CN112329185A - User-side distributed energy system interactive operation evaluation method - Google Patents

User-side distributed energy system interactive operation evaluation method Download PDF

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CN112329185A
CN112329185A CN202011392936.5A CN202011392936A CN112329185A CN 112329185 A CN112329185 A CN 112329185A CN 202011392936 A CN202011392936 A CN 202011392936A CN 112329185 A CN112329185 A CN 112329185A
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pipe network
supply pipe
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崇志强
陈培育
李树青
郗晓光
李振斌
于光耀
吴彬
马世乾
霍现旭
王天昊
姚程
杨帮宇
尚学军
鄂志君
龚成虎
郑卫洪
吴磊
王峥
郭悦
马钢
刘云
刘亚丽
崔洁
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State Grid Corp of China SGCC
State Grid Tianjin Electric Power Co Ltd
Electric Power Research Institute of State Grid Tianjin Electric Power Co Ltd
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State Grid Tianjin Electric Power Co Ltd
Electric Power Research Institute of State Grid Tianjin Electric Power Co Ltd
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Abstract

The invention relates to a user-side distributed energy system interactive operation evaluation method, which comprises the following steps: step 1, establishing an ICES interactive operation economy evaluation index considering the service life of a heat supply pipe network, and evaluating the ICES interactive operation economy considering the service life of the heat supply pipe network; and 2, establishing a low-cycle fatigue life model of the heat supply pipe network, evaluating the low-cycle fatigue life of the heat supply pipe network, and obtaining a main temperature cycle comprising the maximum value and the minimum value of the pipe network temperature in one day by adopting a statistical method of temperature cycle. The invention is beneficial to comprehensively considering the contradiction between the economy and the safety of utilizing flexible resources from the perspective of flexibility.

Description

User-side distributed energy system interactive operation evaluation method
Technical Field
The invention belongs to the technical field of energy system optimization energy management and evaluation, and particularly relates to a user-side distributed energy system interactive operation evaluation method.
Background
The heat supply part in the customer side distributed Energy System (ICES) mainly consists of three parts, namely a heat source, a heat supply pipe network and a heat load. The scale of the heat supply part is limited by the transmission loss of the heat pipe network, so the coupling of the heat supply part and the electric power link is mainly concentrated on the power distribution network and the load side. From the heat source, the district heating system is coupled with the power distribution network through electric energy substitution equipment such as cogeneration equipment, heat pumps and the like, and the heat energy and the electric energy can be converted to a certain extent; in addition, the equipment such as heat accumulating type electric heating has outstanding thermal inertia, and can be more flexibly involved in ICES operation. From the view of the heat supply pipe network, the heat inertia of the heat supply pipe network enables the heat supply pipe network to have natural heat storage characteristics, and the characteristics can be utilized in the ICES to compensate output fluctuation of heat sources such as cogeneration and the like, so that the heat supply pipe network can operate in a more economic and more friendly mode to an electric power system. From the load perspective, a so-called "energy flexible building" can be built based on the virtual energy storage and demand side response technology, and the thermal inertia of the building is utilized to provide services such as peak clipping, valley filling, renewable energy consumption and the like for the power system. At present, many ICES demonstration projects are built at home and abroad, for example, a certain Heat supply system in east Milan Italy, and flexible interconversion substitution and optimal configuration between electricity and Heat under different operating conditions are realized through redundant configuration of energy equipment such as Combined Heat and Power (CHP), Heat Pumps (HP), electric boilers and the like and assisted by Heat storage devices and Heat storage characteristics of a Heat network; ICES demonstration parks with energy stations as the core are successively established in some cities such as Shanghai, Tianjin and the like in China, and flexible operation of the ICES is supported through equipment integration and centralized control of electricity, heat (cold) energy and the like, so that the energy utilization efficiency of the parks is greatly improved. However, the above research fails to reasonably consider the cost or the cost of the flexible resource of the heat supply part used by the ICES to participate in energy scheduling, and the related research is yet to be integrated and deepened.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a user-side distributed energy system interactive operation evaluation method which is reasonable in design and accurate in evaluation result.
The technical problem to be solved by the invention is realized by adopting the following technical scheme:
a user side distributed energy system interactive operation evaluation method comprises the following steps:
step 1, establishing an ICES interactive operation economy evaluation index considering the service life of a heat supply pipe network, and evaluating the ICES interactive operation economy considering the service life of the heat supply pipe network;
step 2, establishing a low cycle fatigue life model of the heat supply pipe network, evaluating the low cycle fatigue life of the heat supply pipe network, and obtaining a main temperature cycle comprising the maximum value and the minimum value of the pipe network temperature in one day by adopting a statistical method of temperature cycle;
moreover, the specific method for establishing the economic evaluation index of the ICES interactive operation considering the service life of the heat supply pipe network in the step 1 comprises the following steps:
an ICES annual operation economic index considering the service life of a heat supply pipe network is constructed
Figure BDA0002813345610000021
The index includes ICES annual operating cost
Figure BDA0002813345610000022
And heat supply network extra life lost annual cost
Figure BDA0002813345610000023
Two parts, as shown in formula (1):
Figure BDA0002813345610000024
the ICES annual operating cost is the sum of operating costs obtained by daily ICES optimal scheduling in a heating season:
Figure BDA0002813345610000025
in the formula: cdp,dOptimizing and scheduling the operation cost of the obtained heating day d for the ICES day ahead; n is a radical ofdThe number of heating days included in one heating season.
The annual cost of the extra service life loss of the heat supply network refers to the extra cost generated by the aggravation of the service life loss of the ICES due to the utilization of the flexibility of the heat supply network; the annual cost of the extra life loss of the heat supply network is evaluated based on the annual cost of the whole life cycle of the heat supply network, and the formula (3) is as follows:
Figure BDA0002813345610000026
in the formula:
Figure BDA0002813345610000027
the annual cost such as the whole life cycle of the heat supply pipe network is considered when the flexibility potential of the heat supply pipe network is considered;
Figure BDA0002813345610000028
the annual cost such as the whole life cycle of the heat supply pipe network is low when the flexibility potential of the heat supply pipe network is not considered.
Figure BDA0002813345610000031
And
Figure BDA0002813345610000032
all for heat supply pipe network life TlifeAs a function of (c).
Moreover, the specific steps of step 1 for evaluating the ice operation economy considering the service life of the heat supply network comprise:
(1) selecting a typical day: because the method for calculating the whole heating season day by day has too large calculation amount, representative typical days are selected for evaluation. For ICES, two scenes of a general heating day and an extremely cold day heating day can be selected as a representative typical day of the whole heating season;
(2) selecting operation constraint of a heat supply pipe network, and determining a boundary utilizing the flexibility of the heat supply pipe network, wherein the selected heat supply pipe network working medium is subjected to gradient constraint;
(3) computing
Figure BDA0002813345610000033
Calling an ICES day-ahead optimization scheduling method according to ICES operation constraints and each typical daily load data to generate an ICES operation scheme and corresponding operation cost Cdp,d. The annual running cost of ICES can be estimated according to the typical daily calculation result
Figure BDA0002813345610000034
(4) Calling the heating pipe according to the typical daily operation optimization schemeNetwork life model evaluation heat supply pipe network life TlifeCombined with calculation of formula (3)
Figure BDA00028133456100000310
(5) Calculating according to equation (1)
Figure BDA0002813345610000035
And evaluating the economy of the selected operation constraint and the corresponding operation plan according to the obtained index result.
