Integrated dynamic simulation method, system and equipment for comprehensive energy system and medium

Abstract

The invention provides an integrated energy system integrated dynamic simulation method, system and device and a medium, and relates to the technical field of energy utilization, and the method comprises the steps: configuring a transfer matrix and a state equation based on an energy network dynamic two-port model, and representing a dynamic transmission process corresponding to a gas network pipeline parameter characteristic and a heat network pipeline parameter characteristic; constructing an equipment dynamic simulation model; a comprehensive energy system model with a dynamic transmission process and an equipment dynamic simulation model is built based on a nonlinear finite difference method, dynamic simulation is conducted on the built comprehensive energy system model, transient behaviors of gas net turbulence and heat pump working medium phase change are captured through a nonlinear partial differential equation, dynamic simulation is achieved, and a simulation result is stored. According to the invention, the transient process can be captured, and dynamic interactive simulation of gas-heat-power grid is supported; the dynamic coupling equipment is abundant, the expansibility and the adaptability are excellent, a novel equipment model or an external control strategy can be accessed, and the method is suitable for various application scenes.

Description

Technical Field

[0001] The present application relates to the technical field of energy utilization, and particularly relates to an integrated dynamic simulation method, system, device and medium for an integrated energy system. Background Art

[0002] As an efficient energy utilization system, the Integrated Energy System (IES) realizes the comprehensive utilization of energy by organically combining different energy forms, effectively improves the energy system efficiency and reduces energy consumption, and has become an important way for energy transformation and upgrading. In the process of planning, designing and constructing IES, the modeling and simulation technology plays a crucial role. IES modeling is mainly divided into two parts: steady-state modeling and dynamic modeling. Among them, steady-state modeling has been relatively mature, while dynamic modeling still faces many technical problems. First of all, IES involves multiple disciplines and fields, and its dynamic modeling needs to solve the key problems of multi-scale modeling and collaborative optimization. At the same time, complex energy supply and demand scenarios put forward higher requirements for the generality and self-adaptability of modeling and data processing.

[0003] IES can integrate various energies such as coal, oil, natural gas, electric energy, and heat energy in the region, and carry out collaborative management and interactive response. IES not only greatly reduces the consumption of fossil energy, reduces the system carbon emissions, but also can optimize the energy structure, improve the overall energy utilization efficiency, effectively enhance the elasticity of the energy system, and provide important support for renewable energy output tracking and fluctuation suppression. Compared with traditional energy systems, its advantages are very obvious. Its modeling can help decision-makers formulate sustainable energy policies, realize coordinated planning and optimal operation among multiple heterogeneous energy subsystems, and at the same time optimize the operation and efficiency of the system, thereby reducing environmental pollution and carbon emissions.

[0004] The development of IES is inseparable from the support of the integrated energy simulation and planning platform. Finding and selecting a suitable platform is of great guiding significance for the design, investment, planning, and development of integrated energy projects. Currently, a comparative analysis is conducted on three typical and commonly used simulation platforms: COMPOSE (compare options for sustainable energy), developed by Aalborg University in Denmark in 2008, supports the research of electricity, heat, and cooling systems; HOMER (hybrid optimization model for electric renewables) is a software developed by the National Renewable Energy Laboratory of the United States, which can perform system optimization and sensitivity analysis. Its simulation time resolution is in minutes, and the simulation time range can reach multiple years; RETScreen Expert, released in September 2016, is a free clean energy management software developed by the Canadian government. This software can achieve a comprehensive identification, evaluation, and optimization of the technical and financial feasibility of potential renewable energy and energy efficiency projects, and can also measure and test the actual performance of equipment and facilities, and formulate energy-saving solutions. The disadvantages of existing solutions are as follows: COMPOSE only particularly focuses on the combined heat and power generation of electric boilers and compression heat pumps for the heat system; the complexity of HOMER's calculation determines that this platform is only applicable to the planning of microgrid scale; RETScreen Expert does not provide the function of optimizing design parameters.

[0005] To sum up, it can be understood that although most of the existing software platforms have their own advantages, they cannot well achieve the joint simulation between the various energy subsystems of the integrated energy system, and there are also some deficiencies. First, the multi-energy flow coupling equipment involves the dynamic interaction of multiple physical fields such as electricity, heat, and chemistry, and its model needs to integrate dynamic processes at different time scales (such as second-level electrical response and hour-level heat diffusion), resulting in a high-dimensional equation and it is difficult to obtain the results required by the demand side; second, the accurate identification of equipment dynamic parameters and the lack of adaptability to multiple working conditions limit the practicality of the model; in addition, traditional energy flow simulation tools (such as energy lumped models) are difficult to be compatible with high-dynamic nonlinear equations. Summary of the Invention

[0006] The present invention provides an integrated dynamic simulation method for an integrated energy system. The method integrates two types of high-precision models and highly emphasizes user-friendliness and engineering practicality. Through a modular architecture and a dynamic model, it realizes the full-dynamic electricity-gas-heat coupling simulation of the network-equipment system, and supports the selection of solution algorithms and parameter configuration to meet the usage requirements.

[0007] The method includes: Based on the dynamic two-port model of the energy network, configure the transfer matrix and state equation to characterize the dynamic transmission process corresponding to the gas network pipeline parameters and the heat network pipeline parameters; Construct a dynamic simulation model of the device, and couple the electrical-gas conversion time delay of P2G, the thermodynamic transient of the phase change of the heat pump working medium, and the dynamic decoupling characteristics of the CHP thermoelectric power. Based on the non-linear finite difference method, build a comprehensive energy system model with a dynamic transmission process and a dynamic simulation model of the device, perform dynamic simulation on the built comprehensive energy system model, capture the transient behavior of gas network turbulence and the phase change of the heat pump working medium with non-linear partial differential equations, achieve dynamic simulation, and save the simulation results.

