CN109066740B - Power grid load model of adjustable electricity heat storage boiler - Google Patents
Power grid load model of adjustable electricity heat storage boiler Download PDFInfo
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- CN109066740B CN109066740B CN201811131765.3A CN201811131765A CN109066740B CN 109066740 B CN109066740 B CN 109066740B CN 201811131765 A CN201811131765 A CN 201811131765A CN 109066740 B CN109066740 B CN 109066740B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J15/00—Systems for storing electric energy
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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Abstract
The invention belongs to the technical field of power grid operation and control, relates to a power grid load model, and particularly relates to a power grid load model of an adjustable electricity and heat storage boiler. The load model provided by the method can realize peak clipping and valley filling, and has important significance for realizing the economical efficiency of power grid dispatching operation. The method comprises the following steps: step 1, considering the electric load and the heat load in the electric heat storage boiler, the conversion between electricity and heat and between heat and heat, the volume of the heat storage tank, the flow and temperature factors of inflow and outflow media, and establishing a detailed energy conversion mathematical model of the adjustable electric heat storage boiler; and 2, simplifying the detailed energy conversion mathematical model of the adjustable electric heat storage boiler in the step 1, and establishing a power grid load model of the adjustable electric heat storage boiler for electric power system analysis and calculation.
Description
Technical Field
The invention belongs to the technical field of power grid operation and control, relates to a power grid load model, and particularly relates to a power grid load model of an adjustable electricity and heat storage boiler.
Background
The wide use of new energy electric vehicles changes the load composition of the power grid; the coal is replaced by electricity, and high-capacity electricity is used for heating and supplying heat, so that the composition and the characteristics of the conventional load are fundamentally changed; in addition, the application of large-capacity energy storage, the use of various economic incentive measures and electricity price measures and the external characteristics of the load are further changed. Along with the change of the overall characteristics of the load of the power grid, the randomness and the elasticity of the load are further increased, effective measures must be taken, the adjustability and the schedulability of the load are fully excavated, and the cooperative scheduling of the power distribution network is realized.
The load of the power system is influenced by various external factors, and the load has the characteristic of continuously changing along with time, and has the characteristics of continuity, periodicity, uncontrollable property and the like. Therefore, the method and the device have the advantages that the electricity utilization characteristics and behavior habits of the users are mastered, the method and the device can be effectively applied to safety assessment and operation planning of the system, and have great significance for the power system. The economic benefit of the electric power can be maximized, and meanwhile, the electric energy of each degree can be more fully utilized by the user, so that the resources are optimally utilized. The method is not only beneficial to reasonable utilization of electric energy, but also is an efficient utilization of environment and primary energy. According to the characteristics and the properties of the load of the power system, the load characteristic curve of the power system can be described, and different load characteristic curves can be caused by the division of different industries.
The aim of the power system is to continuously provide excellent and reliable electric energy for a plurality of users and meet the power consumption requirements of various users. The load in the conventional sense refers to the workload on the grid (substation). However, for a consumer, the load is the sum of the power consumed continuously in the power grid by all consumers of the consumer. The load model provided by the design can realize peak clipping and valley filling, meets the load characteristics required by power grid operation, can be used for calculation of power system analysis, and has important significance for realizing economy of power grid dispatching operation.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the power grid load model of the adjustable electricity and heat storage boiler, the proposed load model can realize peak clipping and valley filling and accords with the load characteristics required by power grid operation, and meanwhile, the load model can be used in the calculation of power system analysis and has important significance for realizing the economy of power grid dispatching operation.
In order to achieve the purpose, the invention adopts the following technical scheme that:
and 2, simplifying the detailed energy conversion mathematical model of the adjustable electric heat storage boiler in the step 1, and establishing a power grid load model of the adjustable electric heat storage boiler for electric power system analysis and calculation.
