CN113156835A - Modeling simulation method for operation control of electricity-heat comprehensive energy system - Google Patents

Abstract

The invention relates to a modeling simulation method for operation control of an electricity-heat comprehensive energy system, which comprises the following steps: establishing a combined heat and power generation unit model, acquiring each component of the combined heat and power generation unit and respectively establishing corresponding models; establishing an absorption refrigerator model, acquiring each component of the absorption refrigerator, and respectively establishing a corresponding static model and a corresponding dynamic model; establishing a thermodynamic network model; and forming an electric-thermal comprehensive energy system transient simulation model based on the cogeneration unit model, the absorption chiller model and the thermal network model, and realizing real-time control simulation of the electric-thermal comprehensive energy system. The method of the invention builds a model for each unit of the electric-thermal comprehensive energy system, combines the models to form an electric-thermal comprehensive energy system transient simulation model, can simulate the operation control of the electric-thermal comprehensive energy system, and realizes the real-time control simulation of the electric-thermal comprehensive energy system.

Description

Modeling simulation method for operation control of electricity-heat comprehensive energy system

Technical Field

The invention relates to modeling simulation of an electricity-heat integrated energy system, in particular to a modeling simulation method for operation control of the electricity-heat integrated energy system.

Background

Under the influence of global warming, the demand for reducing the emission of greenhouse gases is increasing, and it is common knowledge in the industry to reduce the use of fossil fuels and promote the development of renewable energy technology and energy internet technology. Under the background, the comprehensive planning of an electricity-heat comprehensive energy system becomes a hotspot of current research and engineering application, wherein a cogeneration unit can recover and utilize heat energy from exhaust gas discharged by a turbonator while producing electric energy, so as to provide heat for a heat load of a building, thereby achieving the purposes of saving energy, reducing emission and improving the overall efficiency of the comprehensive energy system; the absorption refrigerator can generate refrigeration water by means of heat recovered by a cogeneration unit and supply the refrigeration water to a cold load, and compared with the traditional electric refrigerator, the absorption refrigerator also has the characteristics of energy conservation, emission reduction and higher efficiency.

At present, in the research of the academic world on the electricity-heat comprehensive energy system, the established model and algorithm are difficult to verify. In order to research the operation control of the electric-thermal comprehensive energy system, firstly a simulation model of the electric-thermal comprehensive energy system needs to be established, and how to establish the model to realize the real-time control simulation of the electric-thermal comprehensive energy system becomes a problem which needs to be solved urgently.

Disclosure of Invention

The invention aims to overcome the defect that the simulation model is difficult to build in the electricity-heat comprehensive energy system in the prior art, and provides a modeling simulation method for the operation control of the electricity-heat comprehensive energy system.

In order to achieve the purpose, the invention adopts the following technical scheme:

a modeling simulation method for operation control of an electric-thermal integrated energy system includes:

establishing a combined heat and power generation unit model, acquiring each component of the combined heat and power generation unit and respectively establishing corresponding models;

establishing an absorption refrigerator model, acquiring each component of the absorption refrigerator, and respectively establishing a corresponding static model and a corresponding dynamic model;

establishing a thermodynamic network model;

and forming an electric-thermal comprehensive energy system transient simulation model based on the cogeneration unit model, the absorption refrigerator model and the thermal network model, and realizing real-time control simulation of the electric-thermal comprehensive energy system.

Compared with the prior art, the invention has the beneficial effects that:

the method of the invention builds a model for each unit of the electricity-heat comprehensive energy system, simultaneously builds corresponding models for each component in the cogeneration unit, builds corresponding static models and dynamic models for each component of the absorption refrigerator, combines a thermal network model to form an electricity-heat comprehensive energy system transient simulation model, can simulate the operation control of the electricity-heat comprehensive energy system, and realizes the real-time control simulation of the electricity-heat comprehensive energy system.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic view of an electric-thermal integrated energy system according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an embodiment of an absorption chiller according to the present invention, wherein 1-absorber flow of lithium bromide solution to solution pump, 2-solution pump flow of lithium bromide solution to heat exchanger, 3-heat exchanger flow of lithium bromide solution to generator, 4-generator flow of lithium bromide solution to heat exchanger, 5-heat exchanger flow of lithium bromide solution to absorber, 6-generator flow of water vapor to condenser, 7-condenser flow of water to evaporator, 8-evaporator flow of water vapor to absorber, 9-absorber cooling water inlet, 10-absorber cooling water outlet/condenser cooling water inlet, 11-condenser cooling water outlet, 12-generator hot steam inlet, 13-generator hot steam outlet, 14-evaporator cooling water inlet, 15-refrigerant water outlet of evaporator.

Fig. 3 is a schematic structural diagram of a thermal network according to an embodiment of the present invention.

Fig. 4 is a diagram illustrating a thermodynamic network model based on graph theory of the thermodynamic network shown in fig. 2.

Fig. 5 is a simulation model diagram of a gas turbine in the cogeneration unit according to the embodiment of the present invention.

Fig. 6 is a simulation model diagram of a heat recovery device in a cogeneration unit according to an embodiment of the present invention.

Fig. 7 is a simulation model diagram of an absorption chiller according to an embodiment of the present invention.

Fig. 8 is a simulated model diagram of a thermal conduit in a thermal network in accordance with an embodiment of the present invention.

Fig. 9 is a simulation model diagram of thermal load in a thermal network according to an embodiment of the present invention.

FIG. 10 is a diagram of a thermal load simulation model of the simplified version of FIG. 9.

Fig. 11 is a diagram of a load simulation model of the house in fig. 9.

Fig. 12 is a diagram of a simulation model of the building load in fig. 9.

FIG. 13 is a simulation model diagram of the power subsystem of the present invention.

Fig. 14 is a simulation model diagram of the thermal subsystem of the present invention.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention.

As shown in fig. 1 to 14, an embodiment of the present invention provides a modeling simulation method for operation control of an electric-thermal integrated energy system, including the following steps:

and 102, establishing a combined heat and power generation unit model, acquiring each component of the combined heat and power generation unit and respectively establishing corresponding models.

The cogeneration is to recover the heat in the exhaust heat and smoke discharged from the steam turbine while the generator generates electricity, and is used for producing hot water or hot steam and supplying heat to users. Specifically, the cogeneration machine includes a gas turbine, a generator and a heat recovery device, and therefore, a mathematical model of the gas turbine, a mathematical model of the heat recovery device and a mathematical model of the generator need to be correspondingly established, and the mathematical models are generated in simulation software such as Matlab/Simulink and the likeThe mathematical model of the motor is known and can be directly cited. The heat power P recovered by the heat recovery device from the waste heat flue gas of the gas turbine can be calculated based on the establishment of a mathematical model of the gas turbine and a mathematical model of the heat recovery device_hrDirectly used for heat supply_hr1And inputting the thermal power of the absorption refrigerator so as to establish a connection with the model of the absorption refrigerator. The heat supply mode is that a waste heat boiler produces hot water or steam is directly utilized to supply heat energy to the building load.

Specifically, a gas turbine mathematical model is established based on a Rowen model, wherein the gas turbine mathematical model comprises a speed controller model, a waste heat flue gas temperature controller model, an acceleration controller model, a fuel system model, and a compressor and turbine model.

1.1.1) speed controller model

The main function of the speed controller is to schedule a command P according to the power_setAnd the actual output P of the generator_eAdjusting the output power of the generator to ensure that the cogeneration unit works according to the power dispatching instruction; at the same time, according to the rated rotation speed omega_refWith the actual speed omega of the generator_rAnd the rotation speed of the prime motor is adjusted to keep the frequency of the generator stable.

Based on the above functions, a speed instruction formula output by the speed controller is established, specifically:

wherein, V_ce0Speed command, K, output for speed controller_DroopIs the droop coefficient, T is the time constant, K_pAnd K_iProportional and integral parameters for PI regulation.

