CN109066808B - Active power distribution network operation optimization method adaptive to uncertainty of power output - Google Patents
Active power distribution network operation optimization method adaptive to uncertainty of power output Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/50—Controlling the sharing of the out-of-phase component
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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
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
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Abstract
The invention relates to an active power distribution network operation optimization method adaptive to uncertainty of power output, and belongs to the technical field of active power distribution networks of power systems. The method comprises the steps of describing random uncertainty of power output in a scene mode, considering standby configuration and a standby response participation and random uncertainty elimination mechanism, constructing an active power distribution network operation optimization model adaptive to the power output uncertainty by taking the minimum operation cost of an active power distribution network as a target under the condition of meeting the technical requirement of power distribution network safe operation in a random uncertainty scene, and solving the optimized model by selecting a CONOPT solver based on a GAMS optimization platform. The invention provides an active power distribution network operation optimization model adaptive to power output uncertainty, and shows that the load voltage characteristics have positive effects on reducing the operation cost of a power distribution system, reducing the power exchange with a superior power transmission network and promoting uncertainty elimination, and the positive effects are more obvious when the load voltage response characteristic ratio is larger.
Description
Technical Field
The invention relates to an active power distribution network operation optimization method adaptive to uncertainty of power output, and belongs to the technical field of active power distribution networks of power systems.
Background
The output power of clean power supplies in wind power generation, photovoltaic power generation and other forms has the characteristic of random uncertainty, and the large-scale feeding of the output power into a power distribution network brings a severe challenge to the dispatching and running of a power grid. Therefore, how to fully call flexible resources in the power distribution network and on the premise of guaranteeing safe operation of the power distribution network, the way of consuming renewable energy power generation such as wind power generation and photovoltaic power generation with random uncertainty as much as possible is a hot problem to be solved urgently in the current active power distribution network operation optimization.
Prediction is an important means for grasping the uncertainty of renewable energy power generation, and various prediction methods such as interval prediction, probability prediction and the like exist at present, but the prediction accuracy is still very low. Therefore, the deterministic optimization decision is only carried out according to the expected value of the renewable energy power generation in the power distribution network operation optimization model, so that the system is exposed to higher operation risk, and the operation optimization of the active power distribution network containing the high-permeability renewable energy power generation inevitably leads to an uncertain decision. Modeling uncertainty based on predictions is a prerequisite for reasonable uncertainty elimination for active distribution networks. The mathematical expression for uncertainty is usually in the form of fuzzy numbers, interval numbers and random numbers. The fuzzy number expression needs to use a complex membership function, the interval number expression needs to be realized by robust optimization, the whole process in the interval fluctuation range is feasible, the method is over conservative, and the random number needs to use a probability distribution function form, so that the method is convenient to be linked with the existing prediction methods such as probability prediction, interval prediction and the like. How to call active flexible resources in the power distribution network to reduce the dependence on voltage regulation and frequency modulation resources of a superior power transmission network is the key of uncertainty absorption of the active power distribution network.
Disclosure of Invention
The invention aims to solve the technical problem of providing an active power distribution network operation optimization method adaptive to uncertainty of power output, and reducing dependence on voltage regulation and frequency modulation resources of a superior power transmission network by calling active flexible resources in a power distribution network.
The technical scheme adopted by the invention is as follows: an active power distribution network operation optimization method adaptive to uncertainty of power output comprises the following steps:
step1: depicting the random uncertainty of the power output in a scene mode;
step 2: considering a mechanism of standby configuration and standby response participation in random uncertainty consumption, and aiming at minimizing the operation cost of the active power distribution network;
and step 3: under the condition that the technical requirements of safe operation of the power distribution network under the random uncertainty scene are met, an active power distribution network operation optimization model adaptive to the uncertainty of the power output is constructed;
and 4, step 4: and 4, solving the optimization model in the step 3 by using a CONOPT solver based on a GAMS optimization platform.
Specifically, the specific steps of step1 are as follows:
step1 scene production
The uncertainty of the renewable energy power generation in the whole power distribution system is the combination of random time sequences consistent with the quantity of the renewable energy, and if the quantity of the renewable power sources is r and the forward looking time range comprises t time periods, the output of the renewable power sources can be expressed asWhereinThe output power of the r-th renewable power source in the time period t is represented, one specific implementation of a random time sequence is a scene of the renewable power source power in a forward-looking time range, and each scene in the obtained expected prediction value and the prediction deviation range is endowed with a certain probability value, such as the s-th sceneIts probability value is denoted as ρsEach renewable power supply correspondingly has an expected value and an upper limit and a lower limit of a fluctuation range represented by a prediction deviation in a given time period, so that random sampling in the range corresponds to a specific implementation, the combination of random sampling of all the renewable power supplies in all the time periods forms a scene, and Ns scenes are randomly generated by using the method, so that the method has the advantages of simple and convenient operation, low cost and high reliabilityThe probability of each scene is
Step 2: scene reduction
Let scene i mark P(i)Scene j is marked as P(j)Their occurrence probabilities are respectively denoted as ρiAnd ρjDefining the distance between two scenes as a second-order norm of vector difference between the two scenes:
Dij=||P(i)-P(j)||2 (1)
in the formula, DijI.e. the distance between scene i and scene J, the purpose of scene reduction is to select a subset of scenes that best represents the full scene set, and the objective is to pursue equation (1) to be the minimum given the number of deleted scenes J.
