CN111799842B - Multi-stage power transmission network planning method and system considering flexibility of thermal power generating unit - Google Patents

Multi-stage power transmission network planning method and system considering flexibility of thermal power generating unit Download PDF

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CN111799842B
CN111799842B CN202010758007.5A CN202010758007A CN111799842B CN 111799842 B CN111799842 B CN 111799842B CN 202010758007 A CN202010758007 A CN 202010758007A CN 111799842 B CN111799842 B CN 111799842B
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power
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year
thermal power
transmission line
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CN111799842A (en
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孙东磊
王轶群
鉴庆之
陈博
白娅宁
李文升
赵龙
李瑜
马彦飞
杨波
王延硕
张博颐
朱毅
付一木
魏佳
孙毅
程佩芬
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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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State Grid Corp of China SGCC
Economic and Technological Research Institute of State Grid Shandong Electric Power Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
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Abstract

The invention provides a multi-stage power transmission network planning method and a system considering the flexibility of a thermal power unit.

Description

Multi-stage power transmission network planning method and system considering flexibility of thermal power generating unit
Technical Field
The invention relates to the technical field of power grid planning, in particular to a multi-stage power transmission grid planning method and system considering flexibility of a thermal power unit.
Background
The great development of new energy is a necessary choice for solving the current problems of shortage of fossil energy and environmental pollution. Among new energy power generation technologies, the wind power generation technology is the most mature and has the most large-scale development value, and the wind power in the world presents a large-scale development situation. The wind power generation has obvious anti-peak shaving characteristic under the influence of natural factors, namely, the wind power output is low in the daytime peak load period and high in the nighttime valley load period. Large scale wind integration also presents a significant challenge to power system planning operations.
The output power of the thermal power generating unit can be regulated in a certain range, and plays an important role in balancing large-scale wind power change and promoting wind power consumption. The flexibility of the thermal power generating unit is particularly realized in that the system power unbalance caused by load variation or wind power variation can be tracked at a certain rate, and when the wind power output power is increased, the self output power is reduced to be positioned for clean energy to generate electricity so as to promote wind power absorption. In China, the problems of abundant total quantity and insufficient flexibility of the thermal power generating unit generally exist, and the wind power grid connection consumption is severely limited. In order to solve the problem, the flexibility modification of the thermal power unit needs to be implemented, but the flexibility modification is carried out on the thermal power units, and how to formulate scientific and reasonable flexibility modification time sequence of the thermal power unit is worth in-depth research.
The goal of grid planning is to meet the power delivery requirements by making decisions on the transmission line construction given the load prediction and power supply layout. The traditional power grid planning takes the construction of a target grid frame as a research object to carry out optimization decision, and the time sequence characteristics of the construction of the power grid frame are difficult to reflect. The power grid planning is a long-term and rolling decision process, and the scheme transition among a plurality of planning stages and the constraint of the decision variable value in each stage are required to be considered, and the time value of funds in the planning process must be considered to carry out multi-period coordinated dynamic planning. The simulation of the operation condition of each planning stage in the current multi-stage power grid planning decision generally selects an operation mode corresponding to a peak load, and the change scene of the load and the renewable energy power in each planning stage is less involved.
Disclosure of Invention
The invention aims to provide a multi-stage power transmission network planning method and system considering the flexibility of a thermal power generating unit, and aims to solve the problems of lack of load and wind power consideration in multi-stage power transmission network planning decisions in the prior art, realize a multi-stage combined decision scheme and improve the economy of planning operation investment of a power system.
To achieve the above technical object, the present invention provides a multi-stage power transmission network planning method considering flexibility of a thermal power generating unit, the method comprising the following operations:
constructing a multi-stage power transmission network planning optimization model considering the flexibility transformation of the thermal power generating unit, wherein the optimization model aims at minimizing the sum of the investment cost and the present value of the operation cost in the whole planning period and comprises a plurality of constraint conditions;
and converting the mixed integer nonlinear constraint condition in the optimization model into a mixed integer linear constraint condition, and solving the converted mixed integer linear programming model by a mixed integer linear programming algorithm to obtain a final thermal power unit flexibility transformation and power transmission network multi-stage joint programming scheme.
Preferably, the method further comprises the steps of inputting traditional thermal power unit parameters and current power grid power transmission element parameters before a model is built, inputting maximum load, maximum wind power, 24-hour load power and wind power change per day of each year in a planning period, setting a thermal power unit range capable of participating in flexible transformation according to the running condition of the thermal power unit, setting transformation cost, setting candidate new power transmission line range according to the condition of a power transmission line corridor, setting construction cost, setting a wind power waste cost coefficient and allowable waste power rate of a system.
Preferably, the objective function expression of the optimization model is:
wherein nw is the total number of wind farms; ny is the total years of the planning cycle; ng is the number of the conventional thermal power generating units; nl is the number of transmission line corridors planned to be constructed; alpha w Representing the wind abandoning punishment cost;the power discarding method comprises the steps of (1) setting the power discarding power of a wind power plant w in a typical day h period of an m-month of a y-th year in a planning period; beta g The flexibility transformation cost of the thermal power unit g is represented; />As binary variables, it is indicated whether the thermal power unit g of the y-th year is subjected to flexibility improvement in the planning period, and +.>Indicating that thermal power generating unit g in the y-th year is flexibly transformed in the planning period>The thermal power generating unit g of the y year in the planning period is not subjected to flexibility transformation; c (C) l The investment cost is built for a single-circuit transmission line on the transmission corridor I; />Representing the number of newly-increased transmission lines in the y-th year on the transmission line corridor l; ρ is the rate of occurrence.