And the specific method for establishing the low-cycle fatigue life model of the heat supply pipe network in the step 2 comprises the following steps:
the low cycle fatigue life of a heat supply pipe network is characterized by utilizing an S-N curve, and some standards are based on experimental data, and an empirical formula of the S-N curve is stipulated:
Figure BDA0002813345610000036
in the formula:
Figure BDA0002813345610000037
is the range of a certain stress cycle;
Figure BDA0002813345610000038
for the maximum bearable stress cycle of the heat supply pipe network
Figure BDA00028133456100000311
The number of times of (c); m is a coefficient specified by a standard; gamma raySNIs an intermediate parameter and can take on a value of 5000.
In the evaluation of the low cycle fatigue life of the heat supply pipe network, the stress action on the heat supply pipe network is approximately assumed to be in direct proportion to the temperature:
Figure BDA0002813345610000039
in the formula:
Figure BDA0002813345610000041
to correspond to stress cycle
Figure BDA0002813345610000042
Temperature cycling range of (a); the symbol ". varies" indicates "proportional to". The invention neglects the heat transfer process between the working medium and the heat supply pipe network, and approximately considers that the temperature of a certain position in the heat supply pipe network is equal to the temperature of the working medium in the pipe network. And (3) converting the relation between the stress cycle and the service life of the heat supply pipe network into the relation between the temperature cycle and the service life of the heat supply pipe network.
And the specific steps of evaluating the low cycle fatigue life of the heat supply pipe network in the step 2 comprise:
(1) based on the S-N curves of the pipe network elements, the low cycle fatigue life of the heat supply pipe network can be estimated by using the Poelminglin-nanometer rule, which is based on the following assumptions:
1) the damage to the heat supply pipe network caused by each stress cycle experienced by the heat supply pipe network can be accumulated;
2) the damage caused by each circulation can be drawn by the same SN curve;
3) the damage caused by the circulation is independent of the distribution of the circulation over time.
The criterion for determining that the service life of the heat supply pipe network meets the requirement is as follows:
Figure BDA0002813345610000043
in the formula: r is the serial number of the temperature cycle actually experienced by the heat supply pipe network; n isrThe number of occurrences of the temperature cycle numbered r; n is a radical ofrStress cycle S caused by temperature cycle with number rrSubstituting the maximum cycle number obtained in the formulas (1) to (2); gamma rayfatThe value can be 5-10 according to different engineering grades for a safety factor;
(2) selecting the difference delta T between the highest temperature and the ambient temperature in the operation of the pipe networkrefAs a reference standard, formulae (4) to (5) can be collated with formula (6):
Figure BDA0002813345610000044
in the formula: n is a radical ofeqThe number of times from the equivalent of the temperature cycle actually experienced by the heat supply pipe network to the reference temperature cycle; delta TrTemperature range of temperature cycle, numbered r, ° c; n is a radical ofrefA maximum number of cycles of a reference temperature cycle;
(3) the temperature cycles actually experienced by the heat supply pipe network are classified according to different time scales, and the left part of the inequality of the formula (7) can be rewritten as follows:
Figure BDA0002813345610000051
in the formula:
Figure BDA0002813345610000052
the number of total equivalent reference temperature cycles experienced by the heat supply pipe network in one year; xi takes values of 1, 2, 3 and 4 to respectively represent the temperature cycle actually experienced by the heat supply pipe network in one day, one week, one month and one year; r isξNumbering the temperature cycles; n isr,ξAnd Δ Tr,ξAre respectively numbered as rξThe number of times of occurrence of temperature cycles and the temperature range thereof;
(4) defining the moment when the equivalent reference temperature cycle number of the heat supply pipe network reaches 80% of a standard specified value as a service life end point of the heat supply pipe network providing flexibility potential for the ICES, namely when the equivalent reference temperature cycle number of the heat supply pipe network reaches 200 times, an ICES operator can quit the operation or renew the operation according to the situation; accordingly, the low cycle fatigue life of the heating pipe network can be expressed as:
Figure BDA0002813345610000053
in the formula: t islifeFor the low cycle fatigue life of the heat supply pipe network, the invention is the operation age, year, of the heat supply pipe network participating in the ICES flexibility optimization scheduling; n is a radical oflifeTo supply forThe equivalent reference temperature cycle number of the heat pipe network in the life cycle;
from the above model it can be seen that: t islifeIs directly related to the amplitude and frequency of the temperature cycle experienced by the heating network.
Moreover, the step 2 of obtaining a main temperature cycle including the maximum and minimum values of the temperature of the pipe network in one day by using the statistical method of the temperature cycle comprises the following specific steps:
(1) drawing a temperature-time curve of the pipe network in one day by taking the temperature as a horizontal axis and the time as a vertical downward vertical axis;
(2) taking each extreme point of the curve as a starting point, starting from one extreme point of the curve, enabling the curve to move forward along the curve to a time axis, if the curve meets the next extreme point, vertically falling, if the curve falls on the curve again, continuing to do the movement along the curve, and drawing a trace of the movement of the point;
(3) if the trace can not fall on the curve after falling from a certain extreme point except the most extreme point, keeping the abscissa of the trace unchanged and enabling the trace to fall off from the abscissa again;
(4) if a trace drawn before is encountered in the movement of a certain point, the movement is stopped;
(5) since the heat supply network scheduling is performed in a day period, when the traces from the starting points are drawn, a temperature cycle including the maximum value and the minimum value of the temperature of the heat supply network in one day can be described along the traces from a maximum point of the curve.
Further, the specific steps of step 3 include:
the influence of the flexibility potential of the heat supply pipe network utilized by the ICES on the service life of the heat supply pipe network is considered, and the change of the service life of the heat supply pipe network mainly influences the equal annual value investment cost of the heat supply pipe network
Figure BDA0002813345610000061
Annual operating maintenance costs
Figure BDA0002813345610000062
And residual value equal annual profit
Figure BDA0002813345610000063
As shown in equation (10):
Figure BDA0002813345610000064
1) calculating equal annual value investment cost of heat supply pipe network
A relatively accurate heat supply pipe network investment cost calculation formula suitable for ICES planning is provided, and formula (11) shows:
Figure BDA0002813345610000065
in the formula:
Figure BDA0002813345610000071
the unit fixed cost for heat supply pipe network investment, namely the unit cost of the cost related to the length of the pipeline, such as road breaking, laying and the like, is low;
Figure BDA0002813345610000072
unit variable cost for heat supply pipe network investment, namely unit cost such as material cost and the like related to both pipeline length and capacity;
Figure BDA0002813345610000073
the maximum value of the interactive thermal power of the j-th pipe section, kW, can be calculated according to the formula (12):
Figure BDA0002813345610000074
in the formula: q. q.sjThe mass flow rate of the j section is kg/s, and is a fixed value in the heat network mass adjusting mode;
wherein, the annual value investment cost such as the whole life cycle of the heat supply pipe network can be calculated according to the formula (13):
Figure BDA0002813345610000075
in the formula: drThe current rate is the current rate;
2) calculating annual operation and maintenance cost of heat supply pipe network
The annual operation and maintenance cost of the heat supply pipe network is shown as the formula (14):
Figure BDA0002813345610000076
in the formula:
Figure BDA0002813345610000077
and
Figure BDA0002813345610000078
respectively the annual operating cost of the heat supply network circulating pump and the annual maintenance cost of the heat supply network.
