CN112529370B - Natural gas system reliability assessment method and system considering dynamic effect - Google Patents

Natural gas system reliability assessment method and system considering dynamic effect Download PDF

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CN112529370B
CN112529370B CN202011333595.4A CN202011333595A CN112529370B CN 112529370 B CN112529370 B CN 112529370B CN 202011333595 A CN202011333595 A CN 202011333595A CN 112529370 B CN112529370 B CN 112529370B
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王可欣
石冰珂
王慧轩
徐文阳
邱轩宇
王明明
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Shandong Zhiyuan Electric Power Design Consulting Co ltd
State Grid Corp of China SGCC
Economic and Technological Research Institute of State Grid Shandong Electric Power Co Ltd
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State Grid Corp of China SGCC
Economic and Technological Research Institute of State Grid Shandong Electric Power Co Ltd
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Abstract

The invention discloses a natural gas system reliability assessment method and system considering dynamic effect, wherein the method comprises the following steps: collecting operation data of a natural gas system, and determining the operation state of the natural gas system; establishing an element reliability model for each element according to the running state of the natural gas system; constructing a system reliability model based on the element reliability model; and calculating the reliability parameters of the natural gas system, and judging the reliability of the natural gas system. The method can accurately and effectively calculate the reliability of the natural gas system, and ensures the safe and reliable operation of the natural gas system.

Description

Natural gas system reliability assessment method and system considering dynamic effect
Technical Field
The invention relates to a natural gas system reliability assessment method and system considering dynamic effects, and belongs to the technical field of energy system reliability diagnosis.
Background
At present, with frequent extreme weather such as earthquake, typhoon and tsunami, the problem of reliable operation of a natural gas system is increasingly prominent. In daily operation, factors such as extreme weather may cause a failure of a certain element in the natural gas system, and finally, a large-scale gas cut-off accident may occur in the natural gas system. Therefore, the corresponding reliability evaluation and analysis work of the natural gas system needs to be developed urgently, and a foundation is laid for the reliable operation of the system.
The existing natural gas system reliability evaluation method only considers the steady-state operation process of the natural gas system, namely after a fault occurs, the system is supposed to be transited from one operation state to another operation state instantly. In fact, due to the fact that a natural gas system can store natural gas (hereinafter referred to as "storage in pipe") and has a low movement rate, transition between operation states is slow, and therefore, the traditional analysis method is difficult to effectively reflect the actual operation state of the system. Therefore, a reasonable and correct analysis method is still lacked at the present stage, and the reliability of the natural gas system can be accurately and effectively evaluated, so that the formulation of measures for improving the reliability of the natural gas system is also blind.
Disclosure of Invention
Aiming at the defects of the method, the invention provides the natural gas system reliability assessment method and system considering the dynamic effect, which can accurately and effectively calculate the reliability of the natural gas system and ensure the safe and reliable operation of the natural gas system.
The technical scheme adopted for solving the technical problems is as follows:
on one hand, the natural gas system reliability assessment method considering the dynamic effect provided by the embodiment of the invention comprises the following steps:
collecting operation data of a natural gas system, and determining the operation state of the natural gas system;
establishing an element reliability model aiming at each element according to the running state of the natural gas system;
constructing a system reliability model based on the element reliability model;
and calculating the reliability parameters of the natural gas system, and judging the reliability of the natural gas system.
As a possible implementation manner of this embodiment, the operation data of the natural gas system includes the capacity of the pipeline, the upper limit of the production of the gas source, and the natural gas load of the node.
As a possible implementation manner of this embodiment, the element reliability model includes a reliability model of the gas source and a reliability model of the gas storage device,
reliability model u of the gas source ih (z, t) is:
Figure BDA0002795046100000021
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000022
and
Figure BDA0002795046100000023
respectively represent states l ih The upper limit of the output of the air source h at the lower node i and the corresponding probability, the air source h has K in total ih A state; z is used for distinguishing the values and probabilities of the variables; t is used to refer to time;
reliability model u of the gas storage device iq (z, t) is:
Figure BDA0002795046100000024
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000025
and
Figure BDA0002795046100000026
respectively represent states l iq The upper limit of the output of the gas storage device q at the lower node i and the corresponding probability, the gas source q is K in total iq And (4) a state.