Preferably, the constraint condition includes:
1) Upper and lower limit constraint of active power of conventional thermal power generating unit:
wherein,and->The upper limit and the lower limit of the active power of the thermal power unit g are respectively set; />The method comprises the steps of planning active power of a thermal power unit g in a typical day h period of an mth year in a period; />The method comprises the steps of representing the increased depth peak shaving power of the thermal power unit by the y-th year through flexible transformation; ΔP g The method is characterized by representing the depth peak shaving power which can be increased by modifying the flexibility of the thermal power unit g; />As binary variables, it is indicated whether the thermal power unit g of the y-th year is subjected to flexibility improvement in the planning period, and +.>Indicating that thermal power generating unit g in the y-th year is flexibly transformed in the planning period>The method is characterized in that the thermal power generating unit g of the y-th year does not carry out flexibility transformation in a planning period; z is Z g Is a binary variable, which indicates whether the thermal power unit g is flexibly transformed in the planning period, Z g =1 means that the thermal power generating unit g is flexibly transformed in the planning period, Z g =0 shows that thermal power unit g does not perform flexibility modification in the planning period;
2) Conventional thermal power generating unit climbing constraint:
wherein R is g When the thermal power generating unit g is not modifiedA climbing rate; deltaR g The change quantity of the climbing rate after the flexibility of the thermal power unit g is improved;the active power of the thermal power unit g in the typical day h-1 period of the y-th year, the m-th month in the planning period;
3) Node power balancing constraints:
wherein P is l y,m,h The active power is transmitted to a power transmission line corridor l in a typical day h period of an mth month of a y-th year in a planning period;active power predictive value of wind power plant w in typical day h period of the y-th year, m-month in the planning period; />Active power predictive value of load d in typical day h period of the y-th year, m-month in the planning period; s is S i And E is i The total number of the power transmission lines taking the node i as the head and the terminal node is respectively; g i 、W i And D i Respectively representing the total number of thermal power units, wind power plants and loads on the node i; nb is the number of grid nodes;
4) Discarding wind power constraint:
wherein, gamma y Representing a set y-th allowable wind power rejection rate threshold;
5) Transmission capacity constraint of transmission line:
wherein B is l Susceptance of a single-circuit transmission line on a transmission line corridor l;the voltage phase angle of the node i in the typical day h period of the m-month of the y-th year in the planning period; />The number of the existing transmission lines on the transmission line corridor l is the number of the existing transmission lines; />Representing the number of newly increased transmission lines in the t-th year on the transmission line corridor l; />Power transmission line corridor for typical day-to-h period of the y-th year, the m-th month and the like in planning period
l is the transmission active power;the transmission capacity of a single-circuit transmission line on a transmission line corridor I is used as the transmission capacity of the single-circuit transmission line;
6) Constraint of maximum number of lines which can be expanded in transmission line corridor:
wherein Z is l max The number of the transmission lines can be expanded for the maximum number of the transmission line corridor l;
7) Node voltage phase angle constraint:
wherein,the voltage phase angle of the node i in the typical day h period of the m-month of the y-th year in the planning period;
8) N-1 is the upper and lower limit constraint of the active power of the thermal power unit under the expected accident condition:
wherein, For planning active power of a thermal power unit g under an expected accident k in a typical day h period of an mth month of a y-th year in a period, nk is the total number of expected accidents of a power transmission line N-1;
9) N-1 conventional thermal power generating unit climbing constraint under expected accident condition:
wherein R is g The climbing speed of the thermal power unit g is the climbing speed of the thermal power unit g when not being modified; deltaR g The change quantity of the climbing rate after the flexibility of the thermal power unit g is improved;the active power of the thermal power unit g under the expected accident k in the typical day h period of the y-th year, the m-th month in the planning period; />The active power of the thermal power unit g under the expected accident k in the typical day h-1 period of the y-th year, the m-th month in the planning period;
10 N-1 node power balancing constraints in the event of an expected incident:
wherein,for the power transmission under expected accident k of typical day h period of the y-th year, m-month in the planning periodThe transmission active power of the line corridor l; />The active power of the thermal power unit g under the expected accident k in the typical day h period of the y-th year, the m-th month in the planning period; />The power discarding method comprises the steps of predicting the power discarding power of a wind power plant w under an accident k for a typical day h period of an m-month of a y-th year in a planning period;
11 N-1 rejection of wind volume constraints in case of an expected accident:
wherein,the power discarding method comprises the steps of predicting the power discarding power of a wind power plant w under an accident k for a typical day h period of an m-month of a y-th year in a planning period;
12 Transmission capacity constraint of transmission line under expected accident situation) N-1:
Wherein nl is the total number of transmission line corridors; b (B) l Susceptance of a single-circuit transmission line on a transmission line corridor l; ny is the total years of the planning cycle;the number of the existing transmission lines on the transmission line corridor l is the number of the existing transmission lines; />Representing the t-th year on a power transmission line corridor lThe newly increased number of the transmission lines; />Indicating whether or not there is a line outage in the transmission line corridor under the expected accident k +.>Indicating that there is a line outage in k transmission line hallways in the event of an expected accident,/->Indicating that no line is out of service in the transmission line corridor under the expected accident k; />The method comprises the steps that active power is transmitted to a transmission line corridor l under an expected accident k in a typical day h period of an mth month of a y-th year in a planning period; />Transmission capacity of a single-circuit transmission line on a transmission line corridor l;
13 N-1 node voltage phase angle constraint in the event of an expected incident:
wherein,and (5) predicting the voltage phase angle of the node i under the accident k for the typical day h period of the mth month of the y-th year in the planning period.
Preferably, the nonlinear constraint expression in the transmission capacity constraint of the power transmission line is converted into an equivalent linear expression:
wherein M is a constant.
Preferably, the nonlinear constraint expression in the transmission capacity constraint of the power transmission line in the expected accident situation of the N-1 is converted into an equivalent linear expression, namely:
The invention also provides a multi-stage power transmission network planning system considering the flexibility of the thermal power generating unit, which comprises:
the planning model construction module is used for constructing a multi-stage power transmission network planning optimization model considering the flexibility transformation of the thermal power generating unit, and the optimization model aims at minimizing the sum of the investment cost and the present value of the operation cost in the whole planning period and comprises a plurality of constraint conditions;
and the model solving module is used for converting the mixed integer nonlinear constraint condition in the optimization model into the mixed integer linear constraint condition, and solving the converted mixed integer linear programming model by using a mixed integer linear programming algorithm to obtain a final thermal power unit flexibility transformation and power transmission network multi-stage joint programming scheme.
Preferably, the system further comprises a model parameter setting module, wherein the model parameter setting module is used for inputting traditional thermal power unit parameters and current power grid power transmission element parameters before a model is built, inputting maximum load, maximum wind power, 24-hour load power and wind power change per unit time of each year on a typical day in a planning period, setting a thermal power unit range capable of participating in flexible transformation according to the running condition of the thermal power unit, setting transformation cost, setting candidate new power line range according to the corridor condition of a power transmission line, setting construction cost, and setting a wind power waste wind cost coefficient and a system allowable waste electricity rate.
Preferably, the objective function expression of the optimization model is:
wherein nw is the total number of wind farms; ny is the total years of the planning cycle; ng is the number of the conventional thermal power generating units; nl is the number of transmission line corridors planned to be constructed; alpha w Representing the wind abandoning punishment cost;the power discarding method comprises the steps of (1) setting the power discarding power of a wind power plant w in a typical day h period of an m-month of a y-th year in a planning period; beta g The flexibility transformation cost of the thermal power unit g is represented; />As binary variables, it is indicated whether the thermal power unit g of the y-th year is subjected to flexibility improvement in the planning period, and +.>Indicating that thermal power generating unit g in the y-th year is flexibly transformed in the planning period>The thermal power generating unit g of the y year in the planning period is not subjected to flexibility transformation; c (C) l The investment cost is built for a single-circuit transmission line on the transmission corridor I; />Representing the number of newly-increased transmission lines in the y-th year on the transmission line corridor l; ρ is the rate of occurrence.
