Integrated Power Generation Modeling and Cooperative Control Method of SOFC-GT System for Microgrid Application

Abstract

The present invention discloses an integrated power generation modeling and coordinated control method for a SOFC-GT system for microgrid applications, which relates to the technical field of new energy power generation and is used to solve the technical problems that existing solid oxide fuel cells have slow dynamic response to power requirements and low power generation efficiency; the integrated power generation modeling method for a SOFC-GT system for microgrid applications includes: determining a SOFC power generation model and a GT power generation model; adding a dynamic description of its tail gas output on the basis of the SOFC power generation model; introducing a dynamic description of the bypass SOFC tail gas fuel input on the basis of the GT power generation model, and then obtaining an integrated power generation dynamic model of the SOFC-GT system; the coordinated control method includes: respectively constructing a basic controller for the SOFC power generation unit and a basic controller for the GT power generation unit; and then constructing a top-level adaptive power distribution strategy to achieve integrated power generation. The technical solution of the present invention provides an integrated power generation modeling and coordinated control method for a SOFC-GT system for microgrid applications.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy power generation, and particularly to an integrated power generation modeling and coordinated control method for a SOFC-GT system for microgrid applications. Background Art

[0002] Energy is the cornerstone of human survival and development and the lifeblood of the national economy. At present, the energy supply structure in China still mainly relies on traditional fossil energy power generation, and electric energy is supplied through a centralized large power grid, which has disadvantages such as high energy consumption, large pollution, unsustainability, and poor reliability.

[0003] Compared with renewable energy power generation devices such as photovoltaic and wind power that are currently widely used in the power grid, a solid oxide fuel cell (SOFC for short) has a broader development prospect. Its power generation process is continuous, stable, and controllable, and is not affected by factors such as geographical location and meteorological conditions. However, compared with other energy storage power devices such as supercapacitors or lithium-ion batteries, the dynamic response of SOFC to power requirements is relatively slow, which limits its operation only in the Grid Following (GFL) mode and makes it difficult to operate in the Grid Forming (GFM) mode. In addition, during the operation of a solid oxide fuel cell, a large amount of unreacted fuel and the accompanying heat are discharged as waste gas, which to a certain extent limits the upper limit of its power generation efficiency and causes waste of resources. Summary of the Invention

[0004] The purpose of the present invention is to provide an integrated power generation modeling and coordinated control method for a SOFC-GT system for microgrid applications to solve the technical problems of slow dynamic response of existing solid oxide fuel cells to power requirements and low power generation efficiency. In view of this, the present invention is achieved through the following solutions.

[0005] In a first aspect, the present invention provides an integrated power generation modeling method for a SOFC-GT system for microgrid applications, including:

[0006] Determine a SOFC power generation model and a GT power generation model;

[0007] Add a dynamic description of its tail gas output to the SOFC power generation model;

[0008] Introduce a dynamic description of the bypass SOFC tail gas fuel input to the GT power generation model, and then obtain an integrated power generation dynamic model of the SOFC-GT system;

[0009] Wherein, SOFC represents a solid oxide fuel cell, and GT represents a gas turbine.

[0010] Compared with the prior art, in the integrated power generation modeling method of the SOFC-GT system for microgrid applications of the present invention, by introducing a dynamic description of the bypass SOFC exhaust gas fuel input on the basis of the GT power generation model, the gas turbine and the solid oxide fuel cell are coupled to obtain an integrated power generation dynamic model of the SOFC-GT system. Based on this integrated power generation dynamic model of the SOFC-GT system, the exhaust gas discharged by the solid oxide fuel cell can be fully utilized for secondary power generation, effectively improving the power generation efficiency compared with a single solid oxide fuel cell. At the same time, the natural mechanical inertia of the gas turbine can help the SOFC-GT system achieve grid-connected / island mode operation. This SOFC-GT system is crucial for improving the overall power generation efficiency of the system, enhancing the elasticity and flexibility of the power grid, and ultimately ensuring the safe, reliable, and economic operation of the power grid. Through the above technical solutions of the present invention, the technical problems of slow dynamic response to power requirements and low power generation efficiency of existing solid oxide fuel cells are solved.

[0011] Further, in the integrated power generation modeling and coordinated control method of the SOFC-GT system for microgrid applications of the present invention, the input of the SOFC power generation model is the output current of the SOFC stack at the previous moment and the molar flow rate of the original fuel;

[0012] The output of the SOFC power generation model is the voltage of the SOFC stack and the molar flow rate of the exhaust gas;

[0013] and / or,

[0014] The input of the GT power generation model is the fuel supply control amount, the output electromagnetic power of the generator at the previous moment, and the rotor speed;

[0015] The output of the GT power generation model is three-phase alternating current.

[0016] Further, in the integrated power generation modeling and coordinated control method of the SOFC-GT system for microgrid applications of the present invention, the SOFC power generation model outputs the voltage of the SOFC stack, including:

[0017] The molar flow rate of the original fuel is converted into the molar flow rate of hydrogen after passing through the fuel processing link;

[0018] The partial pressure of the gas is obtained, and the Nernst voltage of the SOFC is obtained through the Nernst voltage equation;

[0019] The numerical quantity is converted into an electrical quantity through a controllable voltage source module inside the engineering design or simulation software;

[0020] The ohmic polarization of the combined action of the stack interior and the wire is equivalently simulated through a series resistor, and then the voltage of the SOFC stack is output through the SOFC power generation model;

[0021] and / or,

[0022] The GT power generation model outputs three-phase alternating current, including:

[0023] The fuel supply control quantity passes through a valve and the fuel system link to obtain the fuel flow supplied by the fuel system;

[0024] After being combined with the bypass SOFC tail gas fuel and then passing through the catalytic combustion delay link, the actual fuel input quantity input to the gas turbine is obtained, and the mechanical torque input to the gas turbine is obtained;

[0025] The difference between the mechanical torque and the output electromagnetic torque of the gas turbine passes through the rotor link to obtain the rotational speed of the gas turbine at the next moment, and is converted into three-phase alternating current through the synchronous generator module of engineering design or simulation software and output.

[0026] In a second aspect, the present invention provides a method for integrated power generation collaborative control of an SOFC-GT system, which is used to control the SOFC-GT system integrated power generation dynamic model obtained by the above-mentioned SOFC-GT system integrated power generation modeling method for microgrid applications. The method for integrated power generation collaborative control of the SOFC-GT system includes:

[0027] Construct a basic controller for the SOFC power generation unit and a basic controller for the GT power generation unit respectively; and then construct a top-level adaptive power distribution strategy to achieve integrated power generation; where:

[0028] The basic controller for the SOFC power generation unit includes the control of the fuel input flow rate, the DC bus voltage, and the power output of the current source inverter;

[0029] The basic controller for the GT power generation unit includes the control of the GT output power and rotational speed considering the input of the bypass SOFC tail gas;

[0030] The top-level adaptive power distribution strategy determines the reference value of the power output of each power generation unit by obtaining the current operating state of each power generation unit, and finally realizes the integrated power generation of the system.