[0008] It should be further noted that the dynamic transmission process of the gas network pipeline is

[0009]

[0010] Among them, is the natural gas density, is the natural gas transmission speed, is the pressure, is the diameter, is the friction coefficient, is the acceleration due to gravity, is the pipeline inclination angle; the subscript in the parameters is the inlet parameter of pipeline the subscript is the outlet parameter of pipeline the superscript represents the parameter of the previous moment, and the superscript represents the parameter of the current moment.

[0011] It should be further noted that in the method, according to the dynamic two-port model of the energy network, the known input parameters are the input and output air pressures and flows of the previous moment, and the output parameters to be obtained are the input and output air pressures and flows of the current moment. From the parameter characteristics of the gas network pipeline, the intermediate conversion relationship is extracted, and the modeling is completed in the Simulink environment to obtain the two-port dynamic model of the gas network.

[0012] It should be further noted that the heat medium transmission characteristics in the heat network pipeline are expressed as:

[0013]

[0014]

[0015] Among them, the variables are all defined inside the heat network pipeline, is the density of water, is the pressure, is the flow rate, is the mass flow rate base value corresponding to the flow velocity base value, is the cross-sectional area, is the acceleration due to gravity, is the pipeline inclination angle, is the specific heat of water, is the diameter, is the friction coefficient, is the heat dissipation coefficient, is the pipeline temperature, is the flow time of water in the heat network pipeline, is the flow distance of water in the pipeline; Define the flow direction as the positive direction, and the discrete node number is , the time step is , the space step is , in the pipeline and the time layer at, the equation is discretely sorted out as:

[0016]

[0017]

[0018] Among them, the subscript is the inlet parameter of the pipeline , the subscript is the outlet parameter of the pipeline , the superscript represents the parameter at the previous moment, and the superscript represents the parameter at the current moment.

[0019] Furthermore, it should be noted that in the electro-gas conversion time delay of the step-coupled P2G, the transfer function of the P2G dynamic model is defined as:

[0020] Among them, 、 are the flow rates of the gas flowing into and out of the volume module respectively, is the reaction ratio of the inflowing gas, is the reactor volume, is the outlet flow rate under the rated condition, is the reactor pressure under the rated condition, s is the Laplace transform variable, p is the pressure, is the representation of the output quantity in the Laplace domain, is the representation of the input quantity in the Laplace domain.

[0021] Further, it should be noted that in the thermodynamic transient of the phase change of the heat pump working medium in the step of constructing the dynamic simulation model of the device, the supply and return water temperatures are defined to satisfy the following equation:

[0022]

[0023] Wherein, represents the pipeline flow rate during the heating process, and represent the supply water temperature and the return water temperature respectively, and represent the specific heat capacity and density of the hot water in the water tank respectively, represents the volume of the hot water storage tank, represents the heat dissipation of the storage water tank, is the loss floor surface temperature, represents the heat generated by the work of the heat pump. For the heat pump system, the heat generated by its work is related to its compressor power and the coefficient of performance of the heat pump and is expressed in the following form: .

[0024] Further, it should be noted that in the dynamic decoupling characteristics of the CHP thermoelectric power in the step of constructing the dynamic simulation model of the device, the CHP is divided into four links: compressor, combustion chamber, turbine, and heat exchanger for modeling. The main formulas for each part are as follows:

[0025] The variable definition range in the formula is within the compressor module, is the required power; is the inlet pressure; is the outlet pressure; is the efficiency; the polytropic index can be expressed as ; is the outlet flow rate; is the equivalent volume of the module; is the average gas constant of the gas; is the outlet temperature;

[0026] The variable definition range in the formula is within the combustion chamber module, is the combustion chamber time constant; is the outlet temperature; is the combustion efficiency; is the inlet air enthalpy value; is the inlet natural gas enthalpy value; is the outlet gas enthalpy value; is the inlet natural gas mass flow rate; is the outlet gas mass flow rate; is the specific heat capacity at constant pressure of the outlet gas; is the net specific energy of natural gas; is the gas mass in the combustion chamber; is the air mass flow rate at the inlet of the combustion chamber; The way of connecting the output end to the turbine input is:

[0027]

[0028] In the formula: is the turbine outlet temperature; is the turbine inlet temperature; is the turbine pressure ratio; is the turbine efficiency; is the power consumed by the turbine; is the reduced flow rate of the turbine; , is the adiabatic index of the gas, is the specific heat capacity at constant pressure of the gas at the outlet of the combustion chamber.

[0029] This application also provides an integrated dynamic simulation system for an integrated energy system. The system includes: A parameter characteristic configuration module, which is used to configure the transfer matrix and state equation using the dynamic two-port model of the energy network to characterize the dynamic transmission process corresponding to the gas network pipeline parameters and the heat network pipeline parameters; A model construction module, which is used to construct a device dynamic simulation model and couple the electrical-gas conversion time delay of P2G, the thermodynamic transient of the phase change of the heat pump working medium, and the dynamic decoupling characteristics of the CHP thermoelectric power; A simulation processing module, which is used to build an integrated energy system model with a dynamic transmission process and a device dynamic simulation model by combining the nonlinear finite difference method, perform dynamic simulation on the built integrated energy system model, capture the transient behavior of gas network turbulence and the phase change of the heat pump working medium with nonlinear partial differential equations, realize dynamic simulation, and save the simulation results.

[0030] According to another embodiment of this application, an electronic device is provided, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the integrated dynamic simulation system for the integrated energy system are implemented.

[0031] According to still another embodiment of this application, a storage medium is further provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the integrated dynamic simulation system for the integrated energy system are implemented.

[0032] As can be seen from the above technical solutions, the present invention has the following advantages: The integrated dynamic simulation method for the integrated energy system provided by this application is based on the dynamic two-port model of the energy network. The characteristic line method is used to construct the time-domain two-port model of the gas network, which reflects the input-output relationship of the gas network. It describes the dynamic transmission characteristics of the gas network pipelines to more accurately characterize the dynamic behavior of the gas network. Compared with the related technologies, it is difficult to accurately characterize the dynamic characteristics of the gas network and the heat network at the same time. By using the dynamic two-port model of the energy network and combining the transfer matrix and the state equation, it can more comprehensively and accurately reflect the dynamic transmission process of the gas network and the heat network.

