Engine power generation system control device

Abstract

To provide a control device for an engine power generation system which can suppress the discharge of harmful substances contained in exhaust to the outside by the early activation of an exhaust purification catalyst and the early warmup of an engine, in the power generation system constituted by an engine which can be supplied with RE fuel and hydrocarbon-based fuel and allows mixed combustion.SOLUTION: A hydrocarbon-based fuel supply quantity or a hydrogen supply quantity to an engine is controlled on the basis of a catalyst activation state which is detected by a catalyst activation state detection part and an engine warmup state detection part.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a control device for an engine power generation system that is compatible with mixed combustion of renewable energy-derived fuels such as hydrogen and hydrocarbon fuels such as gasoline and natural gas. [Background technology]

[0002] As renewable energy expands in an effort to decarbonize energy, the importance of balancing power generation systems that use renewable energy-derived fuels (hereinafter referred to as RE fuels) such as hydrogen is increasing in order to respond to power fluctuations.

[0003] While large-scale gas-fired power plants can be used as adjustable power sources, their output adjustment range is limited to 30% to 100% of rated operation, which does not provide sufficient adjustment power. Furthermore, since the installation location of the facilities is fixed, it is necessary to reinforce the power lines, which increases the facility costs. Furthermore, since the range of fuel procurement for large-scale thermal power plants is limited, it is difficult to effectively utilize renewable fuels, which are ubiquitous in the region.

[0004] Distributed power generation systems that utilize engine generators compatible with RE fuel are promising as systems that can respond to fluctuations in renewable energy while utilizing RE fuel, which is ubiquitous in the region. In particular, by utilizing mass-produced engines such as existing automobile engines or industrial engines and using them as stationary power generation systems, it is possible to minimize initial equipment costs. Furthermore, by using engines that can mix and burn RE fuels such as hydrogen with hydrocarbon fuels such as gasoline or natural gas (hereinafter referred to as co-combustion), it becomes possible to operate the power generation system in accordance with the amount of RE fuel produced or procured, thereby increasing the operating rate.

[0005] A known control device for such an engine power generation system is disclosed in Patent Document 1. Patent Document 1 discloses "a fuel supply device for an internal combustion engine configured to be able to supply hydrogen fuel and hydrocarbon-based fuel independently to a combustion chamber of an internal combustion engine, and having a first combustion control mode in which the hydrocarbon-based fuel is supplied to a radially central portion of the combustion chamber or to a portion of the combustion chamber surrounding an ignition plug provided for the combustion chamber, and the hydrogen fuel is supplied to a space in the combustion chamber surrounding the space to which the hydrocarbon-based fuel is supplied." [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5772958 Summary of the Invention [Problem to be solved by the invention]

[0007] Engine exhaust contains carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and other harmful substances that harm humans, animals, and plants. Therefore, it is necessary to suppress the emission of these harmful substances. To achieve this, it is effective to install an exhaust purification catalyst in the engine's exhaust path to purify harmful substances (such as NOx, THC, and CO) and to reduce harmful substances emitted directly from the engine. First, when using a catalyst, the challenge is to quickly activate the catalyst. This is because raising the catalyst's temperature and activating it effectively purifies harmful substances. Second, to reduce harmful substances emitted directly from the engine, lean combustion, in which the fuel is burned at a leaner ratio (lean) than the stoichiometric air-fuel ratio (the minimum amount of air required for complete combustion), is effective. This is because lean combustion reduces the combustion gas temperature, significantly reducing the amount of NOx produced by combustion. Furthermore, because lean combustion contains oxygen in the exhaust, both THC and CO can be purified using a three-way catalyst. On the other hand, lean combustion reduces combustion stability, so achieving a warm-up state for stable combustion as quickly as possible (hereafter referred to as early engine warm-up) becomes an issue. Furthermore, in a multi-fuel engine that can independently supply multiple fuels, the properties of each fuel must be taken into consideration when solving the above issue.

[0008] In this regard, in the prior art described in Patent Document 1, a mixture of hydrocarbon fuel and hydrogen is burned when the catalyst temperature is raised, which increases the time required to activate the catalyst compared to when only hydrocarbon fuel is burned. This is because the temperature of the exhaust gas generated by the combustion of hydrogen is lower than that of the exhaust gas generated by the combustion of hydrocarbon fuel. Furthermore, the prior art described in Patent Document 1 is limited to configurations that include a means for controlling the spatial distribution of fuel within the combustion chamber. For example, in a configuration in which hydrocarbon fuel and hydrogen are supplied from the middle of the intake pipe, the hydrocarbon fuel and hydrogen are supplied to the combustion chamber in a well-mixed state, making it difficult to apply.

[0009] The present invention has been made in view of the above circumstances, and has an object to provide a control device for an engine power generation system that is capable of quickly activating an exhaust purification catalyst and quickly warming up the engine in a power generation system that is configured with an engine that can be supplied with RE fuel and hydrocarbon-based fuel and can perform mixed combustion. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides a control device for an engine power generation system that generates electricity using an engine that is supplied with hydrocarbon fuel and hydrogen to enable mixed combustion and that is equipped with an engine warm-up state detection unit that detects whether the engine is in a warm-up state, the control device comprising: a catalyst that is provided in an exhaust passage of the engine to purify exhaust gas; and a catalyst activation state detection unit that detects whether the catalyst is in an activated state, the control device for an engine power generation system being characterized in that it controls the amount of hydrocarbon fuel or hydrogen supplied to the engine based on the catalyst activation state detected by the catalyst activation state detection unit and the warm-up state of the engine detected by the engine warm-up state detection unit. [Effects of the Invention]

[0011] According to the present invention, it is possible to control the supply amounts of hydrocarbon fuel and hydrogen depending on the activation state of the catalyst and the warm-up state of the engine, which enables early activation of the catalyst and early warm-up of the engine, thereby making it possible to suppress the emission of harmful substances contained in the exhaust to the outside.

[0012] Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram showing an example in which a power generation system control device according to a first embodiment of the present invention is applied to a power generation system including an engine generator fueled by hydrogen and natural gas. [Figure 2]1 is a block diagram showing an example of the hardware configuration of a power generation system control device according to a first embodiment of the present invention. [Figure 3] 1 is a diagram showing an example of an engine configuration according to a first embodiment of the present invention. [Figure 4] FIG. 3 is a diagram showing another example of the engine configuration according to the first embodiment of the present invention. [Figure 5] FIG. 2 is a diagram showing heat generation histories under natural gas mono-combustion conditions and hydrogen-mixed combustion conditions according to Example 1 of the present invention. [Figure 6] FIG. 3 is a diagram showing the history of the average gas temperature in the cylinder under natural gas mono-combustion conditions and hydrogen-mixed combustion conditions according to Example 1 of the present invention. [Figure 7] FIG. 2 is a diagram showing the amount of heat transferred from gas inside a cylinder to an engine cylinder according to the first embodiment of the present invention. [Figure 8] FIG. 2 is a diagram showing lean limits under natural gas mono-combustion conditions and hydrogen-mixed combustion conditions according to the first embodiment of the present invention. [Figure 9] FIG. 3 is a diagram showing an indicated thermal efficiency at a lean limit according to the first embodiment of the present invention. [Figure 10] FIG. 3 is a diagram showing the amount of NOx generated at the lean limit according to the first embodiment of the present invention. [Figure 11] FIG. 2 is a diagram showing an operation mode according to the first embodiment of the present invention. [Figure 12] FIG. 2 is a diagram showing an example of a flowchart of engine generator control according to the first embodiment of the present invention. [Figure 13] 4 is a time chart of a scene in which the catalyst according to the first embodiment of the present invention is inactive and the engine is started from a cold state. [Figure 14] FIG. 10 is a schematic configuration diagram showing an example in which a power generation system control device according to a second embodiment of the present invention is applied to a power generation system including a plurality of engine generators fueled by hydrogen and natural gas. [Figure 15] FIG. 10 is a block diagram showing an example of the hardware configuration of a power generation system control device according to a second embodiment of the present invention. [Figure 16] FIG. 10 is a diagram showing the indicated thermal efficiency under natural gas mono-combustion conditions and hydrogen co-combustion conditions according to Example 2 of the present invention. [Figure 17] FIG. 6 is a diagram showing an operation mode according to a second embodiment of the present invention. [Figure 18]FIG. 10 is a diagram showing an example of a flowchart of engine generator control according to a second embodiment of the present invention. [Figure 19] 10 is a time chart showing a scene in which the total required output increases from a state in which engine A is operating at a rated speed, and engine B is newly started according to the second embodiment of the present invention. [Figure 20] FIG. 10 is a diagram showing the tendency of CO, HC, and NOx production with respect to the air-fuel ratio in premix combustion in a spark ignition engine according to a third embodiment of the present invention. [Figure 21] FIG. 10 is a diagram showing an example of a flowchart of engine generator control according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the present invention, at least one fuel is hydrogen and the other fuel is a hydrocarbon fuel. In the embodiment, natural gas is exemplified as the hydrocarbon fuel, but diesel or gasoline may also be used. This fuel combination can be selected as appropriate.