[0031] Furthermore, in the method for integrated power generation collaborative control of the SOFC-GT system of the present invention, the construction of the basic controller for the SOFC power generation unit includes:

[0032] Obtain the hydrogen molar flow rate and output current of the SOFC stack, and obtain the fuel utilization rate;

[0033] Determine the target value of the fuel utilization rate, and control the original fuel molar flow rate to keep the fuel utilization rate near the target value of the fuel utilization rate;

[0034] Obtain the SOFC stack voltage and the inductor current inside the Boost converter, determine the voltage target value, and control the DC bus voltage to be stable near the voltage target value;

[0035] Obtain the grid-side inductor voltage and inductor current, obtain the active power and reactive power output by the SOFC power generation unit, and obtain the three-phase grid frequency and phase angle through a phase-locked loop;

[0036] Obtain the voltage of the line capacitor and the current flowing through the power supply-side inductor;

[0037] Design a grid-following operation output power controller for the inverter to control the active power and reactive power output by the SOFC power generation unit in the grid-following mode.

[0038] Furthermore, in the integrated power generation collaborative control method of the SOFC-GT system of the present invention, constructing the basic controller of the GT power generation unit includes:

[0039] Design a speed governor for the GT power generation unit. The speed governor can switch between the grid-following mode and the grid-forming mode of the SOFC-GT system and is used for stable control of the speed of the gas turbine;

[0040] Among them, in the grid-following mode, the speed governor has synchronism. The speed governor can adjust the output power and rotor speed of the gas turbine without steady-state error. The relationship between the output power and the rotor speed is:

[0041] ;

[0042] Wherein:

[0043] ;

[0044] ;

[0045] In the above formula, is the fuel supply control quantity, is the additional fuel compensation quantity, is the scaling coefficient, is the gas turbine rotor speed, is the speed governor time constant, is the Laplace operator, is the fuel supply control quantity of the power link, is the fuel supply control quantity of the speed link, is the gas turbine output reference power, is the gas turbine output power, is the proportional link control gain, is the first integral link control gain, is the second integral link control gain, is the control gain of the third integral link, is the reference speed of the gas turbine rotor, is the droop coefficient;

[0046] In the grid-connected mode, when the governor controls the frequency of the SOFC-GT system to be maintained at the rated value, the output power automatically tracks the actual load power demand. Then, the relationship between the rotor speed and the fuel supply control quantity is:

[0047] ;

[0048] where, is the fuel supply control quantity, is the additional fuel compensation quantity, is the scaling coefficient, is the gas turbine rotor speed, is the governor time constant, is the Laplace operator, is the fuel supply control quantity of the speed link;

[0049] where, the basic controller of the GT power generation unit is a gas turbine fuel controller designed to consider bypassing the SOFC tail gas fuel input; this gas turbine fuel controller takes the rotor speed of the gas turbine at the previous moment and the electromagnetic power output of the generator as inputs.

[0050] Furthermore, in the integrated power generation cooperative control method of the SOFC-GT system of the present invention, during the process of designing the gas turbine fuel controller that considers bypassing the SOFC tail gas fuel input:

[0051] Ensure that the fuel supply quantity is greater than or equal to the minimum warning value of the fuel input quantity;

[0052] For the fuel supply quantity, in addition to the bypass input of the SOFC tail gas fuel, additional fuel compensation needs to be directly provided to the gas turbine from the original fuel system;

[0053] For the fuel compensation, the following formula needs to be satisfied:

[0054] ;

[0055] where, is the additional fuel compensation quantity, is the minimum warning value of the fuel input quantity, is the molar flow rate of the tail gas fuel.

[0056] Furthermore, in the integrated power generation cooperative control method of the SOFC-GT system of the present invention, the control process of the basic controller of the GT power generation unit is:

[0057] When the SOFC-GT system is in the grid-connected mode, the power loop control switch is in the closed state;

[0058] When the SOFC-GT system is in the grid-forming mode, the power loop control switch is in the open state.

[0059] Furthermore, in the integrated power generation collaborative control method of the SOFC-GT system of the present invention, the construction of the top-level adaptive power distribution strategy includes:

[0060] Obtain the hydrogen molar flow rate, output voltage, and tail gas fuel molar flow rate of the SOFC stack;

[0061] Design a top-level online adaptive power distribution strategy;

[0062] Among them, the top-level online adaptive power distribution strategy takes the tail gas fuel molar flow rate as a reference, sets the target power generation values of each power generation unit after the system reaches a steady state, and dynamically adjusts adaptively according to the current operating states of each power generation unit during the dynamic process before reaching the steady state.

[0063] Furthermore, in the integrated power generation collaborative control method of the SOFC-GT system of the present invention, during the process of constructing the top-level adaptive power distribution strategy, the output power that the gas turbine should generate under the supply of the solid oxide fuel cell tail gas is:

[0064] ;

[0065] Among them, is the output power of the gas turbine, is the rated output power of the gas turbine, is the tail gas fuel molar flow rate, is the minimum warning value of the fuel input amount;

[0066] When the output power not satisfied by the SOFC power generation unit during the dynamic operation process of the SOFC-GT system is all borne by the GT power generation module, when the system enters the steady-state operation stage, the target output power of the gas turbine is determined by the SOFC fuel tail gas flow rate;

[0067] The SOFC-GT system can quickly and accurately meet the total power demand;

[0068] As the total power demand changes, the fuel utilization rate of the solid oxide fuel cell is 0.7 - 0.9 p.u., and the overall fuel utilization rate of the system reaches 1 p.u., and all fuels are completely and fully utilized. Description of the Drawings

[0069] The accompanying drawings described herein are used to provide a further understanding of the present invention and form a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0070] Figure 1 is a schematic diagram of the working process of the SOFC-GT system of the present invention;

[0071] Figure 2 is a schematic diagram of the principle of the integrated power generation dynamic model of the SOFC-GT system of the present invention;

[0072] Figure 3 is a schematic diagram of the principle of the cooperative control method of the present invention;

[0073] Figure 4 is a schematic diagram of the dynamic response of the power output of the SOFC-GT system of the present invention under different modes;

[0074] Figure 5 is a schematic diagram of the dynamic response of the parameters of the SOFC-GT system of the present invention under different modes;

[0075] Figure 6 is a schematic diagram of the AC bus voltage waveform when the operation mode of the SOFC-GT system of the present invention is switched. Detailed implementation manners

[0076] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0077] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0078] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined. The meaning of "several" is one or more unless otherwise specifically defined.

[0079] Compared with renewable energy power generation devices such as photovoltaic and wind power that are currently widely applied to the power grid, the Solid Oxide Fuel Cell (SOFC) has a broader development prospect. Its power generation process is continuous, stable, and controllable, and is not affected by factors such as geographical location and meteorological conditions. However, compared with other energy storage power devices such as supercapacitors or lithium-ion batteries, the dynamic response of SOFC to power requirements is relatively slow, which limits it to only operate in the Grid Following (GFL) mode and is difficult to achieve Grid Forming (GFM) operation. In addition, during the operation of SOFC, a large amount of unreacted fuel and the accompanying heat are discharged as waste gas, which to a certain extent limits the upper limit of its power generation efficiency and causes resource waste.

