Micro-grid coordinated control method and system comprising gas turbine generator set and hydrogen energy storage

Abstract

The present application belongs to the technical field of direct current micro-grid control, and discloses a kind of direct current micro-grid coordinated control method containing gas turbine generator set and hydrogen energy storage, the overall control mode of the present application considers the storage state of hydrogen storage tank in system, and the maximum working power of fuel cell, electrolytic cell, determines 6 kinds of operating conditions of system operation for various load conditions of system.The micro-grid system energy designed by the present application is clean, and meets the demand of green energy supply, the coordinated control strategy designed by the present application effectively distributes power to each working unit through energy management system, and through secondary correction of fuel cell power, the bus voltage is restored to stable in time under the impact of various working condition switching and sudden load, with small fluctuation, to meet the stable operation demand of micro-grid.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of direct-current micro-grid control, and particularly relates to a direct-current micro-grid coordinated control method and system containing a gas turbine generator set and hydrogen energy storage. BACKGROUND

[0002] China has vast territory, a large number of islands, and many remote areas, mountainous areas, and plateau regions with complex geographical conditions. These areas are often far away from the main power grid, and the power supply is difficult to guarantee effectively. Especially for islands more than 10 km away from the land and remote areas far away from the center of the power grid, due to the remote geographical location and variable weather conditions, the traditional power line transmission method is costly and difficult to implement. Therefore, establishing a micro-grid system has become an inevitable trend for the development of power systems in these areas, and is a key step to realize energy security and sustainable development.

[0003] As a clean and low-carbon energy form, photovoltaic power generation is abundant in resources in these areas and has become an important part of the micro-grid system. However, due to the special geographical location of islands and remote areas, the output power of photovoltaic power stations is greatly affected by weather conditions and has high volatility, which brings challenges to the stable operation of the micro-grid system and the energy supply of local residents. Therefore, reasonable energy storage configuration and standby power supply in the micro-grid have become an important measure to ensure the stability and reliability of energy supply. Hydrogen energy, with its characteristics of cleanliness, high energy density, abundant reserves, and easy storage and transportation, has become an ideal choice for combination with photovoltaic power generation. Combining hydrogen energy with photovoltaic power generation and equipping with a micro gas turbine power generation system can not only ensure the energy supply of the micro-grid system, but also help reduce environmental pollution and meet the concept of green and sustainable development.

[0004] Due to the involvement of multiple energy forms and equipment types in the micro-grid system, how to realize the coordination and complementarity between photovoltaic, wind power, fuel cells and other energies, and improve energy utilization efficiency, is a complex and important problem. Especially in islands and remote areas, due to the particularity of power supply, the dispatching strategy of the micro-grid system also needs to consider the response measures in emergency situations to ensure that the power system can quickly recover and stabilize power supply in emergency situations.

[0005] Traditional island and remote power supply systems mostly use diesel generator sets as the main power supply source, but diesel generator sets have weak regulation capacity, high emissions, and large operating noise, and the supply of fuel resources in these areas is limited. Using diesel generator sets as the main power source weakens the stability of the microgrid and the environmental protection capacity. Micro gas turbine generator sets, as a more environmentally friendly and efficient power generation method, have broad application prospects in microgrid systems. Gas turbine generator sets are small in pollution, low in noise, good in starting and loading performance, and high in automation degree, which can realize automatic regulation and monitoring of the unit to ensure the reliability of power supply. At the same time, gas turbines can use hydrogen as fuel, which helps to reduce environmental pollution on islands. The gas turbine generator set, as an emergency backup power supply, together with photovoltaic power generation, hydrogen energy storage and other clean energy microgrid systems in island and remote areas, can achieve the purpose of reducing carbon emissions and protecting the environment, and is more conducive to the realization of system coordinated control strategy, and helps to improve the dynamic response capability of microgrid system under load mutation and emergency conditions.

[0006] Domestic and foreign scholars have made more research on the comprehensive energy management strategy of new energy hybrid system combined with hydrogen energy storage and gas turbine comprehensive power generation system, but there are few studies on direct current microgrid system combined with gas turbine, photovoltaic, fuel cell, electrolytic cell and other clean energy. The combination of fuel cells and gas turbines is mainly based on cogeneration, and focuses on electricity, and there is little research on power distribution strategy when fuel cell gas turbine is jointly operated. Therefore, the present application considers the power distribution problem when fuel cell and gas turbine are jointly operated, and proposes a secondary optimization correction of fuel cell power to improve system stability.

[0007] In the actual power source control process, the response characteristics and power supply capacity of different types of power sources such as gas turbine generator sets, hydrogen fuel cells and photovoltaic are quite different; at the same time, considering the environment and safety factors of islands and remote areas, the potential load change mode is complex and diverse, and the control mode and strategy of the power system are quite different from the conventional isolated renewable energy power grid, and are crucial to the stable and reliable operation of the power system.

[0008] Therefore, the application provides a coordinated control method of an island and remote area micro-grid in different operation modes, which comprises a gas turbine generator set, a hydrogen energy storage system and photovoltaic power generation, so as to meet the green low-carbon and safe and stable power supply demand of the island and remote area.

[0009] The photovoltaic, electrolytic tank and fuel cell are used in normal times, the hydrogen storage tank storage state in the system is considered, the micro gas turbine is used as an emergency standby power supply, the overall system is green and clean, and the environment is conducive to being maintained.

[0010] Through the above analysis, the problems and defects of the prior art are:

[0011] There is little research on the direct current micro-grid system of the gas turbine generator set combined with photovoltaic, fuel cell, electrolytic tank and other clean energy, and the combination and use of the fuel cell and the gas turbine are mainly based on cogeneration, and the power distribution strategy of the combined operation of the fuel cell and the gas turbine has not been studied much. SUMMARY

[0012] In view of the problems in the prior art, the application provides a direct current micro-grid coordinated control method and system comprising a gas turbine generator set and hydrogen energy storage.

[0013] The application is implemented as follows: a direct current micro-grid system comprising a gas turbine generator set and hydrogen energy storage, specifically comprising:

[0014] The gas turbine (GT) power generation system is connected to a DC bus through a synchronous generator, the photovoltaic (PV) power generation system, the fuel cell (FC) power generation system, the super capacitor (SC) and the electrolyzer (EL) are connected to the DC bus through a DC / DC converter. The EL produces hydrogen by electrolyzing water and stores the hydrogen in a hydrogen storage tank. The FC is started when the PV power generation system is insufficient, consumes the hydrogen in the hydrogen storage tank to provide power for the system. The GT is started as an emergency main power supply in the case of system emergency to ensure the normal and stable operation of the system in the emergency working condition.

[0015] Another object of the present application is to provide a DC micro-grid coordinated control method comprising a gas turbine generator set and hydrogen energy storage, specifically comprising:

[0016] Considering the hydrogen storage state of the micro-grid system, the maximum output power of the electrolyzer and the fuel cell, and the existence of six typical operating conditions of the system, considering the response characteristics and power supply capacity of the gas turbine generator set, the hydrogen fuel cell and the photovoltaic power supply, and the response capacity of the electrolyzer and the super capacitor, the energy management system distributes the energy of each system, and the reference power signal is transmitted to each control unit. Further, the six typical operating conditions of the system are as follows:

[0017] Condition 1: The photovoltaic PV is normally operated, the electrolyzer EL consumes all the surplus power, the super capacitor SC responds to the high-frequency power of the system in time, and the fuel cell FC and the gas turbine GT are not operated.

[0018] Condition 2: The photovoltaic PV is normally operated, the electrolyzer EL is operated at maximum power, the super capacitor SC consumes the excess power, and the fuel cell FC and the gas turbine GT are not operated.

[0019] Condition 3: The photovoltaic PV is normally operated, the electrolyzer EL is shut down, the super capacitor SC consumes the surplus power, and the fuel cell FC and the gas turbine GT are not operated.

[0020] Condition 4: The photovoltaic PV is normally operated, the fuel cell FC is started, the super capacitor SC responds to the high-frequency power of the system in time, and the electrolyzer EL and the gas turbine GT are not operated.

[0021] Condition 5: The photovoltaic PV is normally operated or the power is too low to be operated, the fuel cell FC is operated at maximum power, the gas turbine FT is started, the super capacitor SC responds to the high-frequency power of the system in time, and the electrolyzer EL is shut down.

[0022] Condition 6: The photovoltaic PV power is too low to be operated or has been operated, the fuel cell FC is stopped, the gas turbine GT is started, the super capacitor SC responds to the high-frequency power of the system in time, and the electrolyzer EL is shut down.