[0015] [Example 1] FIG. 1 is a schematic diagram showing an example in which a power generation system control device according to a first embodiment of the present invention is applied to a power generation system including an engine generator fueled by hydrogen and natural gas.

[0016] The power generation system 100 includes a power generation module GM that is composed of an engine 11, a generator 12, and a power converter 13. The engine 11 is equipped with an electronic control unit (ECU) 15 for controlling the engine 11. The engine 11 is connected to a hydrogen generator 2 via a hydrogen supply device 14, allowing it to be supplied with hydrogen fuel. The engine 11 is also connected to a fuel tank (not shown) that allows it to be supplied with natural gas, allowing it to burn hydrogen fuel, natural gas, or a mixed fuel of hydrogen and natural gas. The output of this power generation module GM is electrically connected to a load-side device 3.

[0017] The minimum configuration of the power generation module GM applicable to the present invention is to include an engine 11 and a generator 12. Depending on whether the load is an AC load or a DC load, an appropriate power converter 13 may be included. The generator 12 may be either an AC generator or a DC generator.

[0018] Furthermore, a three-way catalyst 20 as an exhaust purification catalyst for purifying the exhaust gas, a catalyst upstream temperature sensor 18 for measuring the temperature of the gas flowing into the three-way catalyst 20 (catalyst inlet gas temperature), an air-fuel ratio sensor 17 which is one form of air-fuel ratio detector and detects the air-fuel ratio of the exhaust gas upstream of the three-way catalyst 20, and an oxygen concentration sensor 19 which detects the oxygen concentration of the exhaust gas downstream of the three-way catalyst 20 are provided at appropriate positions in the exhaust passage 16 of the engine 11.

[0019] The three-way catalyst 20 oxidizes hydrocarbons and carbon monoxide in the exhaust and reduces nitrogen oxides simultaneously, converting harmful gas components in the exhaust into carbon dioxide, water vapor, and nitrogen. To maximize the purification efficiency of the three-way catalyst 20, the ratio of the reactive components (HC, NOx, CO, H2) must be stoichiometrically ideal. The range of air-fuel ratios in the air-fuel mixture that achieves this state is called a window, and in a typical spark-ignition engine, this is an extremely narrow range near the theoretical air-fuel ratio (stoichiometry), which is the minimum air-to-fuel ratio required for complete combustion.

[0020] The power generation system control device 1 is mounted on the power generation system 100. The power generation system control device 1 calculates the required load of the power generation system 100 based on the required load Sg1 from the load-side device 3. The power generation system control device 1 also receives supplyable hydrogen amount information Sg2 from the hydrogen generator 2. The power generation system control device 1 also receives information (engine state) Sg3 from the engine 11 regarding the sensors and actuators of the engine 11. The power generation system control device 1 also receives information related to the control of the three-way catalyst 20, such as the air-fuel ratio Sg4, the catalyst inflow gas temperature (also referred to as the catalyst upstream temperature) Sg5, and the oxygen concentration Sg6, from the air-fuel ratio sensor 17, the catalyst upstream temperature sensor 18, and the oxygen concentration sensor 19. Based on this information (Sg1), the power generation system control device 1 sends a command Sd1 regarding the required engine output and whether or not to drive (hereinafter simply referred to as the required output) to the ECU 15 of the engine 11, and controls the hydrogen supply device 14 to achieve a desired hydrogen supply amount (target hydrogen supply amount) Sd2.

[0021] The ECU 15 controls the output of the engine 11 based on the required output Sd1 from the power generation system control device 1. Specifically, the ECU 15 controls the natural gas fuel injection unit, the ignition unit, the throttle valve, and the starter. The engine 11 is, for example, a four-cylinder engine that uses spark ignition combustion and is an example of an internal combustion engine. The generator 12 generates power using the driving force of the engine 11 to achieve a desired power load. The power converter 13 adjusts the voltage and phase of the power generated by the generator 12 and supplies the adjusted power to the load-side device 3.

[0022] Next, an example of the internal configuration of the power generation system control device 1 according to the first embodiment will be described. Fig. 2 is a block diagram showing an example of the hardware configuration of the power generation system control device 1. The power generation system control device 1 is configured using a computer device.

[0023] In Figure 2, the required load Sg1, supplyable hydrogen amount Sg2, and engine status Sg3 output from the load-side device 3, the hydrogen generator 2, and the ECU 15 are input to the input circuit 1a of the power generation system control device 1. However, the input signals are not limited to these. Each signal input to the input circuit 1a is sent to an input port (not shown) within the input / output port 1b. The values ​​sent to the input port are stored in RAM (1c) and processed by the CPU (1e). A control program describing the contents of the processing is written in advance in ROM (1d).

[0024] Values ​​indicating the operating amounts of the controlled objects (engine 11, hydrogen supply device 14, etc.) calculated according to the control program are stored in RAM (1c), then sent to an output port (not shown) within input / output port 1b, and sent via each output section (engine torque control output section 1f, hydrogen supply amount control output section 1g) to each device (ECU 15, hydrogen supply device 14) as a required output Sd1 and a desired hydrogen supply amount (target hydrogen supply amount) Sd2. Note that in FIG. 2, the engine control device (ECU 15) is provided separately from the power generation system control device 1, but this is not limited to this configuration, and functional sections corresponding to the control devices of each device may be provided within the power generation system control device 1.

[0025] FIG. 3 is a diagram showing an example of the configuration of an engine 11 according to the first embodiment. The engine 11 is a four-cylinder automotive engine that performs spark ignition combustion and has been modified so that hydrogen can be supplied to it. An air flow sensor 21 that measures the amount of intake air and an electronically controlled throttle 26 that adjusts the intake pipe pressure are provided at appropriate positions in each intake pipe 27. The engine 11 also has a spark plug 29 for each cylinder that supplies ignition energy to a combustion chamber 28 of each cylinder, and a coolant temperature sensor 24 that measures the temperature of the coolant for the engine 11 is provided at an appropriate position in a cylinder head 30. An exhaust pipe 25 is connected to the exhaust passage 16.

[0026] A natural gas injector 22 for injecting natural gas as fuel is provided inside the combustion chamber 28. The natural gas injector 22 is connected to a fuel tank (not shown) by a fuel pipe. Furthermore, a hydrogen supply passage 23 for supplying hydrogen into the intake pipe 27 is provided, and the hydrogen supply passage 23 is connected to a hydrogen supply device 14 that controls the amount of hydrogen supplied. The hydrogen supply device 14 is connected to the hydrogen generator 2 by a hydrogen pipe.

[0027] With the above configuration, it is possible to switch between engine operation using natural gas (natural gas only), engine operation using hydrogen (hydrogen only), and engine operation using both hydrogen and natural gas (natural gas-hydrogen mixed combustion).

[0028] FIG. 4 is a diagram showing another example of the configuration of the engine 11 according to the first embodiment. The engine 11 is a four-cylinder automotive engine that performs spark ignition combustion and has been modified so that hydrogen can be supplied to it. An air flow sensor 21 that measures the amount of intake air and an electronically controlled throttle 26 that adjusts the intake pipe pressure are provided at appropriate positions in each intake pipe 27. The engine 11 also has a spark plug 29 for each cylinder that supplies ignition energy to a combustion chamber 28 of each cylinder, and a coolant temperature sensor 24 that measures the temperature of the coolant for the engine 11 is provided at an appropriate position in a cylinder head 30. The exhaust pipe 25 is connected to the exhaust passage 16.

