CN109755942A - Extended power flow method and device based on optimization method - Google Patents

Abstract

The extension trend method and device based on optimization method that the invention discloses a kind of, wherein method includes: to limit equation according to the busbar voltage that limitation formula establishes relaxation；The tide optimization problem for having partial voltage control device is established by optimization formula；The Optimized model, the Optimized model of PV bus and the Optimized model of PQ bus of zero injection bus are established by constraint equation；Optimized model, the Optimized model of PV bus and the Optimized model of PQ bus of zero injection bus are solved by the IPM of constant Hessian matrix, to obtain integer tap position, and carry out functional test under the conditions of three-phase equilibrium and imbalance.The convergence of nonlinear-sensitivity method under fully loaded transportation condition can be improved in this method, suitable for infeasible voltage limitation is detected and relaxed under fully loaded transportation condition, it is ensured that Power flow solvability.

Description

Extended power flow method and device based on optimization method

technical field

The present invention relates to the technical field of power system extended power flow, in particular to an extended power flow method and device based on an optimization method.

Background technique

A sensitivity-based approach in the related art to address the local voltage controller applies a constant impedance matrix to derive the nonlinear sensitivity matrix of the local voltage controller. Due to the serious nonlinearity of power flow under heavy load conditions, the distributed network power flow with local voltage controller based on sensitivity method requires more iterations under heavy load conditions.

The nonlinear sensitivity matrix of the voltage-controlled distributed generator can also be derived based on the loop analysis, which proves that the nonlinear sensitivity method has better convergence than the linear sensitivity method, however, in the heavy load case, the nonlinear sensitivity method may There is poor convergence, especially after adjusting the position of the tap changer in heavy load conditions, the bus voltage may still exceed the voltage limit, which needs to be solved urgently.

SUMMARY OF THE INVENTION

The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

Therefore, an object of the present invention is to propose an extended power flow method based on an optimization method, which can improve the convergence of the nonlinear sensitivity method under heavy load conditions, and is suitable for detecting and relaxing infeasible voltage restrictions under heavy load conditions .

Another object of the present invention is to propose an extended power flow device based on an optimization method.

In order to achieve the above object, an embodiment of the present invention proposes an extended power flow method based on an optimization method, which includes the following steps: establishing a relaxed bus voltage limit equation according to a limit formula; establishing a power flow with a local voltage controller through the optimization formula Optimization problem; establish zero-injection bus optimization model, PV bus optimization model and PQ bus optimization model through constraint equations; optimization of the zero-injection bus through IPM (Intelligent Power Module, intelligent power module) of constant Hessian matrix The model, the optimized model of the PV bus, and the optimized model of the PQ bus were solved to obtain integer tap positions and functionally tested under three-phase balanced and unbalanced conditions.

The extended power flow method based on the optimization method in the embodiment of the present invention solves the optimization model of the zero injection bus, the optimization model of the PV bus, and the optimization model of the PQ bus by using the IPM of the constant Hessian matrix, so as to obtain the integer tap position, and then in the The function test is carried out under three-phase balanced and unbalanced conditions to achieve the purpose of expanding power flow based on the optimization method, and solve the nonlinear problem and heavy load condition of the distributed network power flow based on the sensitive method under heavy load conditions. It can improve the convergence of nonlinear sensitivity method under heavy load conditions, and is suitable for detecting and relaxing infeasible voltage limits under heavy load conditions.

In addition, the extended power flow method based on the optimization method according to the above-mentioned embodiment of the present invention may also have the following additional technical features:

Further, in an embodiment of the present invention, the bus voltage limitation equation is established by a limitation formula, and the limitation formula is:

in, is the lower limit of the square of the bus voltage, is the upper limit of the square of the bus voltage, l and u represent non-negative slack variables, U _re and U _im are the real and imaginary parts of the bus voltage complex variable, respectively; g _u is the upper limit of the function, g is the mapping, and g _l is the function lower limit, is the square of the bus voltage.