As a possible implementation manner of this embodiment, the building a system reliability model based on the element reliability model specifically includes: introducing a natural gas dynamic power flow calculation operator omega based on an element reliability model φOTGF Aggregating different element reliability models to construct a system reliability model
Figure BDA0002795046100000027
Figure BDA0002795046100000031
In the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000032
and p l (t) respectively representing the load shedding amount and the corresponding probability of the node i under the state l and the moment t; k represents the total state number of the system; phi represents a functional relation; OTGF is used to refer to natural gas system dynamic load flow calculations.
As a possible implementation manner of this embodiment, the objective function of the system reliability model is:
Figure BDA0002795046100000033
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000034
representing the load shedding amount of the node i under the state l and the time t + delta t; n represents the total number of nodes in the natural gas system;
the constraints of the system reliability model include:
pipeline continuity equation:
Figure BDA0002795046100000035
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000036
indicating the inventory of the pipeline D at the state l and the time t; Δ x represents the length of the pipe; d represents the diameter of the pipe; r represents the heating value of natural gas; psi denotes the coefficient of friction of the pipe; z represents a compression coefficient; ρ is a unit of a gradient n Represents the density of natural gas;
Figure BDA0002795046100000037
and
Figure BDA0002795046100000038
respectively representing the pressure intensity of a node j and a node i at two ends of the pipeline D at the state l and the moment t;
the continuity equation for the pipeline is:
Figure BDA0002795046100000039
in the formula (I), the compound is shown in the specification,
Figure BDA00027950461000000310
and
Figure BDA00027950461000000311
respectively representing the natural gas flow of a node i and a node j at two ends of the pipeline D at the state l and the moment t + delta t;
the pipeline power equation:
Figure BDA0002795046100000041
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000042
represents the average flow on the pipe D at the state l and the time t + delta t; v represents the flow rate of natural gas; f represents the transmission coefficient of the pipeline;
node gas flow balance equation:
Figure BDA0002795046100000043
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000044
and
Figure BDA0002795046100000045
respectively representing the state l and the time t + delta t at the node i q And the output of gas source h;
Figure BDA0002795046100000046
representing the natural gas load of the node i at the state l and the time t; n is a radical of D Representing the total number of natural gas pipelines;
the constraints of the compressor are as follows:
Figure BDA0002795046100000047
in the formula (I), the compound is shown in the specification, cij ξand
Figure BDA0002795046100000048
respectively representing the minimum value and the maximum value of the compression coefficient of the compressor c;
the constraint conditions of the node air pressure are as follows:
Figure BDA0002795046100000049
in the formula (I), the compound is shown in the specification,
Figure BDA00027950461000000410
and
Figure BDA00027950461000000411
respectively representing the minimum value and the maximum value of the air pressure of the node i under the state l;
the constraint conditions of the pipeline flow are as follows:
Figure BDA00027950461000000412
in the formula (I), the compound is shown in the specification,
Figure BDA00027950461000000413
and
Figure BDA00027950461000000414
respectively representing the lower limit and the upper limit of the natural gas flow of the pipeline D under the state l;
the output constraint conditions of the gas source are as follows:
Figure BDA00027950461000000415
the output constraint conditions of gas storage are as follows:
Figure BDA00027950461000000416
the natural gas load reduction constraint conditions are as follows:
Figure BDA00027950461000000417
as a possible implementation manner of this embodiment, the calculating a reliability parameter of the natural gas system and performing reliability judgment on the natural gas system specifically includes:
calculating the average load shedding amount of the natural gas system:
Figure BDA0002795046100000051
wherein egns (T) represents the average load shedding amount of the natural gas system over the total time T;
if the average load shedding amount of the system in the total time T is less than the threshold EGNS limit When the EGNS (T) is less than or equal to EGNS limit If the natural gas system is in the normal state, the reliability of the natural gas system is judged to meet the requirement, and adjustment is not needed; if the system does not meet the requirements, the scheduling mechanism is required to adjust the operation mode, so that the safe and reliable operation of the system is ensured.
In another aspect, a natural gas system reliability evaluation system considering dynamic effects provided in an embodiment of the present invention includes:
the data acquisition module is used for acquiring the operation data of the natural gas system and determining the operation state of the natural gas system;
the element model establishing module is used for establishing an element reliability model aiming at each element according to the running state of the natural gas system;
the system model building module is used for building a system reliability model based on the element reliability model;
and the reliability judgment module is used for calculating the reliability parameters of the natural gas system and judging the reliability of the natural gas system.