[0029] A natural gas injector 22 for injecting natural gas as fuel is provided in the intake pipe 27. The natural gas injector 22 is connected to a fuel tank (not shown) by a fuel pipe. Furthermore, a hydrogen supply passage 23 for supplying hydrogen into the combustion chamber 28 is provided, and the hydrogen supply passage 23 is connected to a hydrogen supply device 14 that controls the amount of hydrogen supplied. The hydrogen supply device 14 is connected to the hydrogen generator 2 by a hydrogen pipe.

[0030] With the above configuration, it is possible to switch between engine operation using natural gas (natural gas only), engine operation using hydrogen (hydrogen only), and engine operation using both hydrogen and natural gas (natural gas-hydrogen mixed combustion).

[0031] The following describes in detail an embodiment of the present invention, firstly explaining key points of control in the embodiment, and then explaining specific processing in the embodiment.

[0032] First, we will explain the key points in control from the perspective of early catalyst activation and early engine warm-up. The conditions shown in Figures 5 to 7 are for mono-fuel natural gas combustion and natural gas / hydrogen mixed combustion, and are the same for each: engine speed and indicated mean effective pressure are constant, the air-fuel ratio is the stoichiometric air-fuel ratio, and the ignition timing is optimal.

[0033] Figure 5 shows the heat release history under natural gas mono-combustion and hydrogen co-firing conditions. The horizontal axis is crank angle, and the vertical axis is heat release rate. Figure 5 shows the heat release history near the compression top dead center during the compression-expansion stroke. Figure 5 shows that hydrogen co-firing makes heat release steeper. The main reason for this is that the laminar burning velocity of hydrogen is significantly higher than that of natural gas, which is primarily composed of methane.

[0034] The in-cylinder average gas temperature histories for natural gas mono-combustion and hydrogen co-firing conditions are shown in Figure 6. As can be seen from Figure 6, as a result of the steeper heat generation with hydrogen co-firing, the time when the in-cylinder average gas temperature reaches its maximum is earlier, and after 30 deg ATDC the in-cylinder average gas temperature is lower than under natural gas mono-combustion.

[0035] Figure 7 shows the amount of heat transfer from the gas inside the cylinder to the engine cylinder (hereafter referred to as cylinder heat transfer). Hydrogen co-firing increases the amount of heat transfer in the cylinder. This is thought to be due to the fact that hydrogen combustion has a much faster combustion speed than natural gas, and the gas flow caused by flame propagation is large, and the flame front reaches the combustion chamber wall quickly, resulting in large gas convection near the wall.

[0036] From the above, from the perspective of early catalyst activation, it is effective to use natural gas exclusively in order to increase the exhaust temperature, and from the perspective of early engine warm-up, it is effective to increase the hydrogen mixture ratio in order to increase the amount of heat transferred to the cylinder.

[0037] Next, the key points of control under the conditions after the catalyst has been activated and the engine has warmed up will be explained.

[0038] Figure 8 shows the lean limit for natural gas mono-combustion and hydrogen co-firing conditions. Here, the lean limit refers to the air-fuel ratio at which the engine's combustion stability reaches its allowable limit. Figure 8 shows that the lean limit is wider under hydrogen co-firing conditions compared to natural gas mono-combustion. This is because the laminar burning velocity of hydrogen is significantly higher than that of natural gas.

[0039] Figure 9 shows the indicated thermal efficiency at the lean limit. From Figure 9, it can be seen that the indicated thermal efficiency at the lean limit is higher under hydrogen co-firing conditions compared to natural gas mono-firing conditions. The main reason for this is that the combustion gas temperature decreases as the degree of leanness increases, resulting in a decrease in cooling loss.

[0040] Figure 10 shows the amount of NOx generated at the lean limit. From Figure 10, it can be seen that under hydrogen co-firing conditions, the amount of NOx generated at the lean limit is significantly lower than under natural gas mono-firing conditions. The main reason for this is that the lower combustion gas temperature suppresses the generation of thermal NOx, which is generated when nitrogen and oxygen react at high temperatures.

[0041] From the above, it is effective to use hydrogen-mixed combustion and lean combustion under conditions after the catalyst has been activated and the engine has warmed up.

[0042] Taking into account the key points of control described above, this embodiment controls the amount of hydrocarbon fuel or hydrogen supplied to the engine based on the catalyst activation state and the engine warm-up state. Specifically, as shown in FIG. 11, three operating modes with different hydrogen mixing ratios and air-fuel ratios are provided, and control is performed to switch between the operating modes depending on the catalyst activation state and the engine warm-up state. Here, the hydrogen mixing ratio is the ratio of the amount of hydrogen to the total amount of fuel (natural gas and hydrogen) supplied to the engine. Note that this ratio may be a calorific value ratio, volume ratio, mass ratio, or the like, and may be selected appropriately. Details of each operating mode are provided below.

[0043] Mode 1 When the catalyst is inactive, only hydrocarbon fuel is supplied to the engine, resulting in hydrocarbon fuel combustion. This increases the exhaust temperature and enables earlier catalyst activation. Ignition retard control may also be performed. This increases the exhaust temperature, enabling earlier catalyst activation. The engine's air-fuel ratio is controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst is equal to or less than a predetermined value C1. The predetermined value C1 is the oxygen concentration of the exhaust gas when the engine is operated at a theoretical air-fuel ratio (stoichiometric). The engine's air-fuel ratio need only be controlled within the catalyst window where the ratio of reactive components (HC, NOx, CO, H2) is stoichiometrically ideal; it does not need to be strictly stoichiometric. This allows the catalyst to purify harmful gas components (HC, CO, NOx) in the exhaust.

[0044] Mode 2 When the catalyst is active and the engine is cold, hydrocarbon fuel and hydrogen are supplied to the engine for hydrogen co-firing. This increases cylinder heat transfer and allows the engine to warm up more quickly. The engine's air-fuel ratio is controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst is below a predetermined value C1. This predetermined value C1 is the oxygen concentration of the exhaust gas when the engine is operated at a theoretical air-fuel ratio (stoichiometry). The air-fuel ratio does not need to be strictly stoichiometric; it only needs to be controlled within the catalyst's window. Under hydrogen co-firing conditions, the combustion temperature increases, increasing the amount of NOx produced. An increase in the amount of hydrogen supplied increases the amount of H2 produced. Meanwhile, a decrease in the amount of hydrocarbon fuel supplied tends to decrease the amount of CO and THC produced. Therefore, the relationship between the air-fuel ratio and exhaust composition under hydrogen co-firing conditions can be determined in advance, and the air-fuel ratio can be controlled so that the ratio of reactive components (HC, NOx, CO, H2) is stoichiometrically ideal. This allows the catalyst to purify harmful gas components (HC, CO, NOx) in the exhaust.

[0045] Mode 3 When the catalyst is active and the engine is warmed up, hydrocarbon fuel and hydrogen are supplied to the engine for hydrogen co-combustion. This allows the lean limit to be expanded. The engine's air-fuel ratio is also controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst is equal to or higher than a predetermined value C2. The predetermined value C2 is the oxygen concentration of the exhaust gas under lean conditions, where the engine's air-fuel ratio can be set to a value that sufficiently satisfies the exhaust gas regulation value without using an aftertreatment device (in other words, when the engine is operated at an air-fuel ratio that keeps the amount of nitrogen oxides directly emitted from the engine below a predetermined value). This reduces NOx emitted from the engine and enables the catalyst to purify CO and HC with high efficiency.

[0046] Next, a specific process of this embodiment will be described.

[0047] An example of a flowchart of engine generator control according to this embodiment is shown in Figure 12. Each step will be described in detail below.

[0048] <Step S1> In step S1, the power generation system control device 1 first reads information (requested load) Sg1 from the connected load-side device 3. The information (requested load) Sg1 from the load-side device 3 is, for example, the current power consumption (voltage and current) of the device on the load side or a predicted value for the future. Also, if the output of the power generation system 100 is connected to a power grid, the information is the current or future power request value from the grid.

[0049] <Step S2> In step S2, the power generation system control device 1 reads information (engine state) Sg3 of the engine 11 from the ECU 15 and the engine 11. The information (engine state) Sg3 from the ECU 15 and the engine 11 includes, for example, the engine state such as the current engine speed, torque, and engine temperature (coolant temperature, intake temperature, etc.), and engine specifications (displacement, compression ratio, fuel supply position, etc.).