[0033] When constructing the device dynamic simulation model in this application, for P2G devices, the time delays caused by factors such as chemical reaction kinetics and catalyst activity during the electro-gas conversion process are considered; for heat pumps, the phase change process of the modeling working medium; for CHP, a dynamic decoupling model of thermoelectric power is established, considering the generation, distribution, and mutual influence of heat and electricity during the combined heat and power generation process to achieve dynamic decoupling control of thermoelectric power. It can consider multiple complex factors at the same time to achieve accurate modeling of the dynamic characteristics of the device. When building the integrated energy system model based on the non-linear finite difference method, the gas network, the heat network, and the device dynamic simulation model are integrated. Through discretization, the continuous partial differential equations are transformed into algebraic equation systems to capture transient behaviors such as gas network turbulence and heat pump working medium phase change. During the simulation process, a suitable numerical solution algorithm is used to solve the non-linear equation system, and according to the set simulation step size and convergence accuracy, the simulation time is gradually advanced to obtain the dynamic response of the system, and the simulation results are saved in the form of data files or graphically. It can effectively handle the complex dynamic behaviors in the integrated energy system and achieve high-precision dynamic simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the present invention, the drawings required to be used in the description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1 It is a flowchart of the integrated dynamic simulation method for the integrated energy system; Figure 2 It is a schematic diagram of the one-key parameter modification interface; Figure 3 It is a schematic diagram of an electronic device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The integrated dynamic simulation method for integrated energy systems involved in this application mainly solves the problems in related technologies. For multi-energy flow coupling devices, there are dynamic interactions in multiple physical fields such as electricity, heat, and chemistry. Their models need to integrate dynamic processes on different time scales, resulting in high equation dimensions and complex solutions. It also solves the problems that the accurate identification of equipment dynamic parameters and the lack of adaptability to multiple working conditions limit the practicality of the model and make it difficult to be compatible with high-dynamic nonlinear equations.

[0037] The integrated dynamic simulation method for integrated energy systems of this application, together with the integrated dynamic simulation software for integrated energy, integrates high-precision models and emphasizes user-friendliness and engineering practicality. Through a modular architecture and dynamic models, it realizes full-dynamic coupling simulation of electricity-gas-heat. Based on the two-port model of the energy network, it accurately characterizes the characteristics of the gas network and the heat network. The coupling device model is constructed on the Simulink platform, covering a variety of dynamic characteristics. The software is easy to operate. Users can drag and drop modules to build models and perform simulations, which provides convenience for the subsequent development of new functions.

[0038] This application proposes a dynamic two-port network model for gas network and heat network pipelines, aiming to systematically characterize the dynamic response process of energy transmission in pipelines through transfer matrices and state variable equations. Compared with traditional lumped parameter models, this model dynamically correlates the physical quantities (such as gas pressure, flow rate, temperature, heat flux) at the inlet and outlet of the pipeline through a two-port network structure, and embeds the characteristics of energy conservation and transmission delay, so as to more accurately describe the non-linear dynamic behaviors such as the transmission characteristics of the gas network and the thermal inertia of the heat network. In addition, from the user's perspective, this application converts complex dynamic mechanism equations into two-port modeling. Users do not need to pay attention to the internal complex logical structure, and only need to change external parameters such as inputs according to their needs. To improve the selectivity and convenience of users in using the integrated dynamic simulation software developed later in this embodiment, this application provides three methods in the process of modeling and simulation: linear finite difference method, non-linear finite difference method, and holomorphic embedding method.

[0039] The following will describe in detail the specific steps of the integrated dynamic simulation method for integrated energy systems. For the purpose of illustration rather than limitation, specific details such as specific system structures and technologies are proposed to thoroughly understand the embodiments of this application. However, those skilled in the art should clearly understand that this application can also be implemented in other embodiments without these specific details.

[0040] It should be understood that when used in the specification of this application, the term "comprising" indicates the existence of the described features, wholes, steps, operations, elements, and / or components, but does not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0041] It should be understood that "one or more" as mentioned in this application refers to one, two or more than two, and "a plurality of" as mentioned in this application refers to two or more than two. In the description of this application, unless otherwise specified, " / " means "or". For example, A / B can mean A or B. "And / or" herein is merely a correlative relationship describing associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone.

[0042] Statements such as "an embodiment" or "some embodiments" described in this application mean that the specific features, structures or characteristics described in this embodiment are included in one or more embodiments of this application. Thus, statements such as "in an embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments" etc. that appear in different places in this application do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways.

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0044] Please refer to Figure 1 The figure shows a flowchart of an integrated dynamic simulation method for an integrated energy system in a specific embodiment. The method includes: S101: Based on the dynamic two-port model of the energy network, configure the transfer matrix and state equation to characterize the dynamic transmission process corresponding to the gas network pipeline parameters and the heat network pipeline parameters.

[0045] In some embodiments, a dynamic two-port network model is constructed, and the dynamic transmission characteristics of the gas network and the heat network are characterized by the transfer matrix and the state equation. Specifically, the transfer matrix of the gas network pipeline needs to include dynamic parameters such as the pressure wave propagation speed and the pipeline friction resistance coefficient, and the state equation is based on the mass conservation and momentum conservation equations, introducing a time delay term to simulate the compression and expansion process of the gas in the pipeline; the transfer matrix of the heat network pipeline needs to consider the thermal conductivity, specific heat capacity and fluid flow characteristics, and the state equation couples the heat conduction equation and the convective heat transfer equation, and describes the dynamic coupling relationship between the temperature field and the flow velocity field through a partial differential equation system.

[0046] Compared with the steady-state or quasi-steady-state models commonly used in the prior art, this method captures the transient characteristics of energy flow transmission, such as pressure fluctuations and temperature diffusion, through a dynamic two-port model, thereby improving the simulation accuracy. By extending the dynamic modeling method of power systems (such as transfer functions) to multi-energy coupling systems and achieving unified solution of cross-scale dynamic processes through the nonlinear finite difference method, the limitations of traditional software that only focuses on a single energy subsystem are overcome.