As a possible implementation manner of this embodiment, the operation data of the natural gas system includes the capacity of the pipeline, the upper limit of the production of the gas source, and the natural gas load of the node.
As a possible implementation manner of this embodiment, the element reliability model includes a reliability model of the gas source and a reliability model of the gas storage device.
As a possible implementation manner of this embodiment, the reliability parameter of the natural gas system is an average load shedding amount of the natural gas system.
The technical scheme of the embodiment of the invention has the following beneficial effects:
according to the method, firstly, the running data of the system is collected through a sensor of the natural gas system, the running state of the system is determined according to the collected data, and on the basis of the current running state, a reliability model of an element is firstly established according to the parameters of the element, then, the models of different elements are aggregated by using a natural gas dynamic power flow calculation operator, the reliability model of the natural gas system is established, and the reliability parameters of the system are calculated. The method can accurately and effectively calculate the reliability of the natural gas system, and when the reliability of the system has problems, the method can issue early warning signals to the scheduling mechanism to assist the scheduling mechanism to arrange corresponding coping strategies, and has important significance for ensuring the safe and reliable operation of the natural gas system.
Description of the drawings:
FIG. 1 is a flow diagram illustrating a method for natural gas system reliability assessment that accounts for dynamic effects in accordance with an exemplary embodiment;
FIG. 2 is a schematic block diagram of a natural gas system according to an exemplary embodiment;
FIG. 3 is a schematic diagram illustrating the structure of a natural gas system reliability evaluation system that accounts for dynamic effects in accordance with an exemplary embodiment.
Detailed Description
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
in order to clearly explain the technical features of the present invention, the present invention will be explained in detail by the following embodiments and the accompanying drawings. The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. It should be noted that the components illustrated in the figures are not necessarily drawn to scale. Descriptions of well-known components and processing techniques and procedures are omitted so as to not unnecessarily limit the invention.
FIG. 1 is a flow diagram illustrating a method for natural gas system reliability assessment that accounts for dynamic effects in accordance with an exemplary embodiment. As shown in fig. 1, a method for evaluating reliability of a natural gas system considering dynamic effects according to an embodiment of the present invention includes the following steps:
collecting operation data of a natural gas system, and determining the operation state of the natural gas system;
establishing an element reliability model for each element according to the running state of the natural gas system;
constructing a system reliability model based on the element reliability model;
and calculating the reliability parameters of the natural gas system, and judging the reliability of the natural gas system.
As shown in fig. 2, the natural gas system mainly includes four parts, namely a gas source, a gas pipeline, a compressor and a natural gas load. Wherein, the natural gas node may have air supply and natural gas load, and the natural gas node is connected through gas transmission pipeline or compressor.
As a possible implementation manner of this embodiment, the operation data of the natural gas system includes the capacity of the pipeline, the upper limit of the production of the gas source, and the natural gas load of the node.
As a possible implementation manner of this embodiment, the element reliability model includes a reliability model of the gas source and a reliability model of the gas storage device,
reliability model u of the gas source ih (z, t) is:
Figure BDA0002795046100000071
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000072
and
Figure BDA0002795046100000073
respectively represent states l ih The upper limit of the output of the air source h at the lower node i and the corresponding probability, the air source h has K in total ih A state; z is used for distinguishing the value and the probability of the variable; t is used to refer to time;
reliability model u of the gas storage device iq (z, t) is:
Figure BDA0002795046100000074
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000075
and
Figure BDA0002795046100000076
respectively represent states l iq The upper limit of the output of the gas storage device q at the lower node i and the corresponding probability are that the gas source q is K in total iq And (4) a state.
As a possible implementation manner of this embodiment, the building a system reliability model based on the element reliability model specifically includes: introducing a natural gas dynamic power flow calculation operator omega based on an element reliability model φOTGF Aggregating different component reliability models to construct a systemSystem reliability model
Figure BDA0002795046100000077
Figure BDA0002795046100000081
In the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000082
and p l (t) respectively representing the load shedding amount and the corresponding probability of the node i under the state l and the moment t; k represents the total state number of the system; phi represents a functional relation; OTGF is used to refer to natural gas system dynamic flow calculations.