Preferably, the constraint condition includes:
1) Upper and lower limit constraint of active power of conventional thermal power generating unit:
wherein,and->The upper limit and the lower limit of the active power of the thermal power unit g are respectively set; />The method comprises the steps of planning active power of a thermal power unit g in a typical day h period of an mth year in a period; />The method comprises the steps of representing the increased depth peak shaving power of the thermal power unit by the y-th year through flexible transformation; ΔP g The method is characterized by representing the depth peak shaving power which can be increased by modifying the flexibility of the thermal power unit g; />As binary variables, it is indicated whether the thermal power unit g of the y-th year is subjected to flexibility improvement in the planning period, and +.>Indicating that thermal power generating unit g in the y-th year is flexibly transformed in the planning period>The method is characterized in that the thermal power generating unit g of the y-th year does not carry out flexibility transformation in a planning period; z is Z g Is a binary variable, which indicates whether the thermal power unit g is flexibly transformed in the planning period, Z g =1 indicates the ruleFlexibility transformation is carried out on thermal power unit g in scribing period, Z g =0 shows that thermal power unit g does not perform flexibility modification in the planning period;
2) Conventional thermal power generating unit climbing constraint:
wherein R is g The climbing speed of the thermal power unit g is the climbing speed of the thermal power unit g when not being modified; deltaR g The change quantity of the climbing rate after the flexibility of the thermal power unit g is improved;the active power of the thermal power unit g in the typical day h-1 period of the y-th year, the m-th month in the planning period;
3) Node power balancing constraints:
wherein,the active power is transmitted to a power transmission line corridor l in a typical day h period of an mth month of a y-th year in a planning period;active power predictive value of wind power plant w in typical day h period of the y-th year, m-month in the planning period; />Active power predictive value of load d in typical day h period of the y-th year, m-month in the planning period; s is S i And E is i The total number of the power transmission lines taking the node i as the head and the terminal node is respectively; g i 、W i And D i Respectively representing the total number of thermal power units, wind power plants and loads on the node i; nb is the number of grid nodes;
4) Discarding wind power constraint:
wherein, gamma y Representing a set y-th allowable wind power rejection rate threshold;
5) Transmission capacity constraint of transmission line:
wherein B is l Susceptance of a single-circuit transmission line on a transmission line corridor l;the voltage phase angle of the node i in the typical day h period of the m-month of the y-th year in the planning period; />The number of the existing transmission lines on the transmission line corridor l is the number of the existing transmission lines; />Representing the number of newly increased transmission lines in the t-th year on the transmission line corridor l; />The active power is transmitted to a power transmission line corridor l in a typical day h period of an mth month of a y-th year in a planning period; />The transmission capacity of a single-circuit transmission line on a transmission line corridor I is used as the transmission capacity of the single-circuit transmission line;
6) Constraint of maximum number of lines which can be expanded in transmission line corridor:
wherein Z is l max Is a power transmission lineThe corridor l can enlarge the number of transmission lines at maximum;
7) Node voltage phase angle constraint:
wherein,the voltage phase angle of the node i in the typical day h period of the m-month of the y-th year in the planning period;
8) N-1 is the upper and lower limit constraint of the active power of the thermal power unit under the expected accident condition:
wherein, For planning active power of a thermal power unit g under an expected accident k in a typical day h period of an mth month of a y-th year in a period, nk is the total number of expected accidents of a power transmission line N-1;
9) N-1 conventional thermal power generating unit climbing constraint under expected accident condition:
wherein R is g The climbing speed of the thermal power unit g is the climbing speed of the thermal power unit g when not being modified; deltaR g The change quantity of the climbing rate after the flexibility of the thermal power unit g is improved;the active power of the thermal power unit g under the expected accident k in the typical day h period of the y-th year, the m-th month in the planning period; />For expected accident k fire in typical day h-1 period of the y-th year, m-month in the planning periodActive power of the motor group g;
10 N-1 node power balancing constraints in the event of an expected incident:
wherein,the method comprises the steps that active power is transmitted to a transmission line corridor l under an expected accident k in a typical day h period of an mth month of a y-th year in a planning period; />The active power of the thermal power unit g under the expected accident k in the typical day h period of the y-th year, the m-th month in the planning period; />The power discarding method comprises the steps of predicting the power discarding power of a wind power plant w under an accident k for a typical day h period of an m-month of a y-th year in a planning period;
11 N-1 rejection of wind volume constraints in case of an expected accident:
wherein,the power discarding method comprises the steps of predicting the power discarding power of a wind power plant w under an accident k for a typical day h period of an m-month of a y-th year in a planning period;
12 Transmission capacity constraint of transmission line under expected accident situation) N-1:
Wherein nl is the total number of transmission line corridors; b (B) l Susceptance of a single-circuit transmission line on a transmission line corridor l; ny is the total years of the planning cycle;the number of the existing transmission lines on the transmission line corridor l is the number of the existing transmission lines; />Representing the number of newly increased transmission lines in the t-th year on the transmission line corridor l; />Indicating whether or not there is a line outage in the transmission line corridor under the expected accident k +.>Indicating that there is a line outage in k transmission line hallways in the event of an expected accident,/->Indicating that no line is out of service in the transmission line corridor under the expected accident k; />The method comprises the steps that active power is transmitted to a transmission line corridor l under an expected accident k in a typical day h period of an mth month of a y-th year in a planning period; />Transmission capacity of a single-circuit transmission line on a transmission line corridor l;
13 N-1 node voltage phase angle constraint in the event of an expected incident:
wherein,and (5) predicting the voltage phase angle of the node i under the accident k for the typical day h period of the mth month of the y-th year in the planning period.
The effects provided in the summary of the invention are merely effects of embodiments, not all effects of the invention, and one of the above technical solutions has the following advantages or beneficial effects:
compared with the prior art, the method has the advantages that based on the time value of funds, the time sequence characteristics of load, wind power and the like are considered, the multi-stage power transmission network planning optimization model which considers the thermal power unit flexibility transformation is constructed, the mixed integer nonlinear constraint condition in the optimization model is converted into the mixed integer linear constraint condition, and the converted mixed integer linear planning model is solved by adopting the mixed integer linear programming method, so that a multi-stage combined decision scheme of the thermal power unit flexibility transformation and power transmission network planning is obtained, and the economy of the power system planning operation investment is improved.
Drawings
FIG. 1 is a flow chart of a multi-stage power transmission network planning method considering the flexibility of a thermal power generating unit according to an embodiment of the present invention;
fig. 2 is a block diagram of a multi-stage power transmission network planning system considering flexibility of a thermal power generating unit according to an embodiment of the present invention.
Detailed Description
In order to clearly illustrate the technical features of the present solution, the present invention will be described in detail below with reference to the following detailed description and the accompanying drawings. The following disclosure provides many different embodiments, or examples, for implementing different structures of the invention. In order to simplify the present disclosure, 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 processes are omitted so as to not unnecessarily obscure the present invention.