[0023] The control mode of each component of the system is as follows:

[0024] Step 1, the system automatically determines the working condition of the system according to the micro-grid load demand, photovoltaic power, electrolytic cell and fuel cell power and hydrogen storage state;

[0025] Step 2, the energy management unit distributes power to each component in the system, such as PV, FC, SC, GT, according to the system load condition and the working condition;

[0026] Step 3, the PV control unit adopts maximum power point tracking control MPPT;

[0027] Step 4, the FC control unit adopts single PI control of current loop;

[0028] Step 5, the control unit selects single PI control of current loop;

[0029] Step 6, the SC control unit uses the switch selection module to switch between two control modes, and the switch signals 1 and 0 correspond to the gas turbine starting and non-starting conditions;

[0030] Step 7, the excitation control unit uses generator excitation control to adjust the bus voltage.

[0031] Further, the PV control unit method:

[0032] The conductance increment method is adopted to realize the maximum power tracking control of photovoltaic, the voltage U pv of the photovoltaic power generation system is divided by the current I pv , and finally the adjusted duty ratio D pv is obtained, and then the signal is transmitted to the photovoltaic power generation system boost circuit.

[0033] Further, the FC control unit method:

[0034] The fuel cell power reference value P fc_ref given by the energy management system is divided by the fuel cell end voltage U fc , to obtain the fuel cell current reference value I fc_ref , which is subtracted from the actual fuel cell current value I fc and passed through a PI controller to obtain the duty ratio D fc , and then the signal is transmitted to the fuel cell power generation system boost circuit.

[0035] Further, the EL control unit method:

[0036] The electrolytic cell power reference value P el_ref given by the energy management system is divided by the electrolytic cell end voltage U el , to obtain the electrolytic cell current reference value I el_ref , which is subtracted from the actual electrolytic cell current value Iel Duty cycle D is obtained by subtracting the bus voltage actual value U el from the bus voltage reference value U dc_ref and passing the signal to the super capacitor boost and buck circuit.

[0037] Further, the SC control unit method:

[0038] Switching between the two control modes is performed by the switch selection module, and switch signals 1 and 0 correspond to the gas turbine starting and non-starting conditions.

[0039] In the non-emergency working condition, i.e., before the gas turbine starts to work, a double-PI control with an inner current loop and an outer voltage loop is adopted, which subtracts the bus voltage actual value U dc_ref from the bus voltage reference value U dc to obtain the super capacitor current reference value I sc_ref by the outer loop PI controller, and subtracts the super capacitor terminal actual current value I sc from the super capacitor current reference value I sc_ref to obtain the duty cycle D sc by the inner loop PI controller, and then transmits the signal to the super capacitor boost and buck circuit.

[0040] In the emergency working condition, i.e., when the gas turbine starts to work and is connected to the circuit for power supply, the super capacitor control mode is changed to single-PI power control of the current loop, which divides the super capacitor power reference value P sc_ref given by the energy management system by the super capacitor terminal voltage U sc to obtain the super capacitor current reference value I sc_ref , subtracts the super capacitor actual current value I sc from the super capacitor current reference value I sc_ref to obtain the duty cycle D sc by the PI controller, and then transmits the signal to the super capacitor boost and buck circuit.

[0041] Further, the excitation control unit method:

[0042] The bus voltage is adjusted by the generator excitation control.

[0043] The steps are as follows: subtracting the bus voltage actual value U dc from the bus voltage reference value U dc_ref , unitizing the difference, and passing the difference through a PI controller to obtain the excitation current reference value I fe_ref , subtracting the actual excitation current value I fe from the excitation current reference value I fe_ref to obtain the duty cycle signal by the inner loop PI controller, passing the duty cycle signal through the excitation amplifier, and then outputting the excitation current I fe by the exciter, and transmitting the excitation current signal to the synchronous generator.

[0044] Another object of the present application is to provide a direct current micro-grid coordinated control system comprising a gas turbine generator set and hydrogen energy storage, specifically comprising:

[0045] The system automatically determines the working condition of the system according to the micro-grid load demand, photovoltaic power, electrolytic cell and fuel cell power and hydrogen storage state;

[0046] The energy management unit distributes power of PV, FC, SC, GT and other components in the system according to the system load condition and working condition;

[0047] The PV control unit is used for maximum power point tracking control MPPT;

[0048] The FC control unit is used for single PI control of current loop;

[0049] The EL control unit is used for single PI control of current loop;

[0050] The SC control unit is used for switching of two control modes through a switch selection module, and switch signals 1 and 0 correspond to the gas turbine starting and non-starting conditions;

[0051] The excitation control unit is used for adjusting the bus voltage through generator excitation control.

[0052] Another object of the present application is to provide a computer device comprising a memory and a processor, the memory storing a computer program, the computer program being executed by the processor to make the processor execute the steps of the direct current micro-grid coordinated control method comprising a gas turbine generator set and hydrogen energy storage.

[0053] Another object of the present application is to provide a computer readable storage medium storing a computer program, the computer program being executed by a processor to make the processor execute the steps of the direct current micro-grid coordinated control method comprising a gas turbine generator set and hydrogen energy storage.

[0054] Another object of the present application is to provide an information data processing terminal for realizing the direct current micro-grid coordinated control system comprising a gas turbine generator set and hydrogen energy storage.

[0055] In combination with the above technical solutions and solved technical problems, the advantages and positive effects of the technical solution to be protected by the present application are analyzed from the following aspects:

[0056] First, in view of the technical problems existing in the above-mentioned prior art, some creative technical effects brought about after solving the problems are described as follows:

[0057] The present application proposes a new type of low-carbon green micro-grid system structure for islands and remote areas. This technology proposes an innovative micro-grid power generation system for islands and remote areas with variable weather conditions, fragile environment, limited resources, and unstable power supply. The system fully combines various renewable energy technologies and energy storage technologies. The system includes a photovoltaic system for fully utilizing solar energy resources, a fuel cell for efficient power generation using hydrogen energy, an electrolyzer driven by surplus energy in the system to produce hydrogen, a gas turbine generator set for timely startup for continuous power supply in emergency situations, and a super capacitor and hydrogen storage tank for storing electrical energy and hydrogen to cope with fluctuations in power demand. This system not only provides stable and reliable power supply for islands and remote areas, effectively reducing dependence on traditional energy sources, but also significantly reduces pollution and damage to the environment through recycling and efficient use of energy.

[0058] The present application realizes the coordinated work and optimized operation of each energy device in the system.

[0059] The present application realizes the coordinated work and optimized operation of each energy device in the system.

[0060] The present application realizes the coordinated work and optimized operation of each energy device in the system.

[0061] The present application realizes the coordinated work and optimized operation of each energy device in the system.

[0062] Second, the main steps of the DC micro-grid coordinated control method, the problems solved and the technical progress brought about:

[0063] The DC micro-grid coordinated control method first implements maximum power point tracking control (MPPT) through the PV control unit. This step aims to maximize the energy output efficiency of the photovoltaic power generation system, ensuring that the photovoltaic panel can generate the most electricity under given conditions, thereby increasing the power supply capacity of the micro-grid.

[0064] Then, by the FC (referring to fuel cell power generation system) control unit and EL (referring to electrolytic tank hydrogen production energy storage system) control unit, the method adopts single PI control of current loop. This control strategy helps to realize accurate regulation of current between components in the microgrid, ensures stable operation of the system, optimizes energy distribution, and improves energy utilization efficiency.

[0065] In order to more flexibly adapt to the operation requirements of the microgrid, the method switches between two control modes through the SC (referring to super capacitor energy storage system) control unit using the switch selection module. Switch signals 1 and 0 represent the start and non-start of the gas turbine respectively, which enables the system to flexibly select whether to start the gas turbine generator set according to the actual energy demand and power load, so as to realize accurate regulation of energy supply.

[0066] Finally, the method adjusts the bus voltage through the excitation control unit using generator excitation control. This step helps to stabilize the bus voltage of the microgrid, ensuring power quality and stable operation of the system. By comprehensively using the above control strategies, the present application solves the problems of unstable operation of the microgrid, low energy utilization efficiency and other problems in the prior art, significantly improving the coordinated control ability and overall performance of the direct current microgrid.

[0067] Third, as the creative auxiliary evidence of the claims of the present application, it is also embodied in the following important aspects:

[0068] (1) The expected income and commercial value of the technical solution of the present application after transformation are:

[0069] First, energy security. The present application can provide a low-carbon, green, environmentally friendly and stable and reliable energy supply solution for remote islands, mountainous areas, highlands and other areas with difficult power supply, effectively solving the long-term power supply problems in these areas and providing a solid energy guarantee for local residents and economic development.

[0070] Second, environmental friendliness and sustainable development. By using clean energy such as photovoltaic and hydrogen energy, as well as clean and efficient gas turbine generator sets as emergency main power supply, the technical solution of the present application can significantly reduce carbon emissions and environmental pollution, meeting the global green energy and sustainable development requirements.

