A combined cooling, heating and power system based on geothermal energy and a method for operating control thereof

Abstract

The application discloses a kind of based on geothermal energy's combined cooling heating and power system and its operation control method, the combined cooling heating and power system includes: middle-deep layer geothermal extraction circulation system, geothermal power generation system, high-temperature heating system, hot refrigerating unit, electric refrigerating unit, PV power generation system, PTST power generation system, heat collection system and heat storage system.In the technical scheme provided by the application, a CCHP system integrating photovoltaic, geothermal energy and solar energy is provided, which improves the diversity and coordination of the system's comprehensive energy and can improve energy use efficiency.In the novel operation control method provided by the application, the optimization of economic indicators and energy consumption indicators in the system is taken as the control target, which can improve the coordination and utilization rate of comprehensive energy.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of new energy power generation, and particularly relates to a combined cooling heating and power system based on geothermal energy and an operation control method thereof. BACKGROUND

[0002] Recent researches show that it is necessary to combine traditional CCHP (Combined Cooling Heating and Power) system with new energy; for example, a microgrid operation optimization model containing various new energy power modules is established, and the coordinated scheduling and conversion among various energies in the microgrid are realized; a CCHP system with a solar photovoltaic panel and a solar collector is established, and it is fully proved that the energy saving and emission reduction performance of the system is better after the introduction of solar energy resources.

[0003] With the increasing penetration speed of new energy type CCHP system, a series of constraints are faced in the innovation of system structure; among them, new energy is used to provide heat energy, and this single utilization form becomes the main reason for restricting the application innovation of CCHP system.

[0004] In addition, the CCHP system has a complex structure, multiple energy form conversion links, and simultaneously outputs heat energy and electric energy, and is usually operated in a "heat determines electricity" or "electricity determines heat" mode; how to realize the maximum utilization efficiency of comprehensive energy and fully exert the advantage that the comprehensive energy efficiency of such system can reach 75% to 90% is the research focus in this field in recent years.

[0005] In summary, the current traditional energy structure still needs to be improved in improving the utilization rate and coordination of new energy; the traditional operation strategy still has great limitations in optimizing various indicators in actual application; therefore, a new combined cooling heating and power system and an operation control method thereof are urgently needed. SUMMARY

[0006] The present application aims to provide a combined cooling heating and power system based on geothermal energy and an operation control method thereof to solve one or more technical problems described above. In the technical solution provided by the present application, a CCHP system integrating photovoltaic, geothermal energy and solar energy is provided, which improves the diversity and coordination of comprehensive energy of the system and can improve the energy use efficiency; in the new operation control method provided by the present application, the optimization of economic and energy consumption indicators in the system is taken as the control target, which can improve the coordination and utilization rate of comprehensive energy.

[0007] To achieve the above-mentioned purposes, the present application adopts the following technical solutions:

[0008] The application provides a cold-heat-power combined supply system based on geothermal energy, which comprises a middle-deep geothermal extraction circulation system, a geothermal power generation system, a high-temperature heat supply system, a heat refrigerator unit, an electric refrigerator unit, a PV power generation system, a PTST power generation system, a heat collection system and a heat storage system.

[0009] The middle-deep geothermal extraction circulation system comprises at least a flow divider and a water pump, and is used for extracting middle-deep geothermal energy and flowing to the geothermal power generation system and the high-temperature heat supply system through the water pump and the flow divider respectively.

[0010] The geothermal power generation system is used for converting geothermal energy into electric energy and supplying the electric network.

[0011] The high-temperature heat supply system comprises a high-temperature heat exchanger and a high-temperature heat storage subsystem, and is used for meeting a heat load through part of geothermal energy and outputting another part of geothermal energy.

[0012] The heat refrigerator unit is used for refrigerating to meet a cold load through the geothermal energy output by the high-temperature heat supply system, and the electric refrigerator unit is used for refrigerating to meet the cold load through the electric energy input by the electric network.

[0013] The PV power generation system is used for converting solar energy into electric energy through photovoltaic power generation and supplying the electric network.

[0014] The PTST power generation system is used for converting solar energy into electric energy through a trough type solar thermal power generator and supplying the electric network.

[0015] The heat storage system is used for storing excess heat when the cold-heat-power combined supply system collects more heat than the required heat, and releasing heat when the collected heat is less than the required heat.

[0016] The heat collection system is used for collecting heat energy from solar energy, part of which flows into the PTST power generation system to generate power, and the rest of which is stored in the heat storage system.

[0017] The application further improves that the backwater of the high-temperature heat supply system after heat exchange is injected back to the ground through an injection pump for the next round of middle-deep geothermal extraction.

[0018] The application further improves that the working medium of the high-temperature heat supply system is heat conducting oil.

[0019] The application provides an operation control method of a cold-heat-power combined supply system based on geothermal energy, which comprises the following steps.

[0020] Step 1: obtaining user load and initial power device capacity in the high-temperature heat supply system, wherein the power device capacity at least comprises the number and capacity of heat pump units.

[0021] Step 2, based on the obtained user load, power device capacity, the heat-to-power ratio of the combined cooling, heating and power system and the user load heat-to-power ratio are calculated;

[0022] Step 3, the heat-to-power ratio of the combined cooling, heating and power system and the user load heat-to-power ratio obtained in step 2 are compared to determine the operation strategy; when the user load heat-to-power ratio is greater than the heat-to-power ratio of the combined cooling, heating and power system, the heat-fixed power operation mode is selected; when the user load heat-to-power ratio is less than or equal to the heat-to-power ratio of the combined cooling, heating and power system, the power-fixed heat operation mode is selected;

[0023] Step 4, based on the operation strategy determined in step 3, the economic indicators and energy consumption indicators of the combined cooling, heating and power system are obtained and it is judged whether the optimal value is reached; if not, the capacity and number of the heat pump unit are changed to obtain a new power device capacity and steps 2 to 4 are repeated until the indicators reach the optimal value, the final power device capacity is obtained, and the operation control of the combined cooling, heating and power system is realized.