1.1.2) waste heat flue gas temperature controller model

The waste heat flue gas temperature controller model is linked with the compressor and turbine model, the waste heat flue gas temperature calculated by the compressor and turbine model is used as input, and the function of the waste heat flue gas temperature controller model is to enable the waste heat flue gas temperature T to be T_exhaustIs held atReference value T of temperature_ref。

The waste heat flue gas temperature controller model comprises a radiation shielding module, a thermal coupling module and a PI controller module, wherein the radiation shielding module and the thermal coupling module are used for simulating time delay caused by corresponding modules in an actual temperature measuring device;

based on a waste heat flue gas temperature controller model, the speed instruction upper limit value V output by a speed controller_{ce_limit1}：

Wherein, T_rs1、T_rs2，T_thFor radiation shielding and thermal coupling coefficients, K_pAnd K_iProportional and integral parameters adjusted for the PI controller module.

1.1.3) acceleration controller model

The acceleration controller model has two functions, namely, the thermal stress is reduced by limiting the acceleration of the rotor when the gas turbine is started, in addition, in the operation process of the gas turbine, the acceleration controller model can inhibit the over-high rotating speed of the rotor of the generator and ensure the normal operation of the unit, and if the operation speed of the generator is close to the rated speed of the generator, the function of the acceleration controller model can be ignored.

Based on the acceleration controller model, the speed command upper limit value V output by the speed controller_{ce_limit2}：

Wherein, T_inertiaIs the inertia constant of the rotor of the generator.

Speed command V of speed regulator_ce0After amplitude limiting, the final speed regulating signal V is obtained_ceMin represents taking the minimum value:

V_ce＝min{V_ce0,V_{ce_limit1},V_{ce_limit2}}。

1.1.4) Fuel System model

The fuel system model has the main function of calculating the consumed power of the fuel in the gas turbine according to the control command of the speed controller and by considering the delay of a gas valve in the actual system and the efficiency conditions of the fuel at different temperatures

The fuel system model comprises a valve regulation module and a fuel regulation module; wherein the power consumption is related to the delay of the gas valve. Gas turbine doing work W on gas turbine_fThe method specifically comprises the following steps:

wherein, T_vpIs the time constant of the valve regulating module, T_fsIs the time constant of the fuel regulating module, reflecting the time delay of the two processes, K_initIs the minimum per unit work done value of the gas turbine.

Taking into account the ambient temperature T_atmTo fuel combustion efficiency eta_fuelInfluence of η_fuelAnd T_atmThe relation between the two is described by a function, and the work of the gas turbine on the gas turbine is calculated to be W under a certain environmental temperature_fFuel P required by gas turbine_fuel. When the output of the cogeneration unit is P_eWhen it is used, its electrical efficiency is eta_eleThe specific function is:

based on the above function, the thermal power P in the waste heat flue gas_exhaustIs composed of

P_exhaust＝P_fuel(1-η_fuel)

1.1.5) compressor and turbine model

The main functions of the compressor and the turbine model are to execute a fuel control signal command issued by the fuel system and calculate the torque T output by the turbine_mAnd the temperature T of the exhaust gas_exhaustThe method specifically comprises the following steps:

wherein, K_HHVTypical values for enthalpy-related coefficients are 1.3, T_refThe reference temperature of the waste gas is a set value, and particularly 510 ℃ can be taken; t is_CRDelay time for combustion reaction, T_TDFor delay of transit time of turbine exhaust system, T_CDIs the time constant of the compressor displacement.

1.2) establishing a mathematical model of a heat recovery device

The heat recovery device of the cogeneration unit can recover the heat of the waste heat flue gas discharged by the gas turbine, produce hot water by a waste heat boiler or directly supply heat energy to the building load by using steam, and can also be input into an absorption refrigerating unit for refrigeration. A mathematical model of the heat recovery device in the cogeneration unit can be established according to the basic laws of energy conservation and thermodynamics.

The energy conservation equation of the cogeneration unit is as follows:

P_fuel＝W_f+P_loss+P_exhaust

wherein, P_fuelAs fuel combustion power, W_fPower for steam to work gas turbine, P_exhaustIs the thermal power, P, of the waste heat flue gas of a gas turbine_lossIs the power loss;

the energy conservation equation of the heat recovery device is as follows:

P_hr＝P_exhaust×η_hr

P_hr1＝(1-δ)P_hr

P_hr1＝C_pwf_w(T_w,out-T_w,in)

wherein, P_hrThermal power, P, recovered for the heat recovery device_hr1The thermal power input to the waste heat boiler model or the thermal load model, delta is the proportion of the recovered heat flowing to the absorption refrigerating unit model, eta_hrFor the efficiency of the heat recovery device model, C_pwIs the specific heat capacity of water, f_wIs the flow rate of water in the heat distribution pipeline, T_w,in，T_w,outThe water inlet temperature and the water outlet temperature of the heat recovery device model are respectively.

Efficiency eta of heat recovery device in consideration of temperature_hrAssuming the inlet and outlet flue gas temperatures of the heat recovery unit are constant, the heat recovery unit efficiency η_hrOnly with ambient temperature T_atmRelated to the ambient temperature T_atmThe improvement will make the heat recovery efficiency eta_hrThe efficiency equation of the heat recovery device is as follows

The efficiency equation of the heat recovery device is as follows

Thermal efficiency eta of cogeneration unit_heatIs composed of

Total efficiency eta of combined heat and power generation unit_CHPIs composed of

Step 102, establishing an absorption chiller model, acquiring each component of the absorption chiller, and respectively establishing a corresponding static model and a corresponding dynamic model.

The cogeneration unit recovers heat in the exhaust-heat flue gas discharged from the gas turbine, and can be input into the absorption refrigeration unit for refrigeration and supply to a cold load, besides flowing to an exhaust-heat boiler and other equipment for producing hot water and supplying to a heat load, thereby forming a combined cooling, heating and power system.

The absorption refrigerator comprises a heat exchanger, a solution pump, an absorber, a condenser, a generator and an evaporator;

respectively establishing static models of the heat exchanger, the solution pump, the absorber, the condenser, the generator and the evaporator, respectively solving based on the static models, and respectively calculating heat transfer coefficients UA of the absorber, the generator, the condenser and the evaporator_a，UA_g，UA_cAnd UA_eAnd establishing a heat transfer coefficient model of each component of the absorption refrigerator, thereby obtaining a dynamic model of the absorption refrigerator.

2.1) construction of the static model of the absorption chiller

As shown in fig. 2, each component constructs a static mathematical model based on the mass conservation principle and the energy conservation principle. The working medium in the absorption refrigerator is a lithium bromide aqueous solution.

2.1.1) construction of a static mathematical model of an absorber

In the absorber, the lithium bromide concentrated solution absorbs the water vapor generated in the evaporator to form a lithium bromide dilute solution, and the heat generated by dilution of the lithium bromide solution is absorbed by cooling water; the lithium bromide dilute solution is driven by the solution pump to flow to the generator through the heat exchanger, so as to start circulation; this process follows the equation of conservation of energy, Q_aThe total heat released in the absorber per second is equal to the heat absorbed by the cooling water flowing through the absorber, and is also equal to the difference between the enthalpy of the substance flowing into the absorber and the enthalpy of the substance flowing out of the absorber, i.e.:

this process follows conservation of mass, including conservation of mass of the lithium bromide solution and conservation of mass of the lithium bromide solute, namely:

wherein, T₁₀For absorber cooling water outlet/condenser cooling waterTemperature of inlet, T_c，inTemperature of cooling water flowing into the absorber, f_cFor the flow rate of cooling water, C_pcIs the specific heat capacity of the cooling water.

2.1.2) constructing a static mathematical model of the Generator

In the generator, the lithium bromide dilute solution is driven by the solution pump, flows in from the absorber through the heat exchanger, is heated and evaporated in the generator, is separated into water vapor and lithium bromide concentrated solution, the water vapor flows in the condenser, and the lithium bromide concentrated solution flows back to the absorber through the heat exchanger; this process follows conservation of energy, Q_gThe total heat absorbed in the generator per second is equal to the heat released by the heating water and also equal to the difference between the enthalpy of the substance flowing out of the generator and the enthalpy of the substance flowing into the generator, i.e.:

Q_g＝f_gC_pg(T_g,in-T_g,out)

Q_g＝f₄h₄+f₆h₆-f₃h₃

this process follows conservation of mass, including conservation of mass of the lithium bromide solution and conservation of mass of the lithium bromide solute, namely:

wherein f is_gFor heating the flow of water, C_pgFor heating the specific heat capacity of the water, T_g，in、R_g，outThe temperatures of the heated water flowing into and out of the generator, respectively.