[0071] Third, economic benefit improvement. In the long run, the microgrid system using clean energy has lower operating costs and higher economic benefits than traditional diesel generators. For remote areas, this not only reduces energy costs, but also promotes the sustainable development of the local economy.

[0072] (2) The technical solution of the present application fills the technical gap in the industry at home and abroad:

[0073] 1. Comprehensive optimization of clean energy micro-grid system: The present invention comprehensively considers the complementation and optimization of various clean energies such as photovoltaic, hydrogen energy, gas turbine, etc., and proposes a coordinated control method of the micro-grid system under different operation modes, which provides a new idea and technical means for the design and operation of the clean energy micro-grid system.

[0074] 2. Power distribution strategy for combined operation of fuel cell and gas turbine: For the power distribution problem of the combined operation of fuel cell and gas turbine aiming at grid stability, which is less studied at home and abroad, the present invention proposes a fuel cell power secondary optimization correction strategy, which improves the stability and reliability of the system, and to some extent fills the technical gap in this regard at home and abroad.

[0075] 3. Stable operation strategy of micro-grid system under extreme conditions: The present invention designs a smooth switching strategy between stable operation and working condition under power mutation and emergency conditions, which ensures that the bus voltage fluctuation is always within a reasonable range under various conditions, and provides an effective solution for the stable operation of the micro-grid system under extreme conditions.

[0076] (3) The technical scheme of the present invention solves the technical problems that people have been eager to solve but have always failed to succeed:

[0077] For remote islands, mountainous areas, plateaus and other remote areas where the distribution network cannot be extended, the power supply has been a difficult problem for a long time. Although people have high expectations for the use of clean energy, due to remote geographical location, variable weather conditions, high cost and difficulty of traditional power transmission, the power supply in these areas has always been difficult to effectively guarantee. The technical scheme of the present invention successfully solves the problem of power supply in these areas by constructing a micro-grid system for islands and remote areas containing gas turbine generator set, hydrogen energy storage system and photovoltaic power generation, and designing a coordinated control method under different operation modes. The system of the present invention not only can provide stable and reliable power supply, but also uses clean energy, which is beneficial to environmental protection and sustainable development. BRIEF DESCRIPTION OF DRAWINGS

[0078] Figure 1 is a flow chart of the coordinated control method of the direct current micro-grid containing the gas turbine generator set and the hydrogen energy storage provided by the embodiment of the present invention.

[0079] Figure 2 is a structure diagram of the micro-grid system provided by the embodiment of the present invention.

[0080] Figure 3 is an energy management flow chart provided by the embodiment of the present invention.

[0081] Figure 4is a system control schematic diagram provided by the embodiment of the present application.

[0082] Figure 5 is an energy management model diagram provided by the embodiment of the present application.

[0083] Figure 6 is a load change characteristic diagram provided by the embodiment of the present application.

[0084] Figure 7 is a solar irradiance value and photovoltaic system power diagram provided by the embodiment of the present application.

[0085] Figure 8 is a system unit power curve diagram provided by the embodiment of the present application.

[0086] Figure 9 is a system operation condition diagram provided by the embodiment of the present application.

[0087] Figure 10 is a direct current bus voltage tracking condition diagram provided by the embodiment of the present application.

[0088] Figure 11 is a system unit power curve diagram provided by the embodiment of the present application, considering power correction.

[0089] Figure 12 is a hydrogen storage tank state diagram provided by the embodiment of the present application.

[0090] Figure 13 is a bus voltage comparison value diagram provided by the embodiment of the present application, considering power correction and not considering correction.

[0091] Figure 14 is a unit output power curve and bus voltage value diagram provided by the embodiment of the present application, from 9-11.2s.(a) Unit power curve when suddenly adding and suddenly removing 30kW;(b) Unit power curve when suddenly adding and suddenly removing 50kW;(c) Bus voltage value.

[0092] Figure 15 is a unit output power curve and bus voltage value diagram provided by the embodiment of the present application, from 6.8-9s.(a) Unit power curve when suddenly adding and suddenly removing 40kW;(b) Unit power curve when suddenly adding and suddenly removing 60kW;(c) Bus voltage value. DETAILED DESCRIPTION

[0093] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application will be further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0094] As Figure 1As shown, the direct current micro-grid coordinated control method provided by the embodiment of the application and comprising a gas turbine generator set and hydrogen storage energy includes the following steps:

[0095] S101, automatically judging system working conditions;

[0096] S102, distributing power of each working condition of the system through an energy management system;

[0097] S103, adopting maximum power point tracking control (MPPT) through a PV control unit;

[0098] S104, adopting single PI control of a current loop through an FC control unit;

[0099] S105, selecting single PI control of a current loop through an EL control unit;

[0100] S106, switching two control modes through a switch selection module of an SC control unit, and switch signals 1 and 0 correspond to the starting and non-starting conditions of the gas turbine;

[0101] S107, adjusting the bus voltage through a generator excitation control of an excitation control unit.

[0102] The working condition judgment method implemented by the embodiment of the application:

[0103] The working condition of the system is automatically judged through detecting grid load demand, photovoltaic power, electrolytic cell and fuel cell power and hydrogen storage state signals.

[0104] The power distribution method implemented by the embodiment of the application:

[0105] Working condition 1: the photovoltaic device normally operates, the electrolytic cell absorbs all surplus power, the super capacitor timely responds to high-frequency power of the system, and the fuel cell and the gas turbine do not operate.

[0106] Working condition 2: the photovoltaic device normally operates, the electrolytic cell operates at maximum power, the super capacitor absorbs excess power, and the fuel cell and the gas turbine do not operate.

[0107] Working condition 3: the photovoltaic device normally operates, the electrolytic cell is shut down, the super capacitor absorbs surplus power, and the fuel cell and the gas turbine do not operate.

[0108] Working condition 4: the photovoltaic device normally operates, the fuel cell is started, the super capacitor timely responds to high-frequency power of the system, and the electrolytic cell and the gas turbine do not operate.

[0109] Working condition 5: the photovoltaic device normally operates or power is too low to be about to be shut down, the fuel cell operates at maximum power, the gas turbine is started, the super capacitor timely responds to high-frequency power of the system, and the electrolytic cell is shut down.

[0110] Case 6: photovoltaic power is too low to exit operation or has exited operation, fuel cell stops operation, gas turbine starts operation, super capacitor timely responds to system high frequency power, electrolytic tank exits operation.

[0111] The PV control unit method provided by the embodiment of the application comprises the following steps:

[0112] The conductance increment method is adopted to realize the maximum power tracking control of the photovoltaic power generation system, the voltage U pv of the photovoltaic power generation system is divided by the current I pv , and finally the adjusted duty ratio D pv is obtained.

[0113] The FC control unit method provided by the embodiment of the application comprises the following steps:

[0114] The fuel cell power reference value P fc_ref given by the energy management system is divided by the fuel cell terminal voltage U fc , and the fuel cell current reference value I fc_ref is obtained. fc The fuel cell current reference value I fc_ref is subtracted from the actual fuel cell current value I fc , and the duty ratio D fc is obtained through the PI controller.

[0115] The EL control unit method provided by the embodiment of the application comprises the following steps:

[0116] The electrolytic tank power reference value P el_ref given by the energy management system is divided by the electrolytic tank terminal voltage U el , and the electrolytic tank current reference value I el_ref is obtained. el The electrolytic tank current reference value I el_ref is subtracted from the actual electrolytic tank current value I el , and the duty ratio D el is obtained through the PI controller.

[0117] The SC control unit method provided by the embodiment of the application comprises the following steps:

[0118] The switch selection module is used to switch between two control modes, and the switch signals 1 and 0 correspond to the gas turbine starting and not starting conditions.

[0119] In the non-emergency case, i.e., before the gas turbine starts to work, the double PI control of the current inner loop and the voltage outer loop is adopted, the bus voltage reference value U dc_ref is subtracted from the actual bus voltage value U dc , the super capacitor current reference value I sc_ref is obtained through the outer loop PI controller, and the super capacitor terminal actual current value I scDifference, through the inner ring PI controller duty cycle D sc , the signal is transmitted to the super capacitor boost and buck circuit;

[0120] In the emergency condition, that is, when the gas turbine is started and connected to the circuit for power supply, the super capacitor control mode is changed to single PI power control of the current loop, and the super capacitor power reference value P sc_ref is divided by the super capacitor terminal voltage U sc , to obtain the super capacitor current reference value I sc_ref , which is subtracted from the actual super capacitor current value I sc and passed through a PI controller to obtain the duty cycle D sc , and then the signal is transmitted to the super capacitor boost and buck circuit.

