CONTROL DEVICE FOR AN ENGINE POWER GENERATION SYSTEM

Abstract

A control device for an engine-power generation system is provided that reduces the external emission of a pollutant contained in exhaust gas by immediately activating an exhaust gas purification catalyst and immediately warming up an engine within a power generation system. This engine allows the supply of renewable energy fuel and hydrocarbon-based fuel, and performs co-combustion. The amount of hydrocarbon-based fuel or hydrogen supplied to the engine is controlled based on the active state of the catalyst, detected by an active catalyst state sensing unit, and the warmed-up state of the engine, detected by an engine warm-up state sensing unit.

Description

Technical field

[0001] The present invention relates to a control device for an engine power generation system that is compatible with the co-combustion of a fuel derived from renewable energy, such as hydrogen, and a hydrocarbon-based fuel, such as gasoline or natural gas. Technical background

[0002] Progress in expanding the use of renewable energy for energy decarbonization increases the importance of setting up power generation systems that use fuels derived from renewable energy (hereinafter referred to as RE fuels (RE for regenerative)), such as hydrogen, to cope with fluctuations in renewable energy power supply.

[0003] Large-scale gas-fired power generation can be used to adjust current or power output; however, its output adjustment range is limited to 30% to 100% of rated operation and does not provide sufficient adjustment current or power. Furthermore, because equipment installation locations are fixed, power lines must be upgraded, and equipment costs are high. Additionally, because large-scale thermal power generation is limited by the range of fuels that can be procured, it can be difficult to effectively utilize renewable energy fuels that are ubiquitous in a region.

[0004] Distributed power generation systems that utilize an engine-driven generator compatible with renewable energy fuels (RE fuels) show great promise as systems capable of managing the transition to renewable energy while using RE fuels, which are readily available in a region. In particular, it is possible to minimize initial equipment costs by using mass-produced engines, such as existing automotive or industrial engines, and employing these engines as stationary power generation systems.Furthermore, engines are used that are capable of performing a mixed combustion (hereinafter referred to as co-combustion) of a renewable energy fuel, such as hydrogen, and a hydrocarbon-based fuel, such as gasoline or natural gas, thereby enabling power generation systems to be operated depending on a production quantity and a procurement quantity of the renewable energy fuel, so that a utilization rate can increase.

[0005] With regard to a control device for an engine-power generation system related thereto, PTL 1 is known. PTL 1 discloses “a fuel supply device for an internal combustion engine, which is configured to be able to independently supply a hydrogen fuel and a hydrocarbon-based fuel to a combustion chamber of an internal combustion engine, and which has a first combustion control mode in which the hydrocarbon-based fuel is supplied to a radially central section of the combustion chamber or a surrounding section of a spark plug provided in the combustion chamber with respect to the combustion chamber, and the hydrogen fuel is supplied to an area surrounding a region to which the hydrocarbon-based fuel is supplied in the combustion chamber.” List of patent literature

[0006] PTL 1: JP 5772958 B Summary of the invention: Technical problem

[0007] Since engine exhaust contains carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and similar substances that are harmful to humans, animals, and plants, it is necessary to reduce the amount of these pollutants emitted. To this end, it is effective to install an exhaust aftertreatment catalyst in the engine's exhaust system to remove pollutants (NOx, THC, CO, etc.) through purification and thus reduce the amount of pollutants emitted directly from the engine. Initially, regarding purification by a catalyst, the immediate activation of the catalyst is a challenge. This is because purification by removing pollutants can only be effectively achieved by increasing the catalyst's temperature and thereby activating it.Next, regarding the reduction of pollutants emitted directly from the engine, lean combustion is effective. In lean combustion, the minimum amount of air required for complete combustion is used, resulting in combustion using a leaner fuel mixture (referred to hereafter as lean) than in a theoretical air-fuel ratio. This is because lean combustion lowers the combustion gas temperature, which significantly reduces the amount of NOx produced by combustion. Furthermore, since oxygen is present in the exhaust gas during lean combustion, cleaning by a three-way catalytic converter can be achieved by removing both THC and CO.Since combustion stability deteriorates in lean combustion, immediately achieving an engine warm-up state in which stable combustion is possible (hereinafter referred to as immediate engine warm-up) is a challenge. Furthermore, in a co-combustion engine, which allows for the independent supply of multiple fuels, it is necessary to address the challenge described above while considering the properties of each fuel.

[0008] In this respect, the conventional technology described in PTL 1 involves the co-combustion of hydrocarbon-based fuel and hydrogen. This results in an increase in catalyst temperature, and consequently, a longer time required to activate the catalyst compared to combustion of hydrocarbon-based fuel alone. This is because the exhaust gas temperature produced by hydrogen combustion is lower than that produced by hydrocarbon-based fuel combustion. Furthermore, the conventional technology described in PTL 1 is limited to a configuration that includes means capable of controlling the spatial distribution of the fuels within the combustion chamber.For example, in a configuration where the hydrocarbon-based fuel and hydrogen are supplied from a middle section of an intake pipe, the hydrocarbon-based fuel and hydrogen are supplied to the combustion chamber in a well-mixed state, and thus it is difficult to apply conventional technology to it.

[0009] The present invention was made in view of such a circumstance, and an object of the present invention is to provide a control device for an engine power generation system which is capable of providing immediate activation of an exhaust gas purification catalyst and immediate warm-up of an engine in a power generation system which includes an engine which allows a RE fuel and a hydrocarbon-based fuel to be supplied and which performs co-combustion. Solution to the problem

[0010] To solve the above problem, the present invention provides a control device for an engine power generation system capable of co-combustion when a hydrocarbon-based fuel and hydrogen are supplied, and which generates electricity through an engine comprising an engine warm-up detection unit that detects whether the engine is in a warm-up state, wherein the control device for the engine power generation system comprises: a catalyst provided in an exhaust gas passage of the engine that cleans an exhaust gas;and an active catalyst state detection unit that detects whether the catalyst is in an active state in which a supply quantity of hydrocarbon-based fuel or a supply quantity of hydrogen to the engine is controlled based on an active catalyst state detected by the active catalyst state detection unit and a warmed-up state of the engine detected by the engine warm-up state detection unit.”; Advantageous effects of the invention

[0011] Since, according to the present invention, it is possible to control the supply quantities of hydrocarbon-based fuel and hydrogen depending on the active state of a catalyst and the warmed-up state of an engine, immediate activation of the catalyst and immediate warm-up of the engine can be carried out, and this can reduce the emission of a pollutant contained in an exhaust gas to the outside.

[0012] Other problems, configurations and effects than those described above are clarified by the following description of embodiments. Brief description of the drawings Fig. Figure 1 is a schematic configuration diagram illustrating an example in which a control device for a power generation system is applied to a power generation system comprising an engine-driven power generator that uses hydrogen and natural gas as fuels, according to a first embodiment of the present invention. Fig. Figure 2 is a block diagram illustrating a hardware configuration example of the control device for a power generation system according to the first embodiment of the present invention. Fig. Figure 3 is a diagram illustrating an example of an engine configuration according to the first embodiment of the present invention. Fig. Figure 4 is a diagram illustrating another example of the engine configuration according to the first embodiment of the present invention. Fig. Figure 5 is a graph illustrating heat generation profiles in a natural gas-only combustion condition and a hydrogen-co-combustion condition according to the first embodiment of the present invention. Fig. Figure 6 is a graph illustrating the average cylinder gas temperature profiles in the natural gas-only combustion condition and the hydrogen-co combustion condition according to the first embodiment of the present invention. Fig. Figure 7 is a graph illustrating the amount of heat transferred from a gas in a cylinder to an engine cylinder according to the first embodiment of the present invention. Fig. Figure 8 is a graph illustrating lean limits of the natural gas-only combustion condition and the hydrogen-co combustion condition according to the first embodiment of the present invention. Fig. Figure 9 is a graph that graphically illustrates a thermal efficiency at the lean limit according to the first embodiment of the present invention. Fig. Figure 10 is a graph illustrating the NOx production quantity at the lean limit according to the first embodiment of the present invention. Fig. Figure 11 is a table illustrating an operating mode according to the first embodiment of the present invention. Fig. Figure 12 is a diagram illustrating an example of a flowchart of a control system for a motor generator according to the first embodiment of the present invention. Fig. Figure 13 is a time diagram of a scene in which a catalyst is inactive and an engine starts in a cold state, according to the first embodiment of the present invention. Fig. Figure 14 is a schematic configuration diagram illustrating an example in which a control device for a power generation system is applied to a power generation system comprising a plurality of engine-power generators using hydrogen and natural gas as fuels, according to a second embodiment of the present invention. Fig. Figure 15 is a block diagram illustrating a hardware configuration example of the control device for a power generation system according to the second embodiment of the present invention. Fig. Figure 16 is a graph that graphically illustrates a heat efficiency of a natural gas-only combustion condition and a hydrogen-co combustion condition according to the second embodiment of the present invention. Fig. Figure 17 is a table illustrating an operating mode according to the second embodiment of the present invention. Fig. Figure 18 is a diagram illustrating an example of a flowchart of a control system for a motor generator according to the second embodiment of the present invention. Fig. Figure 19 is a time graph of a scene in which a total request output increases from a state in which a motor A is operating at nominal power and a motor B is being restarted, according to the second embodiment of the present invention. Fig. Figure 20 is a graph illustrating a production tendency of CO, HC and NOx with respect to an air-fuel ratio during premixed combustion in a spark-ignition engine according to a third embodiment of the present invention. Fig. Figure 21 is a diagram illustrating an example of a flowchart of a control system for a motor generator according to the third embodiment of the present invention. Description of embodiments