[0080] To solve the above technical problems, on the one hand, the present invention provides an integrated power generation modeling method for an SOFC-GT system for microgrid applications, including:

[0081] Determine the SOFC power generation model and the GT power generation model;

[0082] Add a dynamic description of its tail gas output based on the SOFC power generation model;

[0083] Introduce a dynamic description of the bypass SOFC tail gas fuel input based on the GT power generation model, and then obtain the integrated power generation dynamic model of the SOFC-GT system;

[0084] Wherein, SOFC represents a solid oxide fuel cell, and GT represents a gas turbine.

[0085] In the case of adopting the above technical solution, in the integrated power generation modeling method for the SOFC-GT system for microgrid applications of the present invention, by introducing a dynamic description of the bypass SOFC tail gas fuel input based on the GT power generation model, the gas turbine and the solid oxide fuel cell are coupled to obtain the integrated power generation dynamic model of the SOFC-GT system. Based on this integrated power generation dynamic model of the SOFC-GT system, it is possible to make full use of the tail gas discharged by the solid oxide fuel cell for secondary power generation, effectively improving the power generation efficiency compared with a single solid oxide fuel cell. At the same time, the natural mechanical inertia of the gas turbine can assist the SOFC-GT system to achieve Grid Forming / Island mode operation. This SOFC-GT system is crucial for improving the overall power generation efficiency of the system, enhancing the elasticity and flexibility of the power grid, and ultimately ensuring the safe, reliable, and economic operation of the power grid. Through the above technical solution of the present invention, the technical problems of the slow dynamic response of the existing solid oxide fuel cell to power requirements and the low power generation efficiency are solved.

[0086] Second aspect, the present invention provides a coordinated control method for integrated power generation of an SOFC-GT system, which is used to control the integrated power generation dynamic model of the SOFC-GT system obtained by the above-mentioned integrated power generation modeling method for microgrid applications. The coordinated control method for integrated power generation of the SOFC-GT system includes:

[0087] Construct a basic controller for the SOFC power generation unit and a basic controller for the GT power generation unit respectively; and then construct a top-level adaptive power distribution strategy to achieve integrated power generation. Among them:

[0088] The basic controller for the SOFC power generation unit includes the control of fuel input flow rate, DC bus voltage, and the power output of the current source inverter.

[0089] The basic controller for the GT power generation unit includes the control of the GT output power and speed considering the bypass of the SOFC exhaust gas input.

[0090] The top-level adaptive power distribution strategy determines the reference power output value of each power generation unit by obtaining the current operating state of each power generation unit, and finally realizes the integrated power generation of the system.

[0091] Under the above technical solution, in the coordinated control method for integrated power generation of the SOFC-GT system of the present invention, by respectively constructing a basic controller for the SOFC power generation unit and a basic controller for the GT power generation unit, and then constructing a top-level adaptive power distribution strategy, integrated power generation can be achieved, and the coordinated operation of the SOFC / GT power generation units inside the system can be realized. On the premise of ensuring the safe operation of each unit, the fast and efficient integrated power generation of the system can be realized, and at the same time, the system is endowed with the ability to connect to and form a network to meet the flexible operation needs of the microgrid; compared with single SOFC power generation, the integrated power generation system promoted by this technical solution can effectively improve the power response speed, the utilization rate of fuel can reach 100%, and at the same time injects sufficient mechanical inertia into the microgrid, which is of great significance for improving the elasticity and flexibility of the microgrid, promoting the full and efficient utilization of hydrogen-rich fuels, and reducing carbon emissions.

[0092] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with specific embodiments, but the content of the present invention is not limited to the following embodiments.

[0093] The raw materials used in the following embodiments are all commercially available raw materials unless otherwise specified.

[0094] Embodiment 1

[0095] This embodiment provides an integrated power generation modeling method for an SOFC-GT system for microgrid applications, including:

[0096] S100. Determine the SOFC power generation model and the GT power generation model;

[0097] S200. Add a dynamic description of the tail gas output to the SOFC power generation model;

[0098] S300. Introduce a dynamic description of the bypass SOFC tail gas fuel input to the GT power generation model, and then obtain the integrated power generation dynamic model of the SOFC-GT system;

[0099] Among them, SOFC represents a solid oxide fuel cell, and GT represents a gas turbine.

[0100] This embodiment also provides an integrated power generation cooperative control method for the SOFC-GT system, which is used to control the integrated power generation dynamic model of the SOFC-GT system obtained by the above-mentioned integrated power generation modeling method for microgrid applications. The integrated power generation cooperative control method for the SOFC-GT system includes:

[0101] Step 1. Respectively construct the basic controller of the SOFC power generation unit and the basic controller of the GT power generation unit;

[0102] Step 2. Then construct a top-level adaptive power distribution strategy to achieve integrated power generation;

[0103] Among them, the basic controller of the SOFC power generation unit includes the control of the fuel input flow rate, the DC bus voltage, and the power output of the current source inverter;

[0104] The basic controller of the GT power generation unit includes the control of the GT output power and the rotational speed considering the bypass SOFC tail gas input;

[0105] The top-level adaptive power distribution strategy determines the reference power output values of each power generation unit by obtaining the current operating states of each power generation unit, and finally realizes the integrated power generation of the system.

[0106] Embodiment 2

[0107] This embodiment provides an integrated power generation modeling method for the SOFC-GT system for microgrid applications, including:

[0108] S100. Determine the SOFC power generation model and the GT power generation model;

[0109] Among them, the input of the SOFC power generation model is the output current of the SOFC stack at the previous moment and the molar flow rate of the original fuel, and the output of the SOFC power generation model is the SOFC stack voltage and the molar flow rate of the tail gas; the input of the GT power generation model is the fuel supply control amount, the output electromagnetic power of the generator at the previous moment, and the rotor speed, and the output of the GT power generation model is three-phase alternating current;

[0110] The SOFC power generation model outputs the SOFC stack voltage, which may further include:

[0111] S111, the original fuel molar flow rate is converted into the hydrogen molar flow rate after passing through the fuel processing section;

[0112] S112, obtaining the gas partial pressure and obtaining the Nernst voltage of the SOFC through the Nernst voltage equation;

[0113] S113, converting the numerical quantity into an electrical quantity through the controllable voltage source module inside the engineering design or simulation software;

[0114] S114, equivalently simulating the ohmic polarization of the combined action of the stack interior and the wire through a series resistor, and then outputting the SOFC stack voltage through the SOFC power generation model;

[0115] The GT power generation model outputs three-phase alternating current, which may further include:

[0116] S121, the fuel supply control quantity passes through a valve and the fuel system section to obtain the fuel flow rate supplied by the fuel system;

[0117] S122, after merging with the bypass SOFC tail gas fuel and then passing through the catalytic combustion delay section to obtain the actual fuel input quantity input to the gas turbine, and obtaining the mechanical torque input to the gas turbine;

[0118] S123, obtaining the rotational speed of the gas turbine at the next moment by the difference between the mechanical torque and the output electromagnetic torque of the gas turbine, and converting it into three-phase alternating current through the synchronous generator module of the engineering design or simulation software and outputting it;

[0119] S200, adding a dynamic description of its tail gas output on the basis of the SOFC power generation model;

[0120] S300, introducing a dynamic description of the input of the bypass SOFC tail gas fuel on the basis of the GT power generation model, and then obtaining the integrated power generation dynamic model of the SOFC-GT system;

[0121] Among them, SOFC represents a solid oxide fuel cell, and GT represents a gas turbine.