The annual operating cost of the heat supply network circulating pump is shown as the formula (15):
Figure BDA0002813345610000079
in the formula: gamma rayDHNThe electric energy consumed by the unit heat for the circulating pump transmission can be 0.0059[43 ]]，kWh；
The annual maintenance cost of the heat supply pipe network comprises annual cost generated by pipe network maintenance, repair and the like, and is shown in formula (16):
Figure BDA00028133456100000710
in the formula: gamma rayMThe value of the method is 1% for the maintenance rate of the pipe network.
3) Residual value equal annual value income of heat supply pipe network
The annual income of residual value of the heat supply pipe network is residual value income obtained by processing a part which is withdrawn from operation after the pipe network is withdrawn from operation or renovated, and the residual value income is often considered to be generated simultaneously with equipment investment in calculation, as shown in a formula (17):
Figure BDA0002813345610000081
in the formula: gamma rayS,DHNThe value of the method is 3 percent for the residual value rate of the pipe network;
the invention has the advantages and positive effects that:
aiming at the problem of insufficient cost consideration when flexible resources of an ICES heat supply pipe network are utilized, firstly, an ICES interactive operation economic evaluation index considering the service life of the heat supply pipe network is established, and complete steps and a flow of an evaluation method are provided; further establishing a low cycle fatigue life model of the heat supply pipe network and an annual value cost model of the heat supply pipe network in the whole life cycle; and further provides an ICES interactive operation economy evaluation method considering the service life loss of the heat supply pipe network.
Drawings
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is a schematic diagram of the S-N curve of the present invention;
FIG. 3 is a schematic view of a rain flow method calculation temperature cycle process of the present invention;
FIG. 4 is a schematic diagram of an ICES energy plant of the present invention;
FIG. 5 is a schematic diagram of a 44-node heating network configuration of the present invention;
FIG. 6 is a diagram of the general heating solar power, heat load power and time-of-use electricity price of the present invention;
FIG. 7 is a diagram of solar electricity, heat load power and time-of-use electricity price for extremely cold weather heating according to the present invention;
FIG. 8 is a graphical illustration of ICES annual operational economics, ICES annual operational costs and heat supply network extra life lost annual costs for three scenarios of the present invention;
FIG. 9 is a diagram of annual cost construction for the heat supply pipe network in three scenarios of the present invention;
FIG. 10 is a schematic diagram showing the temperature of water supplied to the outlet of the heating head station in a general heating day scenario I according to the rain flow method of the present invention;
FIG. 11 is a schematic diagram showing the temperature of water supplied to the outlet of the heating head station in a general heating day scenario II according to the rain flow method of the present invention;
FIG. 12 is a schematic diagram showing the temperature of water supplied to the outlet of the heating head station in a general heating day scene III in the rain flow method according to the present invention;
Detailed Description
The embodiments of the invention will be described in further detail below with reference to the accompanying drawings:
a user side distributed energy system interactive operation evaluation method comprises the following steps:
step 1, establishing an ICES interactive operation economy evaluation index considering the service life of a heat supply pipe network, and evaluating the ICES interactive operation economy considering the service life of the heat supply pipe network;
the specific steps of establishing the ICES interactive operation economic evaluation index considering the service life of the heat supply pipe network in the step 1 comprise:
in the ICES optimization operation, due to the utilization of the flexibility potential of the heat supply pipe network, the heat supply pipe network is subjected to frequent temperature alternation, the fatigue process of the heat supply pipe network can be accelerated, the heat supply pipe network is damaged in advance, and how to calculate the corresponding cost is needed to be further researched. Therefore, when the ICES utilizes the flexibility potential of the heat supply network, great attention is paid to whether the income brought by the utilization behavior can exceed the loss cost caused by the service life accelerated loss of the heat supply network. If the revenue of the former is sufficient to outweigh the cost of the latter, indicating that the ICES's activity utilizing the flexibility potential of the heating network is economical, the ICES operator may choose to take the heating network out of service or retrofit it when the life of the heating network reaches or approaches the end point. In addition, the set constraints are different when the flexibility potential of the heat supply pipe network is utilized, and the benefits and the cost are influenced.
In order to try to solve the problems from the economical point of view, the invention constructs an ICES annual operation economical index considering the service life of a heat supply pipe network
Figure BDA0002813345610000091
The index includes ICES annual operating cost
Figure BDA0002813345610000092
And heat supply network extra life lost annual cost
Figure BDA0002813345610000093
Two parts, as shown in formula (1):
Figure BDA0002813345610000094
therefore, the proposed ICES annual operation economic index considering the service life of the heat supply pipe network is the expansion of ICES operation cost. The ICES annual operating cost is the sum of operating costs obtained by daily ICES optimal scheduling in a heating season:
Figure BDA0002813345610000095
in the formula: cdp,dOptimizing and scheduling the operation cost of the obtained heating day d for the ICES day ahead; n is a radical ofdThe number of heating days included in one heating season. When the system is not in the heating season, the heat supply network is in the off-stream state, and the flexible resources can not be utilized, so the system is not included in the economic index.
The annual cost of the extra life loss of the heat supply network refers to the extra cost generated by the aggravation of the life loss of the ICES due to the flexibility of the heat supply network. The idea of annual cost such as the whole life cycle in analogy electric power system and ICES, the annual cost of the extra life loss of heat supply network is evaluated based on the annual cost such as the whole life cycle of heat supply network, as shown in formula (3):
Figure BDA0002813345610000101
in the formula:
Figure BDA0002813345610000102
the annual cost such as the whole life cycle of the heat supply pipe network is considered when the flexibility potential of the heat supply pipe network is considered;
Figure BDA0002813345610000103
life cycle of heat supply pipe network without considering flexibility potential of heat supply pipe networkEqual annual value cost, yuan.
Figure BDA0002813345610000104
And
Figure BDA0002813345610000105
all for heat supply pipe network life TlifeAs a function of (c).
The reason for evaluating the annual cost of the extra service life loss of the heat supply network by using the annual cost method of the whole service life cycle is as follows: the heat supply network life reflects the operational age of the heat supply network in the ICES. ICES utilizes the heat supply pipe network flexibility potential to cause its life loss aggravation, service life shorten, generally make the equal annual value cost rise of heat supply pipe network. Only when the annual operating cost saved by the action of utilizing the flexibility of the heat supply network exceeds the increment of the annual value cost of the heat supply network caused by the annual operating cost, the ICES operator can be ensured to obtain economic benefits from the utilization action. Further, under the premise of determining the equipment and load scale of the ICES, an ICES operator always wants to select an operation scheme with lower sum of ICES annual operation cost and annual value cost increment of a heat supply pipe network.
The specific steps of step 1 for evaluating the ICES operation economy considering the service life of the heat supply pipe network comprise:
as shown in fig. 1, the flow of the method for evaluating the economic performance of the ice operation considering the service life of the heat supply pipe network is as follows:
(1) a typical day is selected. Because the method for calculating the whole heating season day by day has too large calculation amount, representative typical days are selected for evaluation. For ICES, two scenes of a general heating day and an extremely cold day heating day can be selected as a representative typical day of the whole heating season.