As a preferred embodiment of the present invention, the step 1 includes:
step 1.1, calculating the heat storage load of a heat storage tank of the electric heat storage boiler;
step 1.2, calculating the maximum heat storage quantity of the heat storage tank according to the heat storage load of the heat storage tank;
and step 1.3, calculating a heat supply load according to the heat storage load in the step 1.1 by combining the flow of hot water injected into the heat storage tank and the flow of hot water flowing out of the heat storage tank, and calculating the heat supply power of the heat storage tank according to the relation between the heat supply output time period and the heat supply load.
As another preferred scheme of the invention, the electric heat storage boiler uses water as a medium to store heat generated by the electric boiler in the heat storage device during the low ebb period of electric power, and a system which is timely supplied to heat utilization equipment can not be started or can be started less at the peak period of electric power utilization, so that the electric power consumption at the peak period is reduced, and the peak shifting and valley filling functions are realized;
the electric heat storage boiler is an adjustable electric heat storage boiler, the load of a power grid of the adjustable electric heat storage boiler is related to parameters such as specific heat, density and volume of a medium, the height of the medium can be measured, and the equivalent temperature can be controlled. The electric heat storage boiler adjusts the power grid load of the electric heat storage boiler by controlling the height of the medium and the equivalent temperature.
As another preferred aspect of the present invention, in establishing a detailed energy conversion mathematical model of an adjustable energy storage boiler, the process of calculating the heat storage amount of the heat storage tank includes:
the formula is calculated according to the law of thermodynamics:
Qt＝C×Mt×ΔT (1)
wherein:
Qt: representing the heat storage load of the heat storage tank;
c: represents the specific heat of the heat storage medium;
m: represents the mass of the heat storage medium;
Δ T: represents a temperature difference that causes a change in thermal load;
t: represents a certain time;
the mass of the heat storage medium is closely related to the volume of the heat storage tank; assuming that the heat storage tank is in a regular shape, if the bottom area of the heat storage tank is S, the height of the liquid level of the water level in the heat storage tank at the time T is h, and the equivalent temperature of the water in the heat storage tank at the time T is TtReference temperature is T0Then, then
Mt＝ρ·S·h (2)
ΔT＝Tt-T0 (3)
Substituting (2) and (3) into (1) to obtain
Qt＝C·ρ·S·h·ΔT (4)
Assuming that the temperature of water in the heat storage tank is distributed in a gradient form, the sensors are sequentially T from top to bottomt 1、Tt 2、Tt 3、Tt nThen formula (4) can be changed to
After finishing, obtaining
Comparing the formula (4) with the formula (6) to define the equivalent temperature of the water in the heat storage tank at the moment t
Then there are:
Qt＝C·ρ·S·h·ΔTt
wherein:
Qt: representing the heat storage load of the heat storage tank;
c: represents the specific heat of the heat storage medium;
ρ: represents the density of the heat storage medium;
s: represents the bottom area S of the heat storage tank;
h: representing that the height of the liquid level of the water level in the heat storage tank is h at the moment t;
ΔTt: representing a temperature difference over a certain period of time leading to a change in thermal load.