The following describes in detail a multi-stage power transmission network planning method and system considering flexibility of a thermal power generating unit according to an embodiment of the present invention with reference to the accompanying drawings.
As shown in fig. 1, the invention discloses a multi-stage power transmission network planning method considering the flexibility of a thermal power generating unit, which comprises the following operations:
s1, inputting parameters of a traditional thermal power unit and parameters of a current power grid power transmission element, inputting maximum load, maximum wind power, 24-hour load power and wind power change per day of each year in a planning period, setting a thermal power unit range capable of participating in flexible transformation according to the running condition of the thermal power unit, setting transformation cost, setting candidate newly-built power line ranges according to the condition of a power transmission line corridor, setting construction cost, and setting a wind power waste cost coefficient and a system allowable waste rate.
S2, constructing a multi-stage power transmission network planning optimization model considering the flexibility transformation of the thermal power generating unit, wherein the optimization model aims at minimizing the sum of the investment cost and the present value of the operation cost in the whole planning period and comprises a plurality of constraint conditions.
The objective function expression of the optimization model is:
wherein nw is the total number of wind farms; ny is the total years of the planning cycle; ng is the number of the conventional thermal power generating units; nl is the number of transmission line corridors planned to be constructed; alpha w Representing the wind abandoning punishment cost; The power discarding method comprises the steps of (1) setting the power discarding power of a wind power plant w in a typical day h period of an m-month of a y-th year in a planning period; beta g The flexibility transformation cost of the thermal power unit g is represented; />Is a binary variable and represents whether the thermal power generating unit g of the y-th year enters in the planning periodLine flexibility improvement (I/O)>Indicating that thermal power generating unit g in the y-th year is flexibly transformed in the planning period>The thermal power generating unit g of the y year in the planning period is not subjected to flexibility transformation; c (C) l The investment cost is built for a single-circuit transmission line on the transmission corridor I; />Representing the number of newly-increased transmission lines in the y-th year on the transmission line corridor l; ρ is the rate of occurrence.
The optimization model includes 13 constraints, specifically as follows:
1) Upper and lower limit constraint of active power of conventional thermal power generating unit:
wherein,and->The upper limit and the lower limit of the active power of the thermal power unit g are respectively set; />The method comprises the steps of planning active power of a thermal power unit g in a typical day h period of an mth year in a period; />The method comprises the steps of representing the increased depth peak shaving power of the thermal power unit by the y-th year through flexible transformation; ΔP g The method is characterized by representing the depth peak shaving power which can be increased by modifying the flexibility of the thermal power unit g; />As binary variables, it is indicated whether the thermal power unit g of the y-th year is subjected to flexibility improvement in the planning period, and +.>Indicating that thermal power generating unit g in the y-th year is flexibly transformed in the planning period >The method is characterized in that the thermal power generating unit g of the y-th year does not carry out flexibility transformation in a planning period; z is Z g Is a binary variable, which indicates whether the thermal power unit g is flexibly transformed in the planning period, Z g =1 means that the thermal power generating unit g is flexibly transformed in the planning period, Z g =0 shows that the thermal power plant g is not flexibly retrofitted during the planning period.
2) Conventional thermal power generating unit climbing constraint:
wherein R is g The climbing speed of the thermal power unit g is the climbing speed of the thermal power unit g when not being modified; deltaR g The change quantity of the climbing rate after the flexibility of the thermal power unit g is improved;the active power of the thermal power unit g in the typical day h-1 period of the y-th year, the m-th month in the planning period.
3) Node power balancing constraints:
wherein,the active power is transmitted to a power transmission line corridor l in a typical day h period of an mth month of a y-th year in a planning period;active power predictive value of wind power plant w in typical day h period of the y-th year, m-month in the planning period; />Active power predictive value of load d in typical day h period of the y-th year, m-month in the planning period; s is S i And E is i The total number of the power transmission lines taking the node i as the head and the terminal node is respectively; g i 、W i And D i Respectively representing the total number of thermal power units, wind power plants and loads on the node i; nb is the grid node number.
4) Discarding wind power constraint:
Wherein, gamma y And the set allowable wind power rejection rate threshold value in the y-th year is shown.
5) Transmission capacity constraint of transmission line:
wherein B is l Susceptance of a single-circuit transmission line on a transmission line corridor l;the voltage phase angle of the node i in the typical day h period of the m-month of the y-th year in the planning period; />The number of the existing transmission lines on the transmission line corridor l is the number of the existing transmission lines; />Representing the number of newly increased transmission lines in the t-th year on the transmission line corridor l; />The active power is transmitted to a power transmission line corridor l in a typical day h period of an mth month of a y-th year in a planning period; />The transmission capacity of the single-circuit transmission line on the transmission line corridor l is obtained.
6) Constraint of maximum number of lines which can be expanded in transmission line corridor:
/>
wherein Z is l max The number of the transmission lines can be expanded for the maximum transmission line corridor l.
7) Node voltage phase angle constraint:
wherein,and the node i voltage phase angle of the typical day h period of the mth month of the y-th year in the planning period is calculated.
8) N-1 is the upper and lower limit constraint of the active power of the thermal power unit under the expected accident condition:
wherein,in order to plan the active power of the thermal power generating unit g under the expected accident k in the typical day h period of the mth year and the mth month in the period, nk is the total number of expected accidents of the power transmission line N-1.
9) N-1 conventional thermal power generating unit climbing constraint under expected accident condition:
Wherein R is g The climbing speed of the thermal power unit g is the climbing speed of the thermal power unit g when not being modified; deltaR g The change quantity of the climbing rate after the flexibility of the thermal power unit g is improved;the active power of the thermal power unit g under the expected accident k in the typical day h period of the y-th year, the m-th month in the planning period; />And the active power of the thermal power unit g under the expected accident k in the typical day h-1 period of the y-th year, the m-th month in the planning period.
10 N-1 node power balancing constraints in the event of an expected incident:
wherein,the method comprises the steps that active power is transmitted to a transmission line corridor l under an expected accident k in a typical day h period of an mth month of a y-th year in a planning period; />The active power of the thermal power unit g under the expected accident k in the typical day h period of the y-th year, the m-th month in the planning period; />And (5) predicting the electric power discarding of the wind power plant w under the accident k for the typical day h period of the mth year in the planning period.
11 N-1 rejection of wind volume constraints in case of an expected accident:
wherein,and (5) predicting the electric power discarding of the wind power plant w under the accident k for the typical day h period of the mth year in the planning period.