(2) Selecting operation constraint of the heat supply pipe network, and determining the boundary utilizing the flexibility of the heat supply pipe network.
(3) Computing
Figure BDA0002813345610000111
Calling ICES day-ahead optimization scheduling method according to ICES operation constraint and each typical daily load data,generating an ICES operating plan and corresponding operating costs Cdp,d. The annual running cost of ICES can be estimated according to the typical daily calculation result
Figure BDA0002813345610000112
(4) According to the typical daily operation optimization scheme, calling the heat supply pipe network life model to evaluate the service life T of the heat supply pipe networklifeCombined with calculation of formula (3)
Figure BDA0002813345610000113
(5) Calculating according to equation (1)
Figure BDA0002813345610000114
And evaluating the economy of the selected operation constraint and the corresponding operation plan according to the obtained index result.
And 2, establishing a low-cycle fatigue life model of the heat supply pipe network, evaluating the low-cycle fatigue life of the heat supply pipe network, and obtaining a main temperature cycle comprising the maximum value and the minimum value of the pipe network temperature in one day by adopting a statistical method of temperature cycle.
Pipeline engineering believes that long term temperature cycling of a pipeline structure will result in fatigue life damage and possible accidents. The reason for this is that in the actual operation of the heat supply pipe network, the temperature fluctuation of the heat supply pipe network can cause the elements in the pipe network to expand or contract with heat, resulting in the mutual stretching or extrusion among the parts of the elements, between the elements, and between the elements and the environment (soil). In heating projects, the forces that are affected by temperature changes and cause pipe network elements to be subjected to are classified as secondary stresses. The stress generally does not directly cause the damage of the pipe network, but causes the pipe network to enter a yielding state, and the pipe network material does not only generate elastic deformation but also generates certain plastic deformation in the process. Since plastic deformation is continuously accumulated in the pipe network, a certain yield state is only allowed to occur a limited number of times, after which the material will possibly crack, which is a low cycle fatigue process of the pipe network material. In an actual heat supply network, low cycle fatigue generally plays a decisive role in the service life of elbows, tees, small-angle break angles, positioning circular welding seams and the like with deviation.
In the actual heat supply network, although the service life of the weak links can be prolonged by additionally arranging the fixed piers, the compensators and the like in the design stage, the cost for installing the compensation materials is high, and the installation of the compensators can adversely affect the overall reliability of the heat supply network, so that the compensation heat supply network can only be selectively additionally arranged and can not completely replace the fatigue analysis process without additionally arranging the compensation heat supply network, and therefore, only the directly-buried heat supply network without additionally arranging the compensators is considered in the invention.
The specific steps of the step 2 comprise:
(1) the relation between a certain stress cycle size borne by a common heat supply pipe network in heat supply engineering (especially some countries in Europe) and the maximum number of times of the stress cycle can be borne by the common heat supply pipe network, namely, the low cycle fatigue life of the heat supply pipe network is described by using an S-N curve. The S-N curve is schematically shown in FIG. 2. There are standards that specify an empirical formula for the S-N curve based on experimental data:
Figure BDA0002813345610000121
in the formula:
Figure BDA0002813345610000122
is the range of a certain stress cycle;
Figure BDA0002813345610000123
for the maximum bearable stress cycle of the heat supply pipe network
Figure BDA0002813345610000124
The number of times of (c); m is a coefficient specified by a standard; gamma raySNIs an intermediate parameter and can take on a value of 5000.
In the evaluation of the low cycle fatigue life of the heat supply pipe network, the stress action on the heat supply pipe network is approximately assumed to be in direct proportion to the temperature:
Figure BDA0002813345610000125
in the formula:
Figure BDA0002813345610000126
to correspond to stress cycle
Figure BDA0002813345610000127
Temperature cycling range of (a); the symbol ". varies" indicates "proportional to". The invention neglects the heat transfer process between the working medium and the heat supply pipe network, and approximately considers that the temperature of a certain position in the heat supply pipe network is equal to the temperature of the working medium in the pipe network. And (3) converting the relation between the stress cycle and the service life of the heat supply pipe network into the relation between the temperature cycle and the service life of the heat supply pipe network.
(2) Based on the S-N curves of the pipe network elements, the low cycle fatigue life of the heat supply pipe network can be evaluated by using the Polmergren-nanometer (Palmgren-Miner) rule. This rule is based on the following assumptions:
1) the damage to the heat supply pipe network caused by each stress cycle experienced by the heat supply pipe network can be accumulated;
2) the damage caused by each circulation can be drawn by the same SN curve;
3) the damage caused by the circulation is independent of the distribution of the circulation over time.
The criterion for determining that the service life of the heat supply pipe network meets the requirement is as follows:
Figure BDA0002813345610000128
in the formula: r is the serial number of the temperature cycle actually experienced by the heat supply pipe network; n isrThe number of occurrences of the temperature cycle numbered r; n is a radical ofrStress cycle S caused by temperature cycle with number rrSubstituting the maximum cycle number obtained in the formulas (1) to (2); gamma rayfatThe value can be 5-10 according to different engineering grades for a safety factor.
In order to make the criterion more intuitive, the difference delta T between the highest temperature and the ambient temperature in the operation of the pipe network is selectedrefAs a reference standard, formulae (4) to (5) can be collated with formula (6):
Figure BDA0002813345610000131
in the formula: n is a radical ofeqThe number of times from the equivalent of the temperature cycle actually experienced by the heat supply pipe network to the reference temperature cycle; delta TrTemperature range of temperature cycle, numbered r, ° c; n is a radical ofrefThe maximum number of cycles of the reference temperature cycle.
The temperature cycles actually experienced by the heat supply pipe network are classified according to different time scales (one day, one week, one month and one year), and the left part of the inequality of the formula (7) can be rewritten as follows:
Figure BDA0002813345610000132
in the formula:
Figure BDA0002813345610000133
the number of total equivalent reference temperature cycles experienced by the heat supply pipe network in one year; xi takes values of 1, 2, 3 and 4 to respectively represent the temperature cycle actually experienced by the heat supply pipe network in one day, one week, one month and one year; r isξNumbering the temperature cycles; n isr,ξAnd Δ Tr,ξAre respectively numbered as rξThe number of occurrences of temperature cycling and the temperature range thereof.
According to international standards, it is required that the number of reference temperature cycles selected in the design verification cannot be less than 250 for the transmission and distribution mains of the heat supply network. N on the right side of the inequality in equation (7)ref/γfatDirectly specifies NeqThe maximum value of (A) is obviously more visual and convenient as the service life criterion of the heat supply pipe network. In consideration of safety, the invention defines the time when the equivalent reference temperature cycle number of the heat supply pipe network reaches 80% of a standard specified value as the service life end point of the heat supply pipe network providing flexibility potential for the ICES by analogy with the definition of the service life end point of the energy storage equipment in the power system, namely when the equivalent reference temperature cycle number of the heat supply pipe network reaches 200 times, the ICES operator can quit the operation or enter the ICES according to the situationAnd (5) performing renovation. Accordingly, the low cycle fatigue life of the heating pipe network can be expressed as:
Figure BDA0002813345610000141
in the formula: t islifeFor the low cycle fatigue life of the heat supply pipe network, the invention is the operation age, year, of the heat supply pipe network participating in the ICES flexibility optimization scheduling; n is a radical oflifeThe equivalent reference temperature cycle number of the heat supply pipe network in the life cycle.