As a possible implementation manner of this embodiment, the objective function of the system reliability model is:
Figure BDA0002795046100000083
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000084
representing the load shedding amount of the node i under the state l and the time t + delta t; n represents the total number of nodes in the natural gas system;
the constraints of the system reliability model include:
pipeline continuity equation:
Figure BDA0002795046100000085
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000086
indicating the inventory of the pipeline D at state l and time t; Δ x represents the length of the pipe; d represents the diameter of the pipe; r represents the heating value of natural gas; psi denotes the coefficient of friction of the pipe; z represents a compression factor; rho n Indicating dayThe density of natural gas;
Figure BDA0002795046100000087
and
Figure BDA0002795046100000088
respectively representing the pressure intensity of a node j and a node i at two ends of the pipeline D at the state l and the moment t;
the continuity equation for the pipeline is:
Figure BDA0002795046100000089
in the formula (I), the compound is shown in the specification,
Figure BDA00027950461000000810
and
Figure BDA00027950461000000811
respectively representing the natural gas flow of a node i and a node j at two ends of the pipeline D at the state l and the moment t + delta t;
the pipeline power equation:
Figure BDA0002795046100000091
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000092
represents the average flow on the pipe D at state i and at time t + Δ t; v represents the flow rate of natural gas; f represents the transmission coefficient of the pipeline;
node gas flow balance equation:
Figure BDA0002795046100000093
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000094
and
Figure BDA0002795046100000095
respectively representing the state l and the time t + delta t at the node i q And the output of gas source h;
Figure BDA0002795046100000096
representing the natural gas load of the node i at the state l and the time t; ND represents the total number of natural gas pipelines;
the constraints of the compressor are as follows:
Figure BDA0002795046100000097
in the formula (I), the compound is shown in the specification, cij ξand
Figure BDA0002795046100000098
respectively representing the minimum value and the maximum value of the compression coefficient of the compressor c;
the constraint conditions of the node air pressure are as follows:
Figure BDA0002795046100000099
in the formula (I), the compound is shown in the specification,
Figure BDA00027950461000000910
and
Figure BDA00027950461000000911
respectively representing the minimum value and the maximum value of the air pressure of the node i under the state l;
the constraint conditions of the pipeline flow are as follows:
Figure BDA00027950461000000912
in the formula (I), the compound is shown in the specification,
Figure BDA00027950461000000913
and
Figure BDA00027950461000000914
respectively representing the lower limit and the upper limit of the natural gas flow of the pipeline D under the state l;
the output constraint conditions of the gas source are as follows:
Figure BDA00027950461000000915
the output constraint conditions of gas storage are as follows:
Figure BDA00027950461000000916
the natural gas load reduction constraint conditions are as follows:
Figure BDA00027950461000000917
as a possible implementation manner of this embodiment, the calculating a reliability parameter of the natural gas system and performing reliability judgment on the natural gas system specifically includes:
calculating the average load shedding amount of the natural gas system:
Figure BDA0002795046100000101
wherein EGNS (T) represents the average load shedding of the natural gas system over a total time T;
if the average load shedding amount of the system in the total time T is less than the threshold value EGNS limit When the EGNS (T) is less than or equal to EGNS limit If the natural gas system is in the normal state, the reliability of the natural gas system is considered to meet the requirement, and adjustment is not needed; if the system does not meet the requirements, the scheduling mechanism is required to adjust the operation mode, so that the safe and reliable operation of the system is ensured.
As shown in fig. 3, a system for evaluating reliability of a natural gas system considering dynamic effects according to an embodiment of the present invention includes:
the data acquisition module is used for acquiring the operation data of the natural gas system and determining the operation state of the natural gas system;
the component model establishing module is used for establishing a component reliability model aiming at each component according to the running state of the natural gas system;
the system model building module is used for building a system reliability model based on the element reliability model;
and the reliability judgment module is used for calculating the reliability parameters of the natural gas system and judging the reliability of the natural gas system.
As a possible implementation manner of this embodiment, the operation data of the natural gas system includes the capacity of the pipeline, the upper limit of the production of the gas source, and the natural gas load of the node.
As a possible implementation manner of this embodiment, the element reliability model includes a reliability model of the gas source and a reliability model of the gas storage device.
As a possible implementation manner of this embodiment, the reliability parameter of the natural gas system is an average load shedding amount of the natural gas system.
The method for evaluating the reliability of the natural gas system by the natural gas system reliability evaluation system considering the dynamic effect comprises the following steps:
1) collecting natural gas system data through a sensor before reliability calculation, and determining the running state of the system, wherein the method comprises the following steps: the capacity of the pipeline, the upper limit of the yield of the gas source, the natural gas load of the node and the like.