12 Transmission capacity constraint of transmission line under expected accident situation) N-1:
wherein nl is the total number of transmission line corridors; b (B) l Susceptance of a single-circuit transmission line on a transmission line corridor l; ny is the total years of the planning cycle;the number of the existing transmission lines on the transmission line corridor l is the number of the existing transmission lines; / >Representing the number of newly increased transmission lines in the t-th year on the transmission line corridor l; />Indicating whether or not there is a line outage in the transmission line corridor under the expected accident k +.>Representing k transmission line walking under expected accidentThe corridor is provided with a line stop>Indicating that no line is out of service in the transmission line corridor under the expected accident k; />The method comprises the steps that active power is transmitted to a transmission line corridor l under an expected accident k in a typical day h period of an mth month of a y-th year in a planning period; />Transmission capacity of a single-circuit transmission line on a transmission line corridor l.
13 N-1 node voltage phase angle constraint in the event of an expected incident:
wherein,and (5) predicting the voltage phase angle of the node i under the accident k for the typical day h period of the mth month of the y-th year in the planning period.
S3, converting the mixed integer nonlinear constraint condition in the optimization model into a mixed integer linear constraint condition, and solving the converted mixed integer linear programming model by a mixed integer linear programming algorithm to obtain a final thermal power unit flexibility transformation and power transmission network multi-stage joint programming scheme.
The mixed integer nonlinear constraint expression is converted into an equivalent mixed integer linear expression, for example, the nonlinear constraint expression in the transmission capacity constraint of the transmission line is converted into an equivalent linear expression:
Wherein M is a constant.
Similarly, the non-linear constraint expression in the transmission capacity constraint of the transmission line in the case of the N-1 predicted accident is converted into an equivalent linear expression, namely:
in order to improve the solving and calculating efficiency after model conversion, the following auxiliary constraint conditions are introduced:
therefore, the optimization model is converted into a mixed integer linear programming model, and the mixed integer linear programming algorithm can be directly used for solving, so that a final thermal power unit flexibility transformation and power transmission network multi-stage joint planning scheme is obtained.
According to the embodiment of the invention, based on the time value of funds, the time sequence characteristics of load, wind power and the like are considered, a multi-stage power transmission network planning optimization model which considers the flexibility transformation of the thermal power unit is constructed, the mixed integer nonlinear constraint condition in the optimization model is converted into the mixed integer linear constraint condition, and the converted mixed integer linear planning model is solved by adopting a mixed integer linear programming method, so that a multi-stage combined decision scheme of the flexibility transformation of the thermal power unit and the power transmission network planning is obtained, and the economy of the power system planning operation investment is improved.
As shown in fig. 2, the embodiment of the invention further discloses a multi-stage power transmission network planning system considering flexibility of the thermal power generating unit, which comprises:
The planning model construction module is used for constructing a multi-stage power transmission network planning optimization model considering the flexibility transformation of the thermal power generating unit, and the optimization model aims at minimizing the sum of the investment cost and the present value of the operation cost in the whole planning period and comprises a plurality of constraint conditions;
and the model solving module is used for converting the mixed integer nonlinear constraint condition in the optimization model into the mixed integer linear constraint condition, and solving the converted mixed integer linear programming model by using a mixed integer linear programming algorithm to obtain a final thermal power unit flexibility transformation and power transmission network multi-stage joint programming scheme.
The system further comprises a model parameter setting module, wherein the model parameter setting module is used for inputting parameters of a traditional thermal power unit and parameters of a current power grid power transmission element before a model is built, inputting maximum load, maximum wind power, 24-hour load power and wind power change per day of each year in a planning period, setting a thermal power unit range capable of participating in flexible transformation according to the running condition of the thermal power unit, setting transformation cost, setting candidate newly-built power transmission line range according to the condition of a power transmission line corridor, setting construction cost, and setting a wind power waste cost coefficient and a system allowable waste rate.
The objective function expression of the optimization model is:
wherein nw is the total number of wind farms; ny is the total years of the planning cycle; ng is the number of the conventional thermal power generating units; nl is the number of transmission line corridors planned to be constructed; alpha w Representing the wind abandoning punishment cost;the power discarding method comprises the steps of (1) setting the power discarding power of a wind power plant w in a typical day h period of an m-month of a y-th year in a planning period; beta g The flexibility transformation cost of the thermal power unit g is represented; />Is a binary variable and represents the thermal power machine of the y year in the planning periodWhether group g is flexibly modified or not>Indicating that thermal power generating unit g in the y-th year is flexibly transformed in the planning period>The thermal power generating unit g of the y year in the planning period is not subjected to flexibility transformation; c (C) l The investment cost is built for a single-circuit transmission line on the transmission corridor I; />Representing the number of newly-increased transmission lines in the y-th year on the transmission line corridor l; ρ is the rate of occurrence.
The optimization model includes 13 constraints, specifically as follows:
1) Upper and lower limit constraint of active power of conventional thermal power generating unit:
wherein,and->The upper limit and the lower limit of the active power of the thermal power unit g are respectively set; />For planning the active power of the thermal power unit g in typical day h period of the y-th year, the m-th month in the periodA rate; />The method comprises the steps of representing the increased depth peak shaving power of the thermal power unit by the y-th year through flexible transformation; ΔP g The method is characterized by representing the depth peak shaving power which can be increased by modifying the flexibility of the thermal power unit g; />As binary variables, it is indicated whether the thermal power unit g of the y-th year is subjected to flexibility improvement in the planning period, and +.>Indicating that thermal power generating unit g in the y-th year is flexibly transformed in the planning period>The method is characterized in that the thermal power generating unit g of the y-th year does not carry out flexibility transformation in a planning period; z is Z g Is a binary variable, which indicates whether the thermal power unit g is flexibly transformed in the planning period, Z g =1 means that the thermal power generating unit g is flexibly transformed in the planning period, Z g =0 shows that the thermal power plant g is not flexibly retrofitted during the planning period. />
2) Conventional thermal power generating unit climbing constraint:
wherein R is g The climbing speed of the thermal power unit g is the climbing speed of the thermal power unit g when not being modified; deltaR g The change quantity of the climbing rate after the flexibility of the thermal power unit g is improved;the active power of the thermal power unit g in the typical day h-1 period of the y-th year, the m-th month in the planning period.
3) Node power balancing constraints:
wherein,the active power is transmitted to a power transmission line corridor l in a typical day h period of an mth month of a y-th year in a planning period;active power predictive value of wind power plant w in typical day h period of the y-th year, m-month in the planning period; />Active power predictive value of load d in typical day h period of the y-th year, m-month in the planning period; s is S i And E is i The total number of the power transmission lines taking the node i as the head and the terminal node is respectively; g i 、W i And D i Respectively representing the total number of thermal power units, wind power plants and loads on the node i; nb is the grid node number.
4) Discarding wind power constraint:
wherein, gamma y And the set allowable wind power rejection rate threshold value in the y-th year is shown.