From the above model it can be seen that: t islifeIs directly related to the amplitude and frequency of the temperature cycle experienced by the heating network. The amplitude of temperature circulation experienced by the pipe network can be reduced by limiting the temperature of the working medium, and the process of temperature change of the pipe network can be slowed down by limiting the temperature gradient of the working medium, so that the reason that the temperature constraint of the working medium and the temperature gradient constraint of the working medium are beneficial to maintaining the safety of the heat supply pipe network and prolonging the service life of the heat supply pipe network is explained from another angle.
(3) A statistical method of temperature cycle is adopted to obtain a main temperature cycle containing the maximum value and the minimum value of the temperature of the pipe network in one day.
The statistical method of the temperature cycle actually experienced by the heat supply pipe network uses the idea of a rain flow counting method. The rain flow counting method is a counting method for characterizing the fatigue damage of mechanical elements, is also suitable for the low-cycle fatigue analysis of a heat supply network, and is currently analogized to the evaluation of the service life damage of a storage battery. The statistical process of the temperature cycle in the present invention is briefly described as follows:
1) drawing a temperature-time curve of the pipe network in one day by taking the temperature as a horizontal axis and the time as a vertical downward vertical axis, as shown in fig. 3;
2) taking each extreme point of the curve as a starting point, starting from one extreme point of the curve, enabling the curve to move forward along the curve to a time axis, if the curve meets the next extreme point, vertically falling, if the curve falls on the curve again, continuing to do the movement along the curve, and drawing a trace of the movement of the point;
3) if the trace can not fall on the curve after falling from a certain extreme point except the most extreme point, keeping the abscissa of the trace unchanged and enabling the trace to fall off from the abscissa again;
4) if a trace drawn before is encountered in the movement of a certain point, the movement is stopped;
5) because the heat supply network scheduling is performed by taking a day as a period, after the traces from the starting points are drawn, a temperature cycle comprising the maximum value and the minimum value of the temperature of the heat supply network in the day can be drawn along the traces from a maximum point of the curve, and the temperature cycle is called as a main temperature cycle in the day. When this main temperature cycle is taken away, the remainder of the curve will leave some small temperature cycles consisting of trace closure. If the small loop nesting occurs, the above process can be repeated for the small loop in which the nesting occurs.
Taking fig. 3 as an example, the drawing process of each trace is shown in fig. 3(a), and the extracted major loop and minor loop are shown in fig. 3 (b). Where the start of each trace is represented by an open circle and the end is represented by a dashed line. The trajectory of the trace is similar to a rain drop falling on a pagoda, and is named as a rain flow method. The statistical method of the temperature cycle is slightly improved on the basis of the classical rain flow counting method, and has the advantages that a main temperature cycle including the maximum value and the minimum value of the temperature of the pipe network in one day can be obtained (the classical rain flow counting method can obtain two half cycles respectively including the maximum value and the minimum value of the temperature of the pipe network in one day), the physical significance is more clear, and the analysis is convenient. When m is not 1, the method of the invention is not completely equivalent to the classical rain flow counting method, but is referred to as the rain flow method in the invention for simplicity.
Step 3, establishing an annual value cost model of the whole life cycle of the heat supply pipe network, and evaluating the cost of the ICES for utilizing the flexibility resources of the heat supply pipe network by calculating the annual cost of the extra life loss of the heat supply pipe network;
when the annual cost method of the whole life cycle is used for evaluating the economy of a certain device in the ICES, factors which are often considered can include the annual investment cost, the annual operation and maintenance cost, the annual risk loss cost, the residual value of the device and the like. The invention mainly focuses on the influence of the ICES on the service life of the ICES by utilizing the flexibility potential of a heat supply pipe networkThe change of service life of the sound and heat supply pipe network mainly influences the equal annual value investment cost
Figure BDA0002813345610000161
Annual operating maintenance costs
Figure BDA0002813345610000162
And residual value equal annual profit
Figure BDA0002813345610000163
As shown in equation (10):
Figure BDA0002813345610000164
according to the definition of the service life of the heat supply pipe network, the fault risk is always maintained at a lower level in the service life, so the influence of the flexibility potential on the fault risk of the heat supply pipe network is not considered temporarily, namely the annual risk loss cost is considered to be a certain value, and the annual risk loss cost is calculated in a formula (3)
Figure BDA0002813345610000165
It is erased, and therefore, it is not considered in the formula (10).
1) Calculating equal annual value investment cost of heat supply pipe network
The investment cost of the heat supply pipe network comprises material cost, road breaking cost, labor cost, engineering equipment cost and the like, and the engineering is generally estimated according to the past experience and in a long-meter manufacturing cost mode. A relatively accurate heat supply pipe network investment cost calculation formula suitable for ICES planning is provided, and formula (11) shows:
Figure BDA0002813345610000166
in the formula:
Figure BDA0002813345610000167
the unit fixed cost for heat supply pipe network investment, namely the unit cost of the cost related to the length of the pipeline, such as road breaking, laying and the like, is low;
Figure BDA0002813345610000168
unit variable cost for heat supply pipe network investment, namely unit cost such as material cost and the like related to both pipeline length and capacity;
Figure BDA0002813345610000169
the maximum value of the interactive thermal power of the j-th pipe section, kW, can be calculated according to the formula (12):
Figure BDA00028133456100001610
in the formula: q. q.sjThe mass flow rate in kg/s in the j-th section is constant in the heat grid mass regulation mode.
Wherein, the annual value investment cost such as the whole life cycle of the heat supply pipe network can be calculated according to the formula (13):
Figure BDA0002813345610000171
in the formula: drThe discount rate is the discount rate.
2) Calculating annual operation and maintenance cost of heat supply pipe network
The annual operation and maintenance cost of the heat supply pipe network can comprise the annual operation cost of the circulating pump, the annual maintenance cost of the heat supply pipe network, the annual loss cost of the pipe network and the like. The annual operation and maintenance cost of the heat supply pipe network is shown as the formula (14):
Figure BDA0002813345610000172
in the formula:
Figure BDA0002813345610000173
and
Figure BDA0002813345610000174
respectively the annual operating cost of the heat supply network circulating pump and the annual maintenance cost of the heat supply network.
The operation cost of the heat supply network circulating pump is mainly determined by the heat exchange amount between each heat exchange station in the heat supply network and the heat supply pipe network. Because the heat load requirement is just met, the ICES only influences the heat exchange quantity between the heat exchange primary station and the heat supply pipe network by utilizing the flexibility potential of the heat supply pipe network, and cannot influence the heat exchange quantity between the heat supply pipe network and the load. In this regard, the annual operating cost of the heat supply network circulation pump in the present invention is shown in the formula (15):
Figure BDA0002813345610000175
in the formula: gamma rayDHNThe electric energy consumed by the unit heat for the circulating pump transmission can be 0.0059[43 ]]，kWh；
The annual maintenance cost of the heat supply pipe network comprises annual cost generated by pipe network maintenance, repair and the like, and is shown in formula (16):
Figure BDA0002813345610000176
in the formula: gamma rayMThe value of the method is 1% for the maintenance rate of the pipe network.