[0013] The following describes embodiments of the present invention with reference to the accompanying drawings. In the present invention, at least one fuel is hydrogen, and the other fuel is a hydrocarbon-based fuel. In the embodiments, natural gas illustrates the hydrocarbon-based fuel, but light oil or gasoline can be used. A suitable combination of fuels can be selected. [First embodiment]

[0014] Fig. Figure 1 is a schematic configuration diagram illustrating an example according to a first embodiment of the present invention, in which a control device for a power generation system is applied to a power generation system comprising an engine-power generator that uses hydrogen and natural gas as fuels.

[0015] A power generation system 100 comprises a power generation module GM, which includes an engine 11, a power generator 12, and a power converter 13. The engine 11 includes an electronic control unit (ECU) 15 for controlling the engine 11. The engine 11 is connected to a hydrogen generation device 2 via a hydrogen supply device 14 and can supply hydrogen fuel. Although not illustrated, the engine is also connected to a fuel tank and can supply natural gas, thus enabling combustion by hydrogen fuel, natural gas, or a mixture of hydrogen and natural gas. An output of the power generation module GM is electrically connected to a load-side instrument 3.

[0016] A minimal configuration of the power generation module GM applicable to the present invention must include the motor 11 and the power generator 12, and the current transformer 13 can be included appropriately depending on whether the load is an AC load or a DC load. Furthermore, the power generator 12 can be either an AC generator or a DC generator.

[0017] Furthermore, a three-way catalyst 20 as an exhaust gas purification catalyst for cleaning an exhaust gas, an upstream catalyst temperature sensor 18, which measures a temperature (catalyst inlet gas temperature) of a gas flowing into the three-way catalyst 20, an air-fuel ratio sensor 17, which is an aspect of an air-fuel ratio detector and detects an air-fuel ratio of the exhaust gas on an upstream side of the three-way catalyst 20, and an oxygen concentration sensor 19, which detects an oxygen concentration of the exhaust gas on a downstream side of the three-way catalyst 20, are provided at respective suitable positions of an exhaust gas channel 16 of the engine 11.

[0018] The three-way catalyst 20 simultaneously oxidizes hydrocarbons and carbon monoxide in the exhaust gas and reduces nitrogen oxides, removing harmful components from the exhaust gas by purifying it into carbon dioxide, water vapor, and nitrogen. To maximize the purification efficiency of the three-way catalyst 20, the ratio of reactive components (HC, NOx, CO, and H2) must be stoichiometrically ideal. A range of air-fuel ratios that achieves the state described above is called a window, and in a typical spark-ignition engine, the mass ratio of air to fuel falls within a very narrow range around a theoretical (stoichiometric) air-fuel ratio, which is the minimum amount of air and fuel required for complete combustion.

[0019] A control device for a power generation system 1 is attached to the power generation system 100. The control device for a power generation system 1 calculates a demand load of the power generation system 100 based on a demand load Sg1 from the load-side instrument 3. Furthermore, the control device for a power generation system 1 receives information Sg2 about the amount of hydrogen that can be supplied by the hydrogen generation device 2. The control device for a power generation system 1 also receives information (engine status) Sg3 from the engine 11 via a sensor or actuator of the engine 11.Furthermore, the control device for a power generation system 1 receives an air-fuel ratio Sg4, a catalyst inlet gas temperature (also referred to as upstream catalyst temperature) Sg5, and an oxygen concentration Sg6 as information relating to the control of the three-way catalyst 20 from the air-fuel ratio sensor 17, the upstream catalyst temperature sensor 18, and the oxygen concentration sensor 19. Based on this information (Sg1), the control device for a power generation system 1 sends a command for an engine request output or ON / OFF drive (hereinafter referred to simply as a request output) Sd1 to the ECU 15 of the engine 11 and controls the hydrogen supply device 14 to achieve a desired supply quantity of hydrogen (target supply quantity of hydrogen) Sd2.

[0020] The ECU 15 controls an output from the engine 11 based on the request output Sd1 from the control device for a power generation system 1. Specifically, the ECU 15 controls a natural gas fuel injection unit, an ignition unit, a throttle valve, and a starter. The engine 11, for example, is a four-cylinder engine using spark ignition and is an example of an internal combustion engine. Driven by the engine 11, the generator 12 produces current to meet a desired power load. The current transformer 13 sets the voltage and phase of the current produced by the generator 12 and delivers the set current to the load-side instrument 3.

[0021] Next, an internal configuration example of the control device for a power generation system 1 according to the first embodiment is described. Fig. Figure 2 is a block diagram illustrating a hardware configuration example of the control device for a power generation system 1. The control device for a power generation system 1 is configured for use with a computer device.

[0022] In Fig. 2. The demand load Sg1, the supplyable quantity of hydrogen Sg2, and the engine state Sg3, output by the load-side instrument 3, the hydrogen generation device 2, and the ECU 15, respectively, are inputted into an input circuit 1a of the control device for a power generation system 1. However, an input signal is not limited to this. Each signal input into the input circuit 1a is sent to an input terminal (not illustrated) in an input / output terminal 1b. A value sent to the input terminal is stored in a RAM (1c) and subjected to arithmetic processing by a CPU (1e). A control program describing the details of the arithmetic processing is pre-written in a ROM (1d).

[0023] Values ​​specifying operating quantities of control targets (of the engine 11, the hydrogen supply device 14, and the like), calculated according to the control program, are stored in the RAM (1c), then sent to an output port (not illustrated) in the input / output port 1b and transmitted as the request output Sd1 and the desired supply quantity of hydrogen (target supply quantity of hydrogen) Sd2 to the respective devices (the ECU 15 and the hydrogen supply device 14) via their respective output units (a control output unit for engine torque 1f and a control output unit for the supply quantity of hydrogen 1g). Fig. 2 the motor control device (ECU 15) is provided separately in the control device for a power generation system 1, but the present invention is not limited to this embodiment, and a functional unit corresponding to a control device of each device may be provided in the control device for a power generation system 1.

[0024] Fig. Figure 3 is a diagram illustrating an example configuration of the engine 11 according to the first embodiment. The engine 11 is a modified engine to allow hydrogen to be supplied to a four-cylinder engine for a motor vehicle that performs spark-ignition combustion. An airflow sensor 21, which measures the intake air volume, and an electronic control throttle 26, which sets an intake manifold pressure, are provided at suitable positions on an intake pipe 27. Additionally, the engine 11 provides a spark plug 29 for each cylinder, which supplies ignition energy to a combustion chamber 28 of each cylinder, and a coolant temperature sensor 24, which measures the temperature of the engine 11's coolant, is provided at a suitable position on a cylinder head 30. An exhaust pipe 25 is connected to an exhaust passage 16.

[0025] A natural gas injection device 22 for injecting natural gas, which is converted into fuel, is provided in the combustion chamber 28. The natural gas injection device 22 is connected to a fuel tank (not illustrated) via fuel piping. Furthermore, a hydrogen supply channel 23 is provided for supplying hydrogen to the inlet pipe 27, and the hydrogen supply channel 23 is connected to the hydrogen supply device 14, which controls the amount of hydrogen supplied. The hydrogen supply device 14 is connected to the hydrogen generation device 2 via hydrogen piping.