[0121] The excitation control unit method provided by the embodiment of the application comprises the following steps:

[0122] The bus voltage is adjusted through generator excitation control;

[0123] The steps are as follows: the bus voltage reference value U dc_ref is subtracted from the actual bus voltage value U dc , and the difference is unitized and then passed through a PI controller to obtain the excitation current reference value I fe_ref , which is subtracted from the actual excitation current value I fe and then passed through an inner ring PI controller to obtain a duty cycle signal, the duty cycle signal is passed through an excitation amplifier and then an excitation machine outputs the excitation current I fe , and the excitation current signal is transmitted to the synchronous generator.

[0124] As shown in Figure 4 , the DC microgrid coordinated control system provided by the embodiment of the application comprises:

[0125] The PV control unit is used for MPPT control by adopting maximum power point tracking.

[0126] The FC control unit is used for single PI control of the current loop.

[0127] The EL control unit is used for single PI control of the current loop.

[0128] The SC control unit is used for switching between the two control modes through a switch selection module, and the switch signals 1 and 0 correspond to the starting and non-starting conditions of the gas turbine.

[0129] The excitation control unit is used for adjusting the bus voltage through generator excitation control.

[0130] Another object of the present application is to provide a computer device comprising a memory and a processor, the memory storing a computer program, the computer program being executed by the processor to cause the processor to perform the steps of the method for coordinated control of a direct-current micro-grid comprising a gas turbine generator set and hydrogen storage.

[0131] Another object of the present application is to provide a computer-readable storage medium storing a computer program, the computer program being executed by a processor to cause the processor to perform the steps of the method for coordinated control of a direct-current micro-grid comprising a gas turbine generator set and hydrogen storage.

[0132] Another object of the present application is to provide an information data processing terminal for implementing the coordinated control system of a direct-current micro-grid comprising a gas turbine generator set and hydrogen storage.

[0133] The embodiments of the present application are as follows:

[0134] I. Micro-grid system composition

[0135] The micro-grid system structure is shown in Figure 2 As shown in Figure 2 , a photovoltaic (SC) power generation system, a fuel cell (FC) power generation system, a super capacitor (SC), an electrolytic cell (EL) are connected to a DC bus through a DC / DC converter, and a gas turbine (GT) power generation system is connected to the DC bus through a synchronous generator. The EL system produces hydrogen by electrolyzing water and stores the hydrogen in a hydrogen storage tank. The FC starts up when the photovoltaic power generation system is insufficient and consumes hydrogen in the hydrogen storage tank to provide power for the system. The GT serves as a main power source in an emergency to ensure normal and stable operation of the system under emergency conditions.

[0136] As shown in Figure 2 , the energy management system receives system power signals, distributes power and coordinates control of the micro-grid system under various operating conditions through the control strategy, so that each unit responds and tracks the reference power in time, maintains the photovoltaic power generation system operating at the maximum power point at all times, maximizes the use of light energy, reduces the light rejection rate, and reduces the output of other units; the state of the hydrogen storage tank is maintained within a safe range; and the bus voltage is stable, with the maximum fluctuation controlled within a certain range.

[0137] II. Micro-grid system coordinated control strategy

[0138] 1. System energy management process

[0139] The micro-grid system control strategy flow chart is shown in Figure 3 .

[0140] Figure 3 , P pvPhotovoltaic power, P load Load power, P t Hydrogen tank pressure, P fc Fuel cell power, P fc_max Fuel cell maximum power, P gt Gas turbine power, P el Electrolyzer power, P el_max Electrolyzer maximum power, ΔP high , ΔP low represent the high and low frequency part of the power difference, subscript ref is the reference power given by the energy management system to each unit, according to the system operating state, it can be divided into the following 6 working conditions.

[0141] (1) Working condition 1: photovoltaic normal operation, electrolyzer absorbs all the surplus power, super capacitor responds to system high frequency power in time, fuel cell and gas turbine do not operate.

[0142] At this time, the photovoltaic power is higher than the system load power, and the hydrogen tank is in good condition, the system surplus power does not exceed the maximum operating power of the electrolyzer, and the super capacitor responds to the high frequency power when the system load power suddenly changes:

[0143] P sc = ΔP high (1)

[0144] The reference power of the electrolyzer is:

[0145] P el_ref = ΔP low (2)

[0146] (2) Working condition 2: photovoltaic normal operation, electrolyzer maximum power operation, super capacitor absorbs excess power, fuel cell and gas turbine do not operate.

[0147] At this time, the photovoltaic power is much higher than the system load power, ΔP is greater than the maximum operating power of the electrolyzer, and the electrolyzer operates at maximum power:

[0148] P el_ref = P el_max (3)

[0149] The super capacitor starts to absorb excess power:

[0150] P sc = ΔP-P el_max (4)

[0151] (3) Case 3: Photovoltaic normal operation, electrolyzer shutdown, super capacitor absorbs surplus power, fuel cell and gas turbine do not operate.

[0152] At this time, photovoltaic power is higher than the system load power, but the hydrogen storage tank reaches the maximum pressure value and cannot continue to store hydrogen, and the electrolyzer must stop running, and the super capacitor should start to absorb all the surplus power:

[0153]

[0154] (4) Case 4: Photovoltaic normal operation, fuel cell starts, super capacitor responds to system high frequency power in time, electrolyzer and gas turbine do not operate.

[0155] At this time, photovoltaic power is insufficient to support load power, the hydrogen storage tank is in good condition, the system power difference does not reach the maximum operating power of the fuel cell, and the difference is fully supplemented by the fuel cell power generation system:

[0156] P fc_ref = | ΔP low | (6)

[0157] The super capacitor only responds to the high frequency part of the system load power mutation:

[0158] P sc = | ΔP high | (7)

[0159] (5) Case 5: photovoltaic normal operation or power too low to exit operation, fuel cell operates at maximum power, gas turbine starts, super capacitor responds to system high frequency power in time, electrolyzer exits operation.

[0160] At this time, the difference between photovoltaic power and load power is greater than the maximum operating power of the fuel cell, the fuel cell operates at maximum power, and the emergency gas turbine is started to supplement the power difference:

[0161] P gt = | ΔP | - P fc_max (8)

[0162] The super capacitor responds to the high frequency part of the system load power mutation:

[0163] P sc_ref = | ΔP high | (9)

[0164] (6) Case 6: photovoltaic power is too low to exit operation or has exited operation, fuel cell stops operating, gas turbine starts, super capacitor responds to system high frequency power in time, electrolyzer exits operation.

[0165] At this time, the photovoltaic output power is still less than the load power, the hydrogen storage tank reaches the minimum pressure value, and the fuel cell must be taken out of operation, and the super capacitor and the gas turbine respectively respond to the high and low frequency power of the load:

[0166]

[0167] 2. System control principle

[0168] The system control principle block diagram is shown in Figure 4 , which includes photovoltaic, fuel cell, electrolytic tank, super capacitor and gas turbine synchronous generator excitation control unit.

[0169] The control principle of each unit will be described as follows.

[0170] 2.1 PV control unit

[0171] In order to get higher photovoltaic cell conversion efficiency, reduce the light rejection rate of the system, and maximize the use of light energy, the photovoltaic control unit of the present technology always adopts maximum power point tracking control (MPPT). The MPPT algorithm can be realized by various methods, such as constant voltage method, perturbation observation method, incremental conductance method, etc. The present technology adopts incremental conductance method to realize maximum power tracking control of photovoltaic, and the voltage U pv and current I pv of the photovoltaic power generation system are input into the MPPT control unit, and finally the adjusted duty ratio D pv is obtained, and then the signal is transmitted to the photovoltaic power generation system boost circuit.

[0172] 2.2 FC control unit

[0173] The fuel cell control unit adopts single PI control of current loop, and the fuel cell power reference value P fc_ref given by the energy management system is divided by the fuel cell terminal voltage U fc to obtain the fuel cell current reference value I fc_ref , which is subtracted from the actual fuel cell current value I fc and passed through the PI controller to obtain the duty ratio D fc , and then the signal is transmitted to the fuel cell power generation system boost circuit.

[0174] 2.3 EL control unit

[0175] The electrolytic tank control unit is similar to the fuel cell, which is also a single PI control of current loop, and the electrolytic tank power reference value P el_ref given by the energy management system is divided by the electrolytic tank terminal voltage U el to obtain the electrolytic tank current reference value I el_ref , which is subtracted from the actual electrolytic tank current value I elDuty cycle D el , which is then transmitted to the supercapacitor boost and buck circuit.

[0176] 2.4 SC control unit

[0177] The supercapacitor control unit designed by the present technology switches between the two control modes through the switch selection module. Switch signals 1 and 0 correspond to the start and non-start conditions of the gas turbine.