[0050] <Step S3> In step S3, the power generation system control device 1 reads hydrogen generation information (supplyable hydrogen amount) Sg2 from the hydrogen generator 2. Here, the hydrogen generator 2 is, for example, a water electrolyzer that generates hydrogen from renewable energy, and information such as the power that can be input to the water electrolyzer and output efficiency is read into the power generation system control device 1.

[0051] <Step S4> In step S4, the power generation system control device 1 reads information related to catalyst control from the air-fuel ratio sensor 17, the catalyst upstream temperature sensor 18, and the oxygen concentration sensor 19. The information related to catalyst control is the air-fuel ratio Sg4, the catalyst inflow gas temperature (catalyst upstream temperature) Sg5, and the oxygen concentration Sg6.

[0052] <Step S5> In step S5, the power generation system control device 1 calculates the total required output required for the power generation system 100 based on the information (required load) Sg1 from the load-side device 3. Here, the total required output for the engine is calculated taking into account losses in the power converter 13 and the generator 12, etc.

[0053] <Step S6> In step S6, the power generation system control device 1 determines the activation state of the catalyst based on the catalyst inlet gas temperature Sg5. Here, if the catalyst inlet gas temperature Tc is equal to or higher than a predetermined temperature Tc0, the catalyst is determined to be activated, and if the catalyst inlet gas temperature Tc is lower than the predetermined temperature Tc0, the catalyst is determined to be inactivated. In this way, by making a determination based on a directly detected value of the temperature of the gas near the catalyst, the activation state of the catalyst can be determined with high accuracy. That is, in this embodiment, the power generation system control device 1 has a catalyst activation state detection unit that detects whether the catalyst is in an activated state. The catalyst activation state detection unit detects the temperature of the gas flowing into the catalyst (catalyst inlet gas temperature) (from the catalyst inlet gas temperature measured by the catalyst upstream temperature sensor 18) and determines that the catalyst is in an activated state when the catalyst inlet gas temperature is equal to or higher than a predetermined value. However, the means for detecting whether the catalyst is in an activated state is not limited to this.

[0054] <Step S7> In step S7, the power generation system control device 1 determines the warm-up state of the engine based on information (engine state) Sg3 from the ECU 15 and the engine 11. Here, if the engine coolant temperature Tw is equal to or higher than a predetermined temperature Tw1, it is determined that the engine is warmed up, and if the engine coolant temperature Tw is lower than the predetermined temperature Tw1, it is determined that the engine is cold. In this way, since the determination is made based on a directly detected value of the engine coolant temperature, the warm-up state of the engine can be determined with high accuracy. That is, in this embodiment, the power generation system control device 1 has an engine warm-up state detection unit that detects whether the engine is warmed up. The engine warm-up state detection unit detects the engine coolant temperature (from the coolant temperature measured by the coolant temperature sensor 24) and determines that the engine is warmed up when the engine coolant temperature is equal to or higher than a predetermined value. However, the means for detecting whether the engine is warmed up is not limited to this.

[0055] <Step S8> In step S8, the power generation system control device 1 calculates the engine operation mode based on the catalyst activation state and engine warm-up state determined in steps S6 and S7. Here, the corresponding operation mode is set from among the operation modes shown in FIG. 11. When the catalyst is inactive (in other words, when the catalyst activation state detection unit detects that the catalyst is inactive), mode 1 (only hydrocarbon fuel is supplied to the engine and hydrocarbon fuel is exclusively burned) is set. This increases the exhaust gas temperature and enables the catalyst to be activated quickly. When the catalyst is active and the engine is cold (in other words, when the catalyst activation state detection unit detects that the catalyst is active and the engine warm-up state detection unit detects that the engine is cold), mode 2 (hydrocarbon fuel and hydrogen are supplied to the engine and hydrogen co-combustion is performed). This increases the amount of heat transfer to the cylinder and enables the engine to be warmed up quickly. When the catalyst is active and the engine is warm (in other words, when the catalyst activation state detection unit detects that the catalyst is active and the engine warm-up state detection unit detects that the engine is warm), mode 3 (hydrocarbon fuel and hydrogen are supplied to the engine for hydrogen co-combustion) is set. This reduces NOx emitted from the engine and enables the catalyst to purify CO and HC with high efficiency.

[0056] <Step S9> In step S9, the power generation system control device 1 calculates the hydrogen mixing ratio based on the operation mode calculated in step S8. At this time, the hydrogen required by the power generation system 100 is set so as to be equal to or not exceed the amount of hydrogen that can be generated from the hydrogen generator 2. For example, the hydrogen mixing ratio relative to the amount of hydrogen that can be generated from the hydrogen generator 2 is set in advance for each operation mode and stored in the ROM of the power generation system control device 1, thereby calculating the hydrogen mixing ratio. For example, by setting the hydrogen mixing ratio to increase as the amount of hydrogen that can be generated increases, engine warm-up can be promoted in mode 2 under conditions where the amount of hydrogen that can be generated is large, and in mode 3 under conditions where the amount of hydrogen that can be generated is large, the engine can be operated under leaner conditions, resulting in highly efficient operation.

[0057] In addition, in mode 2, the hydrogen mixing ratio is set so that the lower the engine coolant temperature, the higher the hydrogen mixing ratio. In other words, in mode 2 (when the engine warm-up state detection unit detects that the engine is cold), the amount of hydrocarbon fuel or hydrogen supplied to the engine is set (controlled) so that the proportion of hydrogen in the total fuel supply amount decreases as the engine coolant temperature increases. As a result, the hydrogen mixing ratio increases as the engine coolant temperature decreases, increasing the amount of heat transfer in the cylinder and facilitating engine warm-up.

[0058] <Step S10> In step S10, the power generation system control device 1 sends the total required output calculated in step S5 to the ECU 15 as an engine torque command value (required output) Sd1, and executes the torque command.

[0059] <Step S11> In step S11, the power generation system control device 1 controls the hydrogen supply amount so as to realize the hydrogen mixed combustion ratio of the engine calculated in step S9, and sends a hydrogen supply amount command value (target hydrogen supply amount) Sd2 to the hydrogen supply device 14, thereby completing the series of controls.

[0060] 13 shows a time chart of a scene in which the catalyst is inactive and the engine is started from a cold condition in this embodiment. The vertical axis, from the top, represents the total required output, catalyst activation state, engine warm-up state, operation mode, hydrogen mixture ratio, catalyst upstream gas air-fuel ratio, engine power generation amount, and cumulative amount of harmful substance emissions, while the horizontal axis represents time. The solid line represents this embodiment, and the dashed line represents the prior art.

[0061] In FIG. 13 , at time t0, information is received from the load-side devices and the total required output is calculated. At this time, the catalyst is inactive and the engine is cold, so in this embodiment, the operating mode is set to mode 1, the hydrogen mixture ratio is set to 0, and the air-fuel ratio is set to stoichiometric. Then, at time t1, the catalyst is activated and the engine is cold, so in this embodiment, the operating mode is set to mode 2, the hydrogen mixture ratio is set to a predetermined value, and the air-fuel ratio is set to stoichiometric. With the catalyst activated, harmful substances are purified, and the cumulative amount of harmful substance emissions remains approximately constant. Furthermore, the colder the engine is (the lower the engine coolant temperature, not shown), the higher the hydrogen mixture ratio is set, thereby facilitating engine warm-up. Then, at time t2, the catalyst is activated and the engine is warmed up, so in this embodiment, the operating mode is set to mode 3, the hydrogen mixture ratio is set to a predetermined value, and the air-fuel ratio is set to lean. In contrast, in the prior art, hydrogen-mixed combustion is performed regardless of the catalyst activation state, which reduces the exhaust gas temperature and delays catalyst activation. As a result, harmful substances are emitted without being purified until the catalyst is activated, and as a result, the cumulative amount of harmful substance emissions increases.

[0062] Although this embodiment does not describe a method for starting the engine, the air-fuel ratio may be enriched to stabilize combustion during the period from engine cranking until combustion stabilizes. Also, by using hydrogen-mixed combustion or hydrogen-only combustion at startup, more stable combustion is possible than with hydrocarbon-based fuel only combustion, and emissions of unburned substances such as CO and THC can be reduced.

[0063] In addition, in this embodiment, the catalyst activity state is directly detected by the catalyst upstream temperature sensor 18, but the catalyst activity state can also be estimated based on the engine operating conditions (e.g., intake air amount, fuel supply amount, ignition timing, engine speed, etc.).