2) Based on the determined operating conditions of the natural gas system, reliability modeling is sequentially carried out on the elements by combining the operating characteristics of the elements and applying a universal generating function:
2.1) reliability model of gas Source
Reliability model u of gas source ih (z, t) can be generally expressed as a multi-state model as follows:
Figure BDA0002795046100000111
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000112
and
Figure BDA0002795046100000113
respectively represent states l ih The upper limit of the output of the air source h at the lower node i and the corresponding probability, the air source h has K in total ih A state; z is used for distinguishing the values and probabilities of the variables; t is used to refer to time.
2.2) reliability model of gas storage device
Reliability model u of gas storage device iq (z, t) can be generally expressed as a multi-state model as follows:
Figure BDA0002795046100000114
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000115
and
Figure BDA0002795046100000116
respectively represent states l iq The upper limit of the output of the gas storage device q at the lower node i and the corresponding probability, the gas source q is K in total iq And (4) a state.
3) Introducing a natural gas dynamic power flow calculation operator omega based on the determined reliability model of each element φOTGF Aggregating models of different elements to construct a reliability model of a natural gas system
Figure BDA0002795046100000117
Figure BDA0002795046100000118
In the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000119
and p l (t) respectively representing the load shedding amount and the corresponding probability of the node i under the state l and the moment t; k denotes the system as a wholeThe number of states; phi represents a functional relation; OTGF is used to refer to natural gas system dynamic load flow calculations.
Ω φOTGF The natural gas dynamic load flow calculation operator is mainly used for calculating the natural gas load shedding amount of the system at the t + delta t moment according to the running state of the system at the t moment under the state l, and a solved model can be expressed as follows:
a) the objective function of the model is:
Figure BDA0002795046100000121
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000122
representing the load shedding amount of the node i under the state l and the time t + delta t; n represents the total number of nodes in the natural gas system.
The constraints of the model include:
b) equation of continuity for pipeline
In consideration of the storage characteristics of the natural gas system, a part of the natural gas may be stored in the pipeline, and thus the injection amount and the outflow amount of the natural gas in the pipeline D are different. Storage of pipeline D at state l and time t
Figure BDA0002795046100000123
Can be expressed as:
Figure BDA0002795046100000124
wherein Δ x represents the length of the pipe; d represents the diameter of the pipe; r represents the heating value of natural gas; psi denotes the coefficient of friction of the pipe; z represents a compression factor; rho n Represents the density of natural gas;
Figure BDA0002795046100000125
and
Figure BDA0002795046100000126
and respectively representing the pressure of a node j and a node i at two ends of the pipeline D at the state l and the moment t.
Based on the obtained inventory, the continuity equation of the pipeline can be expressed as:
Figure BDA0002795046100000127
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000128
and
Figure BDA0002795046100000129
and respectively representing the natural gas flow of the node i and the node j at two ends of the pipeline D at the state l and the moment t + delta t.
c) Equation of pipe dynamics
The power equation of the pipeline is mainly used for describing the change situation of the natural gas flow in the pipeline along with time, and can be specifically expressed as follows:
Figure BDA00027950461000001210
in the formula (I), the compound is shown in the specification,
Figure BDA00027950461000001211
represents the average flow on the pipe D at the state l and the time t + delta t; v represents the flow rate of natural gas; and F represents the transmission coefficient of the pipeline.
d) Nodal gas flow balance equation
For any natural gas node, the natural gas inflow is equal to the outflow, which is specifically expressed as:
Figure BDA0002795046100000131
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000132
and
Figure BDA0002795046100000133
respectively representing the state l and the time t + delta t at the node i q And the output of gas source h;
Figure BDA0002795046100000134
the natural gas load of the node i at the state l and the moment t is represented; n is a radical of D Representing the total number of natural gas pipelines.
e) Compressor restraint
The constraints of the compressor can be expressed as:
Figure BDA0002795046100000135
in the formula, xi cij And
Figure BDA0002795046100000136
respectively representing the minimum and maximum values of the compression factor of the compressor c.
f) Node air pressure restraint
The air pressure of each node is within a certain range, which is specifically represented as:
Figure BDA0002795046100000137
in the formula (I), the compound is shown in the specification,
Figure BDA0002795046100000138
and
Figure BDA0002795046100000139
respectively representing the minimum value and the maximum value of the air pressure of the node i in the state l.