[0047] Optionally, for gas network pipelines, the state equation takes into account the effects of factors such as gas compressibility and friction on gas flow; for heat network pipelines, the effects of factors such as heat conduction and heat convection on heat transfer are considered.

[0048] S102: Construct a device dynamic simulation model and couple the electrical-gas conversion time delay of P2G, the thermodynamic transient of the phase change of the heat pump working medium, and the dynamic decoupling characteristics of the CHP thermoelectric power.

[0049] In some embodiments, a device dynamic simulation model is constructed and the multi-physical field interaction characteristics are coupled. Specifically, for P2G devices, a time delay model of electrical-gas conversion is established, and the chemical reaction lag effect of electrolytic water hydrogen production is simulated through delay differential equations; for heat pumps, a thermodynamic transient model of the phase change of the working medium is introduced, and the transient heat transfer processes of the evaporator and condenser are described by combining the latent heat exchange equation and the dynamic changes of the physical properties of the working medium; for CHP, a dynamic decoupling model of thermoelectric power is constructed, and the real-time power distribution control of cogeneration is achieved by separating the dynamic responses of the mechanical power of the gas turbine and the thermal power of the waste heat boiler. RETScreen Expert in the existing methods ignores the dynamic characteristics of devices or only provides simplified static parameters, while this method solves the problems of difficult identification of device dynamic parameters and poor adaptability to multiple working conditions through the coupling of multi-time scale dynamic equations, integrates high-precision thermodynamic models and power electronic dynamic models, and achieves seamless integration of cross-energy subsystems through modular interfaces.

[0050] S103: Based on the nonlinear finite difference method, build a comprehensive energy system model with a dynamic transmission process and a device dynamic simulation model, perform dynamic simulation on the built comprehensive energy system model, capture the transient behaviors of gas network turbulence and the phase change of the heat pump working medium with nonlinear partial differential equations, achieve dynamic simulation, and save the simulation results.

[0051] In some embodiments, based on the non - linear finite - difference method, the previously constructed dynamic transmission models of the gas network and the heat network, as well as the dynamic simulation models of the equipment, are integrated to build a comprehensive energy system model. The non - linear finite - difference method discretizes the space and time of the system. For the highly non - linear fluid motion such as gas network turbulence and the complex transient behavior involving multi - phase state changes like the phase change of the heat - pump working medium, it is described and captured by non - linear partial differential equations. During the dynamic simulation process, according to the set time step and calculation rules, the equations are gradually solved to obtain the state parameters of the system at different times, such as the pressure, temperature, flow rate, etc. at each node, and these simulation results are saved for subsequent analysis. This step realizes the accurate simulation of the dynamic process of the comprehensive energy system by using the non - linear finite - difference method combined with the solution of non - linear partial differential equations.

[0052] Taking the comprehensive energy system of a certain park as an example, the system includes a natural - gas supply network, a hot - water supply network, and various electric - gas - heat conversion devices, such as P2G devices, heat pumps, and CHP units, etc. To perform an integrated dynamic simulation of this system, first, step S101 is executed. Based on the dynamic two - port model of the energy network, the dynamic transmission models of the gas network and the heat network are constructed. For the gas network, the characteristic - line method is used to establish a time - domain two - port model. Considering factors such as the compressibility of natural gas and the frictional loss of the pipeline, the transfer matrix and the state equation are configured to accurately characterize the dynamic transmission process of natural gas in the pipeline. For the heat network, a similar modeling method is also adopted. Considering factors such as the flow characteristics of hot water and heat loss, the dynamic transmission model of the heat network is established.

[0053] Then, step S102 is executed to construct the dynamic simulation model of the equipment. For the P2G device, the time delay caused by factors such as the chemical reaction kinetics and catalyst activity during the electro - gas conversion process is modeled in detail; for the heat pump, the phase - change process of the working medium is modeled, including the latent heat of phase change, the phase - change temperature range, and the heat - transfer rate, etc.; for the CHP unit, a dynamic decoupling model of thermoelectric power is established, considering the generation, distribution, and mutual influence of heat and electricity during the combined heat and power generation process.

[0054] Finally, step S103 is executed. Based on the non - linear finite - difference method, the gas network, the heat network, and the dynamic simulation models of the equipment are integrated to build a comprehensive energy system model. Through discretization, the continuous partial differential equations are transformed into algebraic equation sets, and numerical solution algorithms such as the Newton - Raphson method are used for solution. During the simulation process, appropriate simulation step sizes and convergence accuracies are set, the simulation time is gradually advanced, the dynamic response of the system is obtained, and the simulation results are saved for subsequent analysis and optimization. Through this integrated dynamic simulation method, the dynamic operation characteristics of the comprehensive energy system of the park can be comprehensively and accurately reflected, providing technical support for the planning, operation, and control of the system.

[0055] Based on the above embodiments, in order to further improve the reliability of the integrated dynamic simulation method for the integrated energy system provided in the above embodiments, the following is a more specific implementation manner. In the following embodiments, from the user's perspective, this embodiment converts the complex dynamic mechanism equations into two-port modeling. Users do not need to pay attention to the internal complex logical structure, but only need to change external parameters such as inputs according to requirements. To improve the selectivity and convenience of users in using the integrated dynamic simulation software developed later in this embodiment, three methods are provided in the process of modeling and simulation: linear finite difference method, nonlinear finite difference method, and holomorphic embedding method. This embodiment mainly introduces the dynamic model of the nonlinear finite difference method. This method extends the traditional finite difference method to handle nonlinear partial differential equations, captures the transient behavior of nonlinear effects (such as gas network turbulence, heat pump working fluid phase change), has high model simulation accuracy, and takes into account both calculation efficiency and calculation cost, with a wide range of audiences.

[0056] In this embodiment, the natural gas network relies on pressure to drive the working fluid to flow, thereby realizing the effective transmission of energy. Under isothermal conditions, the transmission behavior of gas in the pipeline can usually be described by the continuity equation and the momentum equation. If the gas pressure and mass flow rate are selected as the key parameters to describe the system state, then the transmission characteristics of natural gas in the pipeline can be accurately expressed by a set of partial differential equations, including the mass conservation equation (1) and the momentum conservation equation (2).