5) Transmission capacity constraint of transmission line:
wherein B is l Susceptance of a single-circuit transmission line on a transmission line corridor l;the voltage phase angle of the node i in the typical day h period of the m-month of the y-th year in the planning period; />The number of the existing transmission lines on the transmission line corridor l is the number of the existing transmission lines; />Representing the number of newly increased transmission lines in the t-th year on the transmission line corridor l; />The active power is transmitted to a power transmission line corridor l in a typical day h period of an mth month of a y-th year in a planning period; />The transmission capacity of the single-circuit transmission line on the transmission line corridor l is obtained.
6) Constraint of maximum number of lines which can be expanded in transmission line corridor:
wherein Z is l max The number of the transmission lines can be expanded for the maximum transmission line corridor l.
7) Node voltage phase angle constraint:
/>
wherein,and the node i voltage phase angle of the typical day h period of the mth month of the y-th year in the planning period is calculated.
8) N-1 is the upper and lower limit constraint of the active power of the thermal power unit under the expected accident condition:
wherein, In order to plan the active power of the thermal power generating unit g under the expected accident k in the typical day h period of the mth year and the mth month in the period, nk is the total number of expected accidents of the power transmission line N-1.
9) N-1 conventional thermal power generating unit climbing constraint under expected accident condition:
wherein R is g The climbing speed of the thermal power unit g is the climbing speed of the thermal power unit g when not being modified; deltaR g The change quantity of the climbing rate after the flexibility of the thermal power unit g is improved;the active power of the thermal power unit g under the expected accident k in the typical day h period of the y-th year, the m-th month in the planning period; />And the active power of the thermal power unit g under the expected accident k in the typical day h-1 period of the y-th year, the m-th month in the planning period.
10 N-1 node power balancing constraints in the event of an expected incident:
wherein,the method comprises the steps that active power is transmitted to a transmission line corridor l under an expected accident k in a typical day h period of an mth month of a y-th year in a planning period; />The active power of the thermal power unit g under the expected accident k in the typical day h period of the y-th year, the m-th month in the planning period; />And (5) predicting the electric power discarding of the wind power plant w under the accident k for the typical day h period of the mth year in the planning period.
11 N-1 rejection of wind volume constraints in case of an expected accident:
wherein,and (5) predicting the electric power discarding of the wind power plant w under the accident k for the typical day h period of the mth year in the planning period.
12 Transmission capacity constraint of transmission line under expected accident situation) N-1:
Wherein nl is the total number of transmission line corridors; b (B) l Susceptance of a single-circuit transmission line on a transmission line corridor l; ny is the total years of the planning cycle;the number of the existing transmission lines on the transmission line corridor l is the number of the existing transmission lines; />Representing the number of newly increased transmission lines in the t-th year on the transmission line corridor l; />Indicating whether or not there is a line outage in the transmission line corridor under the expected accident k +.>Representing the expected eventsTherefore, the corridor of the lower k transmission lines is provided with line stop, < ->Indicating that no line is out of service in the transmission line corridor under the expected accident k; />The method comprises the steps that active power is transmitted to a transmission line corridor l under an expected accident k in a typical day h period of an mth month of a y-th year in a planning period; />Transmission capacity of a single-circuit transmission line on a transmission line corridor l.
13 N-1 node voltage phase angle constraint in the event of an expected incident:
wherein,and (5) predicting the voltage phase angle of the node i under the accident k for the typical day h period of the mth month of the y-th year in the planning period.
And converting the mixed integer nonlinear constraint condition in the optimization model into a mixed integer linear constraint condition, and solving the converted mixed integer linear programming model by a mixed integer linear programming algorithm to obtain a final thermal power unit flexibility transformation and power transmission network multi-stage joint programming scheme.
The mixed integer nonlinear constraint expression is converted into an equivalent mixed integer linear expression, for example, the nonlinear constraint expression in the transmission capacity constraint of the transmission line is converted into an equivalent linear expression:
wherein M is a constant.
Similarly, the non-linear constraint expression in the transmission capacity constraint of the transmission line in the case of the N-1 predicted accident is converted into an equivalent linear expression, namely:
in order to improve the solving and calculating efficiency after model conversion, the following auxiliary constraint conditions are introduced:
therefore, the optimization model is converted into a mixed integer linear programming model, and the mixed integer linear programming algorithm can be directly used for solving, so that a final thermal power unit flexibility transformation and power transmission network multi-stage joint planning scheme is obtained.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical aspects of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those of ordinary skill in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.

Claims (6)

1. A multi-stage power transmission network planning method taking into account thermal power plant flexibility, the method comprising the operations of:
constructing a multi-stage power transmission network planning optimization model considering the flexibility transformation of the thermal power generating unit, wherein the optimization model aims at minimizing the sum of the investment cost and the present value of the operation cost in the whole planning period and comprises a plurality of constraint conditions; the objective function expression of the optimization model is as follows:
Wherein nw is the total number of wind farms; ny is the total years of the planning cycle; ng is the number of the conventional thermal power generating units; nl is the number of transmission line corridors planned to be constructed; alpha w Representing the wind abandoning punishment cost;the power discarding method comprises the steps of (1) setting the power discarding power of a wind power plant w in a typical day h period of an m-month of a y-th year in a planning period; beta g The flexibility transformation cost of the thermal power unit g is represented; />As binary variables, it is indicated whether the thermal power unit g of the y-th year is subjected to flexibility improvement in the planning period, and +.>Indicating that thermal power generating unit g in the y-th year is flexibly transformed in the planning period>The thermal power generating unit g of the y year in the planning period is not subjected to flexibility transformation; c (C) l The investment cost is built for a single-circuit transmission line on the transmission corridor I; />Representing the number of newly-increased transmission lines in the y-th year on the transmission line corridor l; ρ is the rate of occurrence;
the constraint conditions include:
1) Upper and lower limit constraint of active power of conventional thermal power generating unit:
