power constant control operation shifts to the received power constant control operation. Following the initial step of fixing the throttle in the fully open state, fixing the exhaust side bypass valve in the fully closed state, and controlling the opening degree of the intake side bypass valve to control the output of the internal combustion engine, A control method for a power generator, wherein the intake side and exhaust side bypass valves are fixed in a fully closed state, and the throttle opening is controlled to control the output of the internal combustion engine.

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