Specifically, the minimum objective function of the operation cost of the active power distribution network in step2 is as follows:
in the formula, JGThe method comprises the steps of forming a set for all adjustable synchronous units in a power distribution system; j. the design is a squareWThe method comprises the steps of forming a set for all double-fed wind turbine generators in a power distribution system; j. the design is a squareVThe method comprises the steps of forming a set for all photovoltaic power generation systems in a power distribution system; j. the design is a squareSA collection of all power transmission elements in the power distribution system; pex,0Active power from a superordinate transmission network for an active distribution network, Cex,0Representing the marginal price of electricity of the root node; pgActive power output for the gas turbine g; rhosThe probability of the scene is represented by, representing gas turbine stand-by power;representing the reserve power of the superior power transmission network of the s scene;representing the abandoned wind power of the s scene;marking the light abandoning amount of the photovoltaic power generation system in the scene s; cg() Is a power generation cost characteristic function of the gas turbine g;is a backup cost characteristic function of the gas turbine;the cost function of the abandoned light of the photovoltaic power generation system is obtained;the method comprises the steps of obtaining a characteristic function for the abandoned wind of the doubly-fed wind turbine generator;the characteristic function of the standby cost of the superior transmission network; Δ τ represents the duration of the period.
Specifically, in the step 3, the electrical physical constraint and the safety technical requirement which need to be met by the operation of the power distribution system are taken as constraint conditions, and the constraint conditions are divided into equality constraint and inequality constraint, which are specifically as follows:
equation constraint
(1) Base point power balance constraint:
wherein, PwActive power output, P, for wind turbine dispatchvActive output, P, scheduled for a photovoltaic power generation systemdActive power demand for electrical loads, JDA set of all electrical loads in the power distribution system;
(2) node active power and reactive power balance constraint:
in the formula (4), Pl(s) and Ql(s) are respectively the active power and the reactive power transmitted on the power transmission element l under the scene of s, and can be respectively expressed as formula (5) and formula (6); j. the design is a squareS,iThe node i is a set formed by all power transmission elements with the node i as a first node; j. the design is a squareE,iThe node i is a set formed by all power transmission elements with the node i as a final node; j. the design is a squareNA set formed by all nodes in the power distribution system; j. the design is a squareD,iIs a set formed by all power loads on the node i; pi(s) and Qi(s) are respectively active power and reactive power injected into the node i under the scene of s, and can be respectively expressed as an expression (7) and an expression (8); pd(s) and Qd(s) respectively the active power and reactive power requirements of the power load d in the scene s;
Pl(s)=Vi 2(s)gl-Vi(s)Vj(s)·(glcosθij(s)+blsinθij(s)) (5)
Ql(s)=-Vi 2(s)bl+Vi(s)Vj(s)·(blcosθij(s)-glsinθij(s)) (6)
in the formula, thetaij(s) represents the phase angle difference of the voltage phasors of the node i and the node j under the scene s; vi(s) representing the voltage amplitude of the first node i node of the branch l under the scene s; vj(s) represents the voltage amplitude of the node j at the last node of branch l under scene s; glAnd blRespectively the conductance value and the susceptance value of the power transmission branch l;
wherein, JG,iThe method comprises the steps of (1) forming a set by all synchronous gas turbines on a node i; j. the design is a squareR,iA set of all renewable power sources on node i; j. the design is a squareC,iThe method comprises the following steps of (1) forming a set by all reactive compensation equipment on a node i; pg(s) and Qg(s) respectively the active power and the reactive power output by the synchronous gas turbine g under the scene of s; pr(s) and Qr(s) respectively the active power and the reactive power output by the renewable power source r under the scene of s; qc(s) is the inductive reactive power output by the reactive compensation equipment c under the scene s;
(3) the related equation constraint of the schedulable synchronous unit is as follows:
wherein the content of the first and second substances,the method comprises the following steps of (1) synchronizing g stator reactive current of a unit under an s scene; vi(s) representing the voltage amplitude of a node i where the synchronous unit g is located in the scene s;the voltage is expressed as the no-load voltage set for the excitation control of the synchronous unit g; kgRepresenting the voltage difference adjustment coefficient of the synchronous unit g; eg(s) represents the internal potential of the synchronous unit g under the scene of s; deltag(s) representing the power angle value of the synchronous unit g in the scene of s;a direct-axis reactor of a synchronous unit g;
(4) load voltage characteristics:
in the formula, QdIs the reactive power demand of the electrical load;andrespectively the active power and reactive power requirements of the power load d under the rated voltage level;andthe constant impedance active power and the reactive power of the power load d are respectively;andthe constant current active power and the reactive power of the power load d are respectively part;andrespectively are a constant power active power part and a reactive power part of the power load d; v(s) is the system voltage under the s scene; v0Rated voltage of the system;
② inequality constraint