Further, in an embodiment of the present invention, the power flow optimization problem is established by the following optimization formula, and the optimization formula is:

min∑(u+v)

Among them, t is the transformer tap position, t _min and t _max are the minimum limit and maximum limit of the transformer tap position, h is the map, v is the non-negative slack variable, and st is the constraint condition.

Further, in an embodiment of the present invention, establishing the optimization model of the zero injection bus, the optimization model of the PV bus and the optimization model of the PQ bus, further includes:

For the zero injection bus, the first constraint equation h is expressed as a pair of linear equations:

where I _re and I _im are the real and imaginary parts of the injected current, respectively, Y _zero is the admittance row corresponding to the zero injection bus, U is the complex bus voltage, and are the real and imaginary parts of the equation, respectively.

For the PV bus, the second constraint equation h is expressed in pairs as:

in, is the voltage control target of the PV bus, the subscript PV is the corresponding vector or matrix row of the PV bus, diag is the diagonal matrix, * is the conjugate of the complex variable, S _re is the real part of the injected complex power, is the real part of the equation, Y _PV is the admittance row corresponding to the PQ bus, U _PV is the PV bus voltage, U is the complex bus voltage, is the real part of the square of the PV bus voltage, is the imaginary part of the square of the PV bus voltage.

For the PQ bus, the third constraint equation h is expressed in pairs as:

where S _re and _Sim are the real and imaginary parts of the injected complex power, respectively, and are the real and imaginary parts of the equation, diag is the diagonal matrix, * is the conjugate of the complex variable, subscript PQ is the corresponding vector or matrix row of the PQ bus, U _PQ is the PQ bus voltage, Y _PQ is the corresponding PQ bus The admittance row of the busbar, U is the voltage of the complex busbar.

Further, in one embodiment of the present invention, the integer tap position is obtained by rounding off the decimal value of the tap position.

In order to achieve the above object, another embodiment of the present invention provides an extended power flow device based on an optimization method, including: a restriction equation establishment module for establishing a relaxed bus voltage restriction equation according to the restriction formula; an optimization problem establishment module for using It is used to establish the power flow optimization problem with local voltage controller through the optimization formula; the optimization model establishment module is used to establish the optimization model of the zero-injection bus, the optimization model of the PV bus and the optimization model of the PQ bus through the constraint equation; the power flow expansion module, It is used to solve the optimization model of the zero injection bus, the optimization model of the PV bus and the optimization model of the PQ bus through the IPM of the constant Hessian matrix to obtain the integer tap positions, and carry out the three-phase balanced and unbalanced conditions. function test.

The extended power flow device based on the optimization method in the embodiment of the present invention solves the optimization model of the zero-injection bus, the optimization model of the PV bus, and the optimization model of the PQ bus by using the IPM of the constant Hessian matrix, so as to obtain the integer tap positions, and in the The function test is carried out under three-phase balanced and unbalanced conditions to achieve the purpose of expanding power flow based on the optimization method, and solve the nonlinear problem and heavy load condition of the distributed network power flow based on the sensitive method under heavy load conditions. It can improve the convergence of nonlinear sensitivity method under heavy load conditions, and is suitable for detecting and relaxing infeasible voltage limits under heavy load conditions.

In addition, the extended power flow device based on the optimization method according to the foregoing embodiments of the present invention may also have the following additional technical features:

Further, in an embodiment of the present invention, the restriction formula in the restriction equation establishment module is:

in, is the lower limit of the square of the bus voltage, is the upper limit of the square of the bus voltage, l and u are non-negative slack variables, U _re and U _im are the real and imaginary parts of the bus voltage complex variable, g _u is the upper limit of the function, g is the mapping, and g _l is function lower bound, is the square of the bus voltage.

Further, in an embodiment of the present invention, the optimization formula in the optimization problem establishment module is:

min∑(u+v)

Among them, t is the transformer tap position, t _min and t _max are the minimum limit and maximum limit of the transformer tap position, h is the map, v is the non-negative slack variable, and st is the constraint condition.