[0024] Further improvement of the application is that in step 1, the obtained user load is the average daily user load in summer or winter.

[0025] Further improvement of the application is that in step 2,

[0026] 1) the heat-to-power ratio HPR of the combined cooling, heating and power system C The calculation expression is,

[0027]

[0028] In the formula, Q PR is the system heat supply; W PR is the system power supply;

[0029] Q PR = Q HO t -E hbio ;

[0030] In the formula, Q HO t is the heat provided by the heat supply side of the high-temperature heat supply system to the load; E hbio is the input heat of the heat refrigerator unit;

[0031] Q HO t = m E t Q = m HDR Q;

[0032] In the formula, m E t is the mass flow rate of the flow to the high-temperature heat supply system after the flow is divided by the flow dividing valve; m HDRQ is the mass flow rate of geothermal working medium flowing to the heat extraction cycle after being branched by the flow distribution valve; Q is the heat value of unit flow;

[0033] When the combined cooling heating and power system buys electricity from the power grid, W PR = E buy + E ppho + E ptro ;

[0034] When the combined cooling heating and power system sells electricity to the power grid, W PR = E sell + E ppho + E ptro ;

[0035] In the formula, E buy is the electricity bought by the combined system from the power grid; E sell is the electricity sold by the combined system to the power grid; E ppho is the electricity generated by the PV power generation system; E ptro is the electricity generated by the PTST power generation system.

[0036] 2) The calculation expression of the user load heat-electricity ratio HPR U is,

[0037]

[0038] In the formula, Q US is the heat required by the user heat load; W US is the electricity required by the user electricity load.

[0039] Further improvement of the present application is that, in step 3,

[0040] The heat-fixed electricity operation mode includes: the high-temperature heat supply system preferentially provides heat energy for the system heat load or cold load, and the generated electricity is supplied to the electricity load; if the heat generated under the maximum load is still insufficient to meet the user demand, the heat storage system is used for supplement; on this basis, another part of the electricity load is provided by the PV power generation system and the PTST power generation system, and if the electricity is insufficient, it is purchased from the power grid, and if there is excess electricity, it is sold to the power grid.

[0041] The electricity-fixed heat operation mode includes: the electricity load demand is preferentially supplied by the PV power generation system and the PTST power generation system, and if there is excess electricity, it is sold to the power grid; the cold and heat load at the user end is provided by the high-temperature heat supply system, and the PV power generation system and the PTST power generation system generate electricity to provide to the user; when the heat load is satisfied and the electricity load is not satisfied, the geothermal power generation system continues to operate to generate electricity to provide to the user.

[0042] Further improvement of the present application is that, in step 4,

[0043] The economic index is the equal-year investment cost, and the expression is,

[0044] In the formula, Y CoST is the equal-year investment cost; d is the discount rate; and l is the system expected life;

[0045] The model of the energy consumption index is expressed as,

[0046] In the formula, Y CON is the energy consumption; E buy is the electricity quantity bought from the power grid by the combined heat and power system; η gen is the power generation efficiency of the power generation system; and sigma e is the primary energy conversion coefficient corresponding to the heat energy consumed per kWh of purchased electricity.

[0047] Further improvement of the present application is that, in step 4, based on the operation strategy determined in step 3, the economic index and the energy consumption index of the combined heat and power system are obtained, and it is judged whether the optimal value is reached,

[0048] The expression of the economic index and the expression of the energy consumption index are taken as two objective functions, the objective function values of the two objective functions obtained by using the hill climbing algorithm optimization are obtained, and the optimized economic index and energy consumption index are obtained.

[0049] Compared with the prior art, the present application has the following beneficial effects:

[0050] The combined heat and power system based on geothermal energy provided by the present application is a combined heat and power system mainly using solar thermal power generation and supplemented by photovoltaic and medium-deep geothermal power generation. Specifically, aiming at the technical defect that the new energy is used in a single form in the current traditional CCHP system, the present application constructs a micro energy network based on PV / PTST-CCHP, which has the energy supply capabilities of power generation, heat supply and cold supply. The system of the present application is composed of a medium-deep geothermal energy extraction cycle, a geothermal power generation system, a heat storage device, a high-temperature heat supply system and a reinjection system, and can realize the extraction, storage and utilization of geothermal energy. The power sources in the power grid are composed of renewable energy sources such as wind, light and geothermal power generation system. In summary, the technical scheme provided by the present application has the characteristic of diversified comprehensive energy use, and solves the technical problem of single energy utilization form in the prior art.