(1) The schedulable synchronous unit (small hydroelectric generating set and gas turbine) has the constraint of the upper and lower power limits of the active base points:
wherein, PgBase point power scheduled for the schedulable synchronous unit;andrespectively an upper limit and a lower limit of active power allowed by the synchronous unit g;
(2) the active power output of the wind turbine generator is constrained in a base point mode:
wherein the content of the first and second substances,the expected active power output of the wind turbine generator set;
(3) constraint of active power output of the photovoltaic power generation system in the base point mode:
wherein the content of the first and second substances,an expected active output for the photovoltaic power generation system;
(4) backup capability range constraint provided by the upper level transmission network:
wherein the content of the first and second substances,the maximum standby capacity is provided for the superior transmission network;
(5) and (3) limitation of the spare capacity range of the schedulable synchronous unit:
wherein the content of the first and second substances,an upper limit value of the reserve capacity provided for the synchronous unit;
(6) and (3) output power range constraint of the schedulable synchronous unit:
wherein the content of the first and second substances,andrespectively an upper limit and a lower limit of the excitation potential of the schedulable synchronous unit g; deltag(s) represents a power angle value of the schedulable synchronous unit g under the scene of s;the maximum value of the g stator current of the synchronous unit;
(7) operation range constraint of doubly-fed wind turbine generator
In the formula, Pw(s) is the active power output of the wind turbine generator in the scene of s of the doubly-fed wind turbine generator w; qw(s) is the reactive power output of the wind turbine generator in the scene of s of the doubly-fed wind turbine generator w;the method comprises the steps that the maximum active power which can be output by the doubly-fed wind turbine generator w under the limitation of natural conditions in an s scene is represented; vw(s) is the stator side machine end voltage of the doubly-fed wind turbine generator w under the scene of s;the reactance is the stator reactance of the doubly-fed wind turbine generator w;the excitation reactance is the excitation reactance of the double-fed wind turbine generator w;the maximum current of the w rotor side of the doubly-fed wind turbine generator set is obtained;
(8) photovoltaic power generation system operating range constraints
Wherein: pv(s) represents the active output of the photovoltaic power generation system v in the s scene; qv(s) represents the reactive output of the photovoltaic power generation system v in the s scene;the method comprises the steps that the maximum active power which can be output by a photovoltaic power generation system v under the s scene and limited by natural conditions is represented; vv(s) represents the node voltage of the grid-connected side of the photovoltaic power generation system v under the s scene;representing the maximum load current of the photovoltaic power generation system v inverter;
(9) and (3) limiting the upper limit and the lower limit of the node voltage amplitude:
in the formula (26), Vi maxAnd Vi minRespectively representing the upper limit and the lower limit of the voltage amplitude of the node i; vi(s) is the voltage amplitude of the node i in the scene of s;
(10) the allowable thermal current range constraint of the power transmission element:
in the formula (27), the reaction mixture is,represents the maximum current, I, of the transmission element llij(s) represents the current amplitude of the power transmission element/in s scenario, which can be expressed as:
in the formula (28), YlRepresents the admittance modulus value of the power transmission element l;
(11) and (3) limiting the upper and lower limits of the capacity of the reactive compensation equipment:
in formula (29), Qc(s) represents the reactive power compensated by the reactive power compensation equipment c in the s scenario,andrespectively the maximum compensation reactive power and the minimum compensation reactive power of the reactive compensation equipment c under the scene s; j. the design is a squareCThe method is a set formed by all reactive compensation equipment of the power distribution system.
The invention has the beneficial effects that:
(1) depicting the random uncertainty of the power output in a scene form, including scene production and scene reduction;
(2) the method comprises the steps of considering a mechanism that standby configuration and standby response participate in the elimination of random uncertainty, taking electrical physical constraint and safety technical requirement which are required to be met by the operation of a power distribution system as constraint conditions, meeting the technical requirement of the safe operation of the power distribution network under a random uncertainty scene, fully considering the influence of voltage characteristics on a power balance mode and power flow distribution, and constructing an active power distribution network operation optimization model which is suitable for the uncertainty of power output on the basis of the random scene by aiming at the minimum operation cost of the power distribution system;
(3) the invention considers the load voltage characteristic, eliminates the influence of an uncertainty mechanism and the like, enlarges the feasible region or the optimization space of the power distribution network operation optimization model, improves the power grid operation quality to a certain extent, avoids the defects of conservatism, limitation and the like of the traditional power distribution network operation optimization decision, and realizes advanced optimization decision on the power distribution system active balance mode and the voltage support mode.