2.1.3) constructing a static mathematical model of the condenser

In the condenser, the water vapor flowing from the generator is condensed and then flows toward the evaporator; specifically, the surface temperature of the cooling water pipe is low, and water vapor flowing from the generator condenses into small droplets and adheres to the surface of the cooling water pipe, and then drops to the collecting device and flows to the evaporator. This process follows conservation of energy, Q_cFor the total heat released in the condenser per second, equal to the cooling water flowing through the condenserThe absorbed heat is also equal to the difference between the enthalpy of the water vapor flowing into the condenser and the enthalpy of the condensed water flowing out of the condenser, i.e.:

this process follows the conservation of mass of the water species, namely: f. of₆＝f₇；

Wherein f is_cFor cooling water flow, C_pcFor the specific heat capacity of the cooling water, T₁₀Is the temperature of the cooling water outlet of the absorber/cooling water inlet of the condenser, T_c，outIs the temperature of the condenser cooling water outlet.

2.1.4) constructing a static mathematical model of the evaporator

The evaporator is close to a vacuum environment, the boiling point of water is low, and the water flows into the evaporator from the condenser and then is rapidly cooled and evaporated to absorb a large amount of heat. The refrigerating water pipeline flows through the evaporator, heat is absorbed to generate refrigerating water, and the refrigerating water flows through the building load for cooling and then flows into the evaporator again for refrigerating to complete refrigerating water circulation. In the evaporator, water flows into the evaporator from the condenser to cool and evaporate, and heat is absorbed from a refrigerating water pipeline, the refrigerating water in the refrigerating water pipeline forms a refrigerating cycle, water vapor formed in the evaporator is absorbed by the lithium bromide concentrated solution in the absorber to enter the absorber, and the next cycle is started; this process follows conservation of energy, Q_eThe total heat absorbed in the evaporator per second is equal to the heat released by the cooling water flowing through the evaporator and also equal to the difference between the enthalpy of the water vapor leaving the evaporator and the enthalpy of the condensed water flowing into the evaporator, i.e.:

this process follows the conservation of mass of the water species, namely: f. of₇＝f₈；

Wherein f is_eFor the flow of refrigerating water, C_peSpecific heat capacity of refrigerating water, T_e，out、T_e，inRespectively the inflow temperature and the outflow temperature of the refrigeration water flowing through the evaporator.

2.1.5) construction of a static mathematical model of a solution Pump

The dilute lithium bromide solution is driven by the solution pump, flows from the absorber to the generator through the heat exchanger, and the process follows the mass conservation equation, including the mass conservation of the lithium bromide solution and the mass conservation of the lithium bromide solute, namely:

f₁＝f₂，X₁＝X₂

this process follows conservation of energy, namely:

wherein, W_pElectric power consumed for solution pumps, P_cIs the ambient pressure, P, of the heat exchanger_eIs the ambient pressure of the absorber, eta_pIs the efficiency of the solution pump.

2.1.6) constructing a static mathematical model of a Heat exchanger

In the heat exchanger, the lithium bromide concentrated solution from the generator and the lithium bromide dilute solution from the absorber are subjected to heat exchange, so that the temperature of the lithium bromide dilute solution flowing into the generator is increased, and the energy Q required for heating the lithium bromide dilute solution in the generator is reduced_gThereby increasing the coefficient of performance (COP) of the system_cool

This process follows the conservation of energy that the dilute lithium bromide solution flowing from the absorber to the generator absorbs an amount of heat equal to the amount of heat given off by the concentrated lithium bromide solution flowing from the generator back to the absorber, i.e. that is

f₃h₃-f₂h₂＝f₄h₄-f₅h₅

The mass conservation of the lithium bromide solution and the lithium bromide solute in the process is shown in the following equation

f₂＝f₃ X₂＝X₃

f₄＝f₅，X₄＝X₅。

The temperature of the solution in the heat exchanger is related to the heat exchanger coefficient epsilon, and the equation is as follows

T₁＝T₂

T₅＝T₄-ε(T₄-T₂)。

2.1.7) calculating the refrigeration coefficient

Based on the above formula, the COP of the absorption refrigerator can be calculated_cool(ii) a Coefficient of performance COP_coolEqual to the refrigerating capacity Q of the absorption refrigerator_eEnergy Q required for producing heating water with absorption refrigerator_gAnd the solution pump consumes energy W_pThe ratio of (A) to (B) is as follows:

Q_e+Q_g+W_p＝Q_a+Q_c

2.2) constructing dynamic model of absorption type refrigerating machine model

Based on the above-established static model of each component, its operating point temperature T₁，T₄，T₇，T₈Calculating heat transfer coefficients UA of the absorber, the generator, the condenser and the evaporator respectively based on the solution results of the static models of the components by introducing a logarithmic mean temperature LMTD for the set value_a，UA_g，UA_cAnd UA_eAnd establishing a heat transfer coefficient model of each component in the absorption refrigerator model so as to obtain a dynamic model of the absorption refrigerator.

2.2.1) mathematical model of the absorber

Q_a＝UA_aLMTD_a

Therein, UA_aIs the heat transfer coefficient of the absorber, LMTD_aIs the logarithmic mean temperature difference of the absorber;

2.2.2) mathematical model of the Generator

Q_g＝UA_gLMTD_g

Therein, UA_gFor the heat transfer coefficient of the generator, LMTD_gIs the logarithmic mean temperature difference of the generator;

2.2.3) mathematical model of the condenser

Q_c＝UA_cLMTD_c

In which UA_cIs the heat transfer coefficient of the condenser, LMTD_cIs the logarithmic mean temperature difference of the condenser;

2.2.4) mathematical model of the evaporator

Q_e＝U_eA_eLMTD_e

Therein, UA_eAs heat transfer coefficient of evaporator, LMTD_eIs the logarithmic mean temperature difference of the evaporator;

2.2.5) efficiency calculation

P_cool＝Q_e，

Wherein the COP_coolRefrigeration coefficient, P, for absorption chiller model_coolEta when the energy for producing the heating water is derived from the heat recovered by the model of the cogeneration unit for absorbing the refrigerating power of the model of the refrigerating machine_coolTo consume the refrigeration efficiency of the fuel with respect to the cogeneration unit model.

2.2) construction of dynamic model of absorption chiller

Based on the above-established static model of each component, its operating point temperature T₁，T₄，T₇，T₈Calculating heat transfer coefficients UA of the absorber, the generator, the condenser and the evaporator respectively based on the solution results of the static models of the components by introducing a logarithmic mean temperature LMTD for the set value_a，UA_g，UA_cAnd UA_eAnd establishing a heat transfer coefficient model of each component in the absorption refrigerator model so as to obtain a dynamic model of the absorption refrigerator.

2.2.1) mathematical model of the absorber

Q_a＝UA_aLMTD_a

Therein, UA_aIs the heat transfer coefficient of the absorber, LMTD_aFor the logarithmic mean temperature difference of the absorber, in the actual setting, LMTD can be set_aIs 9.692K, UA_a45.192 kW/K.

2.2.2) mathematical model of the Generator

Q_g＝UA_gLMTD_g

Therein, UA_gFor the heat transfer coefficient of the generator, LMTD_gTo send outThe logarithmic mean temperature difference of the generator can be set in the actual setting process_gIs 21.120K, UA_g21.448 kW/K.

2.2.3) mathematical model of the condenser

Q_c＝UA_cLMTD_c

In which UA_cIs the heat transfer coefficient of the condenser, LMTD_cFor the logarithmic mean temperature difference of the condenser, in the actual setting, LMTD can be set_cIs 11.469K, UA_c33.770 kW/K.

2.2.4) mathematical model of the evaporator

Q_e＝U_eA_eLMTD_e

Therein, UA_eAs heat transfer coefficient of evaporator, LMTD_eFor the logarithmic mean temperature difference of the evaporator, in the actual setting, LMTD can be set_eIs 3.641K, UA_e102.416 kW/K.

2.2.5) efficiency calculation

P_cool＝Q_e

Wherein the COP_coolRefrigeration coefficient, P, for absorption chiller model_coolEta when the energy for producing the heating water is derived from the heat recovered by the model of the cogeneration unit for absorbing the refrigerating power of the model of the refrigerating machine_coolIs relative toThe cooling efficiency of fuel is consumed in the cogeneration unit model.