[0122] This embodiment also provides an integrated power generation cooperative control method for the SOFC-GT system, which is used to control the integrated power generation dynamic model of the SOFC-GT system obtained by the above integrated power generation modeling method for microgrid applications. The integrated power generation cooperative control method for the SOFC-GT system includes:

[0123] Step S100: Construct the basic controllers of the SOFC power generation unit and the GT power generation unit respectively;

[0124] Step S200: Further construct the top - layer adaptive power distribution strategy to achieve integrated power generation;

[0125] Among them, in step S100, the construction of the basic controller of the SOFC power generation unit includes:

[0126] Step S111: Obtain the hydrogen molar flow rate and output current of the SOFC stack, and obtain the fuel utilization rate;

[0127] Step S112: Determine the target value of the fuel utilization rate, and control the original fuel molar flow rate to keep the fuel utilization rate near the target value of the fuel utilization rate;

[0128] Step S113: Obtain the SOFC stack voltage and the inductor current inside the Boost converter, determine the target voltage value, and control the DC bus voltage to be stable near the target voltage value;

[0129] Step S114: Obtain the grid - side inductor voltage and inductor current, and obtain the active power and reactive power output by the SOFC power generation unit, and obtain the three - phase power frequency and phase angle of the grid through a phase - locked loop;

[0130] Step S115: Obtain the voltage of the line capacitor and the current flowing through the power - supply - side inductor;

[0131] Step S116: Design a grid - following operation output power controller for the inverter to control the active power and reactive power output by the SOFC power generation unit in the grid - following mode;

[0132] Among them, in step S100, the construction of the basic controller of the GT power generation unit includes:

[0133] Step S121: Design a speed governor for the GT power generation unit. The speed governor can switch between the grid - following mode and the grid - forming mode of the SOFC - GT system and is used for stable control of the rotational speed of the gas turbine;

[0134] Among them, in the grid - following mode, the speed governor has synchronism. The speed governor can adjust the output power and rotor speed of the gas turbine without steady - state error. The relationship between the output power and the rotor speed is:

[0135] ;

[0136] Wherein:

[0137] ;

[0138] ;

[0139] In the above formula, is the fuel supply control quantity, is the additional fuel compensation quantity, is the scaling factor, is the rotational speed of the gas turbine rotor, is the governor time constant, is the Laplace operator, is the fuel supply control quantity of the power link, is the fuel supply control quantity of the speed link, is the reference power output of the gas turbine, is the power output of the gas turbine, is the control gain of the proportional link, is the control gain of the first integral link, is the control gain of the second integral link, is the control gain of the third integral link, is the reference rotational speed of the gas turbine rotor, is the droop coefficient;

[0140] Step S122, in the grid-connected mode, when the governor controls the frequency of the SOFC-GT system to maintain at the rated value, the output power automatically tracks the actual load power demand, and the relationship between the rotational speed of the rotor and the fuel supply control quantity is:

[0141] ;

[0142] wherein, is the fuel supply control quantity, is the additional fuel compensation quantity, is the scaling factor, is the rotational speed of the gas turbine rotor, is the governor time constant, is the Laplace operator, is the fuel supply control quantity of the speed link;

[0143] wherein, the basic controller of the GT power generation unit is a gas turbine fuel controller designed to consider bypassing the SOFC tail gas fuel input; this gas turbine fuel controller takes the rotational speed of the gas turbine at the previous moment and the electromagnetic power output of the generator as inputs;

[0144] wherein, in step S200, the construction of the top-level adaptive power distribution strategy includes:

[0145] S201, obtaining the hydrogen molar flow rate, output voltage, and tail gas fuel molar flow rate of the SOFC stack;

[0146] S202, designing the top-level online adaptive power distribution strategy;

[0147] Among them, the top - layer online adaptive power distribution strategy takes the molar flow rate of tail - gas fuel as a reference, sets the target power generation values of each power generation unit after the system reaches a steady state, and dynamically adjusts adaptively according to the current operating states of each power generation unit during the dynamic process before reaching the steady state;

[0148] Furthermore, during the process of designing the gas turbine fuel controller considering the bypass of SOFC tail - gas fuel input: ensure that the fuel supply amount is greater than or equal to the minimum warning value of the fuel input amount; for the fuel supply amount, in addition to the bypass input of SOFC tail - gas fuel, additional fuel compensation needs to be directly provided to the gas turbine from the original fuel system;

[0149] For the fuel compensation, the following formula should be satisfied:

[0150] ;

[0151] Among them, is the additional fuel compensation amount, is the minimum warning value of the fuel input amount, is the molar flow rate of tail - gas fuel;

[0152] Furthermore, the control process of the basic controller of the GT power generation unit is as follows:

[0153] When the SOFC - GT system is in the grid - following mode, the power loop control switch is in the closed state;

[0154] When the SOFC - GT system is in the grid - forming mode, the power loop control switch is in the open state;

[0155] Furthermore, in step S200, during the process of constructing the top - layer adaptive power distribution strategy, the output power that the gas turbine should generate under the supply of solid oxide fuel cell tail - gas is:

[0156] ;

[0157] Among them, is the output power of the gas turbine, is the rated output power of the gas turbine, is the molar flow rate of tail - gas fuel, is the minimum warning value of the fuel input amount;

[0158] When the SOFC - GT system is operating dynamically, the output power not satisfied by the SOFC power generation unit will all be borne by the GT power generation module. When the system enters the steady - state operation stage, the target output power of the gas turbine is determined by the SOFC fuel tail - gas flow rate;

[0159] The SOFC-GT system can quickly and accurately meet the total power demand;

[0160] With the change of the total power demand, the fuel utilization rate of the solid oxide fuel cell is 0.7 - 0.9 p.u., and the overall fuel utilization rate of the system reaches 1 p.u., and all fuels are fully utilized.