[0026] The above configuration allows switching between engine drive using natural gas (natural gas combustion only), engine drive using hydrogen (hydrogen combustion only), and engine drive using hydrogen and natural gas at the same time (natural gas-hydrogen co-combustion).

[0027] Fig. Figure 4 is a diagram illustrating another configuration example of the engine 11 according to the first embodiment. The engine 11 is a modified engine to allow hydrogen to be supplied to a four-cylinder engine for a motor vehicle that performs spark-ignition combustion. An airflow sensor 21, which measures the intake air volume, and an electronic control throttle 26, which sets an intake manifold pressure, are provided at suitable positions on an intake pipe 27. Additionally, the engine 11 provides a spark plug 29 for each cylinder, which supplies ignition energy to a combustion chamber 28 of each cylinder, and a coolant temperature sensor 24, which measures the temperature of the engine 11's coolant, is provided at a suitable position on a cylinder head 30. An exhaust pipe 25 is connected to an exhaust passage 16.

[0028] The natural gas injection device 22 for injecting natural gas, which is converted into fuel, is provided in the inlet pipe 27. The natural gas injection device 22 is connected to a fuel tank (not illustrated) by fuel piping. Furthermore, the hydrogen supply channel 23 is provided for supplying hydrogen to the combustion chamber 28, and the hydrogen supply channel 23 is connected to the hydrogen supply device 14, which controls the amount of hydrogen supplied. The hydrogen supply device 14 is connected to the hydrogen generation device 2 by hydrogen piping.

[0029] The above configuration allows switching between engine drive using natural gas (natural gas combustion only), engine drive using hydrogen (hydrogen combustion only), and engine drive using hydrogen and natural gas at the same time (natural gas-hydrogen co-combustion).

[0030] The following describes an embodiment of the present invention. First, key aspects of the control system in the present embodiment are described, and then the specific processing of the present embodiment is described.

[0031] First, key aspects of the control system are described from the perspective of immediate catalyst activation and immediate engine warm-up. The in Fig. 5 to Fig. The 7 illustrated conditions are natural gas-only combustion conditions and natural gas-hydrogen-co combustion conditions and are the same for each condition, where an engine speed and a graphically represented average effective pressure are constant, the air-fuel ratio is the theoretical air-fuel ratio, and an ignition timing is an optimal ignition timing.

[0032] Fig. Figure 5 illustrates heat generation profiles in the natural gas-only combustion condition and the hydrogen-cobalt combustion condition. The horizontal axis represents a crank angle and the vertical axis represents a heat generation rate. Fig. Figure 5 represents the heat generation profile near the top dead center of compression during a compression-expansion cycle. As shown from... Fig. As can be seen in Figure 5, hydrogen co-combustion leads to a rapid increase in heat generation. This is mainly because the laminar combustion rate of hydrogen is significantly higher than that of natural gas, which contains methane as its main component.

[0033] Fig. Figure 6 is a graph illustrating average cylinder gas temperature profiles under natural gas-only combustion conditions and hydrogen-cobalt combustion conditions. As shown from Fig. As can be seen in Figure 6, as a result of the rapid increase in heat generation due to hydrogen-co-combustion, a point in time at which the average cylinder gas temperature reaches a maximum temperature occurs immediately, and from 30 degrees after top dead center (ATDC) the average cylinder gas temperature is lower than that in the natural gas-only combustion condition.

[0034] Fig. Figure 7 illustrates the heat transfer quantity (hereinafter referred to as cylinder heat transfer quantity) from gas in a cylinder to an engine cylinder. The cylinder heat transfer quantity is increased by hydrogen co-combustion. This is because, when hydrogen is burned at a significantly higher combustion rate compared to natural gas, the cylinder heat transfer quantity is influenced by a significant gas flow generated due to flame propagation and high gas convection near a combustion chamber wall surface, resulting from the flame surface rapidly reaching the wall surface.

[0035] As described above, it is effective to perform natural gas-only combustion to increase exhaust gas temperature from the point of view of immediate catalyst activation, and it is effective to increase hydrogen mixture ratio to increase cylinder heat transfer quantity from the point of view of immediate engine warm-up.

[0036] Next, control points are described in a state after the catalyst has been activated and the engine has warmed up.

[0037] Fig. Figure 8 illustrates lean limits for the natural gas-only combustion condition and the hydrogen-cobalt combustion condition. Here, the lean limit specifies an air-fuel ratio at which the engine's combustion stability reaches an acceptable limit. As shown in the diagram... Fig. As can be seen in Figure 8, the lean limit is increased in the hydrogen-co-combustion condition compared to the natural gas-only combustion condition. This is because the laminar flow combustion rate of hydrogen is significantly higher than that of natural gas.

[0038] Fig. Figure 9 illustrates a graphically represented heat efficiency at the lean limit. As shown from Fig. As can be seen in Figure 9, the graphically represented heat efficiency at the lean limit is increased in the hydrogen-cobalt combustion condition compared to the natural gas-only combustion condition. This is mainly because the combustion gas temperature decreases due to an increase in the leanness, and as a result, the cooling loss decreases.

[0039] Fig. Figure 10 illustrates the NOx production rate at the lean limit. As shown from Fig. As can be seen in Figure 10, the amount of NOx produced at the lean limit in the hydrogen-co-combustion condition is significantly reduced compared to the natural gas-only combustion condition. This is mainly due to the lower combustion gas temperature, which reduces the production of thermal NOx, generated by the reaction of nitrogen and oxygen at a high temperature.

[0040] As described above, it is effective to perform hydrogen co-combustion and lean combustion under a condition after the catalyst has been activated and the engine has warmed up.

[0041] Based on the key control points described above, in the present embodiment the supply quantity of hydrocarbon-based fuel or the supply quantity of hydrogen to the engine is controlled based on an active catalyst state and a warmed-up engine state. In particular, as described in Fig. Figure 11 illustrates three operating modes, in which the hydrogen mixture proportions and air-fuel ratios differ. Switching between these modes is controlled based on the active state of the catalyst and the engine's warm-up state. Here, the hydrogen mixture proportion is the percentage of hydrogen relative to the total amount of fuel (natural gas and hydrogen) supplied to the engine. This proportion can be a heat-generating percentage, a volume percentage, a mass percentage, or similar, and can be selected as appropriate. Details of the operating modes are described below. Mode 1

[0042] Under the condition that the catalyst is inactive, only hydrocarbon-based fuel is supplied to the engine, and only hydrocarbon-based combustion takes place. This allows the exhaust gas temperature to rise, enabling the catalyst to activate immediately. Ignition timing retardation can also be implemented. This further increases the exhaust gas temperature and allows the catalyst to activate more quickly. Additionally, 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 lower than a predetermined value, C1. The predetermined value, C1, is the oxygen concentration of the exhaust gas when the engine is operating at the theoretical (stoichiometric) air-fuel ratio.The engine's air-fuel ratio does not need to be strictly stoichiometric, as long as the ratio of reactive components (HC, NOx, CO, and H2) is controlled within a range defined by the catalyst's operating window, where the ratio becomes a stoichiometrically ideal value. This allows the purification process to occur by removing harmful gas components (HC, CO, and NOx) from the exhaust gas via the catalyst. Mode 2

[0043] Provided the catalyst is active and the engine is cold, hydrocarbon-based fuel and hydrogen are supplied to the engine, and hydrogen co-combustion takes place. This increases the amount of heat transferred to the cylinders and allows the engine to warm up quickly. Additionally, the engine's air-fuel ratio is controlled so that the oxygen concentration of the exhaust gas entering the catalyst is equal to or lower than a predetermined value, C1. The predetermined value, C1, is the oxygen concentration of the exhaust gas under operating conditions where the engine's air-fuel ratio is the theoretical (stoichiometric) air-fuel ratio. The air-fuel ratio can be controlled to fall within the catalyst's operating window and does not need to be strictly stoichiometric.In particular, under the hydrogen-co-combustion condition, combustion is heated to a high temperature, increasing NOx production and H2 production due to an increase in hydrogen input. Conversely, CO and THC production tend to decrease due to a reduction in hydrocarbon-based fuel input. Therefore, the relationship between the air-fuel ratio and exhaust gas composition under the hydrogen-co-combustion condition can be predicted, and the air-fuel ratio can be controlled to achieve a stoichiometrically ideal ratio between the reactive components (HC, NOx, CO, and H2). This allows for purification by removing harmful gas components (HC, CO, and NOx) from the exhaust gas via the catalyst. Mode 3

[0044] Provided the catalyst is active and the engine is warmed up, hydrocarbon-based fuel and hydrogen are supplied to the engine, and hydrogen co-combustion takes place. This allows the lean limit to be increased. Furthermore, 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 higher than a predetermined value, C2.The predetermined value C2 is an oxygen concentration of the exhaust gas in a lean condition, in which the engine's air-fuel ratio can be reduced to a value equal to or less than a value by which the amount of NOx produced by the engine can adequately meet an exhaust gas regulation value even without the use of an aftertreatment device (in other words, in a case where the engine is operated at an air-fuel ratio where the amount of nitrogen oxides emitted directly by the engine is equal to or less than a predetermined value). This allows NOx emitted by the engine to be reduced and enables the cleaning process to take place by removing CO and HC with high efficiency through the catalyst.