The heat supply pipe network is well maintained, which is beneficial to prolonging the service life of the heat supply pipe network, but the aging of the whole pipe network cannot be prevented, so the invention does not consider the influence of the change of the maintenance cost on the service life of the pipe network.
3) Residual value equal annual value income of heat supply pipe network
The annual income of residual value of the heat supply pipe network is residual value income obtained by processing a part which is withdrawn from operation after the pipe network is withdrawn from operation or renovated, and the residual value income is often considered to be generated simultaneously with equipment investment in calculation, as shown in a formula (17):
Figure BDA0002813345610000181
in the formula: gamma rayS,DHNThe value of the invention is 3% for the residual value rate of the pipe network.
The invention is further illustrated by the following specific examples:
the embodiment of the present invention still selects the energy station and the 44-node heating network structure, which are shown in fig. 4 and fig. 5, respectively. Two typical days of a general heating day and an extremely cold day are selected, the electricity, heat load and time-of-use electricity price of the days are respectively shown in fig. 6 and fig. 7, the electricity and heat load at the nodes N2-N25 in any scheduling time period are still assumed to be the same, and the ICES electricity and heat load levels are assumed to be stable and do not increase with the year. In the calculation example, a heating season comprises a general heating day of 90 days and an extreme cold day heating day of 60 days. Because the temperature cycle range related to day-ahead scheduling is generally small, m is 2 to highlight the influence of the temperature cycle range on a heat supply pipe network. To match the heat load scale, the HP capacity in this example was 3 MW.
Setting 3 example scenarios:
scene I: the upper limit of the temperature gradient of the working medium of the pipe network is set to be 4 ℃/h;
scene II: but the temperature gradient constraint of the working medium of the pipe network is not considered (the upper limit of the temperature gradient is infinite);
scene III: the flexibility potential of the heat supply pipe network is not utilized (the heat supply network transmission delay shown in the formula (2-5) is not considered), and the upper limit of the temperature gradient is set to be 4 ℃/h;
for the sake of comparison, the calculation is performed according to equation (3) in this example
Figure BDA0002813345610000182
Time unification with scene III as a reference of comparison, i.e.
Figure BDA0002813345610000183
The annual cost such as the whole life cycle of the heat supply pipe network in the scenario III of the present example is uniformly obtained.
The service life of the heat supply network under the three scenes is shown in table 1, and the indexes of the economic performance of ICES annual operation, the annual operation cost of ICES and the annual cost of the extra service life loss of the heat supply network are shown in fig. 8. For the sake of visualization, the three indicators of scene I and scene II in fig. 8 are respectively inferior to scene III as a reference, and the results are listed in table 2.
TABLE 1 Life age of heat supply pipe network under three scenarios
Figure BDA0002813345610000191
TABLE 2 comparison of the three indicators in FIG. 8 (based on scene III)
Figure BDA0002813345610000192
From the above results it can be seen that: from the perspective of ICES annual running economy, the annual running economy of the scene I and the scene II is improved by 1.39% and deteriorated by 1.85% respectively compared with the scene III. This indicates that the operation scheme shown in scenario I is optimal among the three scenarios in this example and should be selected. The flexibility of the heat supply pipe network is utilized more than favorably in the scene II, the annual running economy is the worst, and the ICES is prevented from running in the mode as much as possible.
After the flexibility potential of the heat supply pipe network is considered in the scene I and the scene II, the ICES annual operation cost is lower than that in the scene III, and the ICES annual operation cost in the scene II is the lowest; meanwhile, compared with the scene III, the service life loss of the heat supply pipe network in one year is increased by 7.5% and 15.1% respectively in the scene I and the scene II. The lower the annual operating cost of ICES, the greater the influence on the service life of the heat supply pipe network, and a certain contradiction exists between the ICES and the heat supply pipe network.
The comparison between the scene I and the scene II shows that the introduction of the temperature gradient constraint of the working medium of the pipe network has obvious influence on the three indexes in the graph 8. Although the annual ICES operation cost in the scene I is increased by 5.32 ten thousand yuan compared with the scene II, the annual ICES operation cost is saved by 73.44 ten thousand yuan due to the fact that the ICES operation cost is beneficial to prolonging the service life of a heat supply network, and finally the annual operation economy of the scene I is remarkably superior to that of the scene II.
Detailed analysis will be made below from the perspective of the annual operating cost of the ICES and the annual cost of the extra life loss of the heat supply network, respectively. The ICES annual operating costs were first analyzed. The ICES operating costs for two typical days in the three scenarios are shown in tables 3 and 4. It can be seen that: under two typical days, the ICES operation cost is saved by considering the flexibility potential of the heat supply pipe network in the ICES optimization operation; in this example, in comparison with scenario III, scenario I and scenario II in two typical days, in addition to significantly reducing the cost of electricity purchase for balancing the electrical load, the cost of electricity purchase for driving HP is also significantly reduced, and the cost of gas purchase is significantly increased. Under two typical days, the ICES operation cost is increased by considering the constraint of the working medium temperature gradient compared with not considering the constraint, and the contradiction between the safety and the economy is reflected. However, the two mechanisms of increasing the running cost of scene I compared with scene II in a typical day are not exactly the same: in a common heating day, the gas purchasing cost of the scene I is increased compared with the scene II, and the electricity purchasing cost is reduced; the opposite is true in the extreme cold days of gas heating. The difference between the above mechanisms for changing the operating cost of an ICES is the flexibility to make an ICES exhibit different operating strategies under different loads and equipment conditions.
TABLE 3 ICES operating costs for a typical heating day for three scenarios
Figure BDA0002813345610000201
TABLE 4 ICES operating costs in one day of extreme cold weather heating in three scenarios
Figure BDA0002813345610000202
And then analyzing the influence of different operation strategies of the ICES on the heat supply pipe network through the annual cost of the extra service life of the heat supply network. Fig. 9 shows the composition of annual cost values such as the life cycle of the heat supply pipe network under three scenes. Therefore, the main factor in the equal-annual-value cost of the heat supply pipe network is the equal-annual-value investment cost of the heat supply pipe network, and the equal-annual-value investment cost of the heat supply pipe network is determined by the service life of the heat supply pipe network. In the present example, the annual-value investment costs of the heat supply pipe network in the scene I and the scene II are respectively increased by 4.89% and 9.95% compared with the scene III, and the annual-value investment cost of the heat supply pipe network in the scene II, which is too high, is the main factor of the worst annual economy. In addition, the change rule of the annual value income such as the annual maintenance cost and the residual value of the heat supply pipe network is basically consistent with the annual value investment cost, but the change rule of the operation cost of the heat supply pipe network circulating pump is different, and the scene I and the scene II are respectively increased by 5.22 percent and 4.79 percent compared with the scene III. The lowest operation cost of the heat supply network circulating pump in the scene III is because the heat supply network flexibility potential is not utilized, and the operation cost of the circulating pump in the scene I is higher than that of the scene II, which shows that the introduction of the working medium temperature gradient limitation can bring extra operation cost, and is consistent with the conclusion of ICES annual operation cost.