[0161] Embodiment 3

[0162] In a first aspect, this embodiment provides an integrated power generation modeling method for an SOFC-GT system for microgrid applications, including:

[0163] S100, determining the SOFC power generation model and the GT power generation model;

[0164] Among them, the input of the SOFC power generation model is the output current of the SOFC stack at the previous moment and the molar flow rate of the raw fuel, and the output of the SOFC power generation model is the voltage of the SOFC stack and the molar flow rate of the tail gas; the input of the GT power generation model is the fuel supply control amount, the output electromagnetic power of the generator at the previous moment, and the rotor speed, and the output of the GT power generation model is three-phase alternating current;

[0165] The SOFC power generation model outputs the voltage of the SOFC stack, which may further include:

[0166] S111, the molar flow rate of the raw fuel is converted into the molar flow rate of hydrogen after passing through the fuel processing link;

[0167] S112, obtaining the gas partial pressure, and obtaining the Nernst voltage of the SOFC through the Nernst voltage equation;

[0168] S113, converting the numerical quantity into an electrical quantity through the controllable voltage source module inside the engineering design or simulation software;

[0169] S114, equivalently simulating the ohmic polarization of the combined action of the stack interior and the wire through a series resistor, and then outputting the voltage of the SOFC stack through the SOFC power generation model;

[0170] The GT power generation model outputs three-phase alternating current, which may further include:

[0171] S121, the fuel supply control amount passes through the valve and the fuel system link to obtain the fuel flow rate supplied by the fuel system;

[0172] S122, after merging with the bypass SOFC tail gas fuel and then passing through the catalytic combustion delay link to obtain the actual fuel input amount input to the gas turbine, and obtaining the mechanical torque input to the gas turbine;

[0173] S123: Obtain the rotational speed of the gas turbine at the next moment by the difference between the mechanical torque and the output electromagnetic torque of the gas turbine, and convert it into three-phase alternating current through the synchronous generator module of engineering design or simulation software, and output it.

[0174] S200: Add a dynamic description of its tail gas output on the basis of the SOFC power generation model.

[0175] S300: Introduce a dynamic description of the bypass SOFC tail gas fuel input on the basis of the GT power generation model, and then obtain the integrated power generation dynamic model of the SOFC-GT system.

[0176] Among them, SOFC represents solid oxide fuel cell, and GT represents gas turbine.

[0177] Furthermore, for the SOFC power generation model, the SOFC stack output voltage, hydrogen molar flow rate, partial pressure of hydrogen, partial pressure of oxygen, partial pressure of water vapor, and tail gas fuel molar flow rate are obtained through the following formulas respectively:

[0178] SOFC part: (1)

[0179] In the above formula, is the SOFC stack output voltage, is the hydrogen molar flow rate, is the partial pressure of hydrogen, is the partial pressure of oxygen, is the partial pressure of water vapor, is the number of single cells in the SOFC stack, is the electrode potential, is the gas constant, is the temperature, is the Faraday constant, is the original fuel molar flow rate, is the time constant of is the Laplace operator, is the hydrogen valve molar constant, is the proportionality coefficient, is the output current of the SOFC stack, is the time constant of hydrogen, is the oxygen valve molar constant, is the hydrogen-oxygen ratio, is the time constant of oxygen, is the time constant of water vapor, is the tail gas fuel molar flow rate; is the ohmic polarization loss, , ;

[0180] For the GT power generation model, its fuel input, the mechanical torque output of the gas turbine (Tm), and the rotational speed of the gas turbine (GT) rotor are obtained through the following equations respectively:

[0181] GT part: (2)

[0182] Wherein, is the fuel input, is the natural constant, is the Laplace operator, is the combustion link lag time, is the exhaust fuel molar flow rate, is the fuel supply control quantity, is the intake valve link time constant, is the fuel system link time constant, is the mechanical torque output of the gas turbine, is the rotational speed of the gas turbine rotor, is the electromagnetic torque, is the rotor time constant;

[0183] It should be noted that in the integrated power generation modeling method of the SOFC-GT system for microgrid applications in this embodiment, for the SOFC power generation model, its input quantities are the output current of the SOFC stack at the current moment and the raw fuel molar flow rate from the fuel system that has not been processed , and the raw fuel molar flow rate is converted into the hydrogen molar flow rate input to the internal flow channel of the SOFC stack after passing through the fuel treatment link , and the molar flow rates of the reactants and products consumed by the SOFC stack at the current moment can be obtained by multiplying the output current by the proportionality coefficient . As shown above, after subtracting the two and passing through the "pressure-flow" conversion formula corresponding to each component, the gas partial pressure at the current moment is obtained. The gas partial pressure includes the hydrogen partial pressure , the oxygen partial pressure and the water vapor partial pressure . Then, the Nernst voltage is obtained through the Nernst voltage equation. The numerical quantity is converted into an electrical quantity through a controllable voltage source module inside an engineering design or simulation software (such as MATLAB / Simulink), and the ohmic polarization caused by the combined action of the inside of the SOFC stack and the wire is equivalently simulated by a series resistor, and finally the model output is obtained, that is, the output voltage of the SOFC stack ; further, for the GT dynamic model, its input quantities are the fuel supply control quantity and the generator electromagnetic power at the current moment and the rotational speed of the gas turbine rotor , the fuel supply control quantity After passing through two typical lag links of the valve and the fuel system, the fuel flow supplied by the fuel system is obtained , and then after passing through the catalytic combustion delay link, the actual fuel input quantity input to the gas turbine is obtained , and then the mechanical torque output by the gas turbine is obtained through the mechanical torque formula output by the gas turbine , the mechanical torque output by the gas turbine and the electromagnetic torque are subtracted and combined with the rotor operation expression to obtain the gas turbine speed at the next moment, and finally it is converted into three-phase alternating current output through the synchronous generator module inside the engineering design or simulation software (such as MATLAB / Simulink). Therefore, in this embodiment, firstly, the description of the dynamic process of the exhaust gas output is added on the basis of the original SOFC power generation model, and at the same time, the description of the dynamic process of the bypass SOFC exhaust gas fuel input is added on the basis of the original GT power generation model, and finally an integrated power generation dynamic model of the SOFC-GT system with "hydrogen-electricity" coupling is formed.

[0184] Secondly, this embodiment also provides an integrated power generation cooperative control method for the SOFC-GT system, which is used to control the integrated power generation dynamic model of the SOFC-GT system obtained by the above-mentioned integrated power generation modeling method for microgrid applications. The integrated power generation cooperative control method for the SOFC-GT system includes:

[0185] Step 1, respectively collect the hydrogen molar flow rate and the output current of the SOFC stack, and calculate the fuel utilization rate ; design a fuel controller to maintain the fuel utilization rate near the target value by controlling the original fuel molar flow rate . The closed-loop control law is specifically as follows:

[0186] (3)

[0187] where is the hydrogen molar flow rate of the SOFC stack, is the fuel utilization rate, is the target value, is the control gain of the proportional link, is the control gain of the integral link, is the Laplace operator, is the time constant of;

[0188] For the fuel utilization rate , there is:

[0189] (4)

[0190] Wherein, is the fuel utilization rate, is the proportionality coefficient, is the SOFC output current, is the hydrogen molar flow rate at the SOFC reaction interface;

[0191] Step 2, respectively collect the SOFC output voltage and the inductor current inside the Boost converter , design a voltage outer loop current inner loop dual-loop controller for the Boost converter to maintain the DC bus voltage stable near the target value to effectively cope with the output voltage fluctuation problem caused by the polarization characteristics of the solid oxide fuel cell (SOFC);