wherein,and->The upper limit and the lower limit of the active power of the thermal power unit g are respectively set; />The method comprises the steps of planning active power of a thermal power unit g in a typical day h period of an mth year in a period; />The method comprises the steps of representing the increased depth peak shaving power of the thermal power unit by the y-th year through flexible transformation; ΔP g The method is characterized by representing the depth peak shaving power which can be increased by modifying the flexibility of the thermal power unit g; / >As binary variables, it is indicated whether the thermal power unit g of the y-th year is subjected to flexibility improvement in the planning period, and +.>Indicating that thermal power generating unit g in the y-th year is flexibly transformed in the planning period>The method is characterized in that the thermal power generating unit g of the y-th year does not carry out flexibility transformation in a planning period; z is Z g Is a binary variable, which indicates whether the thermal power unit g is flexibly transformed in the planning period, Z g =1 means that the thermal power generating unit g is flexibly transformed in the planning period, Z g =0 shows that thermal power unit g does not perform flexibility modification in the planning period;
2) Conventional thermal power generating unit climbing constraint:
wherein R is g The climbing speed of the thermal power unit g is the climbing speed of the thermal power unit g when not being modified; deltaR g The change quantity of the climbing rate after the flexibility of the thermal power unit g is improved;the active power of the thermal power unit g in the typical day h-1 period of the y-th year, the m-th month in the planning period;
3) Node power balancing constraints:
wherein P is l y,m,h The active power is transmitted to a power transmission line corridor l in a typical day h period of an mth month of a y-th year in a planning period;active power predictive value of wind power plant w in typical day h period of the y-th year, m-month in the planning period; />Active power predictive value of load d in typical day h period of the y-th year, m-month in the planning period; s is S i And E is i Respectively beginning with node i The total number of transmission lines of the end nodes; g i 、W i And D i Respectively representing the total number of thermal power units, wind power plants and loads on the node i; nb is the number of grid nodes;
4) Discarding wind power constraint:
wherein, gamma y Representing a set y-th allowable wind power rejection rate threshold;
5) Transmission capacity constraint of transmission line:
wherein B is l Susceptance of a single-circuit transmission line on a transmission line corridor l; θ i y,m,h The voltage phase angle of the node i in the typical day h period of the m-month of the y-th year in the planning period;the number of the existing transmission lines on the transmission line corridor l is the number of the existing transmission lines; />Representing the number of newly increased transmission lines in the t-th year on the transmission line corridor l; p (P) l y,m,h The active power is transmitted to a power transmission line corridor l in a typical day h period of an mth month of a y-th year in a planning period; p (P) l max The transmission capacity of a single-circuit transmission line on a transmission line corridor I is used as the transmission capacity of the single-circuit transmission line;
6) Constraint of maximum number of lines which can be expanded in transmission line corridor:
wherein Z is l max Is a power transmission lineThe corridor l can enlarge the number of transmission lines at maximum;
7) Node voltage phase angle constraint:
wherein,the voltage phase angle of the node i in the typical day h period of the m-month of the y-th year in the planning period;
8) N-1 is the upper and lower limit constraint of the active power of the thermal power unit under the expected accident condition:
wherein,for planning active power of a thermal power unit g under an expected accident k in a typical day h period of an mth month of a y-th year in a period, nk is the total number of expected accidents of a power transmission line N-1;
9) N-1 conventional thermal power generating unit climbing constraint under expected accident condition:
wherein R is g The climbing speed of the thermal power unit g is the climbing speed of the thermal power unit g when not being modified; deltaR g The change quantity of the climbing rate after the flexibility of the thermal power unit g is improved;the active power of the thermal power unit g under the expected accident k in the typical day h period of the y-th year, the m-th month in the planning period;the active power of the thermal power unit g under the expected accident k in the typical day h-1 period of the y-th year, the m-th month in the planning period;
10 N-1 node power balancing constraints in the event of an expected incident:
wherein P is l y,m,h,k The method comprises the steps that active power is transmitted to a transmission line corridor l under an expected accident k in a typical day h period of an mth month of a y-th year in a planning period;the active power of the thermal power unit g under the expected accident k in the typical day h period of the y-th year, the m-th month in the planning period;the power discarding method comprises the steps of predicting the power discarding power of a wind power plant w under an accident k for a typical day h period of an m-month of a y-th year in a planning period;
11 N-1 rejection of wind volume constraints in case of an expected accident:
wherein,the power discarding method comprises the steps of predicting the power discarding power of a wind power plant w under an accident k for a typical day h period of an m-month of a y-th year in a planning period;
12 Transmission capacity constraint of transmission line under expected accident situation) N-1:
wherein nl is the total number of transmission line corridors; b (B) l Susceptance of a single-circuit transmission line on a transmission line corridor l; ny is the total years of the planning cycle; The number of the existing transmission lines on the transmission line corridor l is the number of the existing transmission lines; />Representing the number of newly increased transmission lines in the t-th year on the transmission line corridor l; />Indicating whether or not there is a line outage in the transmission line corridor under the expected accident k +.>Indicating that there is a line outage in k transmission line hallways in the event of an expected accident,/->Indicating that no line is out of service in the transmission line corridor under the expected accident k; p (P) l y,m,h,k The method comprises the steps that active power is transmitted to a transmission line corridor l under an expected accident k in a typical day h period of an mth month of a y-th year in a planning period; p (P) l max Transmission capacity of a single-circuit transmission line on a transmission line corridor l;
13 N-1 node voltage phase angle constraint in the event of an expected incident:
wherein,to plan for the periodThe node i voltage phase angle under the expected accident k in the typical day h period of the m month of y years;
and converting the mixed integer nonlinear constraint condition in the optimization model into a mixed integer linear constraint condition, and solving the converted mixed integer linear programming model by a mixed integer linear programming algorithm to obtain a final thermal power unit flexibility transformation and power transmission network multi-stage joint programming scheme.
2. The multi-stage power transmission network planning method considering flexibility of a thermal power unit according to claim 1, further comprising the steps of inputting traditional thermal power unit parameters and current power transmission element parameters of a power transmission network before a model is built, inputting maximum loads, maximum wind power, 24-hour load power and wind power change per month in a planning period, setting a thermal power unit range capable of participating in flexibility transformation according to running conditions of the thermal power unit, setting transformation cost, setting candidate newly built power transmission line ranges according to conditions of a power transmission line corridor, setting construction cost, and setting wind power wind discarding cost coefficients and allowable wind discarding rate of a system.
3. A multi-stage power transmission network planning method taking into account thermal power unit flexibility according to claim 1, wherein the nonlinear constraint expression in the transmission capacity constraint of the power transmission line is converted into an equivalent linear expression:
wherein M is a constant.