And finally, analyzing the relation between the ICES operation strategy and the service life of the heat supply pipe network. Table 5 shows the number of equivalent reference temperature cycles experienced by the heat supply network in one day under three scenarios. It can be seen that under two typical days of ICES, the service life loss of the heat supply pipe network in the scene III is minimum, and the service life loss of the heat supply pipe network in the scene II is maximum, which is the visual performance of contradiction between the benefit of the flexibility potential of the heat supply pipe network and the cost of the service life loss of the heat supply pipe network.
Table 5 number of equivalent reference temperature cycles experienced by the heat supply pipe network in one day under three scenarios (m 2)
Figure BDA0002813345610000211
In order to analyze the cause of the contradiction from the perspective of the service life of the heat supply network, the supply water temperature at the outlet of the heat supply head station treated by the rain flow method is plotted in three scenes by taking a common heating day as an example, as shown in fig. 10 to 12. Since the ICES was scheduled every half hour, the temperature profile was in a staircase wave shape. Where the green solid line portion constitutes the main cycle of the temperature of the heat network at that location during the day and the red solid line portion shows the small temperature cycles dispersed therein. For the case of small loop nesting, no particular distinction is made in the figures. As can be seen from the figure, considering the flexibility of the heat supply network in the optimal scheduling of the ICES not only increases the amplitude of the main temperature cycle in one day, but also significantly increases the frequency and amplitude of the small temperature cycle, thereby increasing the fatigue life loss of the heat supply network by utilizing the flexibility of the heat supply network. Comparing fig. 10 with fig. 11, it can be seen that adding the heat supply network temperature gradient constraint to the ICES optimization scheduling helps to alleviate the above problem to some extent, which is consistent with the previous analysis.
The above analysis shows that: the economic evaluation method provided by the invention is beneficial to comprehensively considering the contradiction between the economic efficiency and the safety of utilizing flexible resources from the perspective of flexibility.
It should be emphasized that the embodiments described herein are illustrative rather than restrictive, and thus the present invention is not limited to the embodiments described in the detailed description, but also includes other embodiments that can be derived from the technical solutions of the present invention by those skilled in the art.

Claims (7)

1. A user side distributed energy system interactive operation assessment method is characterized by comprising the following steps: the method comprises the following steps:
step 1, establishing an ICES interactive operation economy evaluation index considering the service life of a heat supply pipe network, and evaluating the ICES interactive operation economy considering the service life of the heat supply pipe network;
and 2, establishing a low-cycle fatigue life model of the heat supply pipe network, evaluating the low-cycle fatigue life of the heat supply pipe network, and obtaining a main temperature cycle comprising the maximum value and the minimum value of the pipe network temperature in one day by adopting a statistical method of temperature cycle.
2. The method for evaluating the interactive operation of the user-side distributed energy system according to claim 1, wherein: the specific method for establishing the ICES interactive operation economic evaluation index considering the service life of the heat supply pipe network in the step 1 comprises the following steps:
an ICES annual operation economic index considering the service life of a heat supply pipe network is constructed
Figure FDA0002813345600000011
The index includes ICES annual operating cost
Figure FDA0002813345600000012
And heat supply network extra life lost annual cost
Figure FDA0002813345600000013
Two parts, as shown in formula (1):
Figure FDA0002813345600000014
the ICES annual operating cost is the sum of operating costs obtained by daily ICES optimal scheduling in a heating season:
Figure FDA0002813345600000015
in the formula: cdp,dOptimizing and scheduling the operation cost of the obtained heating day d for the ICES day ahead; n is a radical ofdThe number of heating days included in one heating season;
the annual cost of the extra service life loss of the heat supply network refers to the extra cost generated by the aggravation of the service life loss of the ICES due to the utilization of the flexibility of the heat supply network; the annual cost of the extra life loss of the heat supply network is evaluated based on the annual cost of the whole life cycle of the heat supply network, and the formula (3) is as follows:
Figure FDA0002813345600000016
in the formula:
Figure FDA0002813345600000017
the annual cost such as the whole life cycle of the heat supply pipe network is considered when the flexibility potential of the heat supply pipe network is considered;
Figure FDA0002813345600000018
the annual cost such as the whole life cycle of the heat supply pipe network is low when the flexibility potential of the heat supply pipe network is not considered;
Figure FDA0002813345600000019
and
Figure FDA00028133456000000110
all for heat supply pipe network life TlifeAs a function of (c).
3. The method for evaluating the interactive operation of the user-side distributed energy system according to claim 1, wherein: the specific steps of step 1 for evaluating the ICES operation economy considering the service life of the heat supply pipe network comprise:
(1) selecting a typical day: because the method for calculating the whole heating season day by day has too large calculation amount, representative typical days are selected for evaluation; for ICES, two scenes of a general heating day and an extremely cold day heating day can be selected as a representative typical day of the whole heating season;
(2) selecting operation constraint of a heat supply pipe network, and determining a boundary utilizing the flexibility of the heat supply pipe network, wherein the selected heat supply pipe network working medium is subjected to gradient constraint;
(3) computing
Figure FDA0002813345600000021
Calling an ICES day-ahead optimization scheduling method according to ICES operation constraints and each typical daily load data to generate an ICES operation scheme and corresponding operation cost Cdp,d(ii) a The annual running cost of ICES can be estimated according to the typical daily calculation result
Figure FDA0002813345600000022
(4) According to the typical daily operation optimization scheme, calling the heat supply pipe network life model to evaluate the service life T of the heat supply pipe networklifeCombined with calculation of formula (3)
Figure FDA0002813345600000023
(5) Calculating according to equation (1)
Figure FDA0002813345600000024
And evaluating the economy of the selected operation constraint and the corresponding operation plan according to the obtained index result.
4. The method for evaluating the interactive operation of the user-side distributed energy system according to claim 1, wherein: the specific method for establishing the low-cycle fatigue life model of the heat supply pipe network in the step 2 comprises the following steps:
the low cycle fatigue life of a heat supply pipe network is characterized by utilizing an S-N curve, and some standards are based on experimental data, and an empirical formula of the S-N curve is stipulated:
Figure FDA0002813345600000025
in the formula:
Figure FDA0002813345600000026
is the range of a certain stress cycle;
Figure FDA0002813345600000027
for the maximum bearable stress cycle of the heat supply pipe network
Figure FDA0002813345600000028
The number of times of (c); m is a coefficient specified by a standard; gamma raySNIs an intermediate parameter, and can take the value of 5000;
in the evaluation of the low cycle fatigue life of the heat supply pipe network, the stress action on the heat supply pipe network is approximately assumed to be in direct proportion to the temperature:
Figure FDA0002813345600000031
in the formula:
Figure FDA0002813345600000032
to correspond to stress cycle
Figure FDA0002813345600000033
Temperature cycling range of (a); the symbol ". varies" indicates "proportional to"; the inventionThe heat transfer process between the working medium and the heat supply pipe network is slightly considered, and the temperature of a certain position in the heat supply pipe network is approximately equal to the temperature of the working medium in the pipe network; and (3) converting the relation between the stress cycle and the service life of the heat supply pipe network into the relation between the temperature cycle and the service life of the heat supply pipe network.