[0192] For the DC / DC Boost converter, this embodiment adopts dual-loop voltage control, and the specific expression is as follows:

[0193] (5)

[0194] Wherein, is the duty cycle of the PWM drive signal, is the voltage reference / target value, is the SOFC output voltage, is the control gain of the proportional link, is the control gain of the integral link, is the Laplace operator, is the inductor current of the Boost converter, is the control gain of the proportional link, is the control gain of the integral link;

[0195] Step 3, respectively collect the grid-side inductor voltage , inductor current , to obtain the active power and reactive power output by the SOFC power generation unit, and at the same time obtain the three-phase grid frequency and phase angle through the phase-locked loop PLL; at the same time, respectively collect the voltage of the line capacitor , and the current flowing through the power supply-side inductor Design a grid-following controller for the inverter to achieve the active power output of the SOFC power generation unit in the grid-following mode (GFL). / reactive power control;

[0196] Step 4: Based on the modified GT power generation unit model, design a GT fuel controller considering the bypass of the SOFC exhaust fuel input. The controller takes the gas turbine rotor speed and the generator electromagnetic power as inputs. The controller includes a speed control loop and a power control loop (the power control loop is equipped with an operating mode discriminant switch ). When the system operates in the grid-following mode (GFL), the discriminant switch is in the closed state ( ), enabling the GT power generation unit to operate at the target speed and output power. When the system operates in the grid-forming / island mode (GFM), the discriminant switch is in the open state ( ), the power control loop is cut off, and only the GT needs to be ensured to operate at the target speed. The output power of the GT power generation unit follows the load demand changes;

[0197] Furthermore, the design principle of the fuel controller in Step 4 is as follows:

[0198] Considering that the flow rate of the SOFC exhaust gas is inevitably fluctuating when the gas turbine intakes air, therefore, it is first necessary to ensure that the fuel provided for the gas turbine is always sufficient (i.e., the fuel input amount fuel input amount minimum warning value ). In addition to the SOFC exhaust gas, additional fuel compensation needs to be directly provided from the fuel system to the gas turbine. Then, there is:

[0199] (6)

[0200] Wherein, is the additional fuel compensation amount, is the fuel input amount minimum warning value, is the exhaust fuel molar flow rate;

[0201] Furthermore, a governor control is developed for the GT power generation unit to achieve seamless switching between the grid-following mode (GFL) and the grid-forming mode (GFM). Please refer to Figure 3 . In the grid-following mode (GFL), the governor control has synchronous characteristics and can adjust the output power and the rotor speed of the gas turbine without steady-state error (

[0202] Furthermore, the output power and the rotor speed are related as follows:

[0203] (7)

[0204] Where:

[0205] (8)

[0206] (9)

[0207] In the above formula, is the fuel supply control quantity, is the additional fuel compensation quantity, is the scaling coefficient, is the gas turbine rotor speed, is the governor time constant, is the Laplace operator, is the fuel supply control quantity of the power link, is the fuel supply control quantity of the speed link, is the gas turbine output reference power, is the gas turbine output power, is the proportional link control gain, is the first integral link control gain, is the second integral link control gain, is the third integral link control gain, is the gas turbine rotor reference speed, is the droop coefficient;

[0208] Furthermore, in the grid-forming mode, when the governor controls the frequency of the SOFC-GT system to maintain at the rated value, the output power automatically tracks the actual load power demand. Then, the relationship between the gas turbine rotor speed and the fuel supply control quantity is:

[0209] (10)

[0210] Wherein, is the fuel supply control quantity, is the additional fuel compensation quantity, is the scaling coefficient, is the rotor speed, is the governor time constant, is the Laplace operator, is the fuel supply control quantity of the speed link;

[0211] It should be noted that the primary control algorithm of the GT power generation unit developed in this embodiment enables the integrated power generation of the SOFC-GT system (ISGS) to have the operating capabilities in the grid-connected mode and the grid-forming mode, while ensuring that the gas turbine has sufficient fuel supply and maximizing the utilization rate of exhaust gas;

[0212] Step 5: Collect the hydrogen molar flow rate of the SOFC stack , output voltage , and the molar flow rate of the tail gas fuel , design a top-level online adaptive power distribution strategy, and set the target power generation values of each power generation unit after the system reaches a steady state with the molar flow rate of the tail gas fuel as a reference. For the dynamic process before reaching the steady state, it is dynamically and adaptively adjusted according to the current operating status of each power generation unit. Finally, on the basis of realizing the full utilization of the tail gas, the stable and safe operation of each power generation unit is ensured. Compared with the single SOFC power generation unit, this embodiment greatly improves the power response speed of the system and endows the system with the capabilities of grid connection and grid formation. During this process, the output power that the gas turbine can generate is:

[0213] (11)

[0214] Wherein, is the output power of the gas turbine, is the rated output power of the gas turbine, is the molar flow rate of the tail gas fuel, is the lowest warning value of the fuel input;

[0215] Furthermore, when the total power demand is constant when the SOFC-GT system (ISGS) runs to a steady state, the reference output power of the gas turbine can be set to the output power of the gas turbine to achieve the purpose of maximizing the overall fuel utilization rate of the system, and the remaining power demand is satisfied by the SOFC power generation unit; as the power demand changes, in order to maximize the output power response speed of the SOFC and ensure that the fuel utilization rate always remains within the safe range (0.7 - 0.9 p.u.), the value of

[0216] (12)

[0217] Wherein, is the reference value of the SOFC output power, is the upper bound of the power change within the safe operating range of the solid oxide fuel cell, is the lower bound of the power change within the safe operating range of the solid oxide fuel cell, represents the remaining power demand, is the real-time output power of the SOFC;

[0218] Furthermore, in the above formula:

[0219] ; (13)

[0220] ; (14)

[0221] wherein, is the upper bound of the power change within the safe operating range of the solid oxide fuel cell, is the lower bound of the power change within the safe operating range of the solid oxide fuel cell, is the output voltage of the SOFC stack, is the molar flow rate of hydrogen, is the proportionality coefficient;

[0222] In the above and being satisfied, the remaining power demand is then met by the gas turbine; it should be noted that the strategy in this embodiment allocates appropriate power reference values for the operation of the solid oxide fuel cell and the gas turbine. It is precisely based on this regulation that the SOFC-GT system (ISGS) can quickly track the total power demand, maximize the utilization of system fuel, and at the same time ensure the safe operation of each power generation unit.

[0223] Furthermore, based on the above Embodiment 3, parameter settings are made, and when the SOFC-GT system in Embodiment 3 operates in two operating modes, namely the grid-connected mode (GFL) and the grid-forming mode (GFM), its actual effects are evaluated, specifically including:

[0224] (1) Parameter settings

[0225] To verify the effectiveness of this Embodiment 3, the key parameters of the SOFC-GT system are first set as follows:

[0226] The rated total output power of the system is 250 KVA, the rated output powers of the solid oxide fuel cell and the gas turbine are 150 KVA (1 p.u.) and 100 KVA (1 p.u.) respectively, the DC bus reference voltage is 800 V, the rated fuel supply molar flow rate of the gas turbine is 1.2 mol / s (1 p.u.), and the droop coefficient is 0.04.