Further, in an embodiment of the present invention, the optimization model establishment module further includes:

For the zero injection bus, the first constraint equation h is expressed as a pair of linear equations:

where I _re and I _im are the real and imaginary parts of the injected current, respectively, Y _zero is the admittance row corresponding to the zero injection bus, U is the complex bus voltage, and are the real and imaginary parts of the equation, respectively.

For the PV bus, the second constraint equation h is expressed in pairs as:

in, is the voltage control target of the PV bus, the subscript PV is the corresponding vector or matrix row of the PV bus, diag is the diagonal matrix, * is the conjugate of the complex variable, S _re is the real part of the injected complex power, is the real part of the equation, Y _PV is the admittance row corresponding to the PV bus, U _PV is the PV bus voltage, U is the complex bus voltage, is the real part of the square of the PV bus voltage, is the imaginary part of the square of the PV bus voltage.

For the PQ bus, the third constraint equation h is expressed in pairs as:

where S _re and _Sim are the real and imaginary parts of the injected complex power, respectively, and are the real and imaginary parts of the equation, diag is the diagonal matrix, * is the conjugate of the complex variable, subscript PQ is the corresponding vector or matrix row of the PQ bus, U _PQ is the PQ bus voltage, Y _PQ is the corresponding PQ bus The admittance row of the bus voltage, U is the complex bus voltage.

Further, in one embodiment of the present invention, the integer tap position is obtained by rounding off the decimal value of the tap position.

Additional aspects and advantages of the present invention will be set forth, in part, from the following description, and in part will be apparent from the following description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of embodiments taken in conjunction with the accompanying drawings, wherein:

1 is a flowchart of an extended power flow method based on an optimization method according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of an extended power flow device based on an optimization method according to an embodiment of the present invention.

Detailed ways

The following describes in detail the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary, and are intended to explain the present invention and should not be construed as limiting the present invention.

The extended power flow method and apparatus based on the optimization method proposed according to the embodiments of the present invention will be described below with reference to the accompanying drawings. First, the extended power flow method based on the optimization method proposed according to the embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a flowchart of an extended power flow method based on an optimization method according to an embodiment of the present invention.

As shown in Figure 1, the extended power flow method based on the optimization method includes the following steps:

In step S101, a relaxed bus voltage limit equation is established according to the limit equation.

Further, in an embodiment of the present invention, a bus voltage limit equation is established by a limit formula, and the limit formula is:

in, is the lower limit of the square of the bus voltage, is the upper limit of the square of the bus voltage, l and u are non-negative slack variables, U _re and U _im are the real and imaginary parts of the bus voltage complex variable, g _u is the upper limit of the function, g is the mapping, and g _l is the lower limit of the function, is the square of the bus voltage.

In step S102, a power flow optimization problem with a local voltage controller is established through an optimization formula.

Further, in an embodiment of the present invention, the power flow optimization problem is established by the following optimization formula, and the optimization formula is:

min∑(u+v)

Among them, t is the transformer tap position, t _min and t _max are the minimum limit and maximum limit of the transformer tap position, h is the map, v is the non-negative slack variable, and st is the constraint condition.

In step S103, an optimization model of the zero-injection bus, an optimization model of the PV bus, and an optimization model of the PQ bus are established through constraint equations.

Further, in an embodiment of the present invention, establishing an optimization model of the zero injection bus, an optimization model of the PV bus, and an optimization model of the PQ bus, further comprising:

For a zero-injection bus, the first constraint equation h is expressed as a pair of linear equations:

where I _re and I _im are the real and imaginary parts of the injected current, respectively, Y _zero is the admittance row corresponding to the zero injection bus, U is the complex bus voltage, and are the real and imaginary parts of the equation, respectively.

For the PV bus, the second constraint equation h is expressed in pairs as:

in, is the voltage control target of the PV bus; the subscript PV is the corresponding vector or matrix row of the PV bus, diag is the diagonal matrix, * is the conjugate of the complex variable, S _re is the real part of the injected complex power, is the real part of the equation, Y _PV is the admittance row corresponding to the PV bus, U _PV is the PV bus voltage, U is the complex bus voltage, is the real part of the square of the PV bus voltage, is the imaginary part of the square of the PV bus voltage.