[0178] In the non-emergency operating condition, i.e., before the gas turbine is started, a double-PI control with an inner current loop and an outer voltage loop is used. The bus voltage reference value U dc_ref is subtracted from the actual bus voltage value U dc , and the difference is transmitted to the outer loop PI controller to obtain the supercapacitor current reference value I sc_ref . The supercapacitor terminal actual current value I sc is subtracted from the supercapacitor current reference value I sc_ref , and the difference is transmitted to the inner loop PI controller to obtain the duty cycle D sc , which is then transmitted to the supercapacitor boost and buck circuit.

[0179] In the emergency operating condition, i.e., when the gas turbine is started and connected to the circuit for power supply, the supercapacitor control mode is changed to single-PI power control with a current loop. The supercapacitor power reference value P sc_ref given by the energy management system is divided by the supercapacitor terminal voltage U sc to obtain the supercapacitor current reference value I sc_ref . The supercapacitor actual current value I sc is subtracted from the supercapacitor current reference value I sc_ref , and the difference is transmitted to the PI controller to obtain the duty cycle D sc , which is then transmitted to the supercapacitor boost and buck circuit.

[0180] 2.5 Excitation control unit

[0181] The gas turbine power generation system adjusts the bus voltage through generator excitation control. The steps are as follows: the bus voltage reference value U dc_ref is subtracted from the actual bus voltage value U dc , and the difference is unitized and transmitted to the PI controller to obtain the excitation current reference value I fe_ref . The actual excitation current value I fe is subtracted from the excitation current reference value I fe_ref , and the difference is transmitted to the inner loop PI controller to obtain the duty cycle signal. The duty cycle signal is transmitted to the excitation amplifier, and then the excitation current I fe is output by the exciter, and the excitation current signal is transmitted to the synchronous generator.

[0182] 3. Fuel cell output power optimization

[0183] Since in system operation, when the hydrogen storage state reaches the critical value, the fuel cell needs to exit operation immediately, at this time if the fuel cell output power is larger, without taking reasonable control when exiting operation, it will cause greater disturbance to the system, leading to excessive fluctuation of the bus voltage, the system is easy to be unstable. Therefore, the fuel cell output power control needs to be optimized twice, by detecting and analyzing the real-time state of the hydrogen storage tank, setting the second critical value of the hydrogen storage tank state 1.55MPa, when the hydrogen storage tank pressure is lower than 1.55MPa and still has a downward trend, start the gas turbine in advance, set the reference power correction of the fuel cell and electrolytic tank, the gas turbine responds to the lack of power in the system after the fuel cell power correction, the corrected reference power is:

[0184] P fc_ref_new =k1P fc_ref (11)

[0185]

[0186] In the formula, k1 is the power correction coefficient of the fuel cell, P fc_ref_new is the corrected reference power of the fuel cell.

[0187] Three, micro-grid system simulation modeling

[0188] 1. System composition model

[0189] 1.1 Mathematical model of photovoltaic cell

[0190] The simplified photovoltaic cell model built in Simulink uses the U-I characteristic equation of photovoltaic cell, which can be expressed as:

[0191]

[0192] In the formula, I sc is the short-circuit current; U oc is the open-circuit voltage; n s and n p are the number of series and parallel connections in the photovoltaic cell, and C1, C2 can be solved by the following equation:

[0193]

[0194] In the formula, I m and V m are the current and voltage of the photovoltaic cell at the maximum power point, A and V, respectively, and U OC , U m , I sc , I m here are the values corresponding to the temperature of 25℃ and the irradiance value of 1000W / m2.

[0195] When the ambient temperature and solar irradiance change, the photovoltaic cell parameters will also change, and the changed parameters can be expressed as follows:

[0196]

[0197] In the formula, T a is the ambient temperature, ℃; S is the solar irradiance, W / m2; a, b, c are compensation coefficients.

[0198] 1.2 Super capacitor mathematical model

[0199] The super capacitor charging and discharging capacity can be expressed as:

[0200]

[0201] In the formula, n p is the number of super capacitors in parallel, n s is the number of super capacitors in series, C f is the single super capacitor value, U1 and U2 are the initial voltage and state voltage of the super capacitor, respectively.

[0202] 1.3 Fuel cell-hydrogen storage tank-electrolytic tank mathematical model

[0203] The voltage calculation equation of the proton exchange membrane fuel cell is:

[0204] V fc = E nerst -V act -V ohm -V conc (17)

[0205] In the formula, E nerst is the thermodynamic electromotive force; V act is the activation overvoltage; V ohm is the ohmic overvoltage; V conc is the concentration overvoltage.

[0206] Energy loss occurs during the transmission of reaction gas in the proton exchange membrane and the movement of ions, resulting in actual open circuit voltage lower than the theoretical value. According to the causes of voltage loss, it can be divided into activation loss, ohmic loss and concentration loss.

[0207] The total output voltage of the fuel cell stack is:

[0208] V stack = n fc V fc (18)

[0209] In the formula, n fc is the number of cells in the fuel cell stack.

[0210] The internal pressure of the hydrogen storage tank can be calculated based on the ideal gas equation:

[0211]

[0212] In the formula, P t The pressure of the hydrogen storage tank is Pa; P first V is the initial pressure of the hydrogen storage tank, in Pa; V is the volume of the hydrogen storage tank, in m3; n in The amount of hydrogen entering the hydrogen storage tank, in mol; n out The amount of hydrogen leaving the storage tank is expressed in mol; T is the room temperature in K; and R is the ideal gas constant in J / (mol·K).

[0213] The voltage of a proton exchange membrane electrolyzer can be expressed as:

[0214] U cell =U rev +U act +U ohm (20)

[0215] In the formula, U rev U is the reversible voltage of the electrolytic cell, V; act The activation polarization voltage is V; U ohm denoted as ohmic polarization voltage, V.

[0216] The total voltage of the electrolytic cell stack is:

[0217] V el =n el V cell (twenty one)

[0218] In the formula, n el This represents the number of cells in the electrolytic cell stack.

[0219] 1.4 Mathematical Model of Micro Gas Turbine

[0220] A micro gas turbine typically consists of a compressor, combustion chamber, turbine, and rotor. The combustion chamber exhaust temperature function f1 and the turbine torque output function f2 are:

[0221] f1(u1,ω)=950-700(1-u1)+550(1-ω) (22)

[0222] f2(u2,ω)=1.3(u2-0.23)+0.5(1-ω) (23)

[0223] In the formula: u1 is the exhaust port temperature; ω is the generator speed; u2 is the fuel flow rate entering the turbine.

[0224] 1.5 Synchronous Generator Model

[0225] The voltage, flux linkage and torque equations of the synchronous generator in dq coordinate system are as follows:

[0226]

[0227]

[0228] wherein ω1 is the angular speed of the motor rotation; n p is the number of pole pairs of the synchronous motor; L1 is the motor side inductance; R s is the armature resistance of the motor; ψ f is the flux linkage, and the subscripts d and q respectively represent the d-axis and q-axis of the motor.

[0229] 2. Energy management model

[0230] The established energy management system in Matlab / Simulink is shown in Figure 5 .

[0231] The model of the internal energy management system of the micro-grid system is shown in Figure 5 , and it can be seen from Figure 5 that the input value in the energy management system is P pv and P load , the difference ΔP between P pv and P load is divided into high and low frequency parts by a first-order low-pass filter to output the unit power reference values P el_ref , P fc_ref , P sc_ref and the switch signal for controlling the connection or disconnection of the gas turbine power generation system.

[0232] Section IV Specific Implementation Case and Effect

[0233] The system model is modeled in the Matlab / Simulink software, which includes photovoltaic, fuel cell, gas turbine power generation system, electrolytic cell hydrogen production system, super capacitor energy storage system, etc. The system simulation parameters are shown in Table 1.

[0234] Table 1 Simulation Parameters

[0235]

[0236]

[0237] I. Load Characteristics

[0238] As can be seen from Figure 7 , different sudden loads are set at different times in the system to make the system run to each operating condition within 12s of simulation time, so as to verify the overall operating characteristics of the system and the dynamic response characteristics of the system under the set control strategy.

[0239] II. System operation characteristics

[0240] 1. System overall operation characteristics

[0241] The set photovoltaic irradiance value curve simulates the change of solar irradiance intensity within a day under normal conditions, and the solar irradiance value and photovoltaic power output are as shown in Figure 6 .

[0242] As can be seen from Figure 6 , the photovoltaic power generation system starts to work at 1s, the solar irradiance value reaches the maximum value of 1300W / m2 at 4.25s, at this time the photovoltaic power generation power also tracks to the maximum power value of 83kW, and then the irradiance value gradually decreases, and at 7.5s it decreases to 0, and the photovoltaic power generation system exits the work.