5. The method for evaluating the interactive operation of the user-side distributed energy system according to claim 1, wherein: the specific steps of step 2 for evaluating the low cycle fatigue life of the heat supply pipe network comprise:
(1) based on the S-N curves of the pipe network elements, the low cycle fatigue life of the heat supply pipe network can be estimated by using the Poelminglin-nanometer rule, which is based on the following assumptions:
1) the damage to the heat supply pipe network caused by each stress cycle experienced by the heat supply pipe network can be accumulated;
2) the damage caused by each circulation can be drawn by the same SN curve;
3) the damage caused by the circulation is independent of the distribution of the circulation over time;
the criterion for determining that the service life of the heat supply pipe network meets the requirement is as follows:
Figure FDA0002813345600000034
in the formula: r is the serial number of the temperature cycle actually experienced by the heat supply pipe network; n isrThe number of occurrences of the temperature cycle numbered r; n is a radical ofrStress cycle S caused by temperature cycle with number rrSubstituting the maximum cycle number obtained in the formulas (1) to (2); gamma rayfatThe value can be 5-10 according to different engineering grades for a safety factor;
(2) selecting the difference delta T between the highest temperature and the ambient temperature in the operation of the pipe networkrefAs a reference standard, formulae (4) to (5) can be collated with formula (6):
Figure FDA0002813345600000041
in the formula: n is a radical ofeqThe number of times from the equivalent of the temperature cycle actually experienced by the heat supply pipe network to the reference temperature cycle; delta TrTemperature range of temperature cycle, numbered r, ° c; n is a radical ofrefA maximum number of cycles of a reference temperature cycle;
(3) the temperature cycles actually experienced by the heat supply pipe network are classified according to different time scales, and the left part of the inequality of the formula (7) can be rewritten as follows:
Figure FDA0002813345600000042
in the formula:
Figure FDA0002813345600000043
the number of total equivalent reference temperature cycles experienced by the heat supply pipe network in one year; xi takes values of 1, 2, 3 and 4 to respectively represent the temperature cycle actually experienced by the heat supply pipe network in one day, one week, one month and one year; r isξNumbering the temperature cycles; n isr,ξAnd Δ Tr,ξAre respectively numbered as rξThe number of times of occurrence of temperature cycles and the temperature range thereof;
(4) defining the moment when the equivalent reference temperature cycle number of the heat supply pipe network reaches 80% of a standard specified value as a service life end point of the heat supply pipe network providing flexibility potential for the ICES, namely when the equivalent reference temperature cycle number of the heat supply pipe network reaches 200 times, an ICES operator can quit the operation or renew the operation according to the situation; accordingly, the low cycle fatigue life of the heating pipe network can be expressed as:
Figure FDA0002813345600000044
in the formula: t islifeFor the low cycle fatigue life of the heat supply pipe network, the invention is the operation age, year, of the heat supply pipe network participating in the ICES flexibility optimization scheduling; n is a radical oflifeFor equivalent reference temperature cycle experienced by heat supply pipe network in life cycleThe number of times;
from the above model it can be seen that: t islifeIs directly related to the amplitude and frequency of the temperature cycle experienced by the heating network.
6. The method for evaluating the interactive operation of the user-side distributed energy system according to claim 1, wherein: the step 2 of obtaining a main temperature cycle including the maximum value and the minimum value of the temperature of the pipe network in one day by adopting a statistical method of the temperature cycle comprises the following specific steps:
(1) drawing a temperature-time curve of the pipe network in one day by taking the temperature as a horizontal axis and the time as a vertical downward vertical axis;
(2) taking each extreme point of the curve as a starting point, starting from one extreme point of the curve, enabling the curve to move forward along the curve to a time axis, if the curve meets the next extreme point, vertically falling, if the curve falls on the curve again, continuing to do the movement along the curve, and drawing a trace of the movement of the point;
(3) if the trace can not fall on the curve after falling from a certain extreme point except the most extreme point, keeping the abscissa of the trace unchanged and enabling the trace to fall off from the abscissa again;
(4) if a trace drawn before is encountered in the movement of a certain point, the movement is stopped;
(5) since the heat supply network scheduling is performed in a day period, when the traces from the starting points are drawn, a temperature cycle including the maximum value and the minimum value of the temperature of the heat supply network in one day can be described along the traces from a maximum point of the curve.
7. The method for evaluating the interactive operation of the user-side distributed energy system according to claim 1, wherein: the specific steps of the step 3 comprise:
the influence of the flexibility potential of the heat supply pipe network utilized by the ICES on the service life of the heat supply pipe network is considered, and the change of the service life of the heat supply pipe network mainly influences the equal annual value investment cost of the heat supply pipe network
Figure FDA0002813345600000051
Annual operating maintenance costs
Figure FDA0002813345600000052
And residual value equal annual profit
Figure FDA0002813345600000053
As shown in equation (10):
Figure FDA0002813345600000054
1) calculating equal annual value investment cost of heat supply pipe network
A relatively accurate heat supply pipe network investment cost calculation formula suitable for ICES planning is provided, and formula (11) shows:
Figure FDA0002813345600000061
in the formula:
Figure FDA0002813345600000062
the unit fixed cost for heat supply pipe network investment, namely the unit cost of the cost related to the length of the pipeline, such as road breaking, laying and the like, is low;
Figure FDA0002813345600000063
unit variable cost for heat supply pipe network investment, namely unit cost such as material cost and the like related to both pipeline length and capacity;
Figure FDA0002813345600000064
the maximum value of the interactive thermal power of the j-th pipe section, kW, can be calculated according to the formula (12):
Figure FDA0002813345600000065
in the formula: q. q.sjThe mass flow rate of the j-th section, kg/s,a constant value in the heat network medium adjusting mode;
wherein, the annual value investment cost such as the whole life cycle of the heat supply pipe network can be calculated according to the formula (13):
Figure FDA0002813345600000066
in the formula: drThe current rate is the current rate;
2) calculating annual operation and maintenance cost of heat supply pipe network
The annual operation and maintenance cost of the heat supply pipe network is shown as the formula (14):
Figure FDA0002813345600000067
in the formula:
Figure FDA0002813345600000068
and
Figure FDA0002813345600000069
the annual operation cost of the heat supply network circulating pump and the annual maintenance cost of the heat supply network are respectively calculated;
the annual operating cost of the heat supply network circulating pump is shown as the formula (15):
Figure FDA00028133456000000610
in the formula: gamma rayDHNThe electric energy consumed by the unit heat for the circulating pump transmission can be 0.0059[43 ]]，kWh；
The annual maintenance cost of the heat supply pipe network comprises annual cost generated by pipe network maintenance, repair and the like, and is shown in formula (16):
Figure FDA0002813345600000071
in the formula: gamma rayMIs a tubeThe maintenance rate of the network, the value of the invention is 1%;
3) residual value equal annual value income of heat supply pipe network
The annual income of residual value of the heat supply pipe network is residual value income obtained by processing a part which is withdrawn from operation after the pipe network is withdrawn from operation or renovated, and the residual value income is often considered to be generated simultaneously with equipment investment in calculation, as shown in a formula (17):
Figure FDA0002813345600000072
in the formula: gamma rayS,DHNThe value of the invention is 3% for the residual value rate of the pipe network.
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