[0064] Furthermore, in this embodiment, the air-fuel ratio of the engine is determined from the output value of the air-fuel ratio sensor 17, but it may also be calculated based on the intake air amount detected by the air flow sensor 21 and the fuel injection amount.

[0065] As is clear from the above description, this embodiment is an engine power generation system (power generation system 100) that generates power using an engine that is supplied with hydrocarbon fuel and hydrogen and capable of mixed combustion and that has an engine warm-up detection unit that detects whether the engine is in a warm-up state.The engine power generation system control device (power generation system control device 1) includes a catalyst that is provided in the engine's exhaust passage to purify exhaust gases, and a catalyst activation state detection unit that detects whether the catalyst is activated.The engine power generation system control device (power generation system control device 1) is characterized in that it controls the amount of hydrocarbon fuel or hydrogen supplied to the engine (more specifically, the ratio of the amount of hydrocarbon fuel and the amount of hydrogen supplied to the engine) based on the catalyst activation state detected by the catalyst activation state detection unit and the engine warm-up state detected by the engine warm-up state detection unit.This enables early catalyst activation and early engine warm-up, resulting in reduced emissions of harmful substances from power generation system 100.

[0066] [Example 2] A second embodiment of the present invention will be described. In this embodiment, a method of applying a power generation system control device according to the present invention to a power generation system including a plurality of engine generators fueled by hydrogen and natural gas will be described. In the second embodiment described below, the configuration described in the first embodiment is applied except for the differences from the first embodiment.

[0067] Second Embodiment FIG. 14 is a schematic configuration diagram showing an example in which a power generation system control device according to a second embodiment of the present invention is applied to a power generation system including a plurality of engine generators fueled by hydrogen and natural gas.

[0068] The power generation system 100 is configured by connecting multiple sets of power generation modules GM (GM1 to GMn) in parallel, each set consisting of an engine 11, a generator 12, and a power converter 13. Each engine 11 is equipped with an electronic control unit (ECU) 15 for controlling the engines 11. The engines 11 are connected to a hydrogen generator 2 via a hydrogen supply device 14, allowing for the supply of hydrogen fuel. The engines 11 are also connected to a fuel tank (not shown) allowing for the supply of natural gas, thereby enabling combustion of hydrogen, natural gas, or a mixture of hydrogen and natural gas. The outputs of these power generation modules GM (GM1 to GMn) are electrically connected to load-side equipment 3.

[0069] The minimum configuration of the power generation module GM applicable to the present invention is to include an engine 11 and a generator 12. Depending on whether the load is an AC load or a DC load, an appropriate power converter 13 may be included. The generator 12 may be either an AC generator or a DC generator.

[0070] The exhaust pipes of each engine 11 are joined together in an exhaust passage 16. Furthermore, a three-way catalyst 20 as an exhaust purification catalyst that purifies the exhaust, a catalyst upstream temperature sensor 18 that measures the temperature of the gas flowing into the three-way catalyst 20 (catalyst inflow gas temperature), an air-fuel ratio sensor 17 which is one form of air-fuel ratio detector and detects the air-fuel ratio of the exhaust upstream of the three-way catalyst 20, and an oxygen concentration sensor 19 that detects the oxygen concentration of the exhaust downstream of the three-way catalyst 20 are provided in appropriate positions in the exhaust passage 16 after the exhaust pipes of each engine 11 are joined together.

[0071] The power generation system control device 1 is mounted on the power generation system 100. The power generation system control device 1 calculates the required load of the power generation system 100 based on the required load Sg1 from the load-side device 3. Furthermore, the power generation system control device 1 receives supplyable hydrogen amount information Sg2 from the hydrogen generator 2. Furthermore, the power generation system control device 1 receives information (engine state) Sg3 (Sg31 to Sg3n) of the sensors and actuators of each engine 11 from the engine 11. Furthermore, the power generation system control device 1 receives, from the air-fuel ratio sensor 17, the catalyst upstream temperature sensor 18, and the oxygen concentration sensor 19, the air-fuel ratio Sg4, the catalyst inflow gas temperature (catalyst upstream temperature) Sg5, and the oxygen concentration Sg6 as information related to the control of the three-way catalyst 20. Based on this information (Sg1, Sg2, Sg3), the power generation system control device 1 sends the engine required output and commands on whether to drive (hereinafter simply referred to as required output) Sd1 (Sd11 to Sd1n) to the ECU 15 of each engine 11, and controls each hydrogen supply device 14 to achieve the desired hydrogen supply amount (hydrogen supply target amount) Sd2 (Sd21 to Sd2n).

[0072] The ECU 15 controls the output of the engine 11 based on the required output Sd1 from the power generation system control device 1. Specifically, the ECU 15 controls the natural gas fuel injection unit, the ignition unit, the throttle valve, and the starter. The engine 11 is, for example, a four-cylinder engine that uses spark ignition combustion and is an example of an internal combustion engine. The generator 12 generates power using the driving force of the engine 11 to achieve a desired power load. The power converter 13 adjusts the voltage and phase of the power generated by the generator 12 and supplies the adjusted power to the load-side device 3.

[0073] Next, an example of the internal configuration of the power generation system control device 1 according to Example 2 will be described. Fig. 15 is a block diagram showing an example of the hardware configuration of the power generation system control device 1. The power generation system control device 1 is configured using a computer device.

[0074] In FIG. 15, the required load Sg1, the supplyable hydrogen amount Sg2, and the engine state Sg3 (Sg31 to Sg3n) output from the load-side device 3, the hydrogen generator 2, and the ECU 15 are input to the input circuit 1a of the power generation system control device 1. However, the input signals are not limited to these. Each signal input to the input circuit 1a is sent to an input port (not shown) in the input / output port 1b. The values ​​sent to the input port are stored in the RAM (1c) and are processed by the CPU (1e). A control program describing the contents of the processing is written in advance in the ROM (1d).

[0075] Values ​​indicating the operating amounts of the controlled objects (engine 11, hydrogen supply device 14, etc.) calculated according to the control program are stored in RAM (1c) and then sent to an output port (not shown) in input / output port 1b, and then sent via each output section (engine torque control output section 1f, hydrogen supply amount control output section 1g) to each device (ECU 15, hydrogen supply device 14) as required output Sd1 (Sd11-Sd1n) and desired hydrogen supply amount (hydrogen supply target amount) Sd2 (Sd21-Sd2n). Note that in FIG. 15, the control devices (ECU 15) for each engine are provided separately from the power generation system control device 1, but this is not limited to this configuration, and functional sections corresponding to the control devices of each device may be provided within the power generation system control device 1.

[0076] In a configuration with multiple engine generators, the number of operating power generating modules GM can be adjusted according to the total load demand from the load-side devices. For example, assume that i power generating modules are operating at rated power at a certain total required output Pr1, and all operating engines have active catalysts and are warmed up, operating in mode 3 (hydrogen-mixed combustion (lean)) in embodiment 1. In this situation, assume that the total required output from the load-side devices increases to Pr2 at a certain timing. If adjusting the output of the operating modules is not sufficient to accommodate the increase in total required output, k new modules are activated to achieve the total required output Pr2. Since the newly activated k engines are cold, they are operated in mode 2 (hydrogen-mixed combustion (stoichiometric)) in embodiment 1 to quickly warm up. At this time, to maximize the catalytic conversion performance, the air-fuel ratio of the i engines already operating must also be set to stoichiometric. In this embodiment, control is performed under such conditions where a warmed-up engine and a cold engine are operating simultaneously.

[0077] Figure 16 shows the indicated thermal efficiency under conditions of mono-natural gas combustion and hydrogen co-firing. The conditions are the same for both mono-natural gas combustion and natural gas-hydrogen co-firing: engine speed and indicated mean effective pressure are constant, the air-fuel ratio is stoichiometric, and the ignition timing is optimal. Under hydrogen co-firing, the indicated thermal efficiency is lower than under mono-natural gas combustion. The main reason for this is that the amount of heat transfer to the cylinder increases, resulting in increased cooling losses, as shown in Figure 7.

[0078] From the above, it is effective to use natural gas exclusively in terms of the indicated thermal efficiency under theoretical air-fuel ratio conditions.

[0079] Therefore, in this embodiment, the amount of hydrocarbon fuel or hydrogen supplied to each engine is controlled based on the activation state of the catalyst and the warm-up state of each engine. Specifically, as shown in FIG. 17, four operating modes with different hydrogen mixing ratios and air-fuel ratios are provided, and control is performed to switch between the operating modes depending on the activation state of the catalyst and the warm-up state of each engine. Modes 1 and 2 are similar to modes 1 and 2 in embodiment 1, so a description thereof will be omitted. Details of modes 3 and 4 are provided below.