Drawings
FIG. 1 is an overall flow chart of the present invention;
FIG. 2 is a scene reduction flow diagram;
fig. 3 is a modified IEEE33 node power distribution system electrical wiring diagram.
Detailed Description
For the purpose of illustrating the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the accompanying drawings and examples.
Example 1: as shown in fig. 1 to 3, an active power distribution network operation optimization method adapted to uncertainty of power output includes the following steps:
step1: depicting the random uncertainty of the power output in a scene mode;
step 2: considering a mechanism of standby configuration and standby response participation in random uncertainty consumption, and aiming at minimizing the operation cost of the active power distribution network;
and step 3: under the condition that the technical requirements of safe operation of the power distribution network under the random uncertainty scene are met, an active power distribution network operation optimization model adaptive to the uncertainty of the power output is constructed;
and 4, step 4: and 4, solving the optimization model in the step 3 by using a CONOPT solver based on a GAMS optimization platform.
Specifically, the specific steps of step1 are as follows:
step1 scene production
The uncertainty of the renewable energy power generation in the whole power distribution system is the combination of random time sequences consistent with the quantity of the renewable energy, and if the quantity of the renewable power sources is r and the forward looking time range comprises t time periods, the output of the renewable power sources can be expressed asWhereinThe output power of the r-th renewable power source in the time period t is represented, one specific implementation of a random time sequence is a scene of the renewable power source power in a forward-looking time range, and each scene in the obtained expected prediction value and the prediction deviation range is endowed with a certain probability value, such as the s-th sceneIts probability value is denoted as ρsEach renewable power supply correspondingly has an expected value and an upper limit and a lower limit of a fluctuation range represented by a prediction deviation in a given time period, so that random sampling in the range corresponds to a specific implementation, the combination of random sampling of all the renewable power supplies in all the time periods forms a scene, Ns scenes are randomly generated by using the method, and the probability of each scene is the probability of each scene
Step 2: scene reduction
Let scene i mark P(i)Scene j is marked as P(j)Their occurrence probabilities are respectively denoted as ρiAnd ρjDefining the distance between two scenes as a second-order norm of vector difference between the two scenes:
Dij=||P(i)-P(j)||2 (1)
in the formula, DijI.e. the distance between scene i and scene J, the purpose of scene reduction is to select a subset of scenes that best represents the full scene set, and the objective is to pursue equation (1) to be the minimum given the number of deleted scenes J.
The implementation of scene reduction specifically comprises the following steps:
1) initializing the iteration number k to 0, and reducing the set C of scene structureskInitializing to an empty set;
2) calculating the k iteration reduced scene P according to the traversal of the formula (4-2)k;
3) Updating the set of reduced scene constituents, Ck=Ck-1∪{Pk};
4) And updating the iteration number, wherein k is k + 1.
5) Determine if the maximum number of iterations is reached, k < α?
6) Updating the reduced scene set probability distribution, and superposing the reduced scene probability to the retained scene probability closest to the reduced scene probability;
7) a final reduced set of scenes is obtained.
The active power distribution network operation optimization model adaptive to uncertainty of power output is based on a random scene, takes the electrical physical constraint and the safety technical requirement which need to be met by the operation of a power distribution system as constraint conditions, fully considers the mechanism of response uncertainty of the power distribution system, considers the influence of voltage characteristics on a power balance mode and power flow distribution, and achieves advanced optimization decision on an active power balance mode and a voltage support mode of the power distribution system by pursuing the minimum operation cost of the power distribution system.
Further, an active power distribution network operation optimization model adaptive to uncertainty of power output is based on a random scene and aims at pursuing minimum operation cost of a power distribution system, and the minimum objective function of the active power distribution network operation cost in the step2 is as follows:
in the formula, JGThe method is a set formed by all adjustable synchronous units (small hydroelectric generating units and gas turbines) in a power distribution system; j. the design is a squareWThe method comprises the steps of forming a set for all double-fed wind turbine generators in a power distribution system; j. the design is a squareVThe method comprises the steps of forming a set for all photovoltaic power generation systems in a power distribution system; j. the design is a squareSA collection of all power transmission elements in the power distribution system; pex,0Active power from a superordinate transmission network for an active distribution network, Cex,0Representing the marginal price of electricity of the root node; pgActive power output for the gas turbine g; rhosThe probability of the scene is represented by, representing gas turbine stand-by power;representing the reserve power of the superior power transmission network of the s scene;representing the abandoned wind power of the s scene;marking the light abandoning amount of the photovoltaic power generation system in the scene s; cg() Is a power generation cost characteristic function of the gas turbine g;is a backup cost characteristic function of the gas turbine;the cost function of the abandoned light of the photovoltaic power generation system is obtained;the method comprises the steps of obtaining a characteristic function for the abandoned wind of the doubly-fed wind turbine generator;the characteristic function of the standby cost of the superior transmission network; Δ τ represents the duration of the period.