As another preferred scheme of the invention, in the establishment of a detailed energy conversion mathematical model of the adjustable energy storage boiler, the maximum heat storage quantity of the heat storage tank is calculated;
because the specific heat of heat storage tank normal water, density, the basal area is unchangeable at heat-retaining and heat supply in-process, and water level liquid level reaches the maximum value in heat storage tank, calculates the temperature in the heat storage tank and reaches the maximum value, and the process includes:
measuring the height h of the water level when the device is filled with water in the heat storage tankmax；
Measuring the temperature value T when all water in the heat storage tank is hot water and the temperatures of all layers are consistent to be the maximum valuemax，T0Is a reference temperature;
the data is led into the following formula to obtain the maximum heat storage quantity:
Qmax＝C·ρ·S·hmax·(Tmax-T0) (8)
as another preferable aspect of the present invention, in establishing the detailed energy conversion mathematical model of the adjustable energy storage boiler, calculating the heating power of the heat storage tank includes:
calculation based on power and energy
P·tc＝Q (9)
Wherein:
p: the heat supply power of the heat storage tank;
tc: the heat supply power output period of the heat storage tank;
q: the heat supply load of the heat storage tank;
heating power P of heat storage tank in time tg(t)Can be calculated from the following formula
Pg(t)·Δt＝Qout(t)-Qin(t) (10)
Wherein Q isout(t)、Qin(t)Respectively outflow heat load and injection heat load of the heat storage tank at the time t
Suppose that the flow rates of the inlet and outlet of the heat storage tank are G at time tout(t)、Gin(t)The unit is generally expressed in Kg/h, and the water flow velocity is respectively vin(t)、vout(t)The diameter of the tube is Din、DoutThen there is
According to the relation between the flow rate and the flow rate of hot water
Substituting the formula (5) into the formulae (11) and (12) respectively to obtain
Substituting the expressions (11) and (12) into the expression (10) to obtain
Wherein:
Pg(t): representing the heat supply power of the heat storage tank in the time t;
c: represents the specific heat of the heat storage medium;
Gout(t)、Gin(t): respectively representing the flow of an outlet and an inlet of the heat storage tank at the time t, and the unit is generally Kg/h;
Tout(t): temperature representative of the injected heat load;
Tin(t): a temperature representative of the heat load of the effluent;
Δ t: represents a temperature difference that causes a change in thermal load;
T0: representing the reference temperature.
As another preferred scheme of the present invention, in step 2, a detailed energy conversion mathematical model of the adjustable electricity and heat storage boiler is simplified, a power grid load model of the adjustable electricity and heat storage boiler for electric power system analysis and calculation is established, and the finally simplified power grid load model is:
the heat storage capacity of the heat storage tank is as follows:
Qt＝C·ρ·S·h·ΔTt
wherein:
Qt: representing the heat storage load of the heat storage tank;
c: represents the specific heat of the heat storage medium;
ρ: represents the density of the heat storage medium;
s: represents the bottom area S of the heat storage tank;
h: representing that the height of the liquid level of the water level in the heat storage tank at the moment t is h;
ΔTt: a temperature difference representing a change in thermal load over a period of time;
the maximum heat storage capacity of the heat storage tank is;
Qt.max＝C×Mt.max×ΔT
wherein:
Qt.max: representing the heat storage load of the heat storage tank for a certain period of time;
c: represents the specific heat of the heat storage medium;
Mt.max: represents the quality of the heat storage medium over a certain period of time;
Δ T: represents a temperature difference that causes a change in thermal load;
the heat supply power of the heat storage tank is as follows:
wherein:
Pg(t): representing the heat supply power of the heat storage tank in the time t;
c: represents the specific heat of the heat storage medium;
Gout(t)、Gin(t): respectively representing the flow of an outlet and an inlet of the heat storage tank at the time t, and the unit is generally Kg/h;
Tout(t): temperature representative of the injected heat load;
Tin(t): a temperature representative of the heat load of the effluent;
T0: representing the reference temperature.
In the model, the control variables are equivalent temperature of the heat storage tank, flow of an injection port and an outflow port of the heat storage tank, the state variables are heat supply power and heat supply load of the heat storage tank, the heat supply temperature is set by an operator according to user requirements, the volume of water in the heat storage tank can be obtained by an instant monitoring system, and the rest are constants.
Compared with the prior art, the invention has the beneficial effects.
1. A power grid load model of an adjustable electric heat storage boiler can realize peak clipping and valley filling and meet the load characteristics required by power grid operation.
2. The power grid load model of the adjustable electricity heat storage boiler can be used for calculation of power system analysis and has important significance for achieving economy of power grid dispatching operation.
3. The load model can master the electricity utilization characteristics and behavior habits of users, can be effectively applied to the safety assessment and operation planning of the system, and has great significance for the power system. The economic benefit of the electric power can be maximized, and meanwhile, the electric energy of each degree can be more fully utilized by the user, so that the resources are optimally utilized. The method is not only beneficial to reasonable utilization of electric energy, but also is an efficient utilization of environment and primary energy.