[0045] The specific processing of the present embodiment is described below.

[0046] Fig. Figure 12 illustrates an example of a flowchart for a motor generator control system according to the present embodiment. Details of each step are described below. <Schritt S1>

[0047] In step S1, the control device for a power generation system 1 first reads information (demand load) Sg1 from the connected load-side instrument 3. The information (demand load) Sg1 from the load-side instrument 3 is, for example, a current power consumption (voltage and current) or a future forecast value from an instrument on the load side. Additionally, if the output of the power generation system 100 is connected to a power system, the information Sg1 is a current or future power demand value from the system side. <Schritt S2>

[0048] In step S2, the control device for a power generation system 1 reads information (engine status) Sg3 from the ECU 15 or the engine 11. The information (engine status) Sg3 from the ECU 15 or the engine 11 is, for example, an engine status such as a current engine speed or current engine torque, or an engine temperature (a coolant temperature, an intake temperature, or the like), or engine specifications (an exhaust gas volume, a compression ratio, a fuel supply position, or the like). <Schritt S3>

[0049] In step S3, the control device for a power generation system 1 reads the information Sg2 about hydrogen production (supplyable quantity of hydrogen) from the hydrogen generation device 2. Here, the hydrogen generation device 2 is, for example, a water electrolyzer that produces hydrogen from renewable energy, and the control device for a power generation system 1 reads information such as current or power that can be input into the water electrolyzer, or output efficiency. <Schritt S4>

[0050] In step S4, the control device for a power generation system 1 reads information relating to the control of the catalyst from the air-fuel ratio sensor 17, the upstream catalyst temperature sensor 18, or the oxygen concentration sensor 19. The information relating to the control of the catalyst is the air-fuel ratio Sg4, the catalyst inlet gas temperature (upstream catalyst temperature) Sg5, or the oxygen concentration Sg6. <Schritt S5>

[0051] In step S5, the control device for a power generation system 1 calculates a total demand output requested for the power generation system 100, based on the information (demand load) Sg1 from the load-side instrument 3. Here, the total demand output to the motor is calculated, taking into account losses or the like in the current transformer 13 and the power generator 12. <Schritt S6>

[0052] In step S6, the control device for power generation system 1 determines the active state of the catalyst based on the catalyst inlet gas temperature Sg5. If the catalyst inlet gas temperature Tc is equal to or higher than a predetermined temperature Tc0, the control device for power generation system 1 determines that the catalyst is in an active state. If the catalyst inlet gas temperature Tc is lower than the predetermined temperature Tc0, the control device for power generation system 1 determines that the catalyst is in an inactive state. In this way, the active state of the catalyst can be accurately determined by determining a gas temperature near the catalyst based on a directly measured value.In the present embodiment, the control device for a power generation system 1 includes a catalyst active state detection unit that detects whether the catalyst is in the active state. The catalyst active state detection unit detects the temperature of the gas flowing into the catalyst (a catalyst inlet gas temperature) (from the catalyst inlet gas temperature measured by the upstream catalyst temperature sensor 18) and determines that the catalyst is in the active state when the catalyst inlet gas temperature is equal to or greater than a predetermined value. However, the means for detecting whether the catalyst is in the active state are not limited to this. <Schritt S7>

[0053] In step S7, the control device for a power generation system 1 determines the warm-up state of the engine based on the information (engine state) Sg3 from the ECU 15 and the engine 11. If the engine coolant temperature Tw is equal to or higher than a predetermined temperature Tw1, the control device for a power generation system 1 determines that the engine is warm. If the engine coolant temperature Tw is lower than the predetermined temperature Tw1, the control device for a power generation system 1 determines that the engine is cold. Since the determination is based on a value obtained by directly sensing the engine coolant temperature, the warm-up state of the engine can be accurately determined in this way.That is, in the present embodiment, the control device for a power generation system 1 includes a warm-up engine detection unit that detects whether the engine is in the warm-up state. The warm-up engine detection unit detects the engine's coolant temperature (from the coolant temperature measured by the coolant temperature sensor 24) and determines that the engine is in the warm-up state when the engine's coolant temperature is equal to or higher than a predetermined value. However, a means for detecting whether the engine is in the warm-up state is not limited to this. <Schritt S8>

[0054] In step S8, the control device for a power generation system 1 calculates an operating mode of the engine based on the active state of the catalyst and the warmed-up state of the engine, which are determined in steps S6 and S7. Here, the following is taken into account: Fig. The 11 illustrated operating modes determine the corresponding operating mode. If the catalyst is inactive (in other words, if the catalyst active state detection unit registers that the catalyst is inactive), Mode 1 is selected (in which only hydrocarbon-based fuel is supplied to the engine and combustion is carried out using only hydrocarbons). This allows the exhaust gas temperature to increase, enabling the catalyst to activate immediately. If the catalyst is active and the engine is cold (in other words, if the catalyst active state detection unit registers that the catalyst is active and the engine warm-up state detection unit registers that the engine is cold), Mode 2 is selected (in which hydrocarbon-based fuel and hydrogen are supplied to the engine and hydrogen co-combustion is carried out).This allows for an increased amount of cylinder heat transfer and enables the engine to warm up immediately. When the catalyst is active and the engine is warm (in other words, when the catalyst active state detection unit registers that the catalyst is active and the engine warm-up state detection unit registers that the engine is warm), Mode 3 is activated (in which hydrocarbon-based fuel and hydrogen are supplied to the engine and hydrogen-CO combustion takes place). This reduces NOx emissions from the engine and allows for highly efficient CO and HC removal by the catalyst. <Schritt S9>

[0055] In step S9, the control device for power generation system 1 calculates the hydrogen mixture ratio based on the operating mode calculated in step S8. At this point, the hydrogen demand of power generation system 100 is set so that it is equal to or not greater than the amount of hydrogen that can be produced by hydrogen production device 2. For example, the hydrogen mixture ratio is calculated by presetting a hydrogen mixture ratio relative to the amount of hydrogen that can be produced by hydrogen production device 2 for each operating mode and storing the set hydrogen mixture ratio in the ROM of the control device for power generation system 1.For example, by adjusting the hydrogen mixture ratio so that it increases as the amount of hydrogen that can be produced increases, the warm-up of the engine can be further promoted in a condition where the amount of hydrogen that can be produced is large in mode 2, and the engine can be operated in a lean condition in a condition where the amount of hydrogen that can be produced is large in mode 3, so that the engine can be operated with high efficiency.

[0056] Additionally, in Mode 2, the hydrogen mixture ratio is adjusted so that it increases as the engine coolant temperature decreases. In other words, in Mode 2 (when the engine warm-up detection unit detects that the engine is cold), the amount of hydrocarbon-based fuel or hydrogen supplied to the engine is adjusted (controlled) so that the proportion of hydrogen to the total fuel supply decreases as the engine coolant temperature rises. This allows the hydrogen mixture ratio to increase as the engine coolant temperature decreases and the amount of cylinder heat transfer increases, thus promoting engine warm-up. <Schritt S10>

[0057] In step S10, the control device for a power generation system 1 sends the total request output calculated in step S5, as the motor torque command value (request output) Sd1, to the ECU 15 and executes a torque command. <Schritt S11>

[0058] In step S11, the control device for a power generation system 1 performs a control of the hydrogen supply quantity to achieve a hydrogen-co-combustion fraction of the engine, which is calculated in step S9. The command value of the hydrogen supply quantity (target hydrogen supply quantity) Sd2 is sent to the hydrogen supply device 14, and a control sequence is completed.