[0080] Mode 3 When the catalyst is active, the engine is warmed up, and a cold engine is not running at the same time, hydrocarbon fuel and hydrogen are supplied to the warm engine to achieve hydrogen co-combustion. This allows the lean limit to be expanded. The air-fuel ratio of each engine is also controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst is equal to or greater than a predetermined value C2. The predetermined value C2 is the oxygen concentration of the exhaust gas under lean engine air-fuel ratio conditions that can suppress the amount of NOx generated by the engine to a value that is sufficient to meet the emission regulations without using an aftertreatment device (in other words, when the engine is operated at an air-fuel ratio that keeps the amount of nitrogen oxides directly emitted from the engine below a predetermined value). This reduces NOx emitted from the engine when a cold engine is not running at the same time, and enables the catalyst to efficiently purify CO and HC.

[0081] Mode 4 When the catalyst is active, the engine is warmed up, and a cold engine is running at the same time, only hydrocarbon fuel is supplied to the warmed engine, allowing it to burn hydrocarbon fuel exclusively. This allows the warmed engine to operate under highly efficient conditions. The air-fuel ratio of each engine is controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst is below a predetermined value C1. The predetermined value C1 is the oxygen concentration of the exhaust gas when the engine is running at a theoretical air-fuel ratio (stoichiometric). Note that the engine's air-fuel ratio need only be controlled within the catalyst window where the ratio of reactive components (HC, NOx, CO, H2) is stoichiometrically ideal; it does not need to be strictly stoichiometric. This allows the catalyst to purify harmful gas components (HC, CO, NOx) in the exhaust when a cold engine is running at the same time.

[0082] Next, a specific process of this embodiment will be described.

[0083] An example of a flowchart of engine generator control according to this embodiment is shown in Figure 18. Each step will be described in detail below.

[0084] <Step S12> Step S12 is the same process as step S1 in the first embodiment, and therefore a description thereof will be omitted.

[0085] <Step S13> In step S13, the power generation system control device 1 reads information (engine state) Sg3 (Sg31 to Sg3n) of each engine 11 from each ECU 15 and engine 11. The information (engine state) Sg3 from the ECU 15 and engine 11 includes, for example, engine states such as the current engine speed, torque, and engine temperature (coolant temperature, intake temperature, etc.), and engine specifications (displacement, compression ratio, fuel supply position, etc.).

[0086] <Steps S14 to S16> Steps S14 to S16 are the same as steps S3 to S5 in the first embodiment, and therefore a description thereof will be omitted.

[0087] <Step S17> In step S17, the power generation system control device 1 distributes the total required output Sd1 calculated in step S16 to each engine power generation module to obtain individual required outputs Sd11, Sd12, ... Sd1n (processing step S5). For example, the number of engine power generation modules required to be driven is calculated from the total required output Sd1 and the rated output of each engine power generation module, and the total required output Sd1 is distributed evenly among the driven engine power generation modules.

[0088] <Step S18> Step S18 is the same process as step S6 in the first embodiment, and therefore a description thereof will be omitted.

[0089] <Step S19> In step S19, the power generation system control device 1 determines the warm-up state of each engine based on information (engine state) Sg3 (Sg31 to Sg3n) from each ECU 15 and engine 11. Here, if the engine coolant temperature Tw is equal to or higher than a predetermined temperature Tw1, it is determined that the engine is warmed up, and if the engine coolant temperature Tw is lower than the predetermined temperature Tw1, it is determined that the engine is cold. In this way, since the determination is based on a directly detected value of the engine coolant temperature, the warm-up state of the engine can be determined with high accuracy.

[0090] <Step S20> In step S20, the power generation system control device 1 calculates the operating mode for each engine based on the catalyst activation state and the warm-up state of each engine determined in steps S18 and S19. Here, the corresponding operating mode is selected from the operating modes shown in FIG. 17. When the catalyst is inactive (in other words, when the catalyst activation state detection unit detects that the catalyst is inactive), mode 1 is selected (only hydrocarbon fuel is supplied to the engine, resulting in hydrocarbon fuel combustion). This increases the exhaust gas temperature, enabling the catalyst to be activated more quickly. When the catalyst is active and the engine is cold (in other words, when the catalyst activation state detection unit detects that the catalyst is active and the engine warm-up state detection unit detects that the engine is cold), mode 2 is selected (hydrocarbon fuel and hydrogen are supplied to the engine, resulting in hydrogen co-combustion). This increases the amount of heat transfer to the cylinder, enabling the engine to be warmed up more quickly. When the catalyst is active, the engine is warming up, and a cold engine is not running at the same time (in other words, when the catalyst activation state detection unit detects that the catalyst is active, the engine warm-up state detection unit detects that the engine is warmed up, and a cold engine is not running at the same time), mode 3 is set (hydrocarbon fuel and hydrogen are supplied to the warm engine to achieve hydrogen co-combustion). This enables hydrogen co-combustion (lean) when a cold engine is not running at the same time, thereby reducing NOx emissions from the engine and enabling the catalyst to efficiently purify CO and HC. When the catalyst is active, the engine is warming up, and a cold engine is running at the same time (in other words, when the catalyst activation state detection unit detects that the catalyst is active, the engine warm-up state detection unit detects that the engine is warmed up, and a cold engine is running at the same time), mode 4 is set, and only hydrocarbon fuel is supplied to the warm engine to achieve hydrocarbon fuel mono-combustion (stoichiometric). This allows the warmed-up engine to operate under highly efficient conditions, and the catalyst can purify HC, CO, and NOx with high efficiency.

[0091] <Step S21> In step S21, the power generation system control device 1 calculates the hydrogen mixing ratio for each engine based on the operation mode calculated in step S20. The other processing is the same as step S9 in the first embodiment, so detailed description will be omitted.

[0092] <Step S22> In step S22, the power generation system control device 1 sends the torque command values ​​(individual required outputs Sd11, Sd12, . . . Sd1n) for each engine calculated in step S17 to each ECU 15, and executes the torque commands.

[0093] <Step S23> In step S23, the power generation system control device 1 executes hydrogen supply amount control to realize the hydrogen mixed combustion ratio for each engine calculated in step S21. Individual hydrogen supply amount command values ​​(Sd21, Sd22, ... Sd2n) are sent to each hydrogen supply device 14, and the series of controls is completed.

[0094] 19 shows a time chart of a scene in this embodiment where the total required output increases from a state in which engine A is operating at rated power, and engine B is newly started. From the top, the vertical axis represents the total required output, catalyst activation state, warm-up state of engines A and B, operation mode, hydrogen mixture ratio, power generation amount, thermal efficiency, and catalyst upstream gas air-fuel ratio (exhaust air-fuel ratio), and the horizontal axis represents time. The solid line represents this embodiment, and the dashed line represents the prior art.

[0095] In FIG. 19 , at time t5, the total required output increases, and engine B is started to accommodate this. At this time, the catalyst is activated, engine A is warmed up, and engine B is cold. Therefore, in this embodiment, engine A is set to mode 4 (hydrocarbon-based fuel mono-combustion), the hydrogen mixture ratio is 0, and the air-fuel ratio is stoichiometric. Engine B is set to mode 2 (hydrogen-mixed combustion), the hydrogen mixture ratio is a predetermined value, and the air-fuel ratio is stoichiometric. In contrast, in the prior art, both engines A and B are set to the preset mode 2 (hydrogen-mixed combustion), the hydrogen mixture ratio is a predetermined value, and the air-fuel ratio is stoichiometric. Thus, while engine A in the prior art uses hydrogen-mixed combustion, engine A in this embodiment uses hydrocarbon-based fuel mono-combustion, thereby improving the thermal efficiency of engine A compared to the prior art. Furthermore, in this embodiment, the colder the engine is (the lower the engine coolant temperature, not shown), the higher the hydrogen mixture ratio is set. Therefore, engine B can warm up more quickly in this embodiment compared to the prior art. At time t6, in this embodiment, the catalyst becomes active and engine A and engine B are in the warm-up state, and both engines A and B are set to mode 3, the hydrogen mixture ratio to a predetermined value, and the air-fuel ratio to lean, enabling highly thermally efficient operation.In contrast, in the prior art, the catalyst becomes active and engine A and engine B are in the warm-up state at time t7, which is later than time t6, and the period until highly thermally efficient operation is achieved is prolonged.