[0057] (1) (2) Among them, the variables are all defined in the gas network pipeline, is the natural gas density, is the flow time of natural gas, is the natural gas transmission speed, is the flow distance of natural gas, is the pressure, is the diameter, is the friction coefficient, is the acceleration due to gravity, is the pipeline inclination angle.

[0058] In this embodiment, the original equations are discretized. The time term uses first-order forward difference and is expressed in explicit form; the space term uses first-order central difference. Assume that the pipeline is discretized along the axis into nodes , the time step is , and the space step is . At the pipeline and the time layer , the equations are discretely sorted out as: (3) (4) If , then , , ; After simplification, the dynamic explicit equation of the gas network is obtained as follows: (5) (6) In this embodiment, the subscript is defined as the inlet parameter of pipeline , the subscript is the outlet parameter of pipeline , the superscript represents the parameter at the previous moment, and the superscript represents the parameter at the current moment.

[0059] According to the definition of the two-port model, given that the input parameters are the inlet and outlet air pressures and flow rates at the previous moment, the parameters at the previous moment can be obtained in real time through the delay module. The output parameters to be obtained are the inlet and outlet air pressures and flow rates at the current moment. By solving the above equations simultaneously, the intermediate conversion relationship is extracted, and modeling is completed in the Simulink environment, and a two-port dynamic model of the gas network can be obtained.

[0060] For the heat network pipeline of this embodiment, the thermal network relies on the temperature difference to drive the flow of the heat medium, thereby achieving effective heat transfer. Under stable transmission conditions, the transmission characteristics of the heat medium in the pipeline can usually be described by the energy conservation equation and the heat transfer equation. If the temperature and heat flow rate are selected as the core parameters to describe the system state, then the transmission characteristics of the heat medium in the thermal network can be expressed as: (7) (8) (9) Among them, the variables are all defined inside the heat network pipeline, is the density of water, is the pressure, is the flow rate, is the mass flow rate base value corresponding to the flow velocity base value, is the cross-sectional area, is the acceleration due to gravity, is the pipeline inclination angle, is the specific heat of water, is the diameter, is the friction coefficient, is the heat dissipation coefficient, is the pipeline temperature, is the flow time of water in the hot network pipeline, is the flow distance of water in the pipeline.

[0061] In this embodiment, it is assumed that the flow direction is the positive direction, and the discrete node number is , the time step is , and the space step is . At the pipeline and the time layer , the equation is discretely sorted out to get: (10) (11) (12) Extract the parameters of the next moment under the required output item, that is , , and simplify to get: (13) (14) (15) In this embodiment, the subscript is understood as the inlet parameter of the pipeline , the subscript is the outlet parameter of the pipeline , the superscript represents the parameter of the previous moment, and the superscript represents the parameter of the current moment.

[0062] Since it is difficult to treat the hot network as a single model in simulation calculation, the network is split into two parts: the water supply network and the return water network to implement the above mechanism equation and ensure the feasibility of the model. Similar to the treatment of the gas network equation, according to the definition of the two-port model, the known input parameters are the input and output temperatures and flows of the previous moment, and the required output parameters are the input and output temperatures and flows of the current moment. The intermediate conversion relationship is extracted from the above formula, and modeling is completed in the Simulink environment, and a two-port dynamic model of the hot network can be obtained.

[0063] In this embodiment, the Simulink dynamic model of the integrated energy system coupling equipment combines the integrated energy system (IES), and improves the energy utilization efficiency and the renewable energy consumption capacity by coupling various energy forms such as electricity, gas, and heat. As the core link of multi-energy flow interaction, the dynamic characteristics of coupling equipment (such as power-to-gas (P2G), heat pump (HP), and combined heat and power (CHP)) directly affect the operation flexibility, economy, and stability of the system.

[0064] Considering that in the related technologies, the coupling equipment models are mostly constructed based on steady-state or quasi-steady-state assumptions, and their dynamic processes are ignored in the energy flow calculation and system simulation. Although this simplification reduces the computational complexity, it is difficult to accurately depict the system state. To address the above problems, this embodiment proposes a dynamic Simulink model for P2G, HP, and CHP for the user side, providing model support for the integrated dynamic simulation software of the integrated energy system. The power-to-gas equipment can not only be used as the load of the power grid but also exist in the natural gas network in the form of a distributed gas source, realizing the coupling of the electricity and gas networks and the conversion of electricity and gas energy. Currently, the power-to-gas technology mainly includes two categories: power-to-hydrogen and power-to-methane. The chemical principle of power-to-hydrogen is the electrolysis of water reaction, while the chemical principle of power-to-methane is to add a methanation reaction on the basis of power-to-hydrogen. In this embodiment, the modeling of P2G will be based on the principle of power-to-methane.

[0065] Taking the alkaline electrolysis water technology as the modeling basis, the reaction equation is as follows: (16) The hydrogen generated by the reaction can either continue to undergo a methanation reaction to produce methane or be stored as the raw material for a hydrogen fuel cell; the oxygen generated by the reaction also has various uses, such as being filled into the combustion chamber to make the gas burn fully or being stored for other fields.

[0066] The chemical reaction formula of the methanation process is shown in Equation (17), which refers to the process of further reacting the obtained with under the action of a catalyst to obtain . Therefore, the reactants of the reaction are easy to obtain, and the by-product is environmentally friendly, so the reaction has a high environmental protection degree and a low reaction cost.

[0067] (17) Since the alkaline electrolytic cell technology is more mature in industrial application, the electrolytic cell used in the water electrolysis process of this embodiment is modeled using this technology. The electrolytic cell can be regarded as a nonlinear load affected by voltage, and the following mathematical model is established. Electrolytic cell port voltage It can be expressed by a semi-empirical formula: (18) Where: is the number of electrolysis chambers, is the reversible open circuit power threshold, is the Faraday constant, is the number of charge transfers in the reaction. According to the reaction, Take 2, , is the calculation parameter related to ohm voltage, , is the electrolytic current of the electrolytic cell; is the surface area of ​​the electrolysis chamber; is the electrolyte temperature; , , , is the calculation parameter related to polarization overvoltage.