And 103, establishing a thermodynamic network model.

Specifically, the thermal network transfers thermal energy to a thermal load through a thermal pipeline by means of a thermal medium, and a commonly used thermal medium includes steam or hot water. The heat network model of this embodiment includes heat source module, pipeline module and building load, the heat source module is the hot water that cogeneration unit module directly produced or produced through gas boiler, and the heating network uses water as the medium, through pipeline module transportation to building load, for user's heat supply, the water after the cooling passes through the pipeline module flows back to cogeneration unit module or gas boiler continues to heat, realizes heating network circulation. At this time, the pipeline module is divided into a heat distribution pipeline and a water return pipeline.

In the embodiment, a heat source module and a building load in a thermal network model are set as a plurality of nodes, a pipeline module is set as a plurality of edges to form a graph theory, and the thermal network model is established based on the graph theory.

Taking the example that the constructed thermodynamic network comprises a cogeneration unit, a gas boiler, a water pump, two building loads and eight thermodynamic pipelines, abstracting the thermodynamic network into a graph, abstracting the thermodynamic pipelines into sides, abstracting the building loads, the cogeneration unit, the gas boiler and the like into nodes, and because the electric energy consumed by the water pump is extremely small relative to the system, the electric energy can be ignored, so that the thermodynamic network is represented into the graph consisting of six nodes and eight sides.

3.1.1) basic correlation matrix

Based on the graph theory knowledge, for a directed graph containing m nodes and n edges, each node and each edge of the thermodynamic network structure graph can be represented by an incidence matrix A of m multiplied by n orders, wherein a matrix element a_ijIs determined by

The thermodynamic network can be represented by a correlation matrix A of order 6 × 8

Taking a certain node in the incidence matrix A as a reference node, and removing the row in which the node is positioned from A to obtain a basic incidence matrix A of (m-1) multiplied by n orders_c. In the above thermodynamic network, the node v of the cogeneration unit₁As a reference node, the parameters of flow, temperature, pressure and the like are set to known quantities, so that a basic correlation matrix A of 5 x 8 orders can be used_cTo represent

3.1.2) basic Loop matrix

Based on the knowledge of graph theory, for a graph containing m nodes and n edges and having n-m +1 basic loops, the relation between the basic loops and the edges of the graph can be described by a (n-m +1) × n-order basic loop matrix B, wherein the matrix element B_kjIs determined by

Representing the heat network basic loop matrix B; specifically, the above thermodynamic network can be represented by a basic loop matrix B of 3 × 8 order

3.1.3) traffic distribution in said thermodynamic network

Constructing a flow balance equation which is A_cF is 0, where F is the flow vector in each pipe;

constructing a pressure balance equation, namely B delta H is 0, wherein delta H is a pressure loss vector in each pipeline;

constructing a pressure loss vector equation, namely, delta H is K | F | F, wherein K is a resistance coefficient matrix of each pipeline;

the equations are combined to obtain a thermodynamic network equation set, and the flow and pressure loss of each branch in the thermodynamic network can be obtained by solving:

taking the above thermal network as an example, the above equations are constructed.

(1) Equation of flow balance

According to the flow continuity of the thermodynamic network, that is, the water flow injected into each node is equal to the water flow flowing out of each node, we can obtain: a. the_cF is 0, wherein F is [ F ═ F₁ f₂ f₃ f₄ f₅ f₆ f₇ f₈]^TIs the flow vector of the pipeline, f₁,f₂,...,f₈Are respectively an edge e₁,e₂,...,e₈The flow rate of (c).

(2) Equation of pressure equilibrium

In a basic circuit, the sum of the pressure losses of the water flowing in the individual lines is equal to zero, i.e. B Δ H ═ 0, where Δ H ═ Δ H₁ ΔH₂ ΔH₃ ΔH₄ ΔH₅ ΔH₆ ΔH₇ ΔH₈]^TAs vector of pressure loss in the pipe, Δ H₁,ΔH₂,...,ΔH₈Are respectively an edge e₁,e₂,...,e₈Pressure loss of (3).

(3) Vector equation of pressure loss

ΔH＝K|F|F

Wherein K is diag { K ═ K₁ K₂ K₃ K₄ K₅ K₆ K₇ K₈Is a pipeline resistance coefficient matrix of the thermodynamic network, K₁,K₂,...,K₈Are respectively a pipe e₁,e₂,...,e₈The coefficient of resistance of (a).

And (3) obtaining a thermodynamic network equation set in a simultaneous manner, wherein the equation set comprises 16 equations and 16 variables, and solving to obtain the flow and pressure loss of each branch in the thermodynamic network:

3.1.4) thermodynamic network temperature calculation

Constructing a temperature balance equation, and constructing A based on that the temperature at the initial end of the pipeline minus the temperature at the tail end of the pipeline is equal to the temperature drop on the pipeline₁，A₂A matrix, wherein,

A₁element a of_ij' satisfy

A₂Element a of_ij"satisfy

Let A ═ A₁ A₂]Then there is

Wherein T is_out＝[T_i，out]^TIs the return water temperature vector of the node, T_i,outIs the return water temperature, T, of each node_in＝[T_i，in]^TSupply water temperature vector of node, T_i,inThe temperature of the water supply for each node; taking the above thermodynamic network as an example, T_out＝[T_1,out T_2,out T_3,out T_4,out T_5,out T_6,out]^TIs the return water temperature vector of the node, T_i,outIs the return water temperature, T, of each node_in＝[T_1,in T_2,in T_3,in T_4,in T_5,in T_6,in]^TSupply water temperature vector of node, T_i,inThe temperature of the water supply for each node.

Building up heat pipe modulesThe model is used for simulating a transmission link of heat energy; assuming that the thermal conduit has a conduit radius of R_pA heat transfer coefficient of K_p(W/m²DEG C) at an ambient temperature of T_atmThe hot water temperature at the head end of the pipeline is T_sThen the hot water temperature T at l from the head end of the pipeline satisfies the following equation:

C_pfdT＝(T-T_atm)K_p·2πR_pdl

wherein C is_pIs the specific heat capacity of water and f is the flow rate of water. If the length of the pipeline is L_pThe temperature T of the hot water at the end of the pipe_eIs composed of

For the thermodynamic network, the temperature drop Δ T of the jth pipe_jIs composed of

Constructing a thermodynamic node power equation, wherein the thermodynamic node comprises a heat load node, a heat source node and a pipeline junction node;

for the pipeline junction node, the following requirements are met: t is_i,in＝T_i,out；

For the thermal load node, the thermal power consumed by the load is assumed to be P_tli，f_viFor the water flow to the injection node, P is_tli＝C_pf_vi(T_i,in-T_i,out)；

For the heat source node, assume that the thermal power produced is P_tsiThen there is P_tsi＝C_pf_vi(T_i,out-T_i,in)；

Node power equation of thermodynamic network can be constructed by integrating nodes at junctions of heat load, heat source and pipeline

P＝C_pF_v(T_in-T_out)

Wherein P ═ P_i]^TAs a node power vector, P_iFor the injection power of each node, the node of the heat load is a positive value, the node of the heat source is a negative value, and the node of the pipeline intersection is zero;

node traffic matrix F_v＝diag{f_viCan be obtained from the following formula

F_v′＝A₁F＝-A₂F＝[f_v1]^T

F_v＝diag(F_v′)

Taking the above thermodynamic network as an example, P ═ P₁ P₂ P₃ P₄ P₅ P₆]^TAs a node power vector, P_iFor the injected power of each node, the node for the heat load is a positive value, the node for the heat source is a negative value, and the node at the intersection of the pipelines is zero. Node traffic matrix F_v＝diag{f_v1 f_v2 f_v3 f_v4 f_v5 f_v6Can be obtained from the following formula

F_v'＝A₁F＝-A₂F＝[f_v1 f_v2 f_v3 f_v4 f_v5 f_v6]^T

F_v＝diag(F_v')。

3.2) modeling the thermal load

The heat load in this embodiment is mainly a building load, and for the building load, heat exchange between the indoor air and the hot water in the heat supply pipeline needs to be considered, and heat exchange between the indoor air and the external environment through the roof and the wall needs to be considered.