[0059] Fig. Figure 13 is a time graph of a scene in which the catalyst is inactive and the engine is cold-started, in the present embodiment. The vertical axis represents, from top to bottom, the total demand output, the catalyst's active state, the engine's warm-up state, the operating mode, the hydrogen mixture fraction, the catalyst's upstream air-fuel ratio, the engine's power output, and the pollutant emission accumulation. The horizontal axis represents time. A solid line represents the present embodiment, and a dashed line represents the conventional technology.

[0060] In Fig. At time t0, information is received from the load-side instrument, and a total request output is calculated. At this time, since the condition is set in which the catalyst is inactive and the engine is cold, the operating mode is set to Mode 1, the hydrogen mixture fraction is set to 0, and the air-fuel ratio is set to stoichiometric. Subsequently, at time t1, since the condition is set in which the catalyst is active and the engine is cold, the operating mode is set to Mode 2, the hydrogen mixture fraction is set to the predetermined value, and the air-fuel ratio is set to stoichiometric.When the catalyst is activated, pollutants are removed through purification, and the amount of pollutant emissions thereafter remains essentially constant. Since the hydrogen mixture ratio is set to increase when the engine is cold (although not illustrated when the engine coolant temperature decreases), engine warm-up is also promoted. Subsequently, at time t2, given that the condition is set where the catalyst is active and the engine is warm, the operating mode in the present embodiment is set to Mode 3, the hydrogen mixture ratio is set to the predetermined value, and the air-fuel ratio is set to a lean condition. In contrast, in conventional technology, since hydrogen co-combustion occurs independently of the catalyst's active state, the exhaust gas temperature decreases, and catalyst activation is delayed.Consequently, the pollutants are emitted without being cleaned until the catalyst is activated, and as a result, the amount of pollutant emissions accumulates.

[0061] Although no method for starting the engine is described in the present embodiment, the air-fuel ratio can be set to be rich, and combustion can be stabilized during the period from engine start until combustion stabilizes. Furthermore, by performing hydrogen-co-combustion or hydrogen-only combustion at the time of start-up, stable combustion can be achieved compared to hydrocarbon-based fuel-only combustion, and emissions of unburned substances such as CO and THC can be reduced.

[0062] In the present embodiment, the active state of the catalyst is detected directly by the upstream catalyst temperature sensor 18, but the active state of the catalyst can also be estimated based on an operating state of the engine (for example, an intake air quantity, a fuel supply quantity, an ignition timing, an engine speed or the like).

[0063] Furthermore, in the present embodiment, the air-fuel ratio of the engine is obtained from the output value of the air-fuel ratio sensor 17, but can be calculated based on the intake air quantity and a fuel injection quantity detected by the air flow sensor 21.

[0064] As is clear from the above description, the present embodiment is the control device for the engine power generation system (control device for the power generation system 1) for the engine power generation system (power generation system 100) which is capable of co-combustion when hydrocarbon-based fuel and hydrogen are supplied, and which generates power through this engine, which includes the engine warm-up detection unit that detects whether the engine is in the warm-up state, wherein the control device for the engine power generation system (control device for a power generation system 1) comprises: the catalyst provided in the exhaust passage of the engine and which cleans the exhaust gas; and the active catalyst state detection unit that detects whether the catalyst is in the active state.The amount of hydrocarbon-based fuel or hydrogen supplied to the engine (specifically, the proportions of hydrocarbon-based fuel and hydrogen supplied to the engine) is controlled based on the active state of the catalyst, detected by the catalyst state detection unit, and the engine's warm-up state, detected by the engine warm-up detection unit. This enables immediate catalyst activation and immediate engine warm-up, resulting in a reduction of pollutant emissions from the power generation system. [Second embodiment]

[0065] A second embodiment of the present invention is described. In this embodiment, a method for applying the control device for a power generation system according to the present invention to the power generation system comprising a plurality of engine-driven power generators using hydrogen and natural gas as fuels is described. The configurations of the first embodiment are applied to configurations of the second embodiment, which are described below, with the exception of configurations that differ from those described in the first embodiment.

[0066] Fig. Figure 14 is a schematic configuration diagram illustrating an example in which a control device for a power generation system is applied to a power generation system comprising a plurality of engine power generators using hydrogen and natural gas as fuels, according to the second embodiment of the present invention.

[0067] A power generation system 100 comprises multiple sets of parallel-connected power generation modules GM (GM1 to GMn), each comprising a motor 11, a power generator 12, and a power converter 13. The motor 11 includes an electronic control unit (ECU) 15 for controlling each motor 11. The motor 11 is connected to a hydrogen generation device 2 via a hydrogen supply device 14 and can supply hydrogen fuel. Although not illustrated, the motor is also connected to a fuel tank and can supply natural gas, thus enabling combustion by hydrogen, natural gas, or a mixture of hydrogen and natural gas. Outputs of the power generation modules GM (GM1 to GMn) are electrically connected to a load-side instrument 3.

[0068] A minimal configuration of the power generation module GM applicable to the present invention must include the motor 11 and the power generator 12, and the current transformer 13 can be included appropriately depending on whether the load is an AC load or a DC load. Furthermore, the power generator 12 can be either an AC generator or a DC generator.

[0069] The exhaust pipes of the engines 11 converge to form an exhaust gas passage 16. Furthermore, a three-way catalytic converter 20, serving as an exhaust gas purification catalyst for cleaning the exhaust gas, an upstream catalyst temperature sensor 18, which measures the temperature (catalytic converter inlet gas temperature) of a gas flowing into the three-way catalytic converter 20, an air-fuel ratio sensor 17, which is part of an air-fuel ratio detector and detects the air-fuel ratio of the exhaust gas on an upstream side of the three-way catalytic converter 20, and an oxygen concentration sensor 19, which detects the oxygen concentration of the exhaust gas on a downstream side of the three-way catalytic converter 20, are provided at suitable positions within the exhaust gas passage 16, to which the exhaust pipes of the respective engines 11 converge.

[0070] A control device for a power generation system 1 is attached to the power generation system 100. The control device for a power generation system 1 calculates a demand load of the power generation system 100 based on a demand load Sg1 from the load-side instrument 3. Furthermore, the control device for a power generation system 1 receives information Sg2 about the amount of hydrogen that can be supplied by the hydrogen generation device 2. The control device for a power generation system 1 also receives information (engine states) Sg3 (Sg31 to Sg3n) from the engine 11 via sensors or actuators of the respective engine 11.Furthermore, the control device for a power generation system 1 receives an air-fuel ratio Sg4, a catalyst inlet gas temperature (upstream catalyst temperature) Sg5, and an oxygen concentration Sg6 as information relating to the control of the three-way catalyst 20 from the air-fuel ratio sensor 17, the upstream catalyst temperature sensor 18, and the oxygen concentration sensor 19. Based on this information (Sg1, Sg2, and Sg3), the control device for a power generation system 1 sends commands for engine request outputs or ON / OFF driving (hereinafter referred to simply as request outputs) Sd1 (Sd11 to Sd1n) to the ECU 15 of the respective engines 11 and controls the hydrogen supply device 14 to achieve the desired supply quantity of hydrogen (target supply quantity of hydrogen) Sd2 (Sd21 to Sd2n).

[0071] The ECU 15 controls an output from the engine 11 based on the request output Sd1 from the control device for a power generation system 1. Specifically, the ECU 15 controls a natural gas fuel injection unit, an ignition unit, a throttle valve, and a starter. The engine 11, for example, is a four-cylinder engine using spark ignition and is an example of an internal combustion engine. Driven by the engine 11, the generator 12 produces current to achieve a desired output. The current transformer 13 sets the voltage and phase of the current and power generated by the generator 12 and delivers the set current to the load-side instrument 3.

[0072] Next, an internal configuration example of the control device for a power generation system 1 according to the second embodiment is described. Fig. Figure 15 is a block diagram illustrating a hardware configuration example of the control device for a power generation system 1. The control device for a power generation system 1 is configured for use with a computer device.