[0227] (2) Verification process

[0228] When the SOFC-GT system operates in two operating modes, namely the grid-following mode (GFL) and the grid-forming mode (GFM), its actual performance is evaluated, mainly including the following two aspects: First, whether the total output power of the system and the power output of each power generation unit can meet the requirements as scheduled under the condition of changing power demand; Second, whether the dynamic change process of each key parameter inside the system can meet the requirements as scheduled; specifically as follows:

[0229] Please refer to Figure 4 and Figure 5 , the system operates in the grid-following mode (GFL) at the initial moment and switches to the grid-forming mode (GFM) at . The total power demand jumps at , and ; When the system operates in the grid-following mode (GFL), the total power demand of the power grid is 180 kW at , drops to 130 kW at , and rises to 150 kW at , with a maximum change range of 50 kW; When the system operates in the grid-forming mode (GFM), the initial demand power is 170 kW at , jumps to 150 kW at , with a maximum change range of 20 kW.

[0230] (3) Verification results

[0231] Please refer to Figures 4 to 6 , Figure 4 which shows that regardless of the operating conditions, the coordinated control method of the present invention enables the SOFC-GT system (ISGS) to quickly meet the total power demand, and the power response is faster than the maximum response speed of the SOFC power generation unit. Under the action of the adaptive power distribution strategy, each power generation unit of the system can finally reach its respective target output power value. Figure 5 It shows the effectiveness of the primary control of the SOFC power generation unit and the GT power generation unit. It can be observed that the DC bus voltage and the gas turbine rotor speed can quickly and without error track their reference values under the action of the control module. The tail gas fuel molar flow rate can be fully utilized by the gas turbine, and it is ensured that the fuel input amount is not less than the minimum warning value of the fuel input amount ; Further, the AC bus voltage waveform of the SOFC-GT system during the mode switching process is as shown in Figure 6As shown, it can be observed that the SOFC-GT system has a seamless transition from the grid-following mode (GFL) to the grid-forming mode (GFM), successfully switching from the grid-connected mode to the island mode.

[0232] Further, please refer to Figures 1 to 3 , based on the above embodiments, by way of example, in combination with Figures 1 to 3 the technical solution of the present invention will be further described; wherein, Figure 1 is a schematic diagram of the working process of the SOFC-GT system of the present invention, and the specific working process is as follows: First, the grid dispatching center gives the total target output power of the system to the local power adaptive distribution module, which decides the output reference power values of each power generation unit according to the actual operating states of the SOFC power generation unit and the GT power generation unit within the current system, that is, the output reference power of the solid oxide fuel cell and the output reference power of the gas turbine ; Secondly, the SOFC power generation unit adjusts the fuel input flow rate, the DC bus voltage, and the output power of the current-source inverter according to the reference value of the output reference power of the solid oxide fuel cell and finally outputs the required AC power to the grid / local load. Based on the SOFC exhaust gas flow rate, the GT power generation unit adjusts the fuel flow rate through the governor to control the gas turbine speed and output power according to the reference value of the output reference power of the gas turbine and then outputs the required AC power to the grid / local load through the coaxial synchronous generator; Finally, the SOFC-GT system outputs the AC power required by the total target power requirement to achieve integrated power generation. Figure 2 is a schematic diagram of the principle of the integrated power generation dynamic model of the SOFC-GT system of the present invention, Figure 2 which details the dynamic process of the system's integrated power generation. The specific principle is as follows: For the SOFC power generation unit, the model inputs are the output current of the SOFC stack at the previous moment and the original fuel molar flow rate. By the output current the molar flow rates of consumed hydrogen and oxygen and generated water are respectively calculated. The difference from the input reactant flow rate passes through a first-order inertial link to obtain the gas partial pressure and the exhaust gas molar flow rate, and then the Nernst voltage is obtained through the Nernst voltage equation. Finally, the numerical quantity is converted into an electrical quantity through the controllable voltage source module in the engineering design or simulation software and subtracted from the Ohmic polarization to obtain the output voltage of the SOFC power generation unit; For the GT power generation unit, the fuel supply control quantity passes through first-order inertial links such as the intake valve and the fuel system and is added to the SOFC exhaust gas molar flow rate and passes through the lag link of catalytic combustion to obtain the input flow rate , and the current mechanical torque is obtained by combining the gas turbine speed at the previous moment , after subtracting the electromagnetic torque at the previous moment and passing through the rotor integration link, the current speed of the gas turbine is obtained and three-phase alternating current is output through the synchronous generator module inside the engineering design or simulation software. Figure 3 It is a schematic diagram of the principle of the collaborative control method of the present invention. Figure 3 The specific principle is as follows: First, the system total target output power is given by the power grid dispatching center to the power distribution module. By obtaining the SOFC tail gas flow rate at the previous moment , the hydrogen input flow rate of the SOFC and the output voltage of the SOFC , the output reference power values of each power generation unit are obtained through logical judgment, that is, the output reference power of the gas turbine and the output reference power of the gas turbine ; Secondly, for the SOFC power generation unit, the fuel control loop inside it adopts PI control, the DC bus voltage adopts double-loop PI control with voltage outer loop and current inner loop, and the output power of the current-type inverter adopts double-loop PI control with feedforward and feedback combination; Finally, for the GT power generation unit, its internal governor includes a speed control loop and a power control loop, both of which adopt PI control and are compounded in the integral part. Furthermore, by considering the scaling rule of the tail gas flow rate , the fuel supply control quantity is obtained and finally input into the GT power generation unit sub-model to control it.

[0233] In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0234] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claimed rights.

Claims

1. A SOFC-GT system integrated power generation modeling method for microgrid applications, characterized in that: include: Determine the SOFC power generation model and GT power generation model; Based on the SOFC power generation model, a dynamic description of its tail gas output is added; Based on the GT power generation model, a dynamic description of bypass SOFC tail gas fuel input is introduced to obtain a SOFC-GT system integrated power generation dynamic model; Among them, SOFC stands for solid oxide fuel cell, GT stands for gas turbine; The SOFC-GT system integrated power generation coordinated control method constructed based on the SOFC-GT system integrated power generation dynamic model comprises: The basic controller of SOFC power generation unit and the basic controller of GT power generation unit are constructed respectively; then the top-level adaptive power allocation strategy is constructed to realize integrated power generation; among which: The construction of the basic controller of the SOFC power generation unit comprises: Obtain the hydrogen molar flow rate and output current of the SOFC stack, and obtain the fuel utilization rate; Determining a fuel utilization rate target value, and controlling the original fuel molar flow rate so that the fuel utilization rate is maintained near the fuel utilization rate target value; Obtaining the SOFC stack voltage and the internal inductor current of the Boost converter, determining a voltage target value, and controlling the DC bus voltage to be stable near the voltage target value; Obtain the inductor voltage and inductor current on the grid side, obtain the active power and reactive power output by the SOFC power generation unit, and obtain the three-phase electrical frequency and phase angle of the grid through a phase-locked loop; Obtain the voltage of the line capacitor and the current flowing through the inductor on the power supply side; Design a grid-following output power controller for the inverter to control the active power and reactive power output by the SOFC power generation unit in the grid-following mode; Construct the basic controller of the GT power generation unit, including: A speed governor is designed for the GT power generation unit. The speed governor can switch between a grid-following mode and a grid-building mode according to the SOFC-GT system, and is used for smoothly controlling the rotation speed of the gas turbine.