3.2.1) Heat transfer between indoor air and Hot Water pipes

Suppose that the supply water temperature to the building load is T_inReturn water temperature of T_outIndoor air temperature of T_roomThen there is

P_i＝k·A·(T_in-T_room)

P_i＝C_pf_vi(T_in-T_out)

Wherein, P_iThe thermal power transferred from the hot water to the indoor air of the ith node is k, the thermal convection coefficient between the hot water and the indoor air is k, and A is the area of thermal convection;

3.2.2) Heat transfer of indoor air to the external Environment

Including heat transfer from the ambient environment to the shroud, and from the shroud to the indoor air; constructing a heat transfer expression and a heat balance equation based on the different shades and their heat transfer coefficients to obtain the indoor air temperature T of the building load_room。

In practical applications, the shelter is mainly used as a roof, a wall, a window, etc. medium through which indoor air is heat exchanged with the external environment, and the heat transfer forms include heat conduction and heat convection. This heat exchange can be divided into two sub-processes, the heat transfer between the external environment and the roof, walls, windows, etc., and the heat transfer between the roof, walls, windows and the indoor air. The heat transfer process is described below using a wall as an example.

Suppose outdoor ambient temperature is T_atmWall temperature of T_wallThe heat transfer between the wall and the outdoor environment can be expressed by the following equation

Q_wall-atm,1＝k_wall,1·A_wall·(T_wall-T_atm)

Q_wall-atm＝Q_wall-atm,1+Q_wall-atm,2

Wherein Q is_wall-atmFor thermal power, Q, transferred from the wall to the outdoor environment_wall-atm,1Thermal power, Q, transferred to the outdoor environment by the wall in the form of thermal convection_wall-atm,2Thermal power, k, transferred by the wall to the outdoor environment in the form of heat conduction_wall,1Is the coefficient of thermal convection, k, between the wall and the air_wall,2Is the coefficient of thermal conductivity between the wall and the air, A_wallIs the wall area, D_wallIs the wall thickness.

The heat transfer process between the wall and the indoor air can be expressed by the following formula

Q_room-wall,1＝k_wall,1·A_wall·(T_room-T_wall)

Q_room-wall＝Q_room-wall,1+Q_room-wall,2

Wherein Q is_room-wallFor transferring heat from the room air to the wall, Q_room-wall,1For transferring heat power, Q, to the wall in the form of heat convection to the room air_room-wall,2For the heat power transferred from the indoor air to the wall in the form of heat conduction, the heat balance equation of the wall is

Wherein c is_wall is the specific heat capacity of the wall, m_wallIn order to be the quality of the wall,

is the rate of change of the wall temperature.

Similarly, for a roof, the heat transfer process with the outdoor environment can be expressed by

Q_roof-atm,1＝k_roof,1·A_roof·(T_roof-T_atm)

Q_roof-atm＝Q_roof-atm,1+Q_roof-atm

The heat transfer process between the roof and the indoor air can be expressed by the following formula

Q_room-roof,1＝k_roof,1·A_roof·(T_room-T_roof)

Q_room-roof＝Q_room-roof,1+Q_room-roof,2

The heat balance equation of the roof is

For a window, its heat transfer process with the outdoor environment can be expressed by

Q_win-atm,1＝k_win,1·A_win·(T_win-T_atm)

Q_win-atm＝Q_win-atm,1+Q_win-atm,2

The heat transfer process between the window and the indoor air can be expressed by the following formula

Q_room-win,1＝k_win,1·A_win·(T_room-T_win)

Q_room-win＝Q_room-win,1+Q_room-win,2

The thermal equilibrium equation of the window is

The naming of the parameters in the above equations may refer to the naming in the wall equation to determine the meaning of each parameter.

Building loaded indoor airTemperature T of gas_roomCan be obtained from the following formula

Wherein c is the specific heat capacity of air, m is the mass of indoor air,

is the rate of change of the indoor air temperature.

And 104, forming an electric-thermal comprehensive energy system transient simulation model based on the cogeneration unit model, the absorption refrigerator model and the thermal network model, and realizing real-time control simulation of the electric-thermal comprehensive energy system.

4.1. Building simulation model of cogeneration unit

Building a simulation model of the cogeneration unit on Simulink based on a mathematical model of the cogeneration unit;

as shown in fig. 5 and fig. 6, the simulation model of the cogeneration unit includes a gas turbine model, a heat recovery device model and a generator model, wherein the heat recovery device model calculates a thermal power P recovered by the heat recovery device from the waste heat flue gas_hrAnd thermal power P directly used therein for heat supply_hr1The heat supply mode can be that a waste heat boiler produces hot water or directly utilizes steam to supply heat energy to the building load, and the process of producing the hot water can be simulated according to the requirement; specifically, the heat recovery device model calculates the thermal power P recovered by the heat recovery device from the waste heat flue gas_hrAnd thermal power P directly used therein for heat supply_hr1And is combined with P_hr1Inputting a controlled heat flow source model which can be directly quoted from a Simulink element library as a control signal and outputting thermal power P by the controlled heat flow source model_hr1Inputting the heat exchanger model, wherein the controlled heat source model receives an input signal that sets the amount of heat output by the controlled heat source model and is therefore represented by the same symbol; the other end of the heat exchanger model is connected into a hot water pipeline network, so that the process of producing hot water is simulated. Further, the aboveThe generator model comprises a synchronous generator and an excitation system thereof in a Simscape element library of Simulink, and forms a simulation model of the cogeneration unit together with the gas turbine model and the heat recovery device model.

4.2 construction of absorption chiller simulation model

As shown in fig. 7, based on a mathematical model of an absorption refrigerator, a simulation model of a lithium bromide absorption refrigerator is constructed in Simulink, a model is constructed for an absorber, a generator, a condenser and an evaporator according to mathematical formulas of the absorber, the generator, the condenser and the evaporator, for solving a nonlinear equation set, the nonlinear equation set is firstly input into an m function file, the function file is input into an interpolated Matlab Fcn of a Simulink component library, variables to be solved of the nonlinear equation set and initial values thereof are connected with an interpolated Matlab Fcn module, and when parameters of the interpolated Matlab Fcn module are set, an fsolev function of Matlab is selected to iteratively solve the nonlinear equation set.

4.3 construction of thermal network simulation model

As shown in fig. 8, the established mathematical model of the thermal pipeline adopts pipe elements in a thermal liquid library of Simulink to construct a simulation model of the thermal pipeline and simulate a transmission link of thermal energy; the model considers the temperature drop phenomenon caused by heat exchange between hot water and the external environment, and different actual pipe network conditions can be simulated by changing parameters such as the radius, the length and the like of the model. And simulating a consumption link of heat energy through the building load simulation model to establish a heat load model.

As shown in fig. 9, the model is based on the basic law of thermodynamics, and considers heat transfer modes such as heat conduction and heat convection, including energy exchange between windows, walls, roofs and the like in buildings and the outside, wherein links such as heat convection and heat conduction are mainly built by Thermal Elements in the Simscape element library of Simulink. The energy exchange process between the window, wall, roof, etc. in the model and the outside is equivalent to the same energy exchange process, and a simplified thermal load simulation model can be obtained, as shown in fig. 10.

As shown in fig. 11, a heat load model is established by simulating a consumption link of heat energy through a building load simulation model, the heat load model is packaged into a house model, and the three house models are combined and packaged into a building model, so that a final building load simulation model is obtained. And constructing a thermal network simulation model in Simulink based on the thermal pipeline simulation model and the thermal load simulation model established above.

As shown in fig. 12, the model includes a cogeneration unit, a gas boiler, two building loads, and a multi-stage heat pipe, wherein the gas boiler model is formed by using a boiler model in a House heating system algorithm in a Simulink example library.

4.4 construction of simulation model of electric-thermal comprehensive energy system

As shown in fig. 13 and 14, an electric-thermal integrated energy system simulation model is constructed in Simulink based on the cogeneration unit simulation model, the absorption chiller simulation model, the thermal network simulation model, and the component models in the Simulink component library. Specifically, photovoltaic equipment, electric energy storage equipment, an electric load equipment model and a gas turbine of the cogeneration unit model in the Simulink element library are all connected to a 10kV bus and connected with a 35kV power distribution network through a transformer; and the heat recovery device model of the cogeneration unit model is connected into the thermal network model, and the absorption refrigerator model produces heat for heating water and the heat comes from the heat recovery device model of the cogeneration unit.