[0068] The hydrogen production rate of the electrolyzer is ,unit: .

[0069] By combining the above formulas, the hydrogen production rate of the electrolyzer can be solved and used as the input variable of the methanation stage to complete the model construction of the water electrolysis stage.

[0070] Considering the reactor volume effect and chemical reaction process, a mathematical model of methanogenesis is established. of and 4 of Reaction generation 1 of and 2 of Gas, the reactor volume is , gas flow into and out of the volume module The flow rates are , , the reaction ratio of the inflowing gas is , ignoring the temperature change in the reactor, the expression is as follows: (19) Where: is the compression factor, is the gas density in the reaction chamber, is the gas pressure in the reaction chamber.

[0071] According to the gas state equation, the gas pressure is proportional to the density. By controlling the flow rate at the reactor outlet constant, the outlet gas flow rate is proportional to the vessel pressure: (20) In the formula: is the outlet flow rate under the rated condition; is the gas density; is the reactor pressure under the rated working condition.

[0072] Substitute into Equation (19) and perform Laplace transform to obtain the transfer function of the P2G dynamic model as: (21) Finally, complete the construction and encapsulation of the P2G dynamic model in Simulink. The air source heat pump (HP) technology in this embodiment is based on the reverse Carnot cycle, which can convert natural energy (air thermal energy) into high-temperature heat sources for heating or hot water supply. It has high heat collection efficiency, is applicable in the temperature range of -7 to 40 °C throughout the year, has low operating costs, and stable performance. Considering the above advantages, this embodiment selects an air source heat pump for modeling to achieve the dynamic heat and cold exchange of the integrated energy system.

[0073] The supply and return water temperatures satisfy the following equation: (22) (23) Among them, represents the pipeline flow rate during the heating process, and respectively represent the supply water temperature and the return water temperature, and respectively represent the specific heat capacity and density of the hot water in the water tank, represents the volume of the hot water storage tank, represents the heat dissipation of the storage tank, is the loss floor surface temperature, represents the heat generated by the heat pump doing work. For the heat pump system, the heat generated by its work is related to its compressor power and the coefficient of performance of the heat pump and can be expressed in the following form: (24) Here, for the solution of the partial differential equation, the internal component Discrete-Time Integrator is used to solve it, which improves the solution reliability and calculation efficiency.

[0074] The CHP principle of this embodiment is that the compressor compresses air and injects it into the combustion chamber. The compressed air is mixed and burned with natural gas or other fuels in the combustion chamber. The combustion generates heat, causing the gas volume to increase, driving the blades of the steam turbine to rotate, and then driving the generator to generate electricity, realizing gas-electricity conversion in this process. Also, because the exhaust gas temperature of the gas turbine is very high and can be used as a driving heat source, gas-heat conversion is achieved through a heat exchanger. In summary, this embodiment models CHP in four parts: compressor, combustion chamber, turbine, and heat exchanger. The main formulas for each part are as follows: (25) In the formula, the variable definition range is within the compressor module, is the required power; is the inlet pressure; is the outlet pressure; is the efficiency; the polytropic exponent can be expressed as ; is the outlet flow rate; is the module equivalent volume; is the average gas constant of the fuel gas; is the outlet temperature.

[0075] (26) In the formula, the variable definition range is within the combustion chamber module, is the combustion chamber time constant; is the outlet temperature; is the combustion efficiency; is the inlet air enthalpy value; is the inlet natural gas enthalpy value; is the outlet fuel gas enthalpy value; is the inlet natural gas mass flow rate; is the outlet fuel gas mass flow rate; is the specific heat capacity at constant pressure of the outlet fuel gas; is the net specific energy of natural gas; is the fuel gas mass in the combustion chamber; is the air mass flow rate at the inlet of the combustion chamber.

[0076] In this embodiment, when building the combustion chamber, it is considered that the specific heat capacity varies with temperature, which is closer to the actual situation and improves the fineness and accuracy of the model. The mass flow rate, etc. are calculated using the working fluid mass ratio psi and the reaction relationship reaction, and are used for solving the principle formula. The output end is connected to the turbine input.

[0077] (27) (28) In the formula: is the turbine outlet temperature; is the turbine inlet temperature; is the turbine pressure ratio; is the turbine efficiency; is the turbine power consumption; is the turbine reduced flow rate; , is the adiabatic index of the gas, is the specific heat capacity at constant pressure of the gas at the combustor outlet.

[0078] The heat exchanger model is not the key innovation point of this embodiment and will not be elaborated here. Only the core formula is shown: (29) (30) In the formula, is the specific heat capacity at constant pressure of the water in the shell side, is the density of the water in the shell side, is the shell side flow area, is the temperature of the water in the shell side, t is time, is the flow velocity of the water in the shell side, is the axial diffusion coefficient of the water in the shell side, j represents the j-th pipe, , is the heat transfer rate from the tube wall per unit length of the j-th shell side to the water in the shell side, , is the shell side heat transfer coefficient, is the side heat transfer area of the water in the shell side, L is the tube length, is the tube wall temperature of the j-th pipe, The sign of depends on whether the flow direction of the water in the shell side is along the positive x direction. When the flow direction of the water in the shell side is along the positive x direction, takes the positive value and is ; when the flow direction of the water in the shell side is along the negative x direction, takes the negative value and is is the specific heat capacity at constant pressure of the water in the tube side, is the density of the water in the tube side, is the tube side flow area, is the temperature of the water in the j-th tube side, j represents the j-th pipe, , t is time, is the flow velocity of the water in the tube side, x is the selected flow direction of the water at the inlet in the tube side, is the axial diffusion coefficient of the water in the tube side, is the heat transfer rate from the tube wall per unit length of the j-th tube side to the water in the tube side, , is the side heat transfer area of the water in the tube side, is the tube-side heat transfer coefficient, is the tube length, is the wall temperature of pipe j, The sign of depends on whether the current pipe is odd. When j is odd, takes a positive value, which is ; when j is even, takes a negative value, which is .