[0243] The power curves and operating conditions of each unit during system operation are as shown in Figure 8 , 9 .

[0244] As can be seen from Figure 8 , 9 , when the system load changes or an emergency occurs, the system operating conditions automatically respond according to the settings.

[0245] 0-1.73s, the system is in operating condition 4, 0-1s, the system initially carries a load of 30kW, the photovoltaic is not started, and the fuel cell bears the entire load power, 1s, the photovoltaic power generation system starts to work, the fuel cell power gradually decreases, and at 1.73s it decreases to 0, at this time the load power is entirely supplied by the photovoltaic power generation system.

[0246] 1.73-3.6s, since the photovoltaic power output is higher than the load power and continues to increase, the system switches from operating condition 4 to operating condition 1, at this time the super capacitor does not work, the electrolytic tank starts to start, hydrogen is prepared, and at 3.6s it reaches the maximum working power of 50kW;

[0247] 3.6-4s, since the difference between the photovoltaic output power and the load power is higher than the maximum power of the electrolytic tank, the system switches from operating condition 1 to operating condition 2, the electrolytic tank continues to work at the maximum power, and the super capacitor starts to charge to absorb the excess power in the system;

[0248] 4-4.65s, since the load power suddenly increases to 70kW, the system surplus power does not exceed the maximum working power of the electrolytic tank, the system switches from operating condition 2 to operating condition 1, the electrolytic tank absorbs all the surplus power of the system, and the super capacitor only exits the work after responding to the high frequency part of the sudden increase in load power at the 4s;

[0249] 4.65-5.5s, since the hydrogen storage tank pressure has reached the maximum value of 2.1 MPa, the electrolytic cell is out of operation, the system is switched from working condition 1 to working condition 3, the super capacitor is started, and the system surplus power is consumed for a short time;

[0250] 5.5-6.8s, since the load power is higher than the photovoltaic power at this time, the system is switched from working condition 3 to working condition 4, the fuel cell power generation system is started, the system power is supplemented, the super capacitor responds to the high-frequency power of the sudden increase of the load power at the 6th second, at this time, the system photovoltaic and fuel cell work at the same time, and the super capacitor maintains a low power discharge for a short time to maintain the stability of the bus voltage;

[0251] 6.8-9s, since the system load power is large, the fuel cell works at the maximum power, and the sum of the fuel cell and photovoltaic power is less than the load power, the system is switched from working condition 4 to working condition 5, at this time, the standby emergency gas turbine generator is started, the gas turbine generator is connected to the system and works, the bus voltage is maintained by the gas turbine synchronous generator excitation, and the super capacitor control mode is changed from voltage control mode to power control mode;

[0252] 9-11.2s, since the load power is suddenly unloaded to 60kW at the 9th second, which is less than the maximum working power of the fuel cell, the system is switched back to working condition 4 from working condition 5, the gas turbine is out of operation, the fuel cell timely tracks and bears all the load power, and the working mode of the super capacitor is switched back to voltage control;

[0253] 11.2-12s, since the fuel cell needs to work continuously before this time, the system will be switched from working condition 4 to working condition 6, the gas turbine is started in advance, the super capacitor is switched to power control mode at the same time, at the 11.2s, the hydrogen storage tank pressure reaches the minimum pressure of 1.5 MPa, the fuel cell is out of operation, and the gas turbine and the super capacitor timely cooperate to make up the lack of power to maintain the stability of the system.

[0254] The tracking of the actual value and the rated value of the DC bus voltage is shown in Figure 10 .

[0255] It can be seen from Figure 10 that the system is controlled by the super capacitor voltage from 0-6.8s and 9-11.2s to maintain the stability of the bus voltage, and the bus voltage is controlled by the gas turbine synchronous generator excitation from 6.8-9s and 11.2-12s to maintain the stability of the bus voltage. The bus voltage fluctuates under the load mutation or emergency, but it can be tracked to the rated value of 540V in time through control; the system causes the bus voltage to fluctuate under various conditions, as shown in Table 2.

[0256] The coordination between each micro-source and energy storage is good during the whole system operation process, and the working condition switching is smooth. Among them, when the system switches to emergency working condition 6 at 11.2s, the fuel cell needs to exit operation immediately, the gas turbine starts to supplement the power shortage, and the super capacitor control mode needs to be switched. At this time, the maximum bus voltage fluctuation is 5.06%, which meets the requirement that the maximum fluctuation rate is less than 10%.

[0257] Table 2 Voltage fluctuation at each time

[0258]

[0259]

[0260] Since the maximum bus voltage fluctuation rate is 5.06% at 11.2s due to the fuel cell exiting operation, the fuel cell power is optimized and corrected twice, that is, when the hydrogen storage state is about to reach the critical value, the fuel cell power is gradually corrected to make the running power reach the minimum when it needs to exit operation, so as to realize smooth transition of system power. The system unit power curve and hydrogen storage tank state after correction of fuel cell power are shown in Figure 11 , 12 .

[0261] As shown in Figure 12 , the hydrogen storage tank pressure decreases to 1.55MPa at 10.65s, and the fuel cell power is corrected. By predicting the hydrogen storage tank state in advance, as shown in Figure 10 , the gas turbine starts at 10.4s in advance, and the fuel cell power gradually decreases after 10.65s through secondary optimization and correction. The gas turbine and super capacitor cooperate to provide system power shortage to maintain system stability. The system bus voltage and comparison without considering fuel cell power correction are shown in Figure 13 .

[0262] As shown in Figure 13 , when considering the fuel cell power correction, the fuel cell needs to be in a large power drop in a very short time at 11.2s without considering the power correction. And the maximum fluctuation rate of the bus voltage is reduced from 5.06% to 526.4V at 10.82s through fuel cell power correction, and the maximum fluctuation rate of the bus voltage is 2.52%, which greatly maintains the stability of the system bus voltage.

[0263] Since the working condition 4 is that the photovoltaic power is insufficient to support the load power, the hydrogen storage tank is in good condition, the system power difference does not reach the maximum operating power of the fuel cell, and the power difference is supplemented by the fuel cell power generation system, the working condition 5 is that the system demand power is too large, the gas turbine needs to be started and the fuel cell simultaneously supplies power to the system, and the dynamic response capability of the fuel cell and the gas turbine as the main power source is verified in the two working conditions respectively, so the two working conditions are analyzed separately.

[0264] 2. Dynamic response capability of the system in the working condition 4

[0265] 9-11.2s (working condition 4) The output power curves of each unit and the bus voltage value are shown in Figure 14 Fig. 9-11.2s (working condition 4) The output power curves of each unit and the bus voltage value are shown in Figure 14 Fig. 9-11.2s (working condition 4) The output power curves of each unit and the bus voltage value are shown in Figure 14 Fig. 9-11.2s (working condition 4) The output power curves of each unit and the bus voltage value are shown in Figure 14 Fig. 9-11.2s (working condition 4) The output power curves of each unit and the bus voltage value are shown in

[0266] In this working condition, only the power distribution of the fuel cell and the super capacitor is considered.

[0267] As shown in Figure 14 (a), the load power of the system is suddenly reduced from 60kW to 30kW at 9.5s, the super capacitor is charged, absorbs a peak power of 19.2kW at 9.51s, and the fuel cell power is tracked from 60kW to 30kW at 9.55s.

[0268] At 10.5s, the load is suddenly increased from 30kW to 60kW, the super capacitor is discharged, and a peak power of 19.2kW is discharged at 10.51s, and the fuel cell power is tracked from 30kW to 60kW at 10.56s.

[0269] As shown in Figure 14 (b), when the load power is suddenly increased from 30kW to 50kW, the response speed of the super capacitor and the fuel cell is accelerated.

[0270] As shown in Figure 14 (c), under the impact of the sudden unloading of 30kW load, the bus voltage is reduced to 556.2V at 9.519s, and the stable interval is recovered to 3%, and the stable time is 0.019s. Under the impact of the sudden increase of 30kW load, the bus voltage is increased to 523.8V at 10.519s, and the stable interval is recovered to 3%, and the stable time is 0.019s.

[0271] The system under the impact of 50kW load, the bus voltage fluctuation amplitude is 570.2V, the maximum fluctuation rate is 5.59%, and it returns to the stable interval of 3% at 9.51s, and the stable time is 0.01s. Under the impact of 50kW load, the bus voltage fluctuation amplitude is 521.8V, the maximum fluctuation rate is 3.37%, and it returns to the stable interval of 3% at 10.507s, and the stable time is 0.007s.

[0272] Therefore, it can be known that the designed micro-grid system control strategy can effectively maintain the dynamic response ability of the system under severe load conditions and emergency working conditions, and the system bus voltage returns to the stable time extremely fast.