[0096] As described above, in this embodiment, the amount of hydrocarbon fuel or hydrogen supplied to each engine (more specifically, the ratio of the amount of hydrocarbon fuel and the amount of hydrogen supplied to each engine) is controlled based on the catalyst activation state and the warm-up state of each engine. This enables early activation of the catalyst and early warm-up of the engine, thereby reducing harmful substance emissions from the power generation system 100. Furthermore, when a cold engine is operating at the same time, the warmed engine can be operated under conditions of high thermal efficiency, thereby reducing fuel consumption.

[0097] [Example 3] A third embodiment of the present invention will be described. In this embodiment, a method for setting the air-fuel ratio of each engine in a power generation system control device according to the present invention applied to a power generation system consisting of multiple engine generators fueled by hydrogen and natural gas will be described so that the ratio of reaction components (HC, NOx, CO, H2) in the gas flowing into the catalyst becomes a stoichiometrically ideal value. In the third embodiment described below, the configuration described in the second embodiment is applied except for the differences from the second embodiment.

[0098] First, a method for setting the air-fuel ratio of each engine in this embodiment will be described with reference to FIG.

[0099] Figure 20 shows the production trends of CO, HC, and NOx versus air-fuel ratio in premixed combustion in a spark ignition engine. Premixed refers to a state in which air and fuel are mixed uniformly before ignition. Here, we will use a single hydrocarbon fuel or a mixture of hydrocarbon fuel and hydrogen as examples. The production characteristics of each component will be explained below.

[0100] CO and HC Since CO and HC are components of incomplete combustion, they increase as the air-fuel ratio decreases and the mixture becomes richer. When starting the engine, a rich mixture is necessary to stabilize combustion, which tends to produce large amounts of CO.

[0101] NOx NOx is mainly NO, which is produced in large quantities at high temperatures and in the presence of oxygen and nitrogen. The combustion gases are at their highest when the mixture ratio is slightly richer than the stoichiometric air-fuel ratio, where oxygen is present only during combustion, but disappears after combustion, and the amount of oxygen increases in the leaner range. As a result, the amount of NO produced is at its maximum when the mixture ratio is leaner than the stoichiometric air-fuel ratio.

[0102] The air-fuel ratio of each engine is set based on these CO, HC, and NOx production characteristics relative to the air-fuel ratio. For example, imagine a scenario in which engine A is operating at rated power but the total required output increases, and engine B is then started. When engine B starts, its air-fuel ratio is set rich to stabilize combustion. At this time, large amounts of CO and HC are produced. Therefore, engine A's air-fuel ratio is set lean to increase the amounts of NOx and oxygen. This allows the ratio of reactive components in the gas flowing into the catalyst to be stoichiometrically ideal, allowing the catalyst to purify harmful substances with high efficiency.

[0103] Next, a specific process of this embodiment will be described.

[0104] An example of a flowchart of engine generator control according to this embodiment is shown in Figure 21. Each step will be described in detail below.

[0105] <Steps S24 to S33> Steps S24 to S33 are the same as steps S12 to S21 in the second embodiment, and therefore a description thereof will be omitted.

[0106] <Step S34> In step S34, the power generation system control device 1 calculates the air-fuel ratio of each engine based on the information (engine state) Sg3 (Sg31 to Sg3n) from each ECU 15 and engine 11. Here, the air-fuel ratio of the newly started engine is set to rich. Also, the air-fuel ratio of the engines that were already operating is set to lean or stoichiometric. At this time, the air-fuel ratio of each engine is set so that the ratio of reactive components in the gas flowing into the catalyst is stoichiometrically ideal. For example, if there is one newly started engine and two already operating engines, the newly started engine may be set to rich and the already operating engines may all be set to lean, or one may be set to stoichiometric. By controlling the air-fuel ratio of each engine in this way, harmful substances can be purified highly efficiently by the catalyst.

[0107] <Steps S35 and S36> Steps S35 and S36 are the same as steps S22 and S23 in the second embodiment, and therefore their explanation will be omitted.

[0108] In this embodiment, when at least one engine is running, the air-fuel ratio of the newly started engine is controlled to be rich, and the air-fuel ratio of the engines already running is controlled to be lean or stoichiometric. By controlling the air-fuel ratio of each engine in this manner, the ratio of reactive components in the gas flowing into the catalyst becomes stoichiometrically ideal, allowing the catalyst to purify harmful substances with high efficiency. As a result, the amount of harmful substances emitted from the power generation system 100 can be reduced.

[0109] The present invention is not limited to the above-described embodiments, and it goes without saying that various other applications and modifications are possible without departing from the gist of the present invention as set forth in the claims.

[0110] For example, the above-described embodiments have described the configuration of the device and system in detail and specifically in order to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of the embodiments described here with the configuration of other embodiments, and it is also possible to add the configuration of one embodiment to the configuration of another embodiment. Furthermore, it is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0111] In addition, the control lines and information lines shown are those that are considered necessary for the explanation, and do not necessarily show all the control lines and information lines in the product. In reality, it can be assumed that almost all components are interconnected. [Explanation of symbols]

[0112] 1: Power generation system control device (control device for engine power generation system) 1a: Input circuit 1b: Input / output port 1c:RAM 1d:ROM 1e:CPU 1f: Engine torque control output section 1g: Hydrogen supply amount control output section 2: Hydrogen generator 3: Load side equipment 11: Engine 12: Generator 13: Power converter 14: Hydrogen supply device 15:ECU 16: Exhaust passage 17: Air-fuel ratio sensor 18: Catalyst upstream temperature sensor 19: Oxygen concentration sensor 20: Exhaust purification catalyst (three-way catalyst) 21: Air flow sensor 22: Natural gas injection device 23: Hydrogen supply channel 24: Coolant temperature sensor 25: Exhaust pipe 26:Electronically controlled throttle 27: Intake pipe 28: Combustion chamber 29: Spark plug 30: Cylinder head

Claims

1. A control device for an engine power generation system that generates power using an engine that is supplied with hydrocarbon fuel and hydrogen to enable mixed combustion and that has an engine warm-up state detection unit that detects whether the engine is in a warm-up state, the control device comprising: a catalyst that is provided in an exhaust passage of the engine to purify exhaust gas; and a catalyst activation state detection unit that detects whether the catalyst is in an activated state, controlling an amount of hydrocarbon fuel or an amount of hydrogen supplied to the engine based on the catalyst activation state detected by the catalyst activation state detection unit and the engine warm-up state detected by the engine warm-up state detection unit; When the catalyst activation state detection unit detects that the catalyst is activated, a hydrocarbon fuel and hydrogen are supplied to the engine to perform hydrogen mixed combustion; 10. A control device for an engine power generation system, comprising: a control unit for supplying only hydrocarbon fuel to the engine when the catalyst activation state detection unit detects that the catalyst is inactive; and a control unit for supplying only hydrocarbon fuel to the engine to burn hydrocarbon fuel exclusively.

2. A control device for an engine power generation system that generates power using an engine that is supplied with hydrocarbon fuel and hydrogen to enable mixed combustion and that has an engine warm-up state detection unit that detects whether the engine is in a warm-up state, the control device comprising: a catalyst that is provided in an exhaust passage of the engine to purify exhaust gas; and a catalyst activation state detection unit that detects whether the catalyst is in an activated state, controlling an amount of hydrocarbon fuel or an amount of hydrogen supplied to the engine based on the catalyst activation state detected by the catalyst activation state detection unit and the engine warm-up state detected by the engine warm-up state detection unit; When the catalyst activation state detection unit detects that the catalyst is activated, a hydrocarbon fuel and hydrogen are supplied to the engine to perform hydrogen mixed combustion; when the engine warm-up state detection unit detects that the engine is cold, the air-fuel ratio of the engine is controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst is equal to or less than a predetermined value C1; 10. A control device for an engine power generation system, wherein the predetermined value C1 is an oxygen concentration in exhaust gas when the engine is operated at a stoichiometric air-fuel ratio.