[0079] The core function of the integrated dynamic simulation software for the integrated energy system developed in this embodiment is to achieve accurate electro-gas-thermal dynamic simulation, support multi-time scale coupled simulation. Users can select the solution method according to the required accuracy to balance the calculation efficiency and calculation accuracy. When in use, the software provides a drag-and-drop graphical modeling environment. Users can directly call the pre-set dynamic two-port pipe models of the gas network and heat network and the Simulink dynamic models of devices such as P2G, CHP, and heat pumps through the module library, without manually writing complex equations, reducing the modeling threshold. After the simulation example is built, select the solution algorithm on the software operation interface. Users can select according to the characteristics of the system they build. If the system dynamics are mainly linear (such as small disturbance analysis) or fast iteration is required (such as real-time control), select the linear finite difference method; if high-precision non-linear modeling is required and a relatively high calculation cost can be accepted, select the non-linear finite difference method, etc. Then, send a dynamic initialization control instruction to complete the initialization, including reading component parameters, topological connection relationships, etc. After the initialization is completed, set the simulation duration, and then execute the simulation process to achieve the dynamic simulation function. After the simulation is completed, the results can be saved, and the simulation results can be popped up in the form of a report or stored in Excel in the current path.

[0080] In some embodiments, through the distributed parameter network model and the multi-physical field dynamic equations of the devices, the transient process can be captured, supporting the dynamic interaction simulation of the gas-thermal-power grid. By finely building common main coupling devices such as P2G, HP, and CHP in Simulink, including the operating devices in most application scenarios. This embodiment adopts a modular design, which can flexibly access new device models or external control strategies, automatically adapt parameters for different application scenarios, and there is no need to rebuild the network, which is applicable to a variety of application scenarios. In the process of the solution algorithm in this embodiment, there are various choices, the calculation efficiency is balanced, and through the processing of the dynamic two-port model and the parallel solver of Simulink, both the simulation speed and accuracy are taken into account, and users can independently select different solution algorithms according to their own needs. The system provides a user-friendly interface. By developing the user interface of the integrated software, the operation is simple, the starting threshold is low, and a user help manual is configured, and the functional process is clear. The system provides a highly reliable platform for the dynamic simulation, real-time optimal scheduling, and digital twin application of the integrated energy system. Such as Figure 2 gives an interface for one-key parameter modification, which is convenient for users to operate and use.

[0081] The following are embodiments of the integrated dynamic simulation system for a comprehensive energy system provided by the present disclosure. This system and the integrated dynamic simulation method for the comprehensive energy system in the above embodiments belong to the same inventive concept. For the details not described in detail in the embodiments of the integrated dynamic simulation system for the comprehensive energy system, reference may be made to the embodiments of the above integrated dynamic simulation method for the comprehensive energy system.

[0082] The system includes: a parameter characteristic configuration module, which is used to configure the transfer matrix and state equation by using the dynamic two-port model of the energy network to characterize the dynamic transmission process corresponding to the gas network pipeline parameters and the heat network pipeline parameters.

[0083] A model construction module, which is used to construct a device dynamic simulation model and couple the electrical-gas conversion time delay of P2G, the thermodynamic transient of the phase change of the heat pump working medium, and the dynamic decoupling characteristics of the CHP thermoelectric power.

[0084] A simulation processing module, which is used to build a comprehensive energy system model with a dynamic transmission process and a device dynamic simulation model by combining the nonlinear finite difference method, perform dynamic simulation on the built comprehensive energy system model, capture the transient behavior of gas network turbulence and the phase change of the heat pump working medium with nonlinear partial differential equations, realize dynamic simulation, and save the simulation results.

[0085] As Figure 3 shown, the present application also provides an electronic device, including a display module 103, a memory 102, a processor 101, and a computer program stored on the memory and executable on the processor 101. When the processor 101 executes the program, the steps of the integrated dynamic simulation method for the comprehensive energy system are implemented.

[0086] In the embodiments of the present invention, the electronic device includes, but is not limited to, a laptop computer, a desktop computer, a workbench, a personal digital assistant, a server, a blade server, a mainframe computer, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as, a personal digital processor, a cellular phone, a smart phone, a wearable device, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are only examples and are not intended to limit the implementation of the embodiments of the present application described and / or claimed herein.

[0087] In the embodiments of the present application, the processor 101 can be implemented by using at least one of an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), a processor, a controller, a microcontroller, a microprocessor, and an electronic unit designed to execute the functions described herein. In some cases, such an implementation can be implemented in a controller. For a software implementation, an implementation of a process or function can be implemented with a separate software module that allows execution of at least one function or operation. The software code can be implemented by a software application (or program) written in any appropriate programming language. The software code can be stored in a memory and executed by the controller.

[0088] The display module 103 is used to display information input by the user or information provided to the user. The display module 103 may include a display panel, and the display panel may be configured in the form of a liquid crystal display (LCD), an organic light-emitting diode (OLED), or the like.

[0089] The memory 102 can be used to store software programs and various data. The memory 102 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one magnetic disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0090] The present application also provides a storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the integrated energy system integrated dynamic simulation system are implemented.

[0091] The storage medium can adopt any combination of one or more readable media. The readable media can be a readable signal medium or a readable storage medium. The readable storage medium can be, for example but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (a non-exhaustive list) of the readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0092] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An integrated dynamic simulation method for a comprehensive energy system, characterized in that: Methods include: Based on the dynamic two-port model of energy network, the transfer matrix and state equation are configured to characterize the dynamic transmission process corresponding to the parameter characteristics of gas network pipeline and heat network pipeline; Build a dynamic simulation model of the equipment and couple the P2G electricity-gas conversion time lag, the heat pump working fluid phase change thermodynamic transient and the CHP thermoelectric power dynamic decoupling characteristics; Based on the nonlinear finite difference method, a comprehensive energy system model with a dynamic transmission process and equipment dynamic simulation model is built. The built comprehensive energy system model is dynamically simulated, and the nonlinear partial differential equations are used to capture the transient behaviors of gas network turbulence and heat pump working fluid phase change to achieve dynamic simulation and save the simulation results.