[0073] In Fig. The demand load Sg1, the supply quantity of hydrogen Sg2, and the engine states Sg3 (Sg31 to Sg3n), output by the load-side instrument 3, the hydrogen generation device 2, and the ECU 15 respectively, are inputted into an input circuit 1a of the control device for a power generation system 1. However, an input signal is not limited to this. Each signal input to the input circuit 1a is sent to an input terminal (not illustrated) in an input / output terminal 1b. A value sent to the input terminal is stored in a RAM (1c) and subjected to arithmetic processing by a CPU (1e). A control program describing the details of the arithmetic processing is pre-written to a ROM (1d).

[0074] Values ​​specifying operating quantities of control targets (of the engine 11, the hydrogen supply device 14, and the like), calculated according to the control program, are stored in the RAM (1c), then sent to an output port (not illustrated) in the input / output port 1b and transmitted as the request outputs Sd1 (Sd11 to Sd1n) and the desired supply quantities of hydrogen (supply target quantities of hydrogen) Sd2 (Sd21 to Sd2n) to respective devices (the ECU 15 and the hydrogen supply device 14) via respective output units (an engine torque control output unit 1f and a supply quantity hydrogen control output unit 1g). Fig. 15 the motor control devices (ECUs 15) are provided separately in the control device for a power generation system 1, but the present invention is not limited to this embodiment, and functional units corresponding to control devices of respective devices may be provided in the control device for a power generation system 1.

[0075] In a configuration comprising multiple engine-based power generators, the number of operating power generation modules (GM) can be set by the load-side instrument depending on the total demand load. For example, it is assumed that at a given total demand output Pr1, i power generation modules are operating at nominal power, the catalyst is active, all operating engines are warmed up, and operation is in Mode 3 (hydrogen-co-combustion (lean)) in the first embodiment. Under these circumstances, it is assumed that the total demand output from the load-side instrument increases to Pr2 at a certain time. At this time, if it is not possible to handle the increase in total demand output by adjusting the outputs of the operating modules, k modules are re-energized to achieve the total demand output Pr2.Since the k newly started engines are cold, the first embodiment operates in mode 2 (hydrogen-CO combustion (stoichiometric)) to quickly warm up the engines. At this point, to maximize the catalyst's cleaning performance, the air-fuel ratios of the i engines that have already been run must be stoichiometric. In the present embodiment, the control is carried out in such a state that warmed-up and cold engines operate during the same period.

[0076] Fig. Figure 16 illustrates a graphical representation of the thermal efficiency of a natural gas-only combustion condition and a hydrogen-co-combustion condition. The conditions are the natural gas-only combustion conditions and the natural gas-hydrogen-co-combustion conditions, and are the same for each condition, with constant engine speed and graphically represented average effective pressure, the air-fuel ratio being the theoretical air-fuel ratio, and the ignition timing being the optimal ignition timing. In the hydrogen-co-combustion condition, the graphically represented thermal efficiency is lower than that in the natural gas-only combustion condition. This is mainly because the amount of cylinder heat transfer increases, as shown in Figure 16. Fig. 7 illustrates this, and cooling loss increases.

[0077] As described above, from the point of view of the graphically represented thermal efficiency in the theoretical air-fuel ratio condition, it is effective to carry out natural gas-only combustion.

[0078] In the present embodiment, the supply quantities of hydrocarbon-based fuel or hydrogen to the respective engines are controlled based on the active state of the catalyst and the warm-up states of the respective engines. In particular, as shown in Fig. Figure 17 illustrates four operating modes, in which the hydrogen mixture proportions and the air-fuel ratios differ, and the switching between operating modes is controlled depending on the active state of the catalyst and the warm-up state of the respective engines. Since Mode 1 and Mode 2 are similar to the first embodiment, their description is omitted. Details of Mode 3 and Mode 4 are described below. Mode 3

[0079] Under conditions where the catalyst is active and the engines are warmed up, and the cold engines are not running concurrently, hydrocarbon-based fuel and hydrogen are supplied to the warmed-up engines, and hydrogen-co-combustion takes place. This allows the lean limit to be increased. Additionally, 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 higher than the predetermined value C2.The predetermined value C2 is an oxygen concentration of the exhaust gas in an air-fuel ratio condition (lean condition) of the engines, in which the amount of NOx produced by the engines can be reduced to a level equal to or less than a value that can adequately meet an exhaust gas regulation value even without the use of an aftertreatment device (in other words, in a case where the engine is operated at an air-fuel ratio where the amount of nitrogen oxides emitted directly by the engine is equal to or less than a predetermined value). This allows NOx emitted by the engines to be reduced and enables the cleaning process to take place by removing CO and HC with high efficiency through the catalyst when the cold engines are not operating at the same time. Mode 4

[0080] Under conditions where the catalyst is active and the engines are warmed up, and when cold engines are running during the same period, only hydrocarbon-based fuel is supplied to the warmed-up engines, and combustion is carried out exclusively on hydrocarbons. This allows the warmed-up engine to operate at high efficiency. Furthermore, 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 lower than the predetermined value C1. The predetermined value C1 is the oxygen concentration of the exhaust gas under conditions where the engine's air-fuel ratio is at its theoretical (stoichiometric) value.The air-fuel ratio of each engine does not need to be strictly stoichiometric, as long as the ratio of reactive components (HC, NOx, CO, and H2) is controlled within a range of the catalyst's operating window, where the ratio becomes a stoichiometrically ideal value. This allows the purification process to take place by removing harmful gas components (HC, CO, and NOx) from the exhaust gas through the catalyst when the cold engines are running during the same period.

[0081] The specific processing of the present embodiment is described below.

[0082] Fig. Figure 18 illustrates an example of a flowchart for the control of a motor generator according to the present embodiment. Details of each step are described below. <Schritt S12>

[0083] Since the processing in step S12 is similar to that in step S1 of the first embodiment, its description is omitted. <Schritt S13>

[0084] In step S13, the control device for a power generation system 1 reads the information (engine states) Sg3 (Sg31 to Sg3n) of the respective engines 11 from the respective ECUs 15 and the respective engines 11. The information (engine state) Sg3 from the ECU 15 or the engine 11 is, for example, an engine state such as a current engine speed or current engine torque or an engine temperature (a coolant temperature, an intake temperature or the like) or engine specifications (an exhaust gas volume, a compression ratio, a fuel supply position or the like). <Schritte S14 bis S16>

[0085] Since the processing in steps S14 to S16 is similar to that in steps S3 to S5 of the first embodiment, its description is omitted. <Schritt S17>

[0086] In step S17, the control device for a power generation system 1 distributes the total demand outputs Sd1, calculated in step S16, to the respective motor power generation modules and receives individual demand outputs Sd11, Sd12,..., Sd1n (processing step S5). For example, the number of motor power generation modules to be driven is calculated from the total demand outputs Sd1 and the rated outputs of the respective motor power generation modules, and the total demand outputs Sd1 are distributed evenly among the motor power generation modules to be driven. <Schritt S18>

[0087] Since the processing in step S18 is similar to that in step S6 of the first embodiment, its description is omitted. <Schritt S19>

[0088] In step S19, the control device for a power generation system 1 determines the warm-up states of the respective engines based on the information pieces (engine states) Sg3 (Sg31 to Sg3n) from the respective ECUs 15 and the respective engines 11. If the engine coolant temperature Tw is equal to or higher than a predetermined temperature Tw1, the control device for a power generation system 1 determines that the engine is warm. If the engine coolant temperature Tw is lower than the predetermined temperature Tw1, the control device for a power generation system 1 determines that the engine is cold. Since the determination is based on a value obtained by directly sensing the engine coolant temperature, the warm-up state of the engine can be accurately determined in this way. <Schritt S20>