g) Pipe flow restriction
The constraint of the flow of each pipeline is within a certain range, which is specifically expressed as:
Figure BDA00027950461000001310
in the formula (I), the compound is shown in the specification,
Figure BDA00027950461000001311
and
Figure BDA00027950461000001312
respectively representing the lower limit and the upper limit of the natural gas flow rate of the pipeline D under the state l.
h) Output constraint of gas source and gas storage device
The output constraint of the gas source is expressed as:
Figure BDA00027950461000001313
the output constraint of gas storage is expressed as:
Figure BDA00027950461000001314
i) natural gas load shedding constraints
The reduction of the natural gas load of each node meets the following constraint:
Figure BDA0002795046100000141
the natural gas dynamic load flow model can be solved by adopting an interior point method, and the removal amount of the natural gas load of each node in different states is obtained through calculation.
4) Based on the determined removal amount of the natural gas load of each node in different states, the reliability parameter of the natural gas system can be calculated, and is expressed as:
Figure BDA0002795046100000142
where egns (T) represents the average load cut of the natural gas system over the total time T, obtained by integration.
Based on this, if the average load shedding amount of the system in the total time T is less than the threshold value, namely the average load shedding amount meets the formula (16), the reliability of the natural gas system is considered to meet the requirement, and adjustment is not needed; if the system does not meet the requirements, a scheduling mechanism is needed to adjust the operation mode, and the safe and reliable operation of the system is ensured.
EGNS(T)≤EGNS limit (16)
In the formula, EGNS limit A threshold value representing the average load shedding amount.
Because the dynamic characteristic of the natural gas system is coupled to the system reliability modeling, the evaluation method provided by the invention can more accurately and effectively calculate the reliability of the natural gas system and judge whether the system can safely and reliably operate. When the system has a reliability problem, the early warning signal can be rapidly issued to the dispatching mechanism to help the dispatching mechanism to arrange a coping strategy, and the method has important significance for ensuring the reliable operation of the natural gas system.
The reliability evaluation method and the model provided by the invention can be coupled to a regulation and control platform of a natural gas system, the reliability of the natural gas system is monitored and visually displayed in real time, a dynamic reliability monitoring means is provided for the natural gas system, and the safety and the reliability of the system can be improved.
The foregoing is only a preferred embodiment of the present invention, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and these modifications and improvements are also considered to be within the scope of the present invention.

Claims (6)

1. A natural gas system reliability assessment method considering dynamic effects is characterized by comprising the following steps:
collecting operation data of a natural gas system, and determining the operation state of the natural gas system;
establishing an element reliability model for each element according to the running state of the natural gas system;
constructing a system reliability model based on the element reliability model;
calculating the reliability parameters of the natural gas system, and judging the reliability of the natural gas system;
the element reliability model comprises a reliability model of the gas source and a reliability model of the gas storage device,
reliability model u of the gas source ih (z, t) is:
Figure FDA0003769659000000011
in the formula (I), the compound is shown in the specification,
Figure FDA0003769659000000012
and
Figure FDA0003769659000000013
respectively represent states l ih The upper limit of the output of the air source h at the lower node i and the corresponding probability, the air source h has K in total ih A state; z is used for distinguishing the values and probabilities of the variables; t is used to refer to time;
reliability model u of the gas storage device iq (z, t) is:
Figure FDA0003769659000000014
in the formula (I), the compound is shown in the specification,
Figure FDA0003769659000000015
and
Figure FDA0003769659000000016
respectively represent states l iq The upper limit of the output of the gas storage device q at the lower node i and the corresponding probability, the gas source q is K in total iq A state;
the method for constructing the system reliability model based on the element reliability model specifically comprises the following steps: introducing a natural gas dynamic power flow calculation operator omega based on an element reliability model φOTGF Different elementsAggregating the reliability models to construct a system reliability model
Figure FDA0003769659000000017
Figure FDA0003769659000000021