Furthermore, the optimization model fully considers the mechanism of response uncertainty of the power distribution system, considers the influence of voltage characteristics on a power balance mode and power flow distribution, and takes the electrical physical constraint and the safety technical requirement which need to be met by the operation of the power distribution system as constraint conditions to realize advanced optimization decision on the active balance mode and the voltage support mode of the power distribution system.
The equality constraint and the inequality constraint in step 3 are specifically as follows:
equation constraint
(1) Base point power balance constraint:
wherein, PwActive power output, P, for wind turbine dispatchvActive output, P, scheduled for a photovoltaic power generation systemdActive power demand for electrical loads, JDA set of all electrical loads in the power distribution system;
(2) node active power and reactive power balance constraints (power flow equation):
in the formula (4), Pl(s) and Ql(s) are respectively the active power and the reactive power transmitted on the power transmission element l under the scene of s, and can be respectively expressed as formula (5) and formula (6); j. the design is a squareS,iThe node i is a set formed by all power transmission elements with the node i as a first node; j. the design is a squareE,iThe node i is a set formed by all power transmission elements with the node i as a final node; j. the design is a squareNA set formed by all nodes in the power distribution system; j. the design is a squareD,iIs a set formed by all power loads on the node i; pi(s) and Qi(s) are respectively active power and reactive power injected into the node i under the scene of s, and can be respectively expressed as an expression (7) and an expression (8); pd(s) and Qd(s) respectively the active power and reactive power requirements of the power load d in the scene s;
Pl(s)=Vi 2(s)gl-Vi(s)Vj(s)·(glcosθij(s)+blsinθij(s)) (5)
Ql(s)=-Vi 2(s)bl+Vi(s)Vj(s)·(blcosθij(s)-glsinθij(s)) (6)
in the formula, thetaij(s) represents the phase angle difference of the voltage phasors of the node i and the node j under the scene s; vi(s) representing the voltage amplitude of the first node i node of the branch l under the scene s; vj(s) represents the voltage amplitude of the node j at the last node of branch l under scene s; glAnd blRespectively the conductance value and the susceptance value of the power transmission branch l;
wherein, JG,iThe method comprises the steps of (1) forming a set by all synchronous gas turbines on a node i; j. the design is a squareR,iA set of all renewable power sources on node i; j. the design is a squareC,iThe method comprises the following steps of (1) forming a set by all reactive compensation equipment on a node i; pg(s) and Qg(s) respectively the active power and the reactive power output by the synchronous gas turbine g under the scene of s; pr(s) and Qr(s) respectively the active power and the reactive power output by the renewable power source r under the scene of s; qc(s) is the inductive reactive power output by the reactive compensation equipment c under the scene s;
(3) related equation constraint of schedulable synchronous units (small hydroelectric generating units and gas turbines):
wherein the content of the first and second substances,the method comprises the following steps of (1) synchronizing g stator reactive current of a unit under an s scene; vi(s) representing the voltage amplitude of a node i where the synchronous unit g is located in the scene s;denoted as synchronous unit g excitation controlSetting a no-load voltage; kgRepresenting the voltage difference adjustment coefficient of the synchronous unit g; eg(s) represents the internal potential of the synchronous unit g under the scene of s; deltag(s) representing the power angle value of the synchronous unit g in the scene of s;a direct-axis reactor of a synchronous unit g;
(4) load voltage characteristics:
in the formula, QdIs the reactive power demand of the electrical load;andrespectively the active power and reactive power requirements of the power load d under the rated voltage level;andthe constant impedance active power and the reactive power of the power load d are respectively;andthe constant current active power and the reactive power of the power load d are respectively part;andrespectively are a constant power active power part and a reactive power part of the power load d; v(s) is the system voltage under the s scene; v0Rated voltage of the system;
② inequality constraint
(1) The schedulable synchronous unit (small hydroelectric generating set and gas turbine) has the constraint of the upper and lower power limits of the active base points:
wherein, PgBase point power scheduled for the schedulable synchronous unit;andrespectively an upper limit and a lower limit of active power allowed by the synchronous unit g;
(2) the active power output of the wind turbine generator is constrained in a base point mode:
wherein the content of the first and second substances,the expected active power output of the wind turbine generator set;
(3) constraint of active power output of the photovoltaic power generation system in the base point mode:
wherein the content of the first and second substances,an expected active output for the photovoltaic power generation system;
(4) backup capability range constraint provided by the upper level transmission network:
wherein the content of the first and second substances,the maximum standby capacity is provided for the superior transmission network;
(5) and (3) limitation of the spare capacity range of the schedulable synchronous unit:
wherein the content of the first and second substances,an upper limit value of the reserve capacity provided for the synchronous unit;
(6) and (3) output power range constraint of the schedulable synchronous unit:
wherein the content of the first and second substances,andare respectively in schedulable synchronismThe upper and lower limits of the excitation potential of the unit g; deltag(s) represents a power angle value of the schedulable synchronous unit g under the scene of s;the maximum value of the g stator current of the synchronous unit;
(7) operation range constraint of doubly-fed wind turbine generator
In the formula, Pw(s) is the active power output of the wind turbine generator in the scene of s of the doubly-fed wind turbine generator w; qw(s) is the reactive power output of the wind turbine generator in the scene of s of the doubly-fed wind turbine generator w;the method comprises the steps that the maximum active power which can be output by the doubly-fed wind turbine generator w under the limitation of natural conditions in an s scene is represented; vw(s) is the stator side machine end voltage of the doubly-fed wind turbine generator w under the scene of s;the reactance is the stator reactance of the doubly-fed wind turbine generator w;the excitation reactance is the excitation reactance of the double-fed wind turbine generator w;the maximum current of the w rotor side of the doubly-fed wind turbine generator set is obtained;
(8) photovoltaic power generation system operating range constraints
Wherein: pv(s) represents the active output of the photovoltaic power generation system v in the s scene; qv(s) represents the reactive output of the photovoltaic power generation system v in the s scene;the method comprises the steps that the maximum active power which can be output by a photovoltaic power generation system v under the s scene and limited by natural conditions is represented; vv(s) represents the node voltage of the grid-connected side of the photovoltaic power generation system v under the s scene;representing the maximum load current of the photovoltaic power generation system v inverter;
(9) and (3) limiting the upper limit and the lower limit of the node voltage amplitude:
in the formula (26), Vi maxAnd Vi minRespectively representing the upper limit and the lower limit of the voltage amplitude of the node i; vi(s) is the voltage amplitude of the node i in the scene of s;
(10) the allowable thermal current range constraint of the power transmission element:
in the formula (27), the reaction mixture is,represents the maximum current, I, of the transmission element ll,ij(s) represents the current amplitude of the power transmission element/in s scenario, which can be expressed as:
in the formula (28), YlRepresents the admittance modulus value of the power transmission element l;
(11) and (3) limiting the upper and lower limits of the capacity of the reactive compensation equipment:
in formula (29), Qc(s) represents the reactive power compensated by the reactive power compensation equipment c in the s scenario,andrespectively the maximum compensation reactive power and the minimum compensation reactive power of the reactive compensation equipment c under the scene s; j. the design is a squareCThe method is a set formed by all reactive compensation equipment of the power distribution system.
The present invention will be further described with reference to the following specific embodiments.
The invention utilizes an IEEE33 node power distribution system as a basis, distributed renewable energy sources such as wind power, photovoltaic and the like are added for power generation, and synchronous form power sources such as small hydropower, a micro gas turbine and the like are added to verify the effectiveness of the invention. The modified IEEE33 node distribution system electrical wiring diagram is shown in fig. 3, and in an example simulation analysis, the reference power of the distribution system is selected to be 10MVA, the reference voltage is selected to be 12.66kV, the deviation range of the node voltage is assumed to be +/-5% of the rated voltage, and the optimization period is selected to be 15 min. Through simulation calculation, the operation optimization results of the synchronous generator set, the wind turbine generator set and the photovoltaic power generation system are respectively shown in tables 1 to 3, and the target function values, the exchange power from the superior transmission network and the reserve capacity value are shown in a table 4.
TABLE 1 optimization results of synchronous unit operation
TABLE 2 double-fed wind turbine generator system operation optimization results
TABLE 3 photovoltaic power generation system operation optimization results
Table 4 comparison results of operation optimization considering and not considering voltage characteristics
Compared with the random optimization method for the power distribution network without the method, the method has the advantages that the total cost of the optimized operation decided by the method for optimizing the power distribution network operation is low, the exchange power with a superior transmission network is low, and the expected values of the total wind abandon and the light abandon are reduced, so that the economic benefit of considering the response uncertainty of the voltage regulation characteristic participation is demonstrated.
The invention provides an active power distribution network operation optimization model adaptive to power output uncertainty, which shows that the load voltage characteristic has positive influence on reducing the operation cost of a power distribution system, reducing the power exchange with a superior power transmission network and promoting uncertainty elimination, and the positive influence is more obvious when the load voltage response characteristic ratio is larger, so that the feasible region range is expanded from the aspect of mathematical optimization, and the operation benefit of the power distribution system is favorably improved.
While the present invention has been described in detail with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, and various changes can be made without departing from the spirit and scope of the present invention.