[0051] In the operation control method of the present application, the operation strategy with higher fitness is proposed to analyze the energy consumption under different situations and adjust the strategy, so as to optimize the energy consumption index and the economic index. Specifically, aiming at the technical defects that the operation strategy of the existing CCHP system cannot realize the maximum energy comprehensive utilization efficiency and the index optimization, the present application provides a method for calculating the heat and power ratio HPR of the combined heat and power systemC and user load heat power ratio HPR U The ratio of the two, so as to judge the specific operation strategy, and then calculate the economic indicators and energy consumption indicators of the system and judge whether the indicators reach the optimal scheme; The technical scheme of the present application helps to make the design parameters and operation strategy of the system complementary, which can improve the comprehensive performance evaluation index of the system, and solves the technical problems of the above-mentioned inability to maximize energy use efficiency and optimization of indicators. BRIEF DESCRIPTION OF DRAWINGS

[0052] In order to more clearly illustrate the technical scheme in the embodiments of the present application or the prior art, the following briefly introduces the drawings needed to be used in the embodiment or prior art description; Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0053] Figure 1 is a principle schematic block diagram of a combined cooling, heating and power supply system based on geothermal energy provided by the embodiment of the present application;

[0054] Figure 2 is a flow schematic block diagram of an operation control method of a combined cooling, heating and power supply system based on geothermal energy provided by the embodiment of the present application. DETAILED DESCRIPTION

[0055] In order to make the personnel in the technical field better understand the present application scheme, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0056] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0057] The application will be described in further detail below with reference to the drawings:

[0058] The application discloses a combined cooling, heating and power supply system based on geothermal energy, which comprises a middle-deep geothermal extraction circulation system, a geothermal power generation system, a high-temperature heating system, a thermal refrigeration unit, an electric refrigeration unit, a PV power generation system, a PTST power generation system, a heat collection system and a heat storage system.

[0059] The middle-deep geothermal extraction circulation system comprises a shunt valve and a water pump, and the high-temperature heating system comprises a high-temperature heat exchanger and a high-temperature heat storage subsystem; the middle-deep geothermal extraction circulation system is used for extracting middle-deep geothermal energy and flowing to the geothermal power generation system and the high-temperature heating system through the water pump and the shunt valve respectively, the geothermal power generation system is used for converting geothermal energy into electric energy and supplying the electric grid, and the high-temperature heating system is used for meeting a heat load with part of the geothermal energy and outputting another part of the geothermal energy; the thermal refrigeration unit is used for refrigerating to meet a cold load through the geothermal energy output by the high-temperature heating system; the PV power generation system is provided with a photovoltaic array, the photovoltaic array is used for photovoltaic power generation to convert solar energy into electric energy and supply the electric grid; and the PTST power generation system is provided with a trough type solar thermal power (PTST) generator set, the trough type solar thermal power (PTST) generator set is used for converting solar energy into electric energy and supplying the electric grid.

[0060] The heat storage system is used for storing excess heat energy when the combined cooling, heating and power supply system collects more heat than required, and releasing heat when the heat collection is insufficient; and the heat collection system is used for collecting heat energy from solar energy, part of which flows into the PTST power generation system to generate power, and the excess heat energy is stored in the heat storage unit for heat storage.

[0061] Optionally, the high-temperature heating system returns the water to the ground through a reinjection pump for a new round of heat extraction after heat exchange.

[0062] Please refer to Figure 1In the cold and heat combined power supply system based on geothermal energy, the photovoltaic array belongs to a PV power generation system, the heat collection field belongs to a heat collection system, and the shunt valve and the reinjection pump belong to a middle-deep layer geothermal extraction circulation system.

[0063] In the embodiment of the present application, the total electric load amount EL can be composed of the above three parts of electric quantity, E buy and E sell are the grid supplementary electric quantity and more than the sold electric quantity, respectively; the cold network satisfies the cold load through two ways of heat refrigeration and electric refrigeration, and the cold load demand CL of the system is supplied by the heat refrigeration unit and the electric refrigeration unit.

[0064] In the embodiment of the present application, the PV / PTST-CCHP heat and power supply operation mode is as follows: the middle-deep layer geothermal energy extraction circulation system constitutes a double-well system through the shunt valve and the reinjection pump, the heat of the middle-deep layer geothermal energy is distributed to the high-temperature heat supply system and the geothermal power generation system through the shunt valve, and flexible scheduling of heat and electricity is realized; the high-temperature heat supply system can supply heat for the high-temperature heat load and the heat refrigeration unit. In addition, the parabolic trough solar thermal (PTST) power generation technology is introduced in the embodiment of the present application, and the photovoltaic (PV) power generation and the middle-deep layer geothermal energy power generation are auxiliary; the solar energy utilization form in the system of the present application is also different from the previous solar energy collector, and the parabolic trough solar power generation system generates electric energy and provides the electric energy to the user or the large power grid.

[0065] The technical scheme provided by the above embodiment of the present application is based on the PV / PTST-CCHP micro energy network with multiple energy supply capabilities such as power generation, heat supply and cold supply, and the target of improving the coordination between various energies and the single utilization form of new energy is achieved.

[0066] Referring to Figure 2 The operation control method of the above-mentioned combined cooling heating and power system based on geothermal energy provided by the embodiment of the present application comprises the following steps:

[0067] Step 1, obtaining user load and initial power device capacity in high-temperature heating system; the power device capacity comprises the number and capacity of heat pump units;

[0068] Step 2, calculating the combined cooling heating and power system heat-to-power ratio and user load heat-to-power ratio based on the obtained user load and heat pump unit capacity;

[0069] Step 3, comparing the obtained combined cooling heating and power system heat-to-power ratio and user load heat-to-power ratio to determine the operation strategy; when the user load heat-to-power ratio is greater than the combined cooling heating and power system heat-to-power ratio, the heat-to-power operation mode is selected; when the user load heat-to-power ratio is less than or equal to the combined cooling heating and power system heat-to-power ratio, the power-to-heat operation mode is selected;

[0070] Step 4, calculating the economic index and energy consumption index of the combined cooling heating and power system based on the operation strategy obtained in Step 3 and judging whether the index reaches the optimal value; if not, changing the heat pump unit capacity and number and repeating Steps 2 to 4 until the index reaches the optimal value, finally determining the optimal capacity of the heat pump unit and realizing the operation control of the combined cooling heating and power system.