Before the simulation model of the comprehensive energy system runs, the following data input needs to be ensured to be acquired: simulation duration t_simDefault value is 86400s, i.e. time of day; the CHP output plan is a set value of the output power of a cogeneration unit in one day, the photovoltaic array power plan is a set value of the photovoltaic output power in one day, the energy storage charging and discharging plan is a set value of the charging and discharging power in one day, an electric load curve is a predicted value of the electric load size in one day, 15 minutes are taken as a time unit, 96 data points are contained in one day, and data are input into the simulation system in an excel spreadsheet mode; environmental temperature T in combined heat and power generation unit model and heat load model_atmVarying in relation to a cosine function by varying its base value T_biasAmplitude of fluctuation T_ampWhen the temperature conditions of the simulation are changed, the indoor temperature target values of the buildings in the thermal load model are respectively T_set1And T_set2。

The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are within the protection scope of the present invention.

Claims (9)

1. A modeling simulation method for operation control of an electric-thermal comprehensive energy system is characterized in that,

the method comprises the following steps:

establishing a combined heat and power generation unit model, acquiring each component of the combined heat and power generation unit and respectively establishing corresponding models;

establishing an absorption refrigerator model, acquiring each component of the absorption refrigerator, and respectively establishing a corresponding static model and a corresponding dynamic model;

establishing a thermodynamic network model;

and forming an electric-thermal comprehensive energy system transient simulation model based on the cogeneration unit model, the absorption refrigerator model and the thermal network model, and realizing real-time control simulation of the electric-thermal comprehensive energy system.

2. The method according to claim 1, wherein the establishing a cogeneration unit model comprises:

the combined heat and power generator comprises a gas turbine, a generator and a heat recovery device; correspondingly, a gas turbine mathematical model is established based on the Rowen model; establishing a mathematical model of the heat recovery device; establishing a mathematical model of the generator; calculating the heat power P recovered by the heat recovery device from the waste heat smoke_hrDirectly used for heat supply_hr1And inputting the thermal power of the absorption refrigerator, wherein the heat supply mode is to input a waste heat boiler to produce hot water or directly utilize steam to supply heat energy to the building load.

3. The method of claim 2, comprising:

1.1) establishing a gas turbine mathematical model based on a Rowen model, wherein the gas turbine mathematical model comprises a speed controller model, a waste heat flue gas temperature controller model, an acceleration controller model, a fuel system model, a compressor and turbine model;

1.1.1) the speed controller model is used for scheduling instructions P according to power_setAnd the actual output P of the generator_eAdjusting the output power of the generator to enable the cogeneration unit to work according to a power dispatching instruction; and also for the dependence on the nominal speed omega_refWith the actual speed omega of the generator_rAdjusting the rotation speed of a prime mover to keep the frequency of the generator stable; the method specifically comprises the following steps:

wherein, V_ce0Speed command, K, output for speed controller_DroopIs the droop coefficient, T is the time constant, K_pAnd K_iProportional parameters and integral parameters for PI regulation;

1.1.2) the waste heat flue gas temperature controller model is linked with the compressor and turbine model, and the waste heat flue gas temperature calculated by the compressor and turbine model is used as input to ensure the waste heat flue gas temperature T_exhaustMaintained at a temperature reference value T_ref；

The waste heat flue gas temperature controller model comprises a radiation shielding module, a thermal coupling module and a PI controller module, wherein the radiation shielding module and the thermal coupling module are used for simulating time delay caused by corresponding modules in an actual temperature measuring device;

based on the waste heat flue gas temperature controller model, the speed instruction upper limit value V output by the speed controller_{ce_limit1}：

Wherein, T_rs1、T_rs2，T_thFor radiation shielding and thermal coupling coefficients, K_pAnd K_iProportional parameters and integral parameters adjusted by the PI controller module;

1.1.3) the acceleration controller model is used for reducing thermal stress by limiting the acceleration of the rotor when the gas turbine is started and is also used for limiting the rotating speed of the generator rotor during the operation of the gas turbine;

based on the acceleration controller model, the speed command upper limit value V output by the speed controller_{ce_limit2}：

Wherein, T_inertiaIs the inertia constant of the rotor of the generator;

speed command V of speed regulator_ce0After amplitude limiting, the final speed regulating signal V is obtained_ceMin represents taking the minimum value:

V_ce＝min{V_ce0,V_{ce_limit1},V_{ce_limit2}}；

1.1.4) the fuel system model is used for calculating the consumed power of the fuel of the gas turbine according to the control instruction of the speed controller, and comprises a valve regulation module and a fuel regulation module;

wherein the power consumption is related to the delay of the gas valve and the gas turbine performs work W on the gas turbine_fThe method specifically comprises the following steps:

wherein, T_vpIs the time constant of the valve regulating module, T_fsIs the time constant of the fuel regulating module, K_initIs the minimum per unit value of work done for the gas turbine;

taking into account the ambient temperature T_atmTo fuel combustion efficiency eta_fuelInfluence of η_fuelAnd T_atmThe relation between the two is described by a function, and the work of the gas turbine on the gas turbine is calculated to be W under a certain environmental temperature_fFuel P required by gas turbine_fuel(ii) a When the output of the cogeneration unit is P_eWhen it is used, its electrical efficiency is eta_eleThe specific function is:

based on the above function, the thermal power P in the waste heat flue gas_exhaustIs composed of

P_exhaust＝P_fuel(1-η_fuel)

1.1.5) the compressor and turbine model is used for executing a fuel control signal instruction issued by the fuel system and calculating the torque T output by the turbine_mAnd the temperature T of the exhaust gas_exhaustThe method specifically comprises the following steps:

wherein, K_HHVIs a coefficient related to enthalpy, T_refIs the exhaust gas reference temperature, is the set value, T_CRDelay time for combustion reaction, T_TDFor delay of transit time of turbine exhaust system, T_CDIs the time constant of the compressor displacement;

1.2) establishing a mathematical model of a heat recovery device

The heat recovery device is used for recovering the heat of the waste heat flue gas generated by the gas turbine mathematical model, and part of the heat is input into a waste heat boiler model or a heat load model and part of the heat is input into the absorption refrigeration unit model; establishing a mathematical model of the heat recovery device based on the basic laws of energy conservation and thermodynamics;

the energy conservation equation of the cogeneration unit is as follows:

P_fuel＝W_f+P_loss+P_exhaust

wherein, P_fuelAs fuel combustion power, W_fPower for steam to work gas turbine, P_exhaustIs the thermal power, P, of the waste heat flue gas of a gas turbine_lossIs the power loss;

the energy conservation equation of the heat recovery device is as follows:

P_hr＝P_exhaust×η_hr

P_hr1＝(1-δ)P_hr

P_hr1＝C_pwf_w(T_w,out-T_w,in)

wherein, P_hrThermal power, P, recovered for the heat recovery device_hr1Delta is the proportion of the recovered heat which flows to the absorption refrigerating unit, eta is the thermal power for supplying heat_hrFor the efficiency of the heat recovery device, C_pwIs the specific heat capacity of water, f_wIs the flow rate of water in the heat distribution pipeline, T_w,in，T_w,outThe temperature of a water inlet and the temperature of a water outlet of the heat recovery device are respectively;

the efficiency equation of the heat recovery device is as follows

Wherein, T_ex,inFor gas temperature at the inlet of the heat recovery device, T_ex,outFor the gas temperature at the outlet of the heat recovery device, T_atmIs ambient temperature;

thermal efficiency eta of cogeneration unit_heatIs composed of

Total efficiency eta of combined heat and power generation unit_CHPIs composed of

4. The method of claim 1, wherein the establishing an absorption chiller model, obtaining each component of the absorption chiller and establishing a corresponding static model and dynamic model respectively comprises:

the absorption refrigerator comprises a heat exchanger, a solution pump, an absorber, a condenser, a generator and an evaporator;

respectively establishing static models of the heat exchanger, the solution pump, the absorber, the condenser, the generator and the evaporator, respectively solving based on the static models, and respectively calculating heat transfer coefficients UA of the absorber, the generator, the condenser and the evaporator_a，UA_g，UA_cAnd UA_eAnd establishing a heat transfer coefficient model of each component of the absorption refrigerator, thereby obtaining a dynamic model of the absorption refrigerator.