Drawings
The invention is further described with reference to the following figures and detailed description. The scope of the invention is not limited to the following expressions.
FIG. 1 is a graph of the load of an unpowered thermal storage boiler of the present invention.
FIG. 2 is a graph of the load of the grid-powered thermal storage boiler of the present invention.
Detailed Description
The invention discloses a basic idea of a power grid load model of an adjustable electricity heat storage boiler, which comprises the following steps: firstly, a detailed energy conversion mathematical model of the adjustable electricity and heat storage boiler is established, then further simplification is carried out, and a power grid load model of the adjustable electricity and heat storage boiler is established.
The technical scheme provided by the invention is as follows: the electric heat storage boiler is a system which stores heat generated by the electric boiler in a heat storage device by using water as a medium and supplies the heat to heat utilization equipment at a proper time during a power valley period. Therefore, the boiler can be not started or can be started less at the peak time of electricity utilization, and the electricity consumption at the peak time is reduced. In the model, the control variable is the equivalent temperature of the heat storage tank, the flow of an injection port and an outflow port of the heat storage tank, the state variable is the heat supply power of the heat storage tank, the heat supply load and the heat supply temperature are set by operating personnel according to the requirements of users, the volume of water in the heat storage tank can be obtained by an instant monitoring system, and the rest are constants. The method comprises the steps of firstly establishing a detailed energy conversion mathematical model of the adjustable electricity and heat storage boiler, and then further simplifying to establish a power grid load model of the adjustable electricity and heat storage boiler. The load model can be used for calculation of power system analysis, and has important significance for realizing economy of power grid dispatching operation.
Which comprises the following steps:
step 1) considering the processes of electric load, heat load, conversion between electricity and heat and between heat and the like in the electric heat storage boiler, the volume of the heat storage tank, the flow rate of inflow and outflow media, the temperature and the like, and establishing a detailed energy conversion mathematical model of the adjustable electric heat storage boiler.
(1) The heat storage load is related to parameters such as specific heat, density and volume of the medium, wherein the height of the medium can be measured, and the equivalent temperature can be controlled. The electric boiler control system positively controls the heat storage load by controlling the equivalent temperature, so that the heat storage load of the heat storage tank is calculated.
(2) The specific heat, the density and the bottom area of the water in the heat storage tank are not changed in the heat storage and heat supply processes, so that the water level in the heat storage tank reaches the maximum value, the water temperature in the heat storage tank reaches the maximum value, and the maximum heat storage quantity of the heat storage tank is calculated according to the heat storage load calculation formula of the heat storage tank in the step (1).
(3) And (3) according to the calculation formula of the heat storage load in the step (1), combining the flow of hot water injected into the heat storage tank and the flow of hot water flowing out of the heat storage tank, calculating the heat supply load, and finally calculating the heat supply power of the heat storage tank according to the relation between the heat supply output time period and the heat supply load.
And 2) simplifying the detailed energy conversion mathematical model of the adjustable electric heat storage boiler in the step 1, and establishing a power grid load model of the adjustable electric heat storage boiler for electric power system analysis and calculation.
Specifically, the electric heat storage boiler is characterized in that water is used as a medium to store heat generated by the electric boiler in a heat storage device during a power valley period, and a system which is timely supplied to heat utilization equipment can be switched off or switched on less during a power peak period, so that the power consumption in the peak period is reduced, and the peak shifting and valley filling functions are realized. And the load of the power grid of the adjustable electric heat storage boiler is related to parameters such as specific heat, density and volume of the medium, wherein the height of the medium can be measured, and the equivalent temperature can be controlled. The electric heat storage boiler adjusts the power grid load of the electric heat storage boiler by controlling the height of the medium and the equivalent temperature.
Preferably, a detailed energy conversion mathematical model of the electric boiler is established considering the electric load and the heat load of the electric storage boiler, the conversion process between electricity and heat and between heat and heat, the volume of the heat storage tank, the flow rate and the temperature of the inflow and outflow media, and the like.