[0273] 3. Dynamic response ability of the system under working condition 5

[0274] The output power curve of each unit and the bus voltage value of the system at 6.8-9s (working condition 5) are shown in Figure 15 The output power curve of each unit under the impact of 40kW load is shown in Figure 15 (a), the output power curve of each unit under the impact of 60kW load is shown in Figure 15 (b), and the corresponding bus voltage value is shown in Figure 15 (c).

[0275] As shown in Figure 15 (a), the GT power generation system has a power of 30kW at 7.5s, at this time, the load power suddenly increases by 40kW to 140kW, the super capacitor is transiently discharged within 0.001s, and releases a peak power of 37.5kW, then the gas turbine responds and starts to increase the output power, and after about 0.5s, the output power is stabilized at 70kW, and the output power of the super capacitor is reduced to 0 after about 0.5s of responding to the high-frequency peak power.

[0276] At 8.5s, the load power suddenly decreases from 140kW to 100kW, and the super capacitor is also transiently charged within 0.001s, and absorbs a peak power of 39.9kW, then the gas turbine responds and reduces the output power, and after 0.5s, the output power is stabilized at 30kW, and the output power of the super capacitor is reduced to 0 after about 0.5s of responding to the high-frequency peak power.

[0277] As shown in Figure 15 (b), when the load power increases from 40kW to 60kW, the super capacitor and the gas turbine respond in the same way.

[0278] As shown in Figure 15 (c), under the impact of 40kW load, the maximum fluctuation rate of the bus voltage is 2.78%, and it is in the stable interval of 3%, so it can be considered that the system always maintains stability under this impact.

[0279] The system is under the impact of 60kW load, the bus voltage fluctuation amplitude is 519.1V, the maximum fluctuation rate is 3.87%, and it returns to the stable interval of 3% at 7.61s, and the stable time is 0.11s. Under the impact of 60kW load, the bus voltage fluctuation amplitude is 562.5V, the maximum fluctuation rate is 4.17%, and it returns to the stable interval of 3% at 8.63s, and the stable time is 0.13s.

[0280] 4. Conclusion

[0281] The application is different from the traditional new energy micro-grid system, considering the intermittent, fluctuating and random characteristics of the new energy power generation system, which leads to unstable power generation and is difficult to meet the continuous and stable power supply demand of the power grid, photovoltaic, fuel cell and gas turbine power generation system are selected as the system power supply, the mutual conversion of clean energy is considered, that is, the photovoltaic power generation system is controlled by the maximum power point tracking, and the surplus energy is stored by electrolytic tank to produce hydrogen; when the output power of photovoltaic is insufficient, the fuel cell generates electricity by consuming hydrogen; in emergency, the gas turbine is selected as the main power supply, the whole system always realizes the purpose of system coordinated control through the control mode conversion and cooperation of various energy equipment and super capacitor, and also guarantees the green and low-carbon operation effect of the micro-grid.

[0282] And by considering the typical load mode, the storage state of the hydrogen storage tank and the maximum working power of the fuel cell and the electrolytic tank, the coordinated control strategy of the system is designed for six kinds of operating conditions of the system, and the power of the system is distributed by the energy management system, then the power of the fuel cell is corrected twice, and the Figure 10 、 13 It is proved that the control strategy has a great degree of improvement on the influence of bus voltage fluctuation when the load suddenly changes and the working condition switches, and effectively improves the stability of the system operation.

[0283] From the working condition 5, Figure 15 It can be seen that in the emergency working condition, the gas turbine and the super capacitor cooperate, and the response ability to the sudden load of large power is strong, the system can always maintain stability under the sudden load of 40% of the rated power of the gas turbine, the maximum bus voltage fluctuation rate is 2.78%, even under the sudden load of 60% of the rated power of the gas turbine, the bus voltage fluctuation of the system is also low, the maximum fluctuation rate is 4.17%, and the recovery stable time is within 0.2s, which proves that the system has continuous and stable power supply capacity under the emergency working condition.

[0284] It should be noted that the embodiments of the present application can be realized by hardware, software, or a combination of software and hardware. The hardware part can be realized by special logic; the software part can be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or a specially designed hardware. Those skilled in the art can understand that the above-mentioned devices and methods can be realized by computer executable instructions and / or included in processor control codes, such as carrier media, such as magnetic disk, CD or DVD-ROM, programmable memory, such as read-only memory (firmware), or data carrier, such as optical or electronic signal carrier. The device of the present application and its modules can be realized by hardware circuit, such as ultra-large scale integrated circuit or gate array, semiconductor, such as logic chip, transistor, etc., or programmable hardware device, such as field programmable gate array, programmable logic device, etc., can also be realized by software executed by various types of processors, and can also be realized by the combination of the above-mentioned hardware circuit and software, such as firmware.

[0285] The present application provides a direct current microgrid coordinated control method comprising a gas turbine generator set and hydrogen energy storage, which realizes efficient and stable operation of the microgrid through the coordinated work of multiple control units. The following is the detailed working principle:

[0286] Step 1: System working condition judgment

[0287] By detecting the grid load demand, photovoltaic power, electrolytic cell and fuel cell power, and hydrogen storage state signal, the system working condition is automatically judged.

[0288] Step 2: Energy management system for power distribution

[0289] The energy management system reasonably distributes the power of each component in the system under different working conditions to ensure the stable operation of the system under power mutation and emergency conditions and the smooth switching between working conditions, realize the coordinated control operation of the whole system, and maintain the voltage fluctuation of the bus within a reasonable range.

[0290] Step 3: PV control unit adopts maximum power point tracking control (MPPT)

[0291] The photovoltaic (PV) control unit realizes the maximum power output of the photovoltaic power generation system through MPPT technology. The MPPT controller monitors the voltage and current of the photovoltaic module, continuously adjusts the working point, so that the photovoltaic module can output maximum power under different light conditions. MPPT control algorithm includes incremental conductance method, perturbation and observation method, etc., which can quickly respond to light changes and improve the energy utilization efficiency of the photovoltaic system.

[0292] Step 4: FC control unit adopts single PI control of current loop

[0293] Fuel cell (FC) control unit realizes stable control of fuel cell output current through single proportional integral (PI) control of current loop. The PI controller adjusts the output current of the fuel cell to match the set value, ensuring the stable operation of the fuel cell system. PI control of the current loop has fast response and good steady-state performance, which can effectively suppress current fluctuations caused by load changes.

[0294] Step 5: EL control unit selects single PI control of current loop

[0295] Electrolyzer (EL) control unit also uses single PI control of current loop to control hydrogen production by adjusting the input current of the electrolyzer. The PI controller adjusts the actual current of the electrolyzer through feedback to match the set value, ensuring the stable operation of the electrolyzer system. PI control of the current loop can effectively deal with load changes and maintain the efficient working state of the electrolyzer.

[0296] Step 6: SC control unit uses switch selection module to switch between two control modes

[0297] Energy storage control (SC) unit switches between two control modes through switch selection module, according to the start and non-start of gas turbine, switches the corresponding control mode:

[0298] Switch signal is 1 (gas turbine starts): energy storage system enters charging mode, adjusts the charging current of energy storage unit to store excess power.

[0299] Switch signal is 0 (gas turbine does not start): energy storage system enters discharge mode, adjusts the discharge current of energy storage unit to supplement the power demand of microgrid.

[0300] Step 7: Excitation control unit uses generator excitation control to adjust bus voltage

[0301] Excitation control unit adjusts the excitation current of the generator through the excitation system of the generator, thereby adjusting the bus voltage. The excitation controller monitors the bus voltage and adjusts the excitation current in real time to keep the bus voltage within the set range. Excitation control can quickly respond to voltage changes and ensure the voltage stability of the microgrid.

[0302] Workflow:

[0303] 1. Working condition judgment: By detecting the load demand of the power grid, photovoltaic power, electrolyzer and fuel cell power, and hydrogen storage state signal, the system automatically judges the working condition of the system.

[0304] 2. Energy management system power distribution: Energy management system distributes power to each component of the system under different working conditions.

[0305] 3. Photovoltaic power generation (PV control unit): Under light conditions, the PV control unit uses MPPT technology to maximize the output of the photovoltaic system and stably supply power to the microgrid.

[0306] 4. Fuel cell power generation (FC control unit): According to the load demand of the microgrid, the FC control unit adjusts the output current of the fuel cell through single PI control of the current loop to maintain stable operation of the system.

[0307] 5. Electrolyzer operation (EL control unit): In the case of power surplus, the EL control unit adjusts the input current of the electrolyzer through single PI control of the current loop to produce and store hydrogen.

[0308] 6. Energy storage system control (SC control unit): According to the starting state of the gas turbine, the SC control unit switches control modes through the switch selection module to manage the charging and discharging process of the energy storage system and ensure power balance.