3. A control device for an engine power generation system that generates power using an engine that is supplied with hydrocarbon fuel and hydrogen to enable mixed combustion and that has an engine warm-up state detection unit that detects whether the engine is in a warm-up state, the control device comprising: a catalyst that is provided in an exhaust passage of the engine to purify exhaust gas; and a catalyst activation state detection unit that detects whether the catalyst is in an activated state, controlling an amount of hydrocarbon fuel or an amount of hydrogen supplied to the engine based on the catalyst activation state detected by the catalyst activation state detection unit and the engine warm-up state detected by the engine warm-up state detection unit; When the catalyst activation state detection unit detects that the catalyst is activated, a hydrocarbon fuel and hydrogen are supplied to the engine to perform hydrogen mixed combustion; when the engine warm-up state detection unit detects that the engine is warmed up, the air-fuel ratio of the engine is controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst becomes equal to or higher than a predetermined value C2; A control device for an engine power generation system, characterized in that the predetermined value C2 is the oxygen concentration of the exhaust when the engine is operated at an air-fuel ratio such that the amount of nitrogen oxides directly emitted from the engine is equal to or less than a predetermined value.

4. A control device for an engine power generation system that generates power using an engine that is supplied with hydrocarbon fuel and hydrogen to enable mixed combustion and that has an engine warm-up state detection unit that detects whether the engine is in a warm-up state, the control device comprising: a catalyst that is provided in an exhaust passage of the engine to purify exhaust gas; and a catalyst activation state detection unit that detects whether the catalyst is in an activated state, controlling an amount of hydrocarbon fuel or an amount of hydrogen supplied to the engine based on the catalyst activation state detected by the catalyst activation state detection unit and the engine warm-up state detected by the engine warm-up state detection unit; When the catalyst activation state detection unit detects that the catalyst is activated, a hydrocarbon fuel and hydrogen are supplied to the engine to perform hydrogen mixed combustion; a control device for an engine power generation system, characterized in that when the engine warm-up state detection unit detects that the engine is cold, the amount of hydrocarbon fuel supplied to the engine or the amount of hydrogen supplied to the engine is controlled so that the proportion of hydrogen in the total amount of fuel supplied decreases as the engine coolant temperature increases.

5. A control device for an engine power generation system that generates power using an engine that is supplied with hydrocarbon fuel and hydrogen to enable mixed combustion and that has an engine warm-up state detection unit that detects whether the engine is in a warm-up state, the control device comprising: a catalyst that is provided in an exhaust passage of the engine to purify exhaust gas; and a catalyst activation state detection unit that detects whether the catalyst is in an activated state, controlling an amount of hydrocarbon fuel or an amount of hydrogen supplied to the engine based on the catalyst activation state detected by the catalyst activation state detection unit and the engine warm-up state detected by the engine warm-up state detection unit; a control device for an engine power generation system, characterized in that when the catalyst activation state detection unit detects that the catalyst is active and the engine warm-up state detection unit detects that the engine is cold, a hydrocarbon fuel and hydrogen are supplied to the engine to perform hydrogen mixed combustion.

6. A control device for an engine power generation system that generates power using an engine that is supplied with hydrocarbon fuel and hydrogen to enable mixed combustion and that has an engine warm-up state detection unit that detects whether the engine is in a warm-up state, the control device comprising: a catalyst that is provided in an exhaust passage of the engine to purify exhaust gas; and a catalyst activation state detection unit that detects whether the catalyst is in an activated state, the engine power generation system includes a plurality of the engines, an exhaust passage that collects exhaust pipes of the plurality of engines, and the catalyst provided in the exhaust passage; controlling the amount of hydrocarbon fuel supplied to each of the engines or the amount of hydrogen supplied to each of the engines based on the catalyst activation state detected by the catalyst activation state detection unit and the warm-up state of each of the engines detected by the engine warm-up state detection unit; a control device for an engine power generation system, characterized in that when the catalyst activation state detection unit detects that the catalyst is active and the engine warm-up state detection unit detects that the engine is cold, a hydrocarbon fuel and hydrogen are supplied to the engine to perform hydrogen mixed combustion.

7. A control device for an engine power generation system that generates power using an engine that is supplied with hydrocarbon fuel and hydrogen to enable mixed combustion and that has an engine warm-up state detection unit that detects whether the engine is in a warm-up state, the control device comprising: a catalyst that is provided in an exhaust passage of the engine to purify exhaust gas; and a catalyst activation state detection unit that detects whether the catalyst is in an activated state, the engine power generation system includes a plurality of the engines, an exhaust passage that collects exhaust pipes of the plurality of engines, and the catalyst provided in the exhaust passage; controlling the amount of hydrocarbon fuel supplied to each of the engines or the amount of hydrogen supplied to each of the engines based on the catalyst activation state detected by the catalyst activation state detection unit and the warm-up state of each of the engines detected by the engine warm-up state detection unit; When the catalyst activation state detection unit detects that the catalyst is activated, a hydrocarbon fuel and hydrogen are supplied to the engine to perform hydrogen mixed combustion; a control device for an engine power generation system, characterized in that, when the catalyst activation state detection unit detects that the catalyst is active, the engine warm-up state detection unit detects that the engine is warmed up, and a cold engine is not operating at the same time, a hydrocarbon fuel and hydrogen are supplied to the warmed-up engine to perform hydrogen mixed combustion.

8. A control device for an engine power generation system that generates power using an engine that is supplied with hydrocarbon fuel and hydrogen to enable mixed combustion and that has an engine warm-up state detection unit that detects whether the engine is in a warm-up state, the control device comprising: a catalyst that is provided in an exhaust passage of the engine to purify exhaust gas; and a catalyst activation state detection unit that detects whether the catalyst is in an activated state, the engine power generation system includes a plurality of the engines, an exhaust passage that collects exhaust pipes of the plurality of engines, and the catalyst provided in the exhaust passage; controlling the amount of hydrocarbon fuel supplied to each of the engines or the amount of hydrogen supplied to each of the engines based on the catalyst activation state detected by the catalyst activation state detection unit and the warm-up state of each of the engines detected by the engine warm-up state detection unit; When the catalyst activation state detection unit detects that the catalyst is activated, a hydrocarbon fuel and hydrogen are supplied to the engine to perform hydrogen mixed combustion; a control device for an engine power generation system, characterized in that, when the catalyst activation state detection unit detects that the catalyst is active, the engine warm-up state detection unit detects that the engine is warmed up, and a cold engine is operating at the same time, only hydrocarbon-based fuel is supplied to the warm-up engine, causing it to burn hydrocarbon-based fuel exclusively.

9. The control device for an engine power generation system according to claim 8, When the engine warm-up state detection unit detects that the cold engines are operating at the same time, the air-fuel ratio of each engine is controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst is equal to or less than a predetermined value C1; 10. A control device for an engine power generation system, wherein the predetermined value C1 is an oxygen concentration in exhaust gas when the engine is operated at a stoichiometric air-fuel ratio.

10. The control device for an engine power generation system according to claim 7, When the engine warm-up state detection unit detects that the cold engines are not operating at the same time, the air-fuel ratio of each engine is controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst becomes equal to or higher than a predetermined value C2; A control device for an engine power generation system, characterized in that the predetermined value C2 is the oxygen concentration of the exhaust when the engine is operated at an air-fuel ratio such that the amount of nitrogen oxides directly emitted from the engine is equal to or less than a predetermined value.

11. A control device for an engine power generation system that generates power using an engine that is supplied with hydrocarbon fuel and hydrogen to enable mixed combustion and that has an engine warm-up state detection unit that detects whether the engine is in a warm-up state, the control device comprising: a catalyst that is provided in an exhaust passage of the engine to purify exhaust gas; and a catalyst activation state detection unit that detects whether the catalyst is in an activated state, the engine power generation system includes a plurality of the engines, an exhaust passage that collects exhaust pipes of the plurality of engines, and the catalyst provided in the exhaust passage; controlling the amount of hydrocarbon fuel supplied to each of the engines or the amount of hydrogen supplied to each of the engines based on the catalyst activation state detected by the catalyst activation state detection unit and the warm-up state of each of the engines detected by the engine warm-up state detection unit; When the catalyst activation state detection unit detects that the catalyst is activated, a hydrocarbon fuel and hydrogen are supplied to the engine to perform hydrogen mixed combustion; A control device for an engine power generation system, characterized in that when at least one engine is operating, the air-fuel ratio of an engine to be newly started is controlled to be rich, and the air-fuel ratio of an engine already operating is controlled to be lean or stoichiometric.

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