Claims (2)
1. An active power distribution network operation optimization method adaptive to uncertainty of power output is characterized by comprising the following steps: the method comprises the following steps:
step1: depicting the random uncertainty of the power output in a scene mode;
step 2: considering a mechanism of standby configuration and standby response participation in random uncertainty consumption, and aiming at minimizing the operation cost of the active power distribution network;
and step 3: under the condition of meeting the technical requirement of safe operation of the power distribution network in a random uncertainty scene, constructing an active power distribution network operation optimization model adaptive to uncertainty of power output;
and 4, step 4: solving the optimization model in the step 3 by using a CONOPT solver based on a GAMS optimization platform;
the minimum objective function of the operation cost of the active power distribution network in the step2 is as follows:
in the formula, JGThe method comprises the steps of forming a set for all adjustable synchronous units in a power distribution system; j. the design is a squareWThe method comprises the steps of forming a set for all double-fed wind turbine generators in a power distribution system; j. the design is a squareVThe method comprises the steps of forming a set for all photovoltaic power generation systems in a power distribution system; j. the design is a squareSA collection of all power transmission elements in the power distribution system; pex,0Active power from a superordinate transmission network for an active distribution network, Cex,0Representing the marginal price of electricity of the root node; pgActive power output for the gas turbine g; rhosThe probability of the scene is represented by, representing gas turbine stand-by power;representing the reserve power of the superior power transmission network of the s scene;representing the abandoned wind power of the s scene;marking the light abandoning amount of the photovoltaic power generation system in the scene s; cg() Is a power generation cost characteristic function of the gas turbine g;is a backup cost characteristic function of the gas turbine;the cost function of the abandoned light of the photovoltaic power generation system is obtained;the method comprises the steps of obtaining a characteristic function for the abandoned wind of the doubly-fed wind turbine generator;the characteristic function of the standby cost of the superior transmission network; Δ τ represents the duration of the period;
and 3, taking the electrical physical constraint and the safety technical requirement which are required to be met by the operation of the power distribution system as constraint conditions, wherein the constraint conditions are divided into equality constraint and inequality constraint, and the method comprises the following specific steps:
equation constraint
(1) Base point power balance constraint:
wherein, PwActive power output, P, for wind turbine dispatchvActive output, P, scheduled for a photovoltaic power generation systemdActive power demand for electrical loads, JDA set of all electrical loads in the power distribution system;
(2) node active power and reactive power balance constraint:
in the formula (4), Pl(s) and Ql(s) are respectively the active power and the reactive power transmitted on the power transmission element l under the scene of s, and can be respectively expressed as formula (5) and formula (6); j. the design is a squareS,iThe node i is a set formed by all power transmission elements with the node i as a first node; j. the design is a squareE,iThe node i is a set formed by all power transmission elements with the node i as a final node; j. the design is a squareNA set formed by all nodes in the power distribution system; j. the design is a squareD,iIs a set formed by all power loads on the node i; pi(s) and Qi(s) are respectively active power and reactive power injected into the node i under the scene of s, and can be respectively expressed as an expression (7) and an expression (8); pd(s) and Qd(s) respectively the active power and reactive power requirements of the power load d in the scene s;
Pl(s)=Vi 2(s)gl-Vi(s)Vj(s)·(glcosθij(s)+blsinθij(s)) (5)
Ql(s)=-Vi 2(s)bl+Vi(s)Vj(s)·(blcosθij(s)-glsinθij(s)) (6)
in the formula, thetaij(s) represents the phase angle difference of the voltage phasors of the node i and the node j under the scene s; vi(s) representing the voltage amplitude of the first node i node of the branch l under the scene s; vj(s) represents the voltage amplitude of the node j at the last node of branch l under scene s; glAnd blRespectively the conductance value and the susceptance value of the power transmission branch l;
wherein, JG,iThe method comprises the steps of (1) forming a set by all synchronous gas turbines on a node i; j. the design is a squareR,iA set of all renewable power sources on node i; j. the design is a squareC,iThe method comprises the following steps of (1) forming a set by all reactive compensation equipment on a node i; pg(s) and Qg(s) respectively the active power and the reactive power output by the synchronous gas turbine g under the scene of s; pr(s) and Qr(s) respectively the active power and the reactive power output by the renewable power source r under the scene of s; qc(s) is the inductive reactive power output by the reactive compensation equipment c under the scene s;
(3) the related equation constraint of the schedulable synchronous unit is as follows:
wherein the content of the first and second substances,the method comprises the following steps of (1) synchronizing g stator reactive current of a unit under an s scene; vi(s) representing the voltage amplitude of a node i where the synchronous unit g is located in the scene s;the voltage is expressed as the no-load voltage set for the excitation control of the synchronous unit g; kgRepresenting the voltage difference adjustment coefficient of the synchronous unit g; eg(s) represents the internal potential of the synchronous unit g under the scene of s; deltag(s) representing the power angle value of the synchronous unit g in the scene of s;a direct-axis reactor of a synchronous unit g;
(4) load voltage characteristics:
in the formula, QdIs the reactive power demand of the electrical load;andrespectively the active power and reactive power requirements of the power load d under the rated voltage level;andthe constant impedance active power and the reactive power of the power load d are respectively;andthe constant current active power and the reactive power of the power load d are respectively part;andrespectively are a constant power active power part and a reactive power part of the power load d; v(s) is the system voltage under the s scene; v0Rated voltage of the system;