[0071] The principle of the above-mentioned embodiment method of the present application is explained as follows: after the parameters of the heat pump units of the system are determined, the system will have a fixed maximum heat-to-power ratio, i.e. the ratio of the maximum heat to the maximum power that can be provided, so the heat-to-power ratio of the system is a heat-to-power ratio with a small change range, and this parameter is changed at any time for the actual user, which is different every hour. When the user heat-to-power ratio is greater than the system heat-to-power ratio, the heat-to-power operation mode is selected, and when the user heat-to-power ratio is less than the system heat-to-power ratio, the power-to-heat operation mode is selected, so that the waste of energy can be reduced as much as possible.

[0072] In Step 2 of the above-mentioned embodiment of the present application, the step of calculating the combined cooling heating and power system heat-to-power ratio and the user load heat-to-power ratio based on the obtained user load and heat pump unit capacity comprises the following steps:

[0073] The calculation expression of the combined cooling heating and power system heat-to-power ratio is,

[0074] In the formula, HPR C is the heat-to-power ratio of the combined cooling heating and power system; Q PR is the heat supply of the system; W PR is the power supply of the system;

[0075] Q PR = QHO t -E hbio ;

[0076] In the formula, Q HO t In a high-temperature heating system, heat is supplied to the load by heat transfer oil on the heating side; E hbio For the input heat of the refrigeration unit;

[0077] Q HO t =m E t Q = m HDR Q;

[0078] In the formula, m E t This refers to the mass flow rate of the water diverted by the diversion valve to the high-temperature heating system; m HDR Q represents the mass flow rate of the geothermal working fluid after being diverted by the diversion valve to the heat extraction circulation system; Q is the heat value per unit flow rate.

[0079] When the system buys electricity from the grid, W PR =E buy +E ppho +E ptro ;

[0080] When the system sells electricity to the grid, W PR =E sell +E ppho +E ptro ;

[0081] In the formula, E buy E represents the electricity purchased by the combined heat and power (CHP) system from the grid. sell E refers to the electricity sold by the combined heat and power (CHP) system to the grid. ppho E represents the power generation of a PV power generation system. ptro The amount of electricity generated by the geothermal power generation system (PTST);

[0082] E ppho =I·A·η k ;

[0083] In the formula, I is the solar irradiance; A is the effective heat collection area of ​​the PV power generation system; η k The overall efficiency of PV power generation systems;

[0084] E ptro =η e (Q u ±η v Q v );

[0085] In the formula, Q uQ is the effective energy of solar energy collection system benefit v Q is the heat storage amount of heat storage system, and "+" represents heat extraction and "-" represents heat storage e η is the power generation efficiency of the trough heat power generator set, and can be 0.37 v η is the heat exchange efficiency of the heat storage system, and can be 0.75.

[0086] I = I0 (τ b + τ d )

[0087] τ b = a0 + a1 · e -k·m

[0088] τ d = 0.271 - 0.293 τ b

[0089]

[0090] In the formula, I0 is the radiation intensity of sunlight outside the atmosphere; τ b is the direct radiation atmospheric transparency; τ d is the scattering radiation atmospheric transparency; a0, a1, k are physical constants of the standard atmosphere with 23km visibility, and can be 0.95, 0.99, 1.02 respectively; G sc is the solar constant, and is 1353w / m2; n is the day number in a year; m is the atmospheric mass; θ z is the zenith angle.

[0091]

[0092]

[0093] In the formula, T b is the mean solar time (Beijing time, 24-hour system); L is the longitude of the place to be calculated; L m is the Beijing longitude; e is the time difference between true solar time and mean solar time.

[0094] The calculation expression of the user load heat-to-electricity ratio is,

[0095]

[0096] In the formula, Q US is the heat required by the user heat load; W US is the electricity required by the user electric load.

[0097] The step 4 in the above embodiment of the application, based on the operation strategy obtained in the step 3, the economic indicators and energy consumption indicators of the combined cooling, heating and power supply system are calculated, and it is judged whether the indicators reach the optimal step specifically includes:

[0098] The total investment cost in the whole life cycle is converted into the equal annual investment cost, which can be expressed as:

[0099]

[0100] In the formula, Y CoST is the equal annual investment cost; d is the discount rate, which can be 0.08; and 1 is the expected life of the system.

[0101] The energy consumption index model is expressed as:

[0102]

[0103] In the formula, Y CON is the energy consumption; η gen is the power generation efficiency of the power generation system; σ e is the primary energy conversion coefficient corresponding to the heat energy consumed per kWh of power purchase.

[0104] In the embodiments of the present application, the two indexes are two objective function values obtained by the hill climbing algorithm proposed in the present application, and the specific values of the indexes can be output by running the optimization method; whether the indexes reach the optimal value is determined in the process of program running (i.e., the principle of the hill climbing algorithm), and the optimal value is output.

[0105] In the specific example of the embodiments of the present application, the medium-deep geothermal energy extraction circulation system is composed of at least a flow divider and a reinjection pump, the extracted geothermal working medium is flexibly distributed between the power generation system and the heating system through the flow divider, and formula (1) gives a mathematical model of the flow divider;

[0106]

[0107] In the formula, α t and β t are the geothermal energy coefficients for power generation and heating at time t, respectively; m HDR , and are the mass flow rate of the geothermal working medium in the heat extraction circulation, the mass flow rate for the high-temperature heating system, and the mass flow rate for the geothermal power generation system, respectively.