[0089] In step S20, the control device for a power generation system 1 calculates an operating mode for the engines based on the active state of the catalyst and the warm-up states of the respective engines, which are determined in steps S18 and S19. Here, the following is taken into account: Fig. The 17 illustrated operating modes are set accordingly. If the catalyst is inactive (in other words, if the catalyst active state detection unit registers that the catalyst is inactive), Mode 1 is set (in which only hydrocarbon-based fuel is supplied to the engine and combustion is carried out using only hydrocarbons). This allows the exhaust gas temperature to increase and enables the catalyst to be activated immediately. If the catalyst is active and the engine is cold (in other words, if the catalyst active state detection unit registers that the catalyst is active and the engine warm-up state detection unit registers that the engine is cold), Mode 2 is set (in which hydrocarbon-based fuel and hydrogen are supplied to the engine and hydrogen co-combustion is carried out).This allows the cylinder heat transfer rate to be increased, enabling the engine to warm up immediately. Provided the catalyst is active and the engine is warm, and cold engines are not operating concurrently (in other words, when the catalyst active detection unit registers that the catalyst is active, the engine warm-up detection unit registers that the engines are warm, and cold engines are not operating concurrently), Mode 3 is activated (in which hydrocarbon-based fuel and hydrogen are supplied to the warmed-up engines, and hydrogen co-combustion takes place).This allows hydrogen-co-combustion (lean mixture) to be carried out, reducing NOx emissions from the engines and enabling highly efficient CO and HC removal by the catalyst when the cold engines are not operating at the same time. Under the condition that the catalyst is active and the engine is warmed up, and when the cold engines are operating at the same time (in other words, when the catalyst active state detection unit registers that the catalyst is active, the engine warm-up state detection unit registers that the engines are warmed up, and the cold engines are operating at the same time), Mode 4 is activated, and only hydrocarbon-based fuel is supplied to the warmed-up engines, resulting in only hydrocarbon-based (stoichiometric) combustion.This allows the warmed-up engine to operate in a highly efficient state, and enables cleaning to be carried out by removing HC, CO and NOx through the catalyst with high efficiency. <Schritt S21 >

[0090] In step S21, the control device for a power generation system calculates the hydrogen mixture proportions of the respective engines based on the operating modes calculated in step S20. Since the other processing is similar to that in step S9 of the first embodiment, its description is omitted. <Schritt S22>

[0091] In step S22, the control device for a power generation system 1 sends torque command values ​​(individual request outputs Sd11, Sd12,..., Sd1n) for the individual motors, which are calculated in step S17, to the respective ECUs 15 and executes a torque command. <Schritt S23>

[0092] In step S23, the control device for a power generation system 1 controls the hydrogen supply quantity to achieve the hydrogen-co-combustion fractions of the respective engines, which are calculated in step S21. The individual command values ​​for the hydrogen supply quantity (Sd21, Sd22,..., Sd2n) are sent to the hydrogen supply device 14, and a control sequence is completed.

[0093] Fig. Figure 19 is a time graph of a scene in which, according to the present embodiment, a total demand output increases from a state in which engine A is operating at nominal power and engine B is being restarted. The vertical axis represents, from top to bottom, the total demand output, the active state of the catalyst, the warm-up states, the operating modes, the hydrogen mixture proportions, the power generation quantities and thermal efficiencies of both engine A and engine B, and the upstream air-fuel ratio of the catalyst (exhaust-air-fuel ratio), and the horizontal axis represents time. A solid line represents the present embodiment, and a dashed line represents the conventional technology.

[0094] In Fig. 19 At time t5, the total demand output increases, and engine B is restarted to handle this increase. At this time, since a condition is set in which the catalyst is active, engine A is warmed up, and engine B is cold, in the present embodiment, for engine A, the operating mode is set to mode 4 (hydrocarbon-only combustion), the hydrogen mixture fraction is set to 0, and the air-fuel ratio is set to stoichiometric. For engine B, the operating mode is set to mode 2 (hydrogen-CO combustion), the hydrogen mixture fraction is set to the predetermined value, and the air-fuel ratio is set to stoichiometric.On the other hand, in conventional technology, the operating mode for both engine A and engine B is preset to mode 2 (hydrogen co-combustion), the hydrogen mixture proportion is set to a predetermined value, and the air-fuel ratio is adjusted to be stoichiometric. Thus, in conventional technology, hydrogen co-combustion is carried out in engine A, whereas in the present embodiment, combustion is carried out solely on hydrocarbons in engine A. This allows for an improvement in the thermal efficiency of engine A compared to conventional technology.Since, in the present embodiment, the hydrogen mixture proportions are set to increase when the engines are cold (although not illustrated, when the engine coolant temperature decreases), engine B can also be warmed up more quickly in the present embodiment than in conventional technology. At time t6, a condition is set in the present embodiment in which the catalyst is active and both engine A and engine B are warmed up, and the operating mode in both engine A and engine B is set to mode 3, the hydrogen mixture proportion is set to the predetermined value, and the air-fuel ratio is set to a lean mixture so that operation can be carried out with high thermal efficiency.On the other hand, in conventional technology the catalyst is active and engine A and engine B are heated up at time t7 after time t6, and the period until operation with high thermal efficiency is achieved is extended.

[0095] In this embodiment, the supply quantities of hydrocarbon-based fuel or hydrogen (in particular, the proportions of the hydrocarbon-based fuel and hydrogen supplied to the respective engines) are controlled based on the active state of the catalyst and the warm-up state of the respective engines. This enables immediate activation of the catalyst and immediate warm-up of the engines, and a reduction in pollutant emissions from the power generation system 100. Furthermore, if the cold engines are operating during the same period, the warmed-up engines can operate in a state of high thermal efficiency, and fuel consumption can be reduced. [Third embodiment]

[0096] A third embodiment of the present invention is described. In this embodiment, a method for adjusting the air-fuel ratios of individual engines, such that the ratio between the reactive components (HC, NOx, CO, and H2) of the gas flowing into the catalyst becomes a stoichiometrically ideal value, is described in a control device for a power generation system according to the present invention. This method is applied to a power generation system comprising a plurality of engine-based power generators that use hydrogen and natural gas as fuels. The configurations of the second embodiment are applied to configurations of the third embodiment, which are described below, with the exception of configurations that differ from those described in the second embodiment.

[0097] First, a method for adjusting the air-fuel ratios of respective engines, which is carried out in the present embodiment, is described with reference to Fig. 20 described.

[0098] Fig. Figure 20 illustrates the production tendency of CO, HC, and NOx with respect to an air-fuel ratio during premixed combustion in a spark-ignition engine. Premixing refers to a state in which air and a fuel are uniformly mixed before ignition. Here, a single hydrocarbon-based fuel or a mixture of a hydrocarbon-based fuel and hydrogen is described as an example. The production characteristics of each component are described below. CO and HC

[0099] Since CO and HC are components of incomplete combustion, the air-fuel ratio is low, and the air-fuel mixture becomes rich, leading to an increase in CO and HC. At the time of engine start-up or similar events, a rich air-fuel mixture must be used to stabilize combustion, and thus a large amount of CO is likely to be produced. NOx

[0100] NOx is primarily NO, and NO is produced in large quantities at high temperatures and in the presence of oxygen and nitrogen. Combustion gas production is maximized in the case of a slightly richer air-fuel ratio than the theoretical ratio, where oxygen is present only during combustion but not after, and the amount of oxygen increases in a leaner mixture. Consequently, the amount of NO produced reaches its maximum value in a leaner mixture than the theoretical air-fuel ratio.

[0101] The air-fuel ratios of the respective engines are set based on the CO, HC, and NOx production characteristics in relation to the air-fuel ratio. For example, consider a scenario where the total demand increases from a state where engine A is running at nominal power and engine B is restarted. At the time of engine B's start-up, its air-fuel ratio is set to rich to stabilize combustion. At this point, a large amount of CO and HC is produced. Therefore, engine A's air-fuel ratio is set to lean, and the amounts of NOx and oxygen are increased. Accordingly, the ratio between the reactive components of the gas flowing into the catalytic converter is adjusted to an ideal stoichiometric value, and pollutants can be removed with high efficiency through catalytic converter cleaning.

[0102] The specific processing of the present embodiment is described below.

[0103] Fig. Figure 21 illustrates an example of a flowchart for the control of a motor generator according to the present embodiment. Details of each step are described below. <Schritte S24 bis S33>

[0104] Since the processing in steps S24 to S33 is similar to that in steps S12 to S21 of the second embodiment, its description is omitted. <Schritt S34>

[0105] In step S34, the control device for a power generation system calculates the air-fuel ratios of the respective engines based on the information (engine states) Sg3 (Sg31 to Sg3n) from the respective ECUs 15 and the respective engines 11. Here, the air-fuel ratio of a newly started engine is set to rich. Additionally, the air-fuel ratios of all already running engines are set to lean or stoichiometric. At this point, the air-fuel ratios of the respective engines are adjusted so that the ratio between the reactive components of the gas flowing into the catalyst becomes the ideal stoichiometric value. For example, in the case of one newly started engine and two already running engines, the newly started engine can be set to rich, and all already running engines can be set to lean, or one of them can be set to stoichiometric.By controlling the air-fuel ratios of the respective engines in this way, pollutants can be removed with high efficiency through cleaning by the catalyst. <Schritte S35 und S36>

[0106] Since the processing in steps S35 and S36 is similar to that in steps S22 and S23 in the second embodiment, their description is omitted.