Preferably, in establishing the detailed energy conversion mathematical model of the adjustable energy storage and heat storage boiler, the stored heat quantity of the heat storage tank is calculated as follows:
the formula is calculated according to the law of thermodynamics:
Qt＝C×Mt×ΔT (1)
wherein:
Qt: representing the heat storage load of the heat storage tank;
c: represents the specific heat of the heat storage medium;
m: represents the mass of the heat storage medium;
Δ T: represents a temperature difference that causes a change in thermal load;
t: represents a certain time;
the mass of the heat storage medium is closely related to the volume of the heat storage tank. Assuming that the heat storage tank is in a regular shape, if the bottom area of the heat storage tank is S, the height of the liquid level of the water level in the heat storage tank at the time T is h, and the equivalent temperature of the water in the heat storage tank at the time T is TtReference temperature is T0Then, then
Mt＝ρ·S·h (2)
ΔT＝Tt-T0 (3)
Substituting (2) and (3) into (1) to obtain
Qt＝C·ρ·S·h·ΔT (4)
Assuming that the temperature of water in the heat storage tank is distributed in a gradient form, the sensors are sequentially T from top to bottomt 1、Tt 2、Tt 3、Tt nThen formula (4) can be changed to
After finishing, obtaining
Comparing the formula (4) with the formula (6) to define the equivalent temperature of the water in the heat storage tank at the moment t
Then there are:
Qt＝C·ρ·S·h·ΔTt
wherein:
Qt: representing the heat storage load of the heat storage tank;
c: represents the specific heat of the heat storage medium;
ρ: represents the density of the heat storage medium;
s: represents the bottom area S of the heat storage tank;
h: representing that the height of the liquid level of the water level in the heat storage tank is h at the moment t;
ΔTt: representing a temperature difference over a certain period of time leading to a change in thermal load.
Preferably, in establishing the detailed energy conversion mathematical model of the adjustable energy storage and heat storage boiler, the maximum heat storage amount of the heat storage tank is calculated as follows:
because the specific heat, density, the basal area of heat storage tank normal water does not change in heat storage and heat supply process, consequently, according to, the water level liquid level reaches the maximum value in heat storage tank, calculates the temperature in the heat storage tank and reaches the maximum value, and the process is as follows:
(1) measuring the height h of the water level when the device is filled with water in the heat storage tankmax；
(2) Measuring the temperature value T when all water in the heat storage tank is hot water and the temperatures of all layers are consistent to be the maximum valuemax，T0Is a reference temperature;
(3) data is imported into the following formula:
Qmax＝C·ρ·S·hmax·(Tmax-T0) (8)
preferably, in establishing the detailed energy conversion mathematical model of the adjustable energy storage boiler, the heating power of the heat storage tank is calculated as follows:
calculation based on power and energy
P·tc＝Q (9)
Wherein:
p: heating power of heat storage tank
tc: heat supply power output period of heat storage tank
Q: heating load of heat storage tank
Heating power P of heat storage tank in time tg(t)Can be calculated from the following formula
Pg(t)·Δt＝Qout(t)-Qin(t) (10)
Wherein Q isout(t)、Qin(t)Respectively outflow heat load and injection heat load of the heat storage tank at the time t
Suppose that the flow rates of the inlet and outlet of the heat storage tank are G at time tout(t)、Gin(t)The unit is generally expressed in Kg/h, and the water flow velocity is respectively vin(t)、vout(t)The diameter of the tube is Din、DoutThen there is
According to the relation between the flow rate and the flow rate of hot water
Substituting the formula (5) into the formulae (11) and (12) respectively to obtain
Substituting the expressions (11) and (12) into the expression (10) to obtain
Wherein:
Pg(t): representing the heat supply power of the heat storage tank in the time t;
c: represents the specific heat of the heat storage medium;
Gout(t)、Gin(t): respectively representing the flow of an outlet and an inlet of the heat storage tank at the time t, and the unit is generally Kg/h;
Tout(t): temperature representative of the injected heat load;
Tin(t): a temperature representative of the heat load of the effluent;
Δ t: represents a temperature difference that causes a change in thermal load;
T0: representing the reference temperature.