[0108] Exemplary explanation: generally, a geothermal project has at least two sets of water pumps; one set is to extract geothermal working medium from the ground for geothermal resource extraction; and one set is to inject the extracted geothermal working medium into the heating working medium to provide for users. Although the uses are different, the principles and mathematical models are the same.

[0109] Taking the unit for extracting geothermal resources as an example, the mathematical model of the water pump is:

[0110] PS = m DR gH (2)

[0111] P = m S gH (1) DR gH (3)

[0112] In addition, the flow constraint of the water pump unit is

[0113] P = m DR gH (3) S gH (4) H gH (5)

[0114] In the embodiment of the present application, when the temperature, pressure and mass flow of the geothermal working medium obtained from the medium-deep geothermal energy are constant, the system output can track the maximum power generation efficiency condition by adjusting the mass flow of the low-temperature power generation cycle working medium.

[0115] It is assumed that the rated working point of the geothermal power generation system is always maintained at the maximum power generation efficiency condition; at this time, the geothermal power generation system model can be expressed as,

[0116] In the formula, P represents the output power of the geothermal power generation system at the current time; is the power generation efficiency; is the specific heat capacity of the geothermal working medium; T HDR is the temperature of the high-temperature geothermal working medium. Since the temperature of the production well changes slowly in a short time, T HDR can be considered as a constant.

[0117] Under the condition of tracking the maximum power generation efficiency, and can also be considered as constants; therefore, the output electric power of the geothermal power generation system can be expressed as

[0118] The power generation system constraint is

[0119] In the embodiment of the present application, the high-temperature heat supply system is composed of a high-temperature heat exchanger and a high-temperature heat storage subsystem, and adopts heat conducting oil as the working medium; the high-temperature heat exchanger exchanges heat from the high-temperature geothermal working medium to provide high-grade heat energy with a temperature of T H for the high-temperature load, and the model of the high-temperature heat exchanger is ​

[0120] wherein: respectively represent the mass flow rate and the specific heat capacity of the heat transfer oil; T O is the initial temperature of the heat transfer oil.

[0121] When the temperature of the production well, the initial temperature of the heat transfer oil and the heat supply temperature are determined, the heat power obtained and output by the high-temperature heat supply system can be represented as:

[0122] wherein: represents the heat obtained by the heat exchanger from the high-temperature geothermal working medium; represents the heat provided by the heat transfer oil to the load on the heat supply side; η HEX represents the heat exchange efficiency of the high-temperature heat exchanger. The high-temperature heat storage subsystem is composed of a high-temperature heat storage tank, a heat exchange system and an electric heating device, and heat storage and heat release are performed by the heat exchange between the heat transfer oil and the high-temperature heat network.

[0123] The model of the high-temperature heat storage subsystem is represented as

[0124] wherein: and respectively represent the high-temperature heat storage amount, the heat storage / releasing power and the electric heating power at time t; η H is the heat dissipation coefficient; η EQ is the electric heat exchange coefficient; μ Hc , μ Hdc is a 0-1 variable, which ensures that the heat storage and heat release processes cannot be performed simultaneously.

[0125] wherein,

[0126] In the embodiment of the present application, the heat collection field constraints include:

[0127] The heat charging amount:

[0128] The heat releasing amount:

[0129] The capacity constraint is

[0130] In the embodiment of the present application, the mathematical model of the PV power generation model is: E ppho = I·A·η k (14)

[0131] wherein: E pphoPV power generation system output power; I is solar irradiance; A is the effective heat collection area of the photovoltaic system; η k is the comprehensive efficiency of the photovoltaic system.

[0132] In the embodiment of the application, the mathematical model of the PTST power generation model is: E ptro =η e (Q u ±η v Q v ) (15)

[0133] In the formula, E ptro is the power generation of the trough heat generator set; Q u is the effective energy of the solar heat collection system benefit; Q v is the heat storage capacity of the solar heat storage tank, and "+" represents heat extraction and "-" represents heat storage; η e is the power generation efficiency of the trough heat generator set, which can be 0.37; η v is the heat exchange efficiency of the heat storage tank, which can be 0.75.

[0134] In the embodiment of the application, the effective energy of the heat collection system benefit is expressed as: Q u =η m η t IS (16)

[0135] In the formula, η m is the mirror field heat collection efficiency, which can be 0.38; η t is the heat exchange efficiency, which can be 0.95; and S is the mirror field heat collection area.

[0136] In the embodiment of the application, it is explained that after sunset and at night, the heat storage system can effectively extend the power generation time, and in the case of sufficient solar energy during the day, the excess solar radiation can be stored. Therefore, the increase of the heat storage system can effectively ensure that the system has sufficient heat collection capacity, although the system assembly and operation cost will increase, but the annual net power generation will also increase accordingly.

[0137] Solar irradiance is one of the indispensable conditions for calculating the power generation of photovoltaic and photothermal systems, which expresses how much solar radiation reaches the mirror surface per unit area per unit time, which involves the nature of solar radiation, the time and place of any time

[0138] I = I0 (τ b + τ d )

[0139] τ b = a0 + a1 · e -k·m

[0140] τd = 0.271 - 0.293τ b

[0141] The calculation of the solar irradiance is shown in equation (17):

[0142] where I0 is the radiation intensity of sunlight outside the atmosphere; τ b is the direct radiation atmospheric transparency; τ d is the scattered radiation atmospheric transparency; a0, a1, k are physical constants of the standard atmosphere with 23 km visibility, which can be taken as 0.95, 0.99, 1.02, respectively; G sc is the solar constant, taken as 1353 w / m 2 ; n is the day number in a year; m is the atmospheric mass; θ z is the zenith angle.