② inequality constraint
(1) The method comprises the following steps of (1) power upper and lower limit constraint of active base points of a schedulable synchronous unit:
wherein, PgBase point power scheduled for the schedulable synchronous unit;andrespectively an upper limit and a lower limit of active power allowed by the synchronous unit g;
(2) the active power output of the wind turbine generator is constrained in a base point mode:
wherein the content of the first and second substances,the expected active power output of the wind turbine generator set;
(3) constraint of active power output of the photovoltaic power generation system in the base point mode:
wherein the content of the first and second substances,is expected to be provided for a photovoltaic power generation systemOutput power;
(4) backup capability range constraint provided by the upper level transmission network:
wherein the content of the first and second substances,the maximum standby capacity is provided for the superior transmission network;
(5) and (3) limitation of the spare capacity range of the schedulable synchronous unit:
wherein the content of the first and second substances,an upper limit value of the reserve capacity provided for the synchronous unit;
(6) and (3) output power range constraint of the schedulable synchronous unit:
wherein the content of the first and second substances,andrespectively an upper limit and a lower limit of the excitation potential of the schedulable synchronous unit g; deltag(s) represents a power angle value of the schedulable synchronous unit g under the scene of s;the maximum value of the g stator current of the synchronous unit;
(7) operation range constraint of doubly-fed wind turbine generator
In the formula, Pw(s) is the active power output of the wind turbine generator in the scene of s of the doubly-fed wind turbine generator w; qw(s) is the reactive power output of the wind turbine generator in the scene of s of the doubly-fed wind turbine generator w;the method comprises the steps that the maximum active power which can be output by the doubly-fed wind turbine generator w under the limitation of natural conditions in an s scene is represented; vw(s) is the stator side machine end voltage of the doubly-fed wind turbine generator w under the scene of s;the reactance is the stator reactance of the doubly-fed wind turbine generator w;the excitation reactance is the excitation reactance of the double-fed wind turbine generator w;the maximum current of the w rotor side of the doubly-fed wind turbine generator set is obtained;
(8) photovoltaic power generation system operating range constraints
Wherein: pv(s) represents the active output of the photovoltaic power generation system v in the s scene; qv(s) represents the reactive output of the photovoltaic power generation system v in the s scene;the method comprises the steps that the maximum active power which can be output by a photovoltaic power generation system v under the s scene and limited by natural conditions is represented; vv(s) represents the node voltage of the grid-connected side of the photovoltaic power generation system v under the s scene;representing the maximum load current of the photovoltaic power generation system v inverter;
(9) and (3) limiting the upper limit and the lower limit of the node voltage amplitude:
in the formula (26), Vi maxAnd Vi minRespectively representing the upper limit and the lower limit of the voltage amplitude of the node i; vi(s) is the voltage amplitude of the node i in the scene of s;
(10) the allowable thermal current range constraint of the power transmission element:
in the formula (27), the reaction mixture is,represents the maximum current, I, of the transmission element ll,ij(s) represents the current amplitude of the power transmission element/in s scenario, which can be expressed as:
in the formula (28), YlRepresents the admittance modulus value of the power transmission element l;
(11) and (3) limiting the upper and lower limits of the capacity of the reactive compensation equipment:
in formula (29), Qc(s) represents the reactive power compensated by the reactive power compensation equipment c in the s scenario,andrespectively the maximum compensation reactive power and the minimum compensation reactive power of the reactive compensation equipment c under the scene s; j. the design is a squareCThe method is a set formed by all reactive compensation equipment of the power distribution system.
2. The active power distribution network operation optimization method adapting to uncertainty of power output according to claim 1, characterized in that: the specific steps of step1 are as follows:
step1 scene production
The uncertainty of the renewable energy power generation in the whole power distribution system is the combination of random time sequences consistent with the quantity of the renewable energy, and if the quantity of the renewable power sources is r and the forward looking time range comprises t time periods, the output of the renewable power sources can be expressed asWhereinThe output power of the r-th renewable power source in the time period t is represented, one specific implementation of a random time sequence is a scene of the renewable power source power in a forward-looking time range, and each scene in the obtained expected prediction value and the prediction deviation range is endowed with a certain probability value, such as the s-th sceneIts probability value is denoted as ρsEach renewable power supply correspondingly has an expected value and an upper limit and a lower limit of a fluctuation range represented by a prediction deviation in a given time period, so that random sampling in the range corresponds to a specific implementation, the combination of random sampling of all the renewable power supplies in all the time periods forms a scene, Ns scenes are randomly generated by using the method, and the probability of each scene is the probability of each scene
Step 2: scene reduction
Let scene i mark P(i)Scene j is marked as P(j)Their occurrence probabilities are respectively denoted as ρiAnd ρjDefining the distance between two scenes as a second-order norm of vector difference between the two scenes:
Dij=||P(i)-P(j)||2 (1)
in the formula, DijI.e. the distance between scene i and scene J, the purpose of scene reduction is to select a subset of scenes that best represents the full scene set, and the objective is to pursue equation (1) to be the minimum given the number of deleted scenes J.
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