Preferably, the detailed energy conversion mathematical model of the adjustable electricity and heat storage boiler is simplified, a power grid load model of the adjustable electricity and heat storage boiler for electric power system analysis and calculation is established, and finally the simplified power grid load model is
a. The heat storage tank stores heat:
Qt＝C·ρ·S·h·ΔTt
wherein:
Qt: representing the heat storage load of the heat storage tank;
c: represents the specific heat of the heat storage medium;
ρ: represents the density of the heat storage medium;
s: represents the bottom area S of the heat storage tank;
h: representing that the height of the liquid level of the water level in the heat storage tank at the moment t is h;
ΔTt: a temperature difference representing a change in thermal load over a period of time;
b. the maximum heat storage capacity of the heat storage tank;
Qt.max＝C×Mt.max×ΔT
wherein:
Qt.max: representing the heat storage load of the heat storage tank for a certain period of time;
c: represents the specific heat of the heat storage medium;
Mt.max: represents the quality of the heat storage medium over a certain period of time;
Δ T: represents a temperature difference that causes a change in thermal load;
c. heat supply power of the heat storage tank:
wherein:
Pg(t): representing the heat supply power of the heat storage tank in the time t;
c: represents the specific heat of the heat storage medium;
Gout(t)、Gin(t): respectively representing the flow of an outlet and an inlet of the heat storage tank at the time t, and the unit is generally Kg/h;
Tout(t): temperature representative of the injected heat load;
Tin(t): a temperature representative of the heat load of the effluent;
T0: representing the reference temperature.
Preferably, in the above model, the control variables are equivalent temperature of the heat storage tank, flow rates of an injection port and an outflow port of the heat storage tank, the state variables are heating power and heating load of the heat storage tank, the heating temperature is set by an operator according to user requirements, the volume of water in the heat storage tank can be obtained by an instant monitoring system, and the rest are constants.
For example: an IEEE 10 machine 36 node system is adopted for calculation and analysis, 1 adjustable electric heat storage boiler is added on the basis of an IEEE-36 node standard calculation example, and the electric heat storage capacity is 6 MWh.
Fig. 1 is a load curve of the case power grid non-power-on heat storage boiler, and fig. 2 is a load curve of the case power grid power-on heat storage boiler. As shown in fig. 1-2, the heat-storage electric heating system improves the peak clipping and valley filling effects in two aspects, namely, the electric heat-storage boiler increases the electric load, and the heat storage increases the system regulation capacity. If the system uses an electric heat storage boiler to replace a part of the original coal-fired boiler for heat supply, the electric load increases a part of the electric heat storage load, otherwise, when the power of the heat supply network is kept constant, the heat storage device is used for heat supply, the electric heat supply load is reduced, and the coal consumption of the coal-fired unit is reduced. Therefore, the power grid load model of the adjustable electricity heat storage boiler can bring great economic benefits when applied to the power grid.
It should be understood that the detailed description of the present invention is only for illustrating the present invention and is not limited by the technical solutions described in the embodiments of the present invention, and those skilled in the art should understand that the present invention can be modified or substituted equally to achieve the same technical effects; as long as the use requirements are met, the method is within the protection scope of the invention.