[0143] Atmospheric mass and zenith angle:

[0144] cosθ z = sin p sin δ + cos δ cos p cos ω (18)

[0145]

[0146] where p is the latitude of the sought place; δ is the declination angle; α is the solar altitude angle (complementary angle of the zenith angle); ω is the solar hour angle.

[0147] Declination angle and solar hour angle:

[0148]

[0149]

[0150] where T b is the mean solar time (Beijing time, 24-hour system); L is the longitude of the sought place; L m is the Beijing longitude; e is the time difference between the true solar time and the mean solar time.

[0151] In the control method provided by the embodiments of the present application, a mathematical model is established based on the life cycle method, taking economy, energy and environment as targets, and an operation strategy with advantages is selected by comparing indexes. Further, a hill climbing algorithm (HCA) can be applied to optimize the configuration of the system, and the indexes under the optimal configuration are compared with the indexes of the distributed supply system.

[0152] In the embodiment of the present application, a multi-target evaluation system is constructed with the total life cycle cost, primary energy consumption and equivalent CO2 emission as targets, and the corresponding equivalent annual value is used in the total life cycle. The economic model of the PV / PTST-CCHP system includes operation and maintenance cost, system installation cost and interaction cost.

[0153] Total investment cost in the total life cycle: Y total = C an + C yun ± C grid (21)

[0154]

[0155]

[0156] C grid = E buy C buy

[0157] C grid = E se11 C sel1 (22)

[0158] In the formula, Y total is the total investment cost (in the total life cycle) of the system; C an is the system assembly cost; C yun is the system operation and maintenance cost; C grid is the interaction cost of the large power grid and the system (calculated as “+” for purchasing power from the large power grid and “-” for selling power to the large power grid); i is the i-th output unit; t is the time period sequence number per day; j is the quarterly sequence number; k is the day sequence in each quarter; N is the total number of output units; K is the total number of days in each quarter; O is the assembly cost per unit capacity of each module; P is the installed capacity of each module; M is the operation cost per unit capacity and unit time of each module; P out is the output power of each module; E buy is the purchased power; C buy is the power purchase price; E sell is the sold power; C sell is the on-grid power price.

[0159] The total investment cost in the total life cycle is converted into the equivalent annual value investment cost, which can be expressed as:

[0160]

[0161] In the formula, Y CoST is the equivalent annual value investment cost; d is the discount rate, which can be 0.08; 1 is the expected service life of the system.

[0162] In the embodiment of the present application, the energy consumption index model is represented as

[0163] In the formula, Y CON is the energy consumption; η gen is the power generation efficiency of the power generation system; σ e is the primary energy conversion coefficient corresponding to the heat energy consumed per kWh of power purchase.

[0164] The constraint conditions in the embodiment of the present application include:

[0165] Water pump unit flow constraint

[0166] In the formula, m DR is the mass flow of the water pump for extracting geothermal resources; m S is the mass flow of the water pump for supplying heat to the medium-temperature load; and m H is the mass flow of the water pump for supplying heat to the high-temperature load.

[0167] Heat collection field constraint: heat charging amount: Heat releasing amount:

[0168] Capacity constraint

[0169] High-temperature geothermal source heat pump:

[0170] Power generation system constraint:

[0171] Electricity balance P RBH + P RBM + P XH + P XM + P S = P DR + E buy (31); in the formula, E buy is the power purchase amount from the power grid.

[0172] System stable operation constraint: in order to ensure the stable operation of the system, the geothermal supply extraction cycle reserves at least 10% of the geothermal energy for power generation; in order to ensure the long-term stable operation of the geothermal reservoir, the reinjection temperature should also meet the limit of the minimum reinjection temperature . In addition, in order to ensure the heat grade of the medium-temperature heat supply, the outlet temperature of the high-temperature heat exchanger is generally not lower than the waste heat temperature of the geothermal power generation system. Therefore, the system stable constraint can be obtained,

[0173] In the embodiment of the present application, the combined supply system operation strategy includes: the operation strategy determines the output characteristics of the system, and the perspective of which strategy the system is operated from can make the output characteristics of the system more clear and explicit. The basic operation strategies of the combined supply system are generally divided into two types: ordering heating by power (OHP) and ordering power by heating (OPH).

[0174] Ordering power by heating (OPH): under this operation strategy, the high-temperature heat supply system preferentially provides heat energy for the system heat (cold) load, and generates electric energy for the electric load at the same time. If the heat generated under the maximum load is still insufficient to meet the user demand, the heat storage system is used for supplement. On this basis, another part of the electric load is provided by the PV and PTST generators, and finally if the power is insufficient, it is purchased from the large power grid, and if there is excess power, it is sold to the large power grid;