[0309] 7. Bus voltage regulation (excitation control unit): Through the generator excitation system, the excitation control unit adjusts the excitation current of the generator in real time to maintain stable bus voltage.

[0310] Through the coordinated work of the above control units, the DC microgrid of the present application can realize efficient and stable power management, fully utilize photovoltaic power generation, fuel cells and hydrogen energy storage systems, improve energy utilization efficiency and ensure the reliability of power supply.

[0311] III. Evidence of the effects of the embodiments. The embodiments of the present application have achieved some positive effects during research and development or use, and indeed have great advantages compared with the prior art. The following content is described in combination with test data, charts, etc.

[0312] The positive effects achieved during the research and development or use of the embodiments of the present application, and the advantages compared with the prior art are as follows:

[0313] 1. Positive effects:

[0314] From the data in Table 2, it can be seen that when the system is running, the fluctuation amplitude of the bus voltage is generally small under various working condition switching and sudden load impact, and the voltage fluctuation rate is mostly kept below 3%, and after the secondary correction of the fuel cell power, the highest one does not exceed 5%, which is far less than the requirement of 10% for stable operation, which shows that the coordinated control strategy designed in the application has strong stability when applied to the micro-grid system of islands and remote areas, and proves that the system can effectively respond to greater load fluctuations and achieve stable power supply. And the bus voltage can quickly recover to a stable state, which proves the fast response and regulation capacity of the system. Whether facing photovoltaic start-up, load mutation or hydrogen tank pressure change reaching the critical value, the system can effectively cope with it through the coordinated control strategy, which reflects the strong adaptability of the system.

[0315] 2. Advantages compared with prior art:

[0316] Compared with the traditional micro-grid control method, the application designs a more refined coordinated control strategy by comprehensively considering factors such as the storage state of the hydrogen tank, the maximum working power of the fuel cell and the electrolytic tank, etc. to cope with the situation of hydrogen excess or hydrogen deficiency, which can more effectively realize the reasonable distribution of power and the stable control of bus voltage. At the same time, through the effective scheduling of the energy management system and the secondary correction of the fuel cell power, the system can ensure stable operation while improving energy utilization efficiency and reducing operating cost.

[0317] At the same time, the application is different from the traditional diesel generator mode used in islands and remote areas, realizes the coordinated cooperation between the gas turbine generator set, the hydrogen fuel cell and the photovoltaic three clean power sources with large differences in response characteristics and power supply capacity, and considers the joint energy storage mode of the electrolytic tank and the super capacitor, which is less researched at present. It meets the demand of green energy supply, has lower carbon emission and better environmental protection benefit, realizes the coordinated control operation of the multi-source hybrid energy storage complex system, and has great technical advantages and market potential in the field of direct current micro-grid control technology.

[0318] The above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto, and any modification, equivalent replacement and improvement made by any person skilled in the art within the technical range disclosed by the application, as long as it is within the spirit and principles of the application, should be covered within the protection scope of the application.

Claims

1. A method for coordinated control of a direct-current microgrid comprising a gas turbine generator set and hydrogen energy storage, specifically comprising: Considering the hydrogen storage state of the microgrid system, the maximum output power of the electrolyzer and the fuel cell, there are six typical operating conditions in the system; they are respectively: Condition 1: photovoltaic (PV) normal operation, electrolyzer (EL) absorbs all surplus power, super capacitor (SC) responds to high-frequency power in time, fuel cell (FC) and gas turbine (GT) do not operate; Condition 2: PV normal operation, EL maximum power operation, SC absorbs excess power, FC and GT do not operate; Condition 3: PV normal operation, EL is shut down, SC absorbs surplus power, FC and GT do not operate; Condition 4: PV normal operation, FC starts, SC responds to high-frequency power in time, EL and GT do not operate; Condition 5: PV normal operation or power is too low to be about to exit operation, FC operates at maximum power, GT starts, SC responds to high-frequency power in time, EL exits operation; Condition 6: PV power is too low to be about to exit operation or has exited operation, FC stops operating, GT starts, SC responds to high-frequency power in time, EL exits operation; The method comprises the following steps: Step 1: the system automatically determines the operating condition of the system according to the microgrid load demand, PV power, EL and FC power and hydrogen storage state; Step 2: the energy management unit distributes power to PV, FC, SC and GT in the system according to the system load condition and operating condition; Step 3: the PV control unit adopts maximum power point tracking control (MPPT); Step 4: the FC control unit adopts single PI control of current loop; Step 5: the control unit selects single PI control of current loop; Step 6: the SC control unit switches two control modes through a switch selection module, and the switch signals 1 and 0 correspond to the starting and non-starting conditions of the gas turbine; Step 7: the excitation control unit adjusts the bus voltage through generator excitation control; The method of the PV control unit: Maximum power point tracking (MPPT) of the photovoltaic system was achieved using the incremental conductance method, which controls the voltage of the photovoltaic power generation system. With current The input is sent to the MPPT control unit, and the adjusted duty cycle is finally obtained. The signal is then transmitted to the boost circuit of the photovoltaic power generation system. The method of the FC control unit: Fuel cell power reference value given by energy management system Divide by fuel cell terminal voltage Get fuel cell current reference value Subtract fuel cell actual current value Pass through PI controller to get duty ratio Signal is then transmitted to fuel cell power generation system boost circuit The method of the EL control unit: The power reference value of electrolytic cell given by energy management system Divide by the end voltage of electrolytic cell Subtract the actual current value of electrolytic cell Pass through PI controller to get duty ratio Then the signal is transmitted to the electrolytic cell system buck circuit.​ 2. The method of claim 1, wherein the method is characterized by, The method of the SC control unit: Switch two control modes through a switch selection module, and the switch signals 1 and 0 correspond to the starting and non-starting conditions of the gas turbine; In non-emergency working condition, i.e. before the gas turbine is started, a double PI control with current inner loop and voltage outer loop is adopted, the bus voltage reference value is subtracted from the bus voltage actual value , the super capacitor current reference value is obtained through the outer loop PI controller , and the super capacitor terminal actual current value is subtracted therefrom, the duty cycle is obtained through the inner loop PI controller , and the signal is then transmitted to the super capacitor boost and buck circuit. In emergency operating condition, i.e. when the gas turbine is started and connected to the power grid, the supercapacitor control mode is changed to a single PI power control of the current loop, with the supercapacitor power reference value given by the energy management system The supercapacitor current reference value is obtained by dividing the supercapacitor terminal voltage by the supercapacitor terminal voltage The difference between the supercapacitor current reference value and the actual supercapacitor current value is passed through a PI controller to obtain the duty cycle which is then passed to the supercapacitor boost-buck circuit.

3. The method of claim 1, wherein the method is characterized by, The method of the excitation control unit: Adjust the bus voltage through generator excitation control; The steps are, bus voltage reference value is subtracted from bus voltage actual value , and after the difference is unitized, the excitation current reference value is obtained through PI control , actual excitation current value is subtracted, and the duty cycle signal is obtained through the inner loop PI controller, the duty cycle signal passes through the excitation amplifier and then the excitation machine outputs the excitation current , and the excitation current signal is transmitted to the synchronous generator.

4. A direct current microgrid coordinated control system comprising a gas turbine generator set and hydrogen energy storage for implementing the method of claim 1-3, characterized in that, The coordinated control system of the direct-current microgrid comprising a gas turbine generator set and hydrogen energy storage comprises: The system automatically determines the operating condition of the system according to the microgrid load demand, PV power, EL and FC power and hydrogen storage state; The energy management unit distributes power to PV, FC, SC and GT in the system according to the system load condition and operating condition; The PV control unit is used to adopt maximum power point tracking control (MPPT); The FC control unit is used to adopt single PI control of current loop; An EL control unit is configured to select a single PI control of a current loop; An SC control unit is configured to switch between two control modes through a switch selection module, and switch signals 1 and 0 correspond to the starting and non-starting conditions of the gas turbine; An excitation control unit is configured to adjust the bus voltage through generator excitation control.

5. A computer device, comprising: The computer device comprises a memory and a processor, the memory stores a computer program, and the computer program is executed by the processor to enable the processor to execute the steps of the method for coordinating control of a direct-current microgrid comprising a gas turbine generator set and hydrogen energy storage according to any one of claims 1-3. 6.A computer readable storage medium storing a computer program, the computer program being executed by a processor to enable the processor to execute the steps of the method for coordinating control of a direct-current microgrid comprising a gas turbine generator set and hydrogen energy storage according to any one of claims 1-3.

7. An information data processing terminal, characterized by The information data processing terminal is configured to implement the system for coordinating control of a direct-current microgrid comprising a gas turbine generator set and hydrogen energy storage according to claim 4.

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