Claims (7)
1. A grid load model for an adjustable electrical storage heat boiler, comprising:
step 1, considering the electric load and the heat load in the electric heat storage boiler, the conversion between electricity and heat and between heat and heat, the volume of the heat storage tank, the flow and temperature factors of inflow and outflow media, and establishing a detailed energy conversion mathematical model of the adjustable electric heat storage boiler;
the step 1 comprises the following steps:
step 1.1, calculating the heat storage load of a heat storage tank of the electric heat storage boiler;
step 1.2, calculating the maximum heat storage quantity of the heat storage tank according to the heat storage load of the heat storage tank;
step 1.3, calculating a heat supply load according to the heat storage load in the step 1.1 by combining the flow of hot water injected into the heat storage tank and the flow of hot water flowing out of the heat storage tank, and calculating the heat supply power of the heat storage tank according to the relation between a heat supply output time period and the heat supply load;
step 2, simplifying a detailed energy conversion mathematical model of the adjustable electric heat storage boiler in the step 1, and establishing a power grid load model of the adjustable electric heat storage boiler for electric power system analysis and calculation;
establishing a power grid load model of the adjustable electricity heat storage boiler for analyzing and calculating the power system, wherein the finally simplified power grid load model is as follows:
the heat storage capacity of the heat storage tank is as follows:
Qt＝C·ρ·S·h·ΔTt
wherein:
Qt: representing the heat storage load of the heat storage tank;
c: represents the specific heat of the heat storage medium;
ρ: represents the density of the heat storage medium;
s: represents the bottom area S of the heat storage tank;
h: representing that the height of the liquid level of the water level in the heat storage tank at the moment t is h;
ΔTt: a temperature difference representing a change in thermal load over a period of time;
the maximum heat storage capacity of the heat storage tank is;
Qt.max＝C×Mt.max×ΔT
wherein:
Qt.max: representing the heat storage load of the heat storage tank for a certain period of time;
c: represents the specific heat of the heat storage medium;
Mt.max: represents the quality of the heat storage medium over a certain period of time;
Δ T: represents a temperature difference that causes a change in thermal load;
the heat supply power of the heat storage tank is as follows:
wherein:
Pg(t): representing the heat supply power of the heat storage tank in the time t;
c: represents the specific heat of the heat storage medium;
Gout(t)、Gin(t): respectively representing the flow of an outlet and an inlet of the heat storage tank at the time t, and the unit is generally Kg/h;
Tout(t): temperature representative of the injected heat load;
Tin(t): a temperature representative of the heat load of the effluent;
T0: representing the reference temperature.
2. A grid load model of an adjustable electrical storage heat boiler according to claim 1, characterized in that: in the establishment of the detailed energy conversion mathematical model of the adjustable electricity and heat storage boiler, the heat storage amount of the heat storage tank is calculated, and the process comprises the following steps:
the formula is calculated according to the law of thermodynamics:
Qt＝C×Mt×ΔT (1)
wherein:
Qt: representing the heat storage load of the heat storage tank;
c: represents the specific heat of the heat storage medium;
Mt: represents the mass of the heat storage medium;
Δ T: represents a temperature difference that causes a change in thermal load;
t: represents a certain time;
the mass of the heat storage medium is closely related to the volume of the heat storage tank; assuming that the heat storage tank is in a regular shape, if the bottom area of the heat storage tank is S, the height of the liquid level of the water level in the heat storage tank at the time T is h, and the equivalent temperature of the water in the heat storage tank at the time T is TtReference temperature is T0Then, then
Mt＝ρ·S·h (2)
ΔT＝Tt-T0 (3)
Substituting (2) and (3) into (1) to obtain
Qt＝C·ρ·S·h·ΔT (4)
Assuming that the temperature of water in the heat storage tank is distributed in a gradient form, the sensors are sequentially T from top to bottomt 1、Tt 2、Tt 3、Tt nThen formula (4) can be changed to
After finishing, obtaining
Comparing the formula (4) with the formula (6) to define the equivalent temperature of the water in the heat storage tank at the moment t
Then there are:
Qt＝C·ρ·S·h·ΔTt
wherein:
Qt: representing the heat storage load of the heat storage tank;
c: represents the specific heat of the heat storage medium;
ρ: represents the density of the heat storage medium;
s: represents the bottom area S of the heat storage tank;
h: representing that the height of the liquid level of the water level in the heat storage tank is h at the moment t;
n: the sensor label represents the heat storage tank from top to bottom;
ΔTt: representing a temperature difference over a certain period of time leading to a change in thermal load.