In the formula (I), the compound is shown in the specification,
Figure FDA0003769659000000022
and p l (t) respectively representing the load shedding amount and the corresponding probability of the node i under the state l and the moment t; k represents the total state number of the system; phi represents a functional relation; the OTGF is used for referring to the dynamic load flow calculation of a natural gas system;
the objective function of the system reliability model is:
Figure FDA0003769659000000023
in the formula (I), the compound is shown in the specification,
Figure FDA0003769659000000024
representing the load shedding amount of the node i under the state l and the time t + delta t; n represents the total number of nodes in the natural gas system;
the constraints of the system reliability model include:
pipeline continuity equation:
Figure FDA0003769659000000025
in the formula (I), the compound is shown in the specification,
Figure FDA0003769659000000026
indicating the inventory of the pipeline D at state l and time t; Δ x represents the length of the pipe; d represents the diameter of the pipe; r represents the heating value of natural gas(ii) a Psi denotes the coefficient of friction of the pipe; z represents a compression factor; rho n Represents the density of natural gas;
Figure FDA0003769659000000027
and
Figure FDA0003769659000000028
respectively representing the pressure intensities of a node j and a node i at two ends of the pipeline D at the state l and the moment t;
the continuity equation for the pipeline is:
Figure FDA0003769659000000029
in the formula (I), the compound is shown in the specification,
Figure FDA00037696590000000210
and
Figure FDA00037696590000000211
respectively representing the natural gas flow of a node i and a node j at two ends of the pipeline D at the state l and the moment t + delta t;
the pipeline power equation:
Figure FDA0003769659000000031
in the formula (I), the compound is shown in the specification,
Figure FDA0003769659000000032
represents the average flow on the pipe D at state i and at time t + Δ t; v represents the flow rate of natural gas; f represents the transmission coefficient of the pipeline;
node gas flow balance equation:
Figure FDA0003769659000000033
in the formula (I), the compound is shown in the specification,
Figure FDA0003769659000000034
and
Figure FDA0003769659000000035
respectively representing the state l and the time t + delta t at the node i q And the output of gas source h;
Figure FDA0003769659000000036
representing the natural gas load of the node i at the state l and the time t; ND represents the total number of natural gas pipelines;
the constraints of the compressor are as follows:
Figure FDA0003769659000000037
in the formula (I), the compound is shown in the specification, ci ξ j and
Figure FDA0003769659000000038
respectively representing the minimum value and the maximum value of the compression coefficient of the compressor c;
the constraint conditions of the node air pressure are as follows:
Figure FDA0003769659000000039
in the formula (I), the compound is shown in the specification,
Figure FDA00037696590000000310
and
Figure FDA00037696590000000311
respectively representing the minimum value and the maximum value of the air pressure of the node i under the state l;
the constraint conditions of the pipeline flow are as follows:
Figure FDA00037696590000000312
in the formula (I), the compound is shown in the specification,
Figure FDA00037696590000000313
and
Figure FDA00037696590000000314
respectively representing the lower limit and the upper limit of the natural gas flow of the pipeline D under the state l;
the output constraint conditions of the gas source are as follows:
Figure FDA00037696590000000315
the output constraint conditions of gas storage are as follows:
Figure FDA0003769659000000041
the natural gas load reduction constraint conditions are as follows:
Figure FDA0003769659000000042
2. the natural gas system reliability assessment method considering dynamic effect according to claim 1, wherein the operation data of the natural gas system comprises the capacity of the pipeline, the upper limit of the production of the gas source and the natural gas load of the node.
3. The method for evaluating the reliability of a natural gas system considering the dynamic effect as claimed in claim 1, wherein the calculating of the reliability parameter of the natural gas system to perform the reliability judgment of the natural gas system comprises:
calculating the average load shedding amount of the natural gas system:
Figure FDA0003769659000000043
wherein EGNS (T) represents the average load shedding of the natural gas system over a total time T;
if the average load shedding amount of the system in the total time T is less than the threshold EGNS limit When the EGNS (T) is less than or equal to EGNS limit If the natural gas system is in the normal state, the reliability of the natural gas system is considered to meet the requirement, and adjustment is not needed; if the system does not meet the requirements, the scheduling mechanism is required to adjust the operation mode, so that the safe and reliable operation of the system is ensured.