[0107] In this embodiment, when at least one engine is operating, the air-fuel ratio of the newly started engine is controlled to be rich, and the air-fuel ratio of the already operating engine is controlled to be lean or stoichiometric. By controlling the air-fuel ratios of the respective engines in this way, the ratio between the reactive components of the gas flowing into the catalyst becomes a stoichiometric ideal value, and the pollutants can be removed with high efficiency by purification through the catalyst. As a result, the amount of pollutant emissions from the power generation system can be reduced.

[0108] The present invention is not limited to the embodiments described above, and it is needless to say that various other application examples and modification examples can be made without departing from the core of the present invention as described in the claims.

[0109] For example, the embodiments described above are provided to describe the configurations of the devices and the system in detail and specifically, in order to describe the present invention in an easily understandable manner, and the present invention is not necessarily limited to embodiments that have all the described configurations. Furthermore, a part of a configuration of one embodiment described herein can be replaced by a configuration of another embodiment, and a configuration of one embodiment can also be added to a configuration of another embodiment. It is also possible to add, remove, and replace other configurations with respect to a part of the configurations of the respective embodiments.

[0110] Furthermore, control lines and information lines indicate what is considered necessary for the description and do not necessarily list all control lines and information lines on a product. In practice, it can be assumed that almost all configurations are interconnected. Reference symbol list 1 Control device for a power generation system (control device for a motor power generation system) 1a Input circuit 1b Input / Output Connection 1c RAM 1d ROM 1e CPU 1f Control output unit for motor torque 1g control output unit for hydrogen supply quantity 2 Hydrogen generation device 3 load-side instrument 11 Engine 12 power generators 13 current transformers 14 Hydrogen supply device 15 ECU 16 Exhaust gas passage 17 Air-fuel ratio sensor 18 Upstream catalyst temperature sensor 19 Oxygen concentration sensor 20 Exhaust gas purification catalyst (three-way catalyst) 21 Airflow sensor 22 Natural gas injection device 23 Hydrogen supply channel 24 Coolant temperature sensor 25 Exhaust pipe 26 electronically controlled throttles 27 Inlet pipe 28 Combustion chamber 29 Spark plug 30 cylinder head QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 5772958 B

[0006]

Claims

[1] An engine power generation system control device for an engine power generation system capable of performing co-combustion when a hydrocarbon-based fuel and hydrogen are supplied and performing power generation by an engine, comprising an engine warm-up state detection unit that detects whether the engine is in a warm-up state, the engine power generation system control device comprising: a catalyst provided in an exhaust passage of the engine and purifying an exhaust gas; and an active catalyst state detection unit that detects whether the catalyst is in an active state, wherein a supply amount of hydrocarbon-based fuel or a supply amount of hydrogen to the engine is controlled based on an active state of the catalyst detected by the active catalyst state detecting unit and a warmed-up state of the engine detected by the engine warm-up state detecting unit. [2] A control device for an engine power generation system according to claim 1, wherein proportions of supply amounts of a hydrocarbon-based fuel and the hydrogen to the engine are controlled based on the active state of the catalyst detected by the active catalyst state detecting unit and the warmed-up state of the engine detected by the engine warm-up state detecting unit. [3] A control device for an engine power generation system according to claim 1, wherein, when the catalyst active state detecting unit detects that the catalyst is inactive, only a hydrocarbon-based fuel is supplied to the engine and only hydrocarbon-based combustion is performed. [4] A control device for an engine power generation system according to claim 1, wherein, when the catalyst active state detecting unit detects that the catalyst is active, a hydrocarbon-based fuel and hydrogen are supplied to the engine and hydrogen co-combustion is performed. [5] A control device for a motor power generation system according to claim 4, wherein, when the engine warm-up condition detecting unit detects that the engine is cold, an air-fuel ratio of the engine is controlled so that an oxygen concentration of an exhaust gas flowing into the catalyst becomes equal to or lower than a predetermined value C1, and the predetermined value C1 is an oxygen concentration of an exhaust gas in a case where the engine is operated when an air-fuel ratio of the engine is a theoretical air-fuel ratio. [6] A control device for a motor power generation system according to claim 4, wherein, when the engine warm-up condition detecting unit detects that the engine is warmed up, an air-fuel ratio of the engine is controlled so that an oxygen concentration of an exhaust gas flowing into the catalyst becomes equal to or higher than a predetermined value C2, and the predetermined value C2 is an oxygen concentration of an exhaust gas in a case where the engine is operated at an air-fuel ratio at which an amount of nitrogen oxides directly emitted from the engine becomes equal to or smaller than a predetermined value. [7] A control device for a motor power generation system according to claim 1, wherein the catalyst active state detecting unit detects a catalyst inflow gas temperature, which is a temperature of the gas flowing into the catalyst, and determines that the catalyst is in an active state when the catalyst inflow gas temperature is equal to or higher than a predetermined value, and / or the engine warm-up state detecting unit detects a cooling water temperature of the engine and determines that the engine is in the warm-up state when the cooling water temperature of the engine is equal to or higher than a predetermined value. [8] A control device for an engine power generation system according to claim 4, wherein, when the engine warm-up state detecting unit detects that the engine is cold, the supply amount of hydrocarbon-based fuel or the supply amount of hydrogen to the engine is controlled so that a proportion of a hydrogen amount to a total fuel supply amount decreases as a cooling water temperature of the engine increases. [9] A control device for a motor power generation system according to claim 1, wherein the engine power generation system comprises a plurality of the engines, an exhaust passage formed by converging exhaust pipes of the plurality of respective engines, and the catalyst provided in the exhaust passage, and the supply amount of hydrocarbon-based fuel or the supply amount of hydrogen to each of the engines is controlled based on the active state of the catalyst detected by the active catalyst state detecting unit and the warmed-up state of each of the engines detected by the engine warm-up state detecting unit. [10] A control device for an engine power generation system according to claim 9, wherein, when the catalyst active state detecting unit detects that the catalyst is active and the engine warm-up state detecting unit detects that the engine is cold, a hydrocarbon-based fuel and hydrogen are supplied to each of the engines and hydrogen co-combustion is performed. [11] The control device for an engine power generation system according to claim 9, wherein, when the catalyst active state detecting unit detects that the catalyst is active, the engine warm-up state detecting unit detects that the engines are warmed up, and the cold engines are not operated in the same period, the hydrocarbon-based fuel and hydrogen are supplied to the warmed up engines, and the hydrogen co-combustion is performed. [12] A control device for an engine power generation system according to claim 9, wherein, when the catalyst active state detecting unit detects that the catalyst is active, the engine warm-up state detecting unit detects that the engines are warmed up, and the cold engines operate in the same period, only the hydrocarbon-based fuel is supplied to the warmed-up engines, and combustion is performed with only the hydrocarbon-based fuel. [13] A control device for a motor power generation system according to claim 12, wherein, when the engine warm-up condition detecting unit detects that the cold engines are operating in the same period, an air-fuel ratio of each of the engines is controlled so that an oxygen concentration of an exhaust gas flowing into the catalyst becomes equal to or lower than a predetermined value C1, and the predetermined value C1 is an oxygen concentration of an exhaust gas in a case where the engine is operated when an air-fuel ratio of the engine is a theoretical air-fuel ratio. [14] A control device for a motor power generation system according to claim 11, wherein, when the engine warm-up condition detecting unit detects that the cold engines are not operating in the same period, an air-fuel ratio of each of the engines is controlled so that an oxygen concentration of an exhaust gas flowing into the catalyst becomes equal to or higher than a predetermined value C2, and the predetermined value C2 is an oxygen concentration of an exhaust gas in a case where the engine is operated at an air-fuel ratio at which an amount of nitrogen oxides directly emitted from the engine is equal to or less than a predetermined value. [15] A control device for an engine power generation system according to claim 9, wherein, when at least one engine is operated, an air-fuel ratio of a newly started engine is controlled to be rich, and an air-fuel ratio of an already operated engine is controlled to be lean or stoichiometric.

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