[0175] Ordering power by heating (OPH): under this operation strategy, the electric load demand is preferentially supplied by the PV generator set and the PTST generator set, and if there is excess power, it is sold to the large power grid. Since the PV generator set and the PTST generator set only provide electric energy for the system, under the ordering power by heating strategy, the cold and heat load at the user end is provided by the high-temperature heat supply system, and at the same time, the PV generator set and the PTST generator set will generate electric energy to provide for the user. When the heat load is satisfied, the electric load is not satisfied, and the geothermal power generation system needs to continue to operate to generate electric energy to provide for the user, at this time the heat energy generated will be wasted. But when the heat load is satisfied, the electric load is also satisfied, which is the most ideal state, and no excess heat is wasted. Under the ordering power by heating strategy, the electric load is provided by the PV generator set and the PTST generator set, when it can meet the electric load demand, the geothermal power generation system does not need to supply power to the electric load, but through the high-temperature heat supply system to satisfy the cold and heat load. When it cannot meet the electric load demand, the geothermal power generation system operates to make up for the lack of power, and the heat load generated at the same time is provided to the user. If this part of the heat is more than the cold and heat load demand, the excess part is wasted, and if it is less than the cold and heat load demand, the heat load is satisfied by the high-temperature heat supply system, and the cold load is satisfied by the heat collection field.

[0176] System design parameters and operation strategy optimization, including: for the already built combined cooling heating and power system, better optimization operation strategy can effectively reduce the operation cost, and for the design of combined cooling heating and power system, the optimization of design parameters and operation strategy operation complement each other, both will cause the influence on the comprehensive evaluation index of the whole system, therefore, the optimization should be carried out simultaneously to better reflect the system performance and user demand. The design parameters of the system include the selection of power device, refrigeration and heating device, specific equipment capacity, quantity, electric refrigeration rate, etc. After determining the actual cooling and heating demand of the user, the configuration and operation strategy of the combined cooling heating and power system, the capacity of the power device of the system will have a certain range of variation, and the capacity of the refrigeration and heating device will be determined along with the determination of the capacity of the power device. The optimization of design parameters mainly involves finding the optimal power device capacity to make the evaluation indexes of the whole system under the selected operation strategy optimal, i.e. the capacity and number of heat pump units.

[0177] In the optimization process, the capacity and number of heat pump units will affect the power purchase amount from the power grid, equipment cost and other factors, and the electricity price will affect the economic index. The energy balance of the whole system mainly includes cold balance, heat balance and electricity balance. In the parameter optimization process, the average daily user cooling and heating load in summer and winter is selected as the user demand for system parameter optimization.

[0178] Purely heat-to-power and power-to-heat operation system will cause energy waste in a year. From the whole year, heat-to-power has greater advantages in heat, so it is better to adopt heat-to-power operation strategy in most of the time of the system. However, the energy supply and use of buildings should also be considered, so the heat-to-power ratio (HPR, Heat Power to Ratio) can be introduced. The heat-to-power ratio of the user is defined as follows:

[0179]

[0180] The embodiment of the application further explains that the hill climbing algorithm (HCA) is a local optimization method using a heuristic method, which is an improvement of depth-first search. It uses feedback information to help generate decisions about solutions. The hill climbing algorithm has the advantages of avoiding traversal and selecting part of nodes through heuristics, thereby improving efficiency. After comparison with a plurality of algorithms, the hill climbing algorithm is more suitable for the operation strategy mentioned in the patent and is beneficial to the optimization of indexes, so that the algorithm is selected to solve the problem. The main steps of the hill climbing algorithm are as follows:

[0181] 1) Randomly select a starting point.

[0182] 2) Compare the adjacent point with the current point each time, and take the better point as the next step of climbing.

[0183] 3) Repeat step 2) until there are no more any adjacent points greater than this point.

[0184] 4) Select this point as the hill climbing peak, which is the optimal solution of the algorithm.

[0185] Where, select 2 target functions: economic index, energy index, then have:

[0186]

[0187]

[0188] Adopt the hill climbing algorithm (HCA) to find the optimal solution that makes the PV / PTST-CCHP system obtain the best economic benefit and the lowest energy consumption under the premise of the optimal energy and environmental indicators, and find the optimal power device capacity, i.e. the capacity and number of heat pump units.

[0189] Those skilled in the art will understand that embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) having computer-usable program code embodied therein.

[0190] The present application is described with reference to the flowcharts and / or block diagrams of the methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as combinations of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions, which are executed via the processor of the computer or other programmable data processing apparatus, generate a means for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 The flow or flows and / or blocks in a flowchart and / or block diagram Figure 1 Means for carrying out the functions specified in the flowchart

[0191] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to work in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including instruction means, which implement the functions specified in the flowcharts and / or block diagrams. Figure 1 The flow or flows and / or blocks in a flowchart and / or block diagram Figure 1 Means for carrying out the functions specified in the flowchart

[0192] These computer program instructions can also be loaded into a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 Figure 1

[0193] Finally, it should be noted that the above examples are merely intended to describe the technical solutions of the present application, rather than limiting the same. Although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered within the protection scope of the claims of the present application.​​