4. A natural gas system reliability evaluation system considering dynamic effects, comprising:
the data acquisition module is used for acquiring the operation data of the natural gas system and determining the operation state of the natural gas system;
the component model establishing module is used for establishing a component reliability model aiming at each component according to the running state of the natural gas system;
the system model building module is used for building a system reliability model based on the element reliability model;
the reliability judgment module is used for calculating the reliability parameters of the natural gas system and judging the reliability of the natural gas system;
the element reliability model comprises a reliability model of the gas source and a reliability model of the gas storage device,
reliability model u of the gas source ih (z, t) is:
Figure FDA0003769659000000051
in the formula (I), the compound is shown in the specification,
Figure FDA0003769659000000052
and
Figure FDA0003769659000000053
respectively represent states l ih The upper limit of the output of the air source h at the lower node i and the corresponding probability, the air source h is K in total ih A state; z is used for distinguishing the values and probabilities of the variables; t is used to refer to time;
reliability model u of the gas storage device iq (z, t) is:
Figure FDA0003769659000000054
in the formula (I), the compound is shown in the specification,
Figure FDA0003769659000000055
and
Figure FDA0003769659000000056
respectively represent states l iq The upper limit of the output of the gas storage device q at the lower node i and the corresponding probability are that the gas source q is K in total iq A state;
the system model building module is specifically configured to: introducing a natural gas dynamic power flow calculation operator omega based on an element reliability model φOTGF Aggregating different element reliability models to construct a system reliability model
Figure FDA0003769659000000057
Figure FDA0003769659000000058
In the formula (I), the compound is shown in the specification,
Figure FDA0003769659000000059
and p l (t) respectively representing the load shedding amount and the corresponding probability of the node i under the state l and the moment t; k represents the total state number of the system; phi represents a functional relation; the OTGF is used for referring to the dynamic load flow calculation of a natural gas system;
the objective function of the system reliability model is:
Figure FDA00037696590000000510
in the formula (I), the compound is shown in the specification,
Figure FDA0003769659000000061
representing the load shedding amount of the node i under the state l and the time t + delta t; n represents the total number of nodes in the natural gas system;
the constraints of the system reliability model include:
pipeline continuity equation:
Figure FDA0003769659000000062
in the formula (I), the compound is shown in the specification,
Figure FDA0003769659000000063
indicating the inventory of the pipeline D at the state l and the time t; Δ x represents the length of the pipe; d represents the diameter of the pipe; r represents the heating value of natural gas; psi denotes the coefficient of friction of the pipe; z represents a compression factor; rho n Represents the density of natural gas;
Figure FDA0003769659000000064
and
Figure FDA0003769659000000065
respectively representing the pressure intensity of a node j and a node i at two ends of the pipeline D at the state l and the moment t;
the continuity equation for the pipeline is:
Figure FDA0003769659000000066
in the formula (I), the compound is shown in the specification,
Figure FDA0003769659000000067
and
Figure FDA0003769659000000068
respectively representing the natural gas flow of a node i and a node j at two ends of the pipeline D at the state l and the moment t + delta t;
the pipeline power equation:
Figure FDA0003769659000000069
in the formula (I), the compound is shown in the specification,
Figure FDA00037696590000000610
represents the average flow on the pipe D at state i and at time t + Δ t; v represents the flow rate of natural gas; f represents the transmission coefficient of the pipeline;
node gas flow balance equation:
Figure FDA00037696590000000611
in the formula (I), the compound is shown in the specification,
Figure FDA00037696590000000612
and
Figure FDA00037696590000000613
respectively representing the output quantities of the gas storage device q and the gas source h at the node i in the state l and the time t + delta t;
Figure FDA00037696590000000614
representing the natural gas load of the node i at the state l and the time t; n is a radical of D Representing the total number of natural gas pipelines;
the constraints of the compressor are as follows:
Figure FDA0003769659000000071
in the formula (I), the compound is shown in the specification, cij ξand
Figure FDA0003769659000000072
respectively representing the minimum value and the maximum value of the compression coefficient of the compressor c;
the constraint conditions of the node air pressure are as follows:
Figure FDA0003769659000000073
in the formula (I), the compound is shown in the specification,
Figure FDA0003769659000000074
and
Figure FDA0003769659000000075
respectively representing the minimum value and the maximum value of the air pressure of the node i in the state l;
the constraint conditions of the pipeline flow are as follows:
Figure FDA0003769659000000076
in the formula
Figure FDA0003769659000000077
And
Figure FDA0003769659000000078
respectively representing the lower limit and the upper limit of the natural gas flow of the pipeline D under the state l;
the output constraint conditions of the gas source are as follows:
Figure FDA0003769659000000079
the output constraint conditions of gas storage are as follows:
Figure FDA00037696590000000710
the natural gas load reduction constraint conditions are as follows:
Figure FDA00037696590000000711
5. the natural gas system reliability evaluation system considering dynamic effect according to claim 4, wherein the operation data of the natural gas system includes a capacity of a pipeline, an upper limit of a production of a gas source, and a natural gas load of a node.
6. The natural gas system reliability evaluation system considering dynamic effect according to claim 4, wherein the natural gas system reliability parameter is an average load shedding amount of a natural gas system.
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