2. The integrated dynamic simulation method of the comprehensive energy system according to claim 1 is characterized in that: The dynamic transmission process of the gas network pipeline is: in, is the density of natural gas, is the natural gas transmission speed, For pressure, is the diameter, is the friction coefficient, is the acceleration due to gravity, is the pipe inclination angle; the subscript in the parameter For pipeline The entry parameter of For pipeline The export parameter of Indicates the parameter of the previous moment, with a superscript Represents the parameter at the current moment.

3. The integrated dynamic simulation method of the comprehensive energy system according to claim 2 is characterized in that: In the method, according to the dynamic two-port model of the energy network, the known input parameters are the input and output pressure and flow at the previous moment, and the required output parameters are the input and output pressure and flow at the current moment. The intermediate conversion relationship is extracted from the parameter characteristics of the gas network pipeline, and the modeling is completed in the Simulink environment to obtain the two-port dynamic model of the gas network.

4. The integrated dynamic simulation method of a comprehensive energy system according to claim 1 or 2, characterized in that: The heat medium transmission characteristics in the heat network pipeline are expressed as: Among them, the variables are defined as within the heat network pipeline. is the density of water, For pressure, For flow, is the mass flow rate base value corresponding to the velocity base value, is the cross-sectional area, is the acceleration due to gravity, is the pipe inclination angle, is the specific heat of water, is the diameter, is the friction coefficient, is the heat dissipation coefficient, is the pipe temperature, is the flow time of water in the heat network pipe, is the flow distance of water in the pipe; Define the flow direction as In the positive direction, the discrete nodes are numbered , the time step is , the spatial step length is , in the pipeline and time layer The equation is discretized to get: Among them, the subscript For pipeline The entry parameter of For pipeline The export parameter of Indicates the parameter of the previous moment, with a superscript Represents the parameter at the current moment.

5. The integrated dynamic simulation method of a comprehensive energy system according to claim 1 or 2, characterized in that: In the electric-gas conversion delay of the step-coupled P2G, the P2G dynamic model transfer function is defined as: in, , are the flow rates of gas flowing into and out of the volume module, respectively, is the reaction ratio of the inflowing gas, is the reactor volume, is the outlet flow rate under rated conditions, is the reactor pressure under rated conditions, s is the Laplace transform variable, p is the pressure, is the representation of the output in the Laplace domain, is the representation of the input quantity in the Laplace domain.

6. The integrated dynamic simulation method of a comprehensive energy system according to claim 1 or 2, characterized in that: In the thermodynamic transient state of the heat pump working fluid phase change in the step of building the dynamic simulation model of the equipment, the supply and return water temperatures are defined to satisfy the following equations: in, Indicates the pipeline flow rate of the heating process, and Represent the supply water temperature and return water temperature respectively. and They represent the specific heat capacity and density of the hot water in the tank, Indicates the volume of the hot water tank. Indicates the heat dissipation of the water tank. To lose floor surface temperature, Indicates the heat generated by the heat pump. For a heat pump system, the heat generated by its work is proportional to the compressor power. , Heat pump performance coefficient Related, expressed as follows: 。 7. The integrated dynamic simulation method of a comprehensive energy system according to claim 1 or 2, characterized in that: In the step of constructing the dynamic decoupling characteristics of the CHP thermoelectric power of the equipment dynamic simulation model, the CHP is divided into four parts: compressor, combustion chamber, turbine, and heat exchanger for modeling. The main formulas of each part are as follows: The variable definition range in the formula is within the compressor module. is the required power; is the inlet pressure; is the outlet pressure; is the efficiency; the polynomial index can be expressed as ; is the export flow; is the module equivalent volume; is the average gas constant of fuel gas; is the outlet temperature; The variable definition range in the formula is within the combustion chamber module. is the combustion chamber time constant; is the outlet temperature; For combustion efficiency; is the inlet air enthalpy; is the inlet natural gas enthalpy; is the outlet gas enthalpy; is the inlet natural gas mass flow rate; is the outlet gas mass flow rate; is the constant pressure specific heat capacity of the outlet gas; is the net specific energy of natural gas; is the combustion chamber gas quality; is the air mass flow rate at the combustion chamber inlet; The output is connected to the turbine input in the following way: Where: is the turbine outlet temperature; is the turbine inlet temperature; is the turbine pressure ratio; is the turbine efficiency; The power consumed by the turbine; is the turbine equivalent flow rate; , is the gas adiabatic index, is the constant pressure specific heat capacity of the combustion chamber outlet gas.

8. An integrated dynamic simulation system for a comprehensive energy system, characterized in that: The system is used to implement the integrated dynamic simulation method of the comprehensive energy system as described in any one of claims 1 to 7; The system includes: The parameter feature configuration module is used to use the energy network dynamic two-port model to configure the transfer matrix and state equation to characterize the dynamic transmission process corresponding to the gas network pipeline parameter characteristics and the heat network pipeline parameter characteristics; Model building module, used to build a dynamic simulation model of the equipment, and couple the P2G electric-gas conversion time lag, the heat pump working fluid phase change thermodynamic transient and the CHP thermoelectric power dynamic decoupling characteristics; The simulation processing module is used to combine the nonlinear finite difference method to build a comprehensive energy system model with a dynamic transmission process and equipment dynamic simulation model, perform dynamic simulation on the built comprehensive energy system model, capture the transient behavior of gas network turbulence and heat pump working fluid phase change with nonlinear partial differential equations, realize dynamic simulation, and save the simulation results.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the integrated dynamic simulation method for a comprehensive energy system as described in any one of claims 1 to 7 are implemented.

10. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the integrated dynamic simulation method for a comprehensive energy system as described in any one of claims 1 to 7 are implemented.

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