4. A multi-stage power transmission network planning method taking into account thermal power unit flexibility according to claim 1, wherein the non-linear constraint expression in the transmission capacity constraint of the power transmission line in the event of N-1 predicted accident is converted into an equivalent linear expression, namely:
5. a multi-stage power transmission grid planning system that accounts for thermal power generation unit flexibility, the system comprising:
the planning model construction module is used for constructing a multi-stage power transmission network planning optimization model considering the flexibility transformation of the thermal power generating unit, and the optimization model aims at minimizing the sum of the investment cost and the present value of the operation cost in the whole planning period and comprises a plurality of constraint conditions; the objective function expression of the optimization model is as follows:
wherein nw is the total number of wind farms; ny is the total years of the planning cycle; ng is the number of the conventional thermal power generating units; nl is the number of transmission line corridors planned to be constructed; alpha w Representing the wind abandoning punishment cost;the power discarding method comprises the steps of (1) setting the power discarding power of a wind power plant w in a typical day h period of an m-month of a y-th year in a planning period; beta g The flexibility transformation cost of the thermal power unit g is represented; />As binary variables, it is indicated whether the thermal power unit g of the y-th year is subjected to flexibility improvement in the planning period, and +.>Indicating that thermal power generating unit g in the y-th year is flexibly transformed in the planning period>The thermal power generating unit g of the y year in the planning period is not subjected to flexibility transformation; c (C) l The investment cost is built for a single-circuit transmission line on the transmission corridor I; />Representing the number of newly-increased transmission lines in the y-th year on the transmission line corridor l; ρ is the rate of occurrence;
the constraint conditions include:
1) Upper and lower limit constraint of active power of conventional thermal power generating unit:
wherein,and->The upper limit and the lower limit of the active power of the thermal power unit g are respectively set; />For planning the y-th year m in the periodActive power of thermal power unit g in month typical day h period; />The method comprises the steps of representing the increased depth peak shaving power of the thermal power unit by the y-th year through flexible transformation; ΔP g The method is characterized by representing the depth peak shaving power which can be increased by modifying the flexibility of the thermal power unit g; />As binary variables, it is indicated whether the thermal power unit g of the y-th year is subjected to flexibility improvement in the planning period, and +.>Indicating that thermal power generating unit g in the y-th year is flexibly transformed in the planning period >The method is characterized in that the thermal power generating unit g of the y-th year does not carry out flexibility transformation in a planning period; z is Z g Is a binary variable, which indicates whether the thermal power unit g is flexibly transformed in the planning period, Z g =1 means that the thermal power generating unit g is flexibly transformed in the planning period, Z g =0 shows that thermal power unit g does not perform flexibility modification in the planning period;
2) Conventional thermal power generating unit climbing constraint:
wherein R is g The climbing speed of the thermal power unit g is the climbing speed of the thermal power unit g when not being modified; deltaR g The change quantity of the climbing rate after the flexibility of the thermal power unit g is improved;the active power of the thermal power unit g in the typical day h-1 period of the y-th year, the m-th month in the planning period;
3) Node power balancing constraints:
wherein P is l y,m,h The active power is transmitted to a power transmission line corridor l in a typical day h period of an mth month of a y-th year in a planning period;active power predictive value of wind power plant w in typical day h period of the y-th year, m-month in the planning period; />Active power predictive value of load d in typical day h period of the y-th year, m-month in the planning period; s is S i And E is i The total number of the power transmission lines taking the node i as the head and the terminal node is respectively; g i 、W i And D i Respectively representing the total number of thermal power units, wind power plants and loads on the node i; nb is the number of grid nodes;
4) Discarding wind power constraint:
Wherein, gamma y Representing a set y-th allowable wind power rejection rate threshold;
5) Transmission capacity constraint of transmission line:
wherein B is l Susceptance of a single-circuit transmission line on a transmission line corridor l;the voltage phase angle of the node i in the typical day h period of the m-month of the y-th year in the planning period; />The number of the existing transmission lines on the transmission line corridor l is the number of the existing transmission lines; />Representing the number of newly increased transmission lines in the t-th year on the transmission line corridor l; p (P) l y,m,h The active power is transmitted to a power transmission line corridor l in a typical day h period of an mth month of a y-th year in a planning period; p (P) l max The transmission capacity of a single-circuit transmission line on a transmission line corridor I is used as the transmission capacity of the single-circuit transmission line;
6) Constraint of maximum number of lines which can be expanded in transmission line corridor:
wherein Z is l max The number of the transmission lines can be expanded for the maximum number of the transmission line corridor l;
7) Node voltage phase angle constraint:
wherein,the voltage phase angle of the node i in the typical day h period of the m-month of the y-th year in the planning period;
8) N-1 is the upper and lower limit constraint of the active power of the thermal power unit under the expected accident condition:
wherein,for planning active power of a thermal power unit g under an expected accident k in a typical day h period of an mth month of a y-th year in a period, nk is the total number of expected accidents of a power transmission line N-1;
9) N-1 conventional thermal power generating unit climbing constraint under expected accident condition:
Wherein R is g The climbing speed of the thermal power unit g is the climbing speed of the thermal power unit g when not being modified; deltaR g The change quantity of the climbing rate after the flexibility of the thermal power unit g is improved;the active power of the thermal power unit g under the expected accident k in the typical day h period of the y-th year, the m-th month in the planning period;the active power of the thermal power unit g under the expected accident k in the typical day h-1 period of the y-th year, the m-th month in the planning period;
10 N-1 node power balancing constraints in the event of an expected incident:
wherein P is l y,m,h,k The method comprises the steps that active power is transmitted to a transmission line corridor l under an expected accident k in a typical day h period of an mth month of a y-th year in a planning period;the active power of the thermal power unit g under the expected accident k in the typical day h period of the y-th year, the m-th month in the planning period;the power discarding method comprises the steps of predicting the power discarding power of a wind power plant w under an accident k for a typical day h period of an m-month of a y-th year in a planning period;
11 N-1 rejection of wind volume constraints in case of an expected accident:
wherein,the power discarding method comprises the steps of predicting the power discarding power of a wind power plant w under an accident k for a typical day h period of an m-month of a y-th year in a planning period;
12 Transmission capacity constraint of transmission line under expected accident situation) N-1:
wherein nl is the total number of transmission line corridors; b (B) l Susceptance of a single-circuit transmission line on a transmission line corridor l; ny is the total years of the planning cycle;the number of the existing transmission lines on the transmission line corridor l is the number of the existing transmission lines; / >Representing a power lineThe number of the transmission lines newly added in the t-th year on the corridor l; />Indicating whether or not there is a line outage in the transmission line corridor under the expected accident k +.>Indicating that there is a line outage in k transmission line hallways in the event of an expected accident,/->Indicating that no line is out of service in the transmission line corridor under the expected accident k; p (P) l y,m,h,k The method comprises the steps that active power is transmitted to a transmission line corridor l under an expected accident k in a typical day h period of an mth month of a y-th year in a planning period; p (P) l max Transmission capacity of a single-circuit transmission line on a transmission line corridor l;
13 N-1 node voltage phase angle constraint in the event of an expected incident:
wherein,the voltage phase angle of the node i under the expected accident k in the typical day h period of the m-month of the y-th year in the planning period;
and the model solving module is used for converting the mixed integer nonlinear constraint condition in the optimization model into the mixed integer linear constraint condition, and solving the converted mixed integer linear programming model by using a mixed integer linear programming algorithm to obtain a final thermal power unit flexibility transformation and power transmission network multi-stage joint programming scheme.
6. The multi-stage power transmission network planning system considering flexibility of a thermal power unit according to claim 5, further comprising a model parameter setting module for inputting parameters of a traditional thermal power unit and parameters of power transmission elements of a current power network before constructing a model, and inputting maximum load, maximum wind power, 24-hour load power and standard values of wind power change of typical days each year per month in a planning period, setting a thermal power unit range capable of participating in flexibility improvement according to the running condition of the thermal power unit, setting improvement cost, setting candidate new power transmission line range according to the condition of a power transmission line corridor, setting construction cost, and setting a wind power wind discarding cost coefficient and a system allowable electricity discarding rate.
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