2. The SOFC-GT system integrated power generation modeling method for microgrid application according to claim 1 is characterized in that: The input of the SOFC power generation model is the output current of the SOFC stack at the last moment and the original fuel molar flow rate; The output of the SOFC power generation model is the SOFC stack voltage and the molar flow rate of the tail gas; and / or, The input of the GT power generation model is the fuel supply control amount, the electromagnetic power output of the generator at the last moment, and the rotor speed; The output of the GT power generation model is three-phase alternating current.

3. The SOFC-GT system integrated power generation modeling method for microgrid application according to claim 2 is characterized in that: The SOFC power generation model outputs the SOFC stack voltage, including: The original fuel molar flow is converted into hydrogen molar flow after the fuel processing step; Obtain the gas partial pressure and obtain the Nernst voltage of SOFC through the Nernst voltage equation; Convert numerical quantities into electrical quantities through controllable voltage source modules within engineering design or simulation software; The ohmic polarization of the cell stack and the wires is simulated by equivalently simulating the ohmic polarization of the cell stack by series resistance, and then the SOFC cell stack voltage is outputted by the SOFC power generation model; and / or, The GT power generation model outputs three-phase alternating current, including: The fuel supply control quantity is obtained by passing through the valve and the fuel system link to obtain the fuel flow supplied by the fuel system; After being combined with the bypass SOFC tail gas fuel and then passing through the catalytic combustion delay link, the actual fuel input to the gas turbine is obtained, and the input mechanical torque of the gas turbine is obtained; The speed of the gas turbine at the next moment is obtained by the difference between the mechanical torque of the gas turbine and the output electromagnetic torque through the rotor link, and is converted into three-phase alternating current and output through the synchronous generator module of the engineering design or simulation software.

4. The SOFC-GT system integrated power generation modeling method for microgrid application according to claim 3 is characterized in that: In the process of the SOFC-GT system integrated power generation coordinated control method constructed based on the SOFC-GT system integrated power generation dynamic model: The basic controller of the SOFC power generation unit includes control of fuel input flow, DC bus voltage, and current-source inverter power output; The GT power generation unit basic controller includes GT output power and speed control considering bypass SOFC tail gas input; The top-level adaptive power allocation strategy determines the respective power output reference values ​​by acquiring the current operating status of each power generation unit, and finally realizes the integrated power generation of the system.

5. The SOFC-GT system integrated power generation modeling method for microgrid application according to claim 1 is characterized in that: In the process of building the basic controller of the GT power generation unit: In the grid-following mode, the speed governor has synchronization, and the speed governor can adjust the output power and rotor speed of the gas turbine without steady-state error. The relationship between the output power and the rotor speed is: ； in: ； ； In the above formula, To control the amount of fuel supply, is the additional fuel compensation amount, is the scaling factor, is the gas turbine rotor speed, is the speed regulator time constant, is the Lagrangian operator, The fuel supply control quantity for the power stage, The fuel supply control quantity for the speed link, is the reference power output of the gas turbine, is the gas turbine output power, is the proportional link control gain, is the control gain of the first integral link, is the control gain of the second integral link, is the control gain of the third integral link, is the reference speed of the gas turbine rotor, is the droop coefficient; In the grid-building mode, when the speed regulator controls the frequency of the SOFC-GT system to maintain the rated frequency, the output power automatically tracks the actual load power demand, and the relationship between the rotor speed and the fuel supply control amount is: ； in, To control the amount of fuel supply, is the additional fuel compensation amount, is the scaling factor, is the gas turbine rotor speed, is the speed regulator time constant, is a pull operator, Provides control quantity of fuel supply for speed link; Among them, the basic controller of the GT power generation unit is a gas turbine fuel controller designed to consider the bypass SOFC tail gas fuel input; the gas turbine fuel controller takes the rotor speed of the gas turbine at the previous moment and the electromagnetic power output of the generator as input.

6. The SOFC-GT system integrated power generation modeling method for microgrid application according to claim 5 is characterized in that: The process of designing a gas turbine fuel controller that considers bypassing the SOFC tail gas fuel input: Ensure that the fuel supply is greater than or equal to the minimum warning value of fuel input; Regarding the supply amount of the fuel, in addition to the bypass input of the SOFC tail gas fuel, it is also necessary to directly provide additional fuel compensation to the gas turbine from the original fuel system; For the fuel compensation, the following equation must be satisfied: ； in, is the additional fuel compensation amount, is the minimum warning value of fuel input, is the molar flow rate of exhaust fuel.

7. The SOFC-GT system integrated power generation modeling method for microgrid application according to claim 5 is characterized in that: The control process of the basic controller of the GT power generation unit is: When the SOFC-GT system is in the grid-following mode, the power loop control switch is in a closed state; When the SOFC-GT system is in the grid-building mode, the power ring control switch is in an open state.

8. The SOFC-GT system integrated power generation modeling method for microgrid application according to claim 1 is characterized in that: The constructing of the top-level adaptive power allocation strategy includes: Obtaining hydrogen molar flow rate, output voltage and tail gas fuel molar flow rate of the SOFC stack; Design top-level online adaptive power allocation strategy; Among them, the top-level online adaptive power allocation strategy uses the exhaust fuel molar flow rate as a reference to set the target power generation value of each power generation unit after the system is in steady state, and the dynamic process before steady state is dynamically adaptively adjusted according to the current operating status of each power generation unit.

9. The SOFC-GT system integrated power generation modeling method for microgrid application according to claim 1 or 8, characterized in that: In the process of constructing the top-level adaptive power allocation strategy, the output power that the gas turbine should generate when supplied by the tail gas of the solid oxide fuel cell is: ； in, is the output power of the gas turbine, is the rated output power of the gas turbine, is the exhaust fuel molar flow rate, It is the minimum warning value of fuel input; When the SOFC-GT system is in dynamic operation, the unsatisfied output power of the SOFC power generation unit will be borne entirely by the GT power generation module. When the system enters the steady-state operation stage, the target output power of the gas turbine is determined by the SOFC fuel tail gas flow rate. The SOFC-GT system can quickly and accurately meet the total power demand; As the total power demand changes, the fuel utilization of the solid oxide fuel cell is 0.7~0.9pu, and the overall fuel utilization of the system reaches 1p.u., and all fuel is fully utilized.

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