Claims

1. A combined cooling, heating and power system based on geothermal energy, characterized in that, Comprise: The middle-deep geothermal extraction circulation system, the geothermal power generation system, the high-temperature heat supply system, the heat refrigerator unit, the electric refrigerator unit, the PV power generation system, the PTST power generation system, the heat collection system and the heat storage system; wherein, The middle-deep geothermal extraction circulation system at least comprises a flow divider and a water pump, and is used for extracting middle-deep geothermal energy and flowing to the geothermal power generation system and the high-temperature heat supply system through the water pump and the flow divider respectively; The geothermal power generation system is used for converting geothermal energy into electric energy and supplying the electric network; The high-temperature heat supply system comprises a high-temperature heat exchanger and a high-temperature heat storage subsystem, and is used for meeting a heat load through a part of geothermal energy and outputting another part of geothermal energy; The heat refrigerator unit is used for refrigerating to meet a cold load through the geothermal energy output by the high-temperature heat supply system; and the electric refrigerator unit is used for refrigerating to meet the cold load through the electric energy input by the electric network; The PV power generation system is used for converting solar energy into electric energy through photovoltaic power generation and supplying the electric network; The PTST power generation system is used for converting solar energy into electric energy through a trough type solar thermal power generator and supplying the electric network; The heat storage system is used for storing excess heat when the combined cooling, heating and power supply system collects more heat than the required heat, and releasing heat when the collected heat is less than the required heat; The heat collection system is used for collecting heat energy from solar energy, part of which flows into the PTST power generation system for power generation, and the rest of which is stored in the heat storage system; The operation control method of the combined cooling, heating and power supply system based on geothermal energy comprises the following steps: Step 1, obtaining user load and initial power device capacity in the high-temperature heat supply system; wherein the power device capacity at least comprises the number and capacity of heat pump units; Step 2, calculating the combined cooling, heating and power supply system heat-to-power ratio and the user load heat-to-power ratio based on the obtained user load and power device capacity; Step 3, comparing the combined cooling, heating and power supply system heat-to-power ratio and the user load heat-to-power ratio obtained in step 2 to determine the operation strategy; wherein when the user load heat-to-power ratio is greater than the combined cooling, heating and power supply system heat-to-power ratio, the heat-to-power fixed electricity operation mode is selected; and when the user load heat-to-power ratio is less than or equal to the combined cooling, heating and power supply system heat-to-power ratio, the electricity-to-heat fixed operation mode is selected; Step 4, obtaining economic indicators and energy consumption indicators of the combined cooling, heating and power supply system based on the operation strategy determined in step 3 and judging whether the optimal value is reached; if not, changing the heat pump unit capacity and number to obtain new power device capacity and repeating steps 2 to 4 until the indicators reach the optimal value, obtaining the final power device capacity and realizing the operation control of the combined cooling, heating and power supply system.

2. The combined cooling and power system of claim 1, wherein, The backwater of the high-temperature heat supply system after heat exchange is injected back to the ground by a reinjection pump for the next round of middle-deep geothermal extraction.

3. The combined cooling and power system of claim 1, wherein, The working medium used by the high-temperature heat supply system is heat conducting oil.

4. The combined cooling and power system of claim 1, wherein, In step 1 of the operation control method, the obtained user load is the average daily user load in summer or winter.

5. The combined cooling and power system of claim 1, wherein, In step 2 of the operation control method, 1) Heat-to-power ratio of a combined cooling, heating and power system The calculation expression is, ； In the formula, Qsys is the amount of heat supplied to the system; Qsys is the amount of power supplied to the system; ； In the formula, Qsup is the heat provided by the heat supply side to the load in the high-temperature heat supply system; Qin is the input heat of the heat refrigerator unit; ； In the formula, is the mass flow rate of the geothermal working fluid flowing to the high-temperature heat supply system after being branched by the flow divider; is the mass flow rate of the geothermal working fluid flowing to the heat extraction circulation after being branched by the flow divider; Q is the heat value of unit flow; A combined cooling and power system buys electricity from the grid when, ; A combined cooling and power system sells power to a power grid, ; wherein is the amount of electricity bought by the cogeneration system from the grid; is the amount of electricity sold by the cogeneration system to the grid; is the amount of electricity generated by the PV power system; is the amount of electricity generated by the PTST power system; 2) user load to heat power ratio The calculation expression is, ； wherein Qh is the heat required for the user thermal load; Qe is the electricity required for the user electrical load.

6. The combined cooling and power system of claim 1, wherein, In step 3 of the operation control method, The heat-fixed electricity operation mode includes: the high-temperature heat supply system preferentially provides heat energy for the system heat load or cold load, and the generated electricity is supplied to the electricity load; if the heat generated under the maximum load operation is still insufficient to meet the user demand, the heat storage system is used for supplement; on this basis, another part of the electricity load is provided by the PV power generation system and the PTST power generation system, and if the electricity is insufficient, it is purchased from the power grid, and if there is excess electricity, it is sold to the power grid; The electricity-fixed heat operation mode includes: the electricity load demand is preferentially supplied by the PV power generation system and the PTST power generation system, and if there is excess electricity, it is sold to the power grid; the cold and heat load of the user end is provided by the high-temperature heat supply system, and the PV power generation system and the PTST power generation system generate electricity to provide for the user; when the heat load is satisfied and the electricity load is not satisfied, the geothermal power generation system continues to operate to generate electricity to provide for the user.

7. The combined cooling and power system of claim 1, wherein, In step 4 of the operation control method, The economic index is the equal annual value investment cost, and the expression is ； wherein is the equal annual investment cost; is the discount rate; is the system expected lifetime; The model of the energy consumption index is ； In the formula, is the energy consumption amount; is the electricity amount bought from the power grid by the combined heat and power system; is the power generation efficiency of the power generation system; is the primary energy conversion coefficient corresponding to the heat energy consumed per kWh of purchased electricity amount.

8. The combined cooling and power system of claim 7, wherein, In step 4 of the operation control method, based on the operation strategy determined in step 3, the economic index and the energy consumption index of the combined cooling, heating and power system are obtained, and it is judged whether the optimal value is reached, The expression of the economic index and the expression of the energy consumption index are used as two objective functions, the objective function values of the two objective functions obtained by using the hill climbing algorithm optimization are obtained, and the optimized economic index and energy consumption index are obtained.

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