5. The method of claim 4, comprising:

the working medium in the absorption refrigerator is a lithium bromide aqueous solution, and each component constructs a static mathematical model based on a mass conservation principle and an energy conservation principle;

2.1) construction of the static model of the absorption chiller

2.1.1) construction of a static mathematical model of an absorber

In the absorber, the lithium bromide concentrated solution absorbs the water vapor generated in the evaporator to form a lithium bromide dilute solution, and the heat generated by diluting the lithium bromide solution is generated byCooling water absorption; the lithium bromide dilute solution is driven by the solution pump to flow to the generator through the heat exchanger, so as to start circulation; this process follows the equation of conservation of energy, Q_aThe total heat released in the absorber per second is equal to the heat absorbed by the cooling water flowing through the absorber, and is also equal to the difference between the enthalpy of the substance flowing into the absorber and the enthalpy of the substance flowing out of the absorber, i.e.:

Q_a＝f_cC_pc(T₁₀-T_c,in)

Q_a＝f₅h₅+f₈h₈-f₁h₁

this process follows conservation of mass, including conservation of mass of the lithium bromide solution and conservation of mass of the lithium bromide solute, namely:

f₁＝f₅+f₈

f₁X₁＝f₅X₅

wherein, T₁₀Is the temperature of the cooling water outlet of the absorber/cooling water inlet of the condenser, T_c，inTemperature of cooling water flowing into the absorber, f_cFor the flow rate of cooling water, C_pcThe specific heat capacity of the cooling water;

2.1.2) constructing a static mathematical model of the Generator

In the generator, the lithium bromide dilute solution is driven by the solution pump, flows in from the absorber through the heat exchanger, is heated and evaporated in the generator, is separated into water vapor and lithium bromide concentrated solution, the water vapor flows in the condenser, and the lithium bromide concentrated solution flows back to the absorber through the heat exchanger; this process follows conservation of energy, Q_gThe total heat absorbed in the generator per second is equal to the heat released by the heating water and also equal to the difference between the enthalpy of the substance flowing out of the generator and the enthalpy of the substance flowing into the generator, i.e.:

Q_g＝f_gC_pg(T_g,in-T_g,out)

Q_g＝f₄h₄+f₆h₆-f₃h₃

this process follows conservation of mass, including conservation of mass of the lithium bromide solution and conservation of mass of the lithium bromide solute, namely:

f₃＝f₄+f₆

f₃X₃＝f₄X₄

wherein f is_gFor heating the flow of water, C_pgFor heating the specific heat capacity of the water, T_g，in、T_g，outThe temperatures of the heated water flowing into and out of the generator, respectively;

2.1.3) constructing a static mathematical model of the condenser

In the condenser, the water vapor flowing from the generator is condensed and then flows toward the evaporator; this process follows conservation of energy, Q_cThe total quantity of heat released in the condenser per second is equal to the quantity of heat absorbed by the cooling water flowing through the condenser, and is also equal to the difference between the enthalpy of the water vapor flowing into the condenser and the enthalpy of the condensed water flowing out of the condenser, i.e., the difference is

Q_c＝f_cC_pc(T_c,out-T₁₀)

Q_c＝f₆h₆-f₇h₇

This process follows the conservation of mass of the water species, namely:

f₆＝f₇

wherein f is_cFor cooling water flow, C_pcFor the specific heat capacity of the cooling water, T₁₀Is the temperature of the cooling water outlet of the absorber/cooling water inlet of the condenser, T_c，outThe temperature of the cooling water outlet of the condenser;

2.1.4) constructing a static mathematical model of the evaporator

In the evaporator, water flows into the evaporator from the condenser to cool and evaporate, and heat is absorbed from a refrigerating water pipeline, the refrigerating water in the refrigerating water pipeline forms a refrigerating cycle, water vapor formed in the evaporator is absorbed by the lithium bromide concentrated solution in the absorber to enter the absorber, and the next cycle is started; this process follows energyConservation, Q_eThe total heat absorbed in the evaporator per second is equal to the heat released by the cooling water flowing through the evaporator and also equal to the difference between the enthalpy of the water vapor leaving the evaporator and the enthalpy of the condensed water flowing into the evaporator, i.e.:

Q_e＝f_eC_pe(T_e,out-T_e,in)

Q_e＝f₈h₈-f₇h₇

this process follows the conservation of mass of the water species,

f₇＝f₈

wherein f is_eFor the flow of refrigerating water, C_peSpecific heat capacity of refrigerating water, T_e，out、T_e，inThe inflow temperature and the outflow temperature of the refrigeration water flowing through the evaporator are respectively;

2.1.5) construction of a static mathematical model of a solution Pump

The dilute lithium bromide solution is driven by the solution pump, flows from the absorber to the generator through the heat exchanger, and the process follows the mass conservation equation, including the mass conservation of the lithium bromide solution and the mass conservation of the lithium bromide solute, namely:

f₁＝f₂

X₁＝X₂

this process follows conservation of energy, namely:

wherein, W_pElectric power consumed for solution pumps, P_cIs the ambient pressure, P, of the heat exchanger_eIs the ambient pressure of the absorber, eta_pThe efficiency of the solution pump;

2.1.6) constructing a static mathematical model of a Heat exchanger

In a heat exchanger, the lithium bromide concentrated solution from the generator exchanges heat with the lithium bromide dilute solution from the absorber, and this process follows conservation of energy, and the amount of heat absorbed by the lithium bromide dilute solution flowing from the absorber to the generator is equal to the amount of heat released by the lithium bromide concentrated solution flowing from the generator back to the absorber, i.e. the amount of heat is equal to the amount of heat released by the lithium bromide concentrated solution flowing from the generator back to the absorber

f₃h₃-f₂h₂＝f₄h₄-f₅h₅

The mass conservation of the lithium bromide solution and the lithium bromide solute in the process is shown in the following equation

f₂＝f₃ X₂＝X₃

f₄＝f₅，X₄＝X₅

The temperature of the solution in the heat exchanger is related to the heat exchanger coefficient epsilon, and the equation is as follows

T₁＝T₂

T₅＝T₄-ε(T₄-T₂)

2.1.7) calculating the refrigeration coefficient

Coefficient of performance COP_coolEqual to the refrigerating capacity Q of the absorption refrigerator_eEnergy Q required for producing heating water with absorption refrigerator_gAnd the solution pump consumes energy W_pThe ratio of (A) to (B) is as follows:

Q_e+Q_g+W_p＝Q_a+Q_c

2.2) construction of dynamic model of absorption chiller

Based on the above-established static model of each component, its operating point temperature T₁，T₄，T₇，T₈For the set value, the solution based on the static model of each component is carried out by introducing the log mean temperature LMTDThe results calculate the heat transfer coefficients UA of the absorber, generator, condenser and evaporator, respectively_a，UA_g，UA_cAnd UA_eEstablishing a heat transfer coefficient model of each component in the absorption refrigerator model so as to obtain a dynamic model of the absorption refrigerator;

2.2.1) mathematical model of the absorber

Q_a＝UA_aLMTD_a

Therein, UA_aIs the heat transfer coefficient of the absorber, LMTD_aIs the logarithmic mean temperature difference of the absorber;

2.2.2) mathematical model of the Generator

Q_g＝UA_gLMTD_g

Therein, UA_gFor the heat transfer coefficient of the generator, LMTD_gIs the logarithmic mean temperature difference of the generator;

2.2.3) mathematical model of the condenser

Q_c＝UA_cLMTD_c

In which UA_cIs the heat transfer coefficient of the condenser, LMTD_cIs the logarithmic mean temperature difference of the condenser;

2.2.4) mathematical model of the evaporator

Q_e＝U_eA_eLMTD_e

Therein, UA_eAs heat transfer coefficient of evaporator, LMTD_eIs the logarithmic mean temperature difference of the evaporator;

2.2.5) efficiency calculation

P_cool＝Q_e

Wherein the COP_coolRefrigeration coefficient, P, for absorption chiller model_coolEta when the energy for producing the heating water is derived from the heat recovered by the model of the cogeneration unit for absorbing the refrigerating power of the model of the refrigerating machine_coolTo consume the refrigeration efficiency of the fuel with respect to the cogeneration unit model.