3. A grid load model of an adjustable electrical storage heat boiler according to claim 2, characterized in that: calculating the maximum heat storage quantity of the heat storage tank in a detailed energy conversion mathematical model of the adjustable electricity and heat storage boiler;
because the specific heat of heat storage tank normal water, density, the basal area is unchangeable at heat-retaining and heat supply in-process, and water level liquid level reaches the maximum value in heat storage tank, calculates the temperature in the heat storage tank and reaches the maximum value, and the process includes:
measuring the height h of the water level when the device is filled with water in the heat storage tankmax；
Measuring the temperature value T when all water in the heat storage tank is hot water and the temperatures of all layers are consistent to be the maximum valuemax，T0Is a reference temperature;
the data is led into the following formula to obtain the maximum heat storage quantity:
Qmax＝C·ρ·S·hmax·(Tmax-T0) (8)。
4. a grid load model of an adjustable electrical storage heat boiler according to claim 2, characterized in that: in the process of establishing a detailed energy conversion mathematical model of the adjustable electricity and heat storage boiler, calculating the heat supply power of the heat storage tank comprises the following steps:
calculation based on power and energy
P·tc＝Q (9)
Wherein:
p: the heat supply power of the heat storage tank;
tc: the heat supply power output period of the heat storage tank;
q: the heat supply load of the heat storage tank;
heating power P of heat storage tank in time tg(t)Can be calculated from the following formula
Pg(t)·Δt＝Qout(t)-Qin(t) (10)
Wherein Q isout(t)、Qin(t)Respectively the outflow heat load and the injection heat load of the heat storage tank at the time t;
suppose that the flow rates of the inlet and outlet of the heat storage tank are G at time tout(t)、Gin(t)The unit is generally expressed in Kg/h, and the water flow velocity is respectively vin(t)、vout(t)The diameter of the tube is Din、DoutThen there is
According to the relation between the flow rate and the flow rate of hot water
Substituting the formula (13) into the formulae (11) and (12) respectively to obtain
Substituting the expressions (11) and (12) into the expression (10) to obtain
Wherein:
Pg(t): representing the heat supply power of the heat storage tank in the time t;
c: represents the specific heat of the heat storage medium;
g: water flow representing a thermal storage tank;
d: represents the pipe diameter of the thermal storage tank;
Gout(t)、Gin(t): respectively represents the flow rates of the outlet and the inlet of the heat storage tank at the time t, and the unit is oneGenerally expressed as Kg/h;
Tout(t): temperature representative of the injected heat load;
Tin(t): a temperature representative of the heat load of the effluent;
Δ t: represents a temperature difference that causes a change in thermal load;
T0: representing the reference temperature.
5. A grid load model of an adjustable electrical storage heat boiler according to claim 1, characterized in that: the electric heat storage boiler uses water as a medium to store heat generated by the electric boiler in the heat storage device during the electricity valley period, and a system which is timely supplied to heat utilization equipment can be used for not starting or starting less than the electric boiler during the electricity peak period, so that the electricity consumption in the peak period is reduced, and the peak shifting and valley filling effects are realized.
6. A grid load model of an adjustable electrical storage heat boiler according to claim 1, characterized in that: the electric heat storage boiler is an adjustable electric heat storage boiler, the load of a power grid of the adjustable electric heat storage boiler is related to parameters such as specific heat, density and volume of a medium, wherein the height of the medium is measurable, and the equivalent temperature is controllable; the electric heat storage boiler adjusts the power grid load of the electric heat storage boiler by controlling the height of the medium and the equivalent temperature.
7. A grid load model of an adjustable electrical storage heat boiler according to claim 1, characterized in that: the control variables are equivalent temperature of the heat storage tank, flow of an injection port and an outflow port of the heat storage tank, the state variables are heat supply power and heat supply load of the heat storage tank, the heat supply temperature is set by operating personnel according to user requirements, the volume of water in the heat storage tank can be obtained by an instant monitoring system, and the rest are constants.
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