6. The method of claim 1, wherein the establishing a thermodynamic network model comprises:

the heat network model comprises a heat source module, a pipeline module and a building load, wherein the heat source module is steam directly generated by the cogeneration unit module or hot water generated by a gas boiler and is transported to the building load through the pipeline module, and the cooled water flows back to the cogeneration unit module or the gas boiler through the pipeline module to be continuously heated, so that heat network circulation is realized;

setting a heat source module and a building load in the thermal network model as a plurality of nodes, setting a pipeline module as a plurality of edges to form a graph theory, and establishing the thermal network model based on the graph theory.

7. The method of claim 6, wherein said modeling a thermodynamic network further comprises

3.1.1) basic correlation matrix

Based on the graph theory knowledge, for a directed graph containing m nodes and n edges, an incidence matrix A of m multiplied by n orders can be used for representing each node and each edge of the structure graph of the thermodynamic network, wherein a matrix element a_ijIs determined by

Node v of the combined heat and power generation unit model₁Setting the parameters of the combined heat and power generation unit model as known quantities to obtain a basic incidence matrix A as reference nodes_c；

3.1.2) basic Loop matrix

Based on the knowledge of graph theory, for a graph containing m nodes and n edges and having n-m +1 basic loops, the relation between the basic loops and the edges of the graph can be described by a (n-m +1) × n-order basic loop matrix B, wherein the matrix element B_kjIs determined by

Representing the heat network basic loop matrix B;

3.1.3) traffic distribution in said thermodynamic network

Constructing a flow balance equation of

A_cF＝0

Wherein F is the flow vector in each pipeline;

constructing a pressure balance equation of

BΔH＝0

Wherein Δ H is the pressure loss vector in each pipe;

constructing a vector equation of pressure loss, i.e.

ΔH＝K|F|F

Wherein K is a resistance coefficient matrix of each pipeline;

the equations are combined to obtain a thermodynamic network equation set, and the flow and pressure loss of each branch in the thermodynamic network can be obtained by solving:

3.1.4) thermodynamic network temperature calculation

Constructing a temperature balance equation, and constructing A based on that the temperature at the initial end of the pipeline minus the temperature at the tail end of the pipeline is equal to the temperature drop on the pipeline₁，A₂A matrix, wherein,

A₁element a of_ij' satisfy

A₂Element a of_ij"satisfy

Let A ═ A₁ A₂]

A'^TT＝ΔT

Then there is T ═ T_out T_in]

Wherein T is_out＝[T_i，out]^TIs the return water temperature vector of the node, T_i,outIs the return water temperature, T, of each node_in＝[T_i，in]^TSupply water temperature vector of node, T_i,inThe temperature of the water supply for each node;

constructing a model of the thermal pipeline module for simulating a transmission link of heat energy; assuming that the thermal conduit has a conduit radius of R_pA heat transfer coefficient of K_p(W/m²DEG C) at an ambient temperature of T_atmThe hot water temperature at the head end of the pipeline is T_sThen the hot water temperature T at a distance of l from the head end of the pipeline satisfies the following equation

C_pfdT＝(T-T_atm)K_p·2πR_pdl

Wherein C is_pIs the specific heat capacity of water, and f is the flow rate of water; if the length of the pipeline is L_pThe temperature T of the hot water at the end of the pipe_eIs composed of

For the thermodynamic network, the temperature drop Δ T of the jth pipe_jIs composed of

Constructing a power equation of the thermal nodes, wherein the thermal nodes comprise heat load nodes, heat source nodes and pipeline junction nodes;

for the pipeline junction node, satisfy

T_i,in＝T_i,out

For the thermal load node, the thermal power consumed by the load is assumed to be P_tli，f_viFor the water flow to fill the node, there are

P_tli＝C_pf_vi(T_i,in-T_i,out)

For the heat source node, assume that the thermal power produced is P_tsiThen there is

P_tsi＝C_pf_vi(T_i,out-T_i,in)

Node power equation of thermodynamic network can be constructed by integrating nodes at junctions of heat load, heat source and pipeline

P＝C_pF_v(T_in-T_out)

Wherein P ═ P_i]^TAs a node power vector，P_iFor the injection power of each node, the node of the heat load is a positive value, the node of the heat source is a negative value, and the node of the pipeline intersection is zero;

node traffic matrix F_v＝diag{f_viCan be obtained from the following formula

F_v′＝A₁F＝-A₂F＝[f_v1]^T

F_v＝diag(F_v′)；

3.2) modeling the thermal load

3.2.1) Heat transfer between indoor air and Hot Water pipes

Suppose that the supply water temperature to the building load is T_inReturn water temperature of T_outIndoor air temperature of T_roomThen there is

P_i＝k·A·(T_in-T_room)

P_i＝C_pf_vi(T_in-T_out)

Wherein, P_iThe thermal power transferred from the hot water to the indoor air of the ith node is k, the thermal convection coefficient between the hot water and the indoor air is k, and A is the area of thermal convection;

3.2.2) Heat transfer of indoor air to the external Environment

Including heat transfer from the ambient environment to the shroud, and from the shroud to the indoor air; constructing a heat transfer expression and a heat balance equation based on the different shades and their heat transfer coefficients to obtain the indoor air temperature T of the building load_room。

8. The method according to claim 1, wherein the step of forming an electric-thermal integrated energy system transient simulation model based on the cogeneration unit model, the absorption chiller model and the thermal network model, and the step of implementing the real-time control simulation of the electric-thermal integrated energy system comprises:

4.1) construction of simulation model of cogeneration unit

Building a simulation model of the cogeneration unit on Simulink based on a mathematical model of the cogeneration unit;

the simulation model of the cogeneration unit comprises a gas turbine model, a heat recovery device model and a generator model, wherein the heat recovery device model calculates the thermal power P recovered by the heat recovery device from the waste heat and the flue gas_hrAnd thermal power P directly used therein for heat supply_hr1And simulating the process of producing hot water;

the generator model comprises a synchronous generator and an excitation system thereof in a Simscape element library of Simulink;

4.2) construction of simulation model of absorption refrigerator

Based on a mathematical model of the absorption refrigerator, constructing a simulation model of the lithium bromide absorption refrigerator on Simulink, iterating a nonlinear equation set in the model by using a fsolve function of Matlab, inputting a function file of the nonlinear equation set into an Interpreted Matlab Fcn of a Simulink element library, connecting corresponding input quantity and providing an initial value of a variable to be solved, and solving the nonlinear equation set;

4.3) constructing a thermal network simulation model

The established mathematical model of the thermal pipeline adopts pipe elements in a thermal liquid library of Simulink to construct a simulation model of the thermal pipeline and simulate a transmission link of heat energy;

simulating a consumption link of heat energy through a building load simulation model, establishing a heat load model, packaging the heat load model into a house model, and packaging the three house models into a building model in a combined manner, thereby obtaining a final building load simulation model;

constructing a thermal network simulation model in Simulink based on the thermal pipeline simulation model and the thermal load simulation model established above;

4.4) establishing simulation model of electric-thermal comprehensive energy system

And an electric-thermal comprehensive energy system simulation model constructed in the Simulink is based on the combined heat and power generation unit simulation model, the absorption refrigeration machine simulation model, the thermal power network simulation model and the component models in the Simulink component library.

9. The method of claim 8, further comprising,

the electric-thermal comprehensive energy system simulation model is constructed, and the following data are input:

simulation duration t_sim；

Ambient temperature T varying as a function of the cosine_atmIncluding the associated parameter base value T_biasAnd the fluctuation amplitude T_amp；

The indoor temperature target value of the building is T_set1And T_set2；

The CHP output plan is a set value of the output power of the cogeneration unit in one day;

photovoltaic array output plan, namely a set value of photovoltaic output power in one day;

an energy storage charging and discharging plan, namely a set value of charging and discharging power in one day;

and (4) an electric load curve, namely a predicted value of the electric load in one day.

Images