For the PQ bus, the third constraint equation h is expressed in pairs as:

where S _re and _Sim are the real and imaginary parts of the injected complex power, respectively, and are the real and imaginary parts of the equation, respectively, diag is the diagonal matrix, * is the conjugate of the complex variable, subscript PQ is the corresponding vector or matrix row of the PQ bus, U _PQ is the PQ bus voltage, Y _PQ is the corresponding PQ bus The admittance row of the bus voltage, U is the complex bus voltage.

In step S104, the optimization model of the zero injection bus, the optimization model of the PV bus, and the optimization model of the PQ bus are solved by the IPM of the constant Hessian matrix to obtain the integer tap positions, and under the three-phase balanced and unbalanced conditions Perform functional testing.

Further, in one embodiment of the present invention, the integer tap positions are obtained by rounding off the fractional value of the tap positions.

In a specific embodiment of the present invention, under the condition of three-phase equilibrium, the extended power flow method based on the optimization method proposed by the embodiment of the present invention includes the following steps:

S1: Collect data on distributed network power flow under light or heavy loads with sensitivity-based methods that do not take into account nonlinearities of local voltage controllers.

S2: Establish the relaxed bus voltage limit equation.

in, is the lower limit of the square of the bus voltage, is the upper limit of the square of the bus voltage, l and u are non-negative slack variables, U _re and U _im are the real and imaginary parts of the bus voltage complex variable, g _u is the upper limit of the function, g is the mapping, and g _l is the lower limit of the function, is the square of the bus voltage.

S3: Formulate an optimization problem for power flow expansion with local voltage controllers.

min∑(u+v)

Among them, U _re and U _im are the real and imaginary parts of the bus voltage complex variable, t is the transformer tap position, t _min and t _max are the minimum and maximum limits of the transformer tap position, h is the mapping, v is a non-negative slack variable, and st is a constraint condition.

S4: Establish the zero-injection bus constraint equation.

where I _re and I _im are the real and imaginary parts of the injected current, respectively, Y _zero is the admittance row corresponding to the zero injection bus, U is the complex bus voltage, and are the real and imaginary parts of the equation, respectively.

S5: Establish the PV bus constraint equation.

in, is the voltage control target of the PV bus, the subscript PV is the corresponding vector or matrix row of the PV bus, diag is the diagonal matrix, * is the conjugate of the complex variable, and S _re is the real part of the injected complex power; is the real part of the equation, Y _PV is the admittance row corresponding to the PV bus, U _PV is the PV bus voltage, U is the complex bus voltage, is the real part of the square of the PV bus voltage, is the imaginary part of the square of the PV bus voltage.

S6: Establish a PQ bus constraint equation.

where S _re and _Sim are the real and imaginary parts of the injected complex power, respectively, and are the real and imaginary parts of the equation, respectively, diag is the diagonal matrix, * is the conjugate of the complex variable, subscript PQ is the corresponding vector or matrix row of the PQ bus, U _PQ is the PQ bus voltage, Y _PQ is the corresponding PQ bus The admittance row of the bus voltage, U is the complex bus voltage.

S7: Apply Matlab and solve the above optimization problem with IPM with constant Hessian matrix.

S8: Compare the number of iterations and time required by the sensitivity method and the extended power flow method to verify the functionality of the method in the embodiment of the present invention.

In another specific embodiment of the present invention, under non-equilibrium conditions, the extended power flow method based on the optimization method proposed by the embodiment of the present invention includes the following steps:

S1: Establish the relaxed bus voltage limit equation.

in, is the lower limit of the square of the bus voltage, is the upper limit of the square of the bus voltage, l and u are the non-negative slack variables U _re and U _im are the real and imaginary parts of the bus voltage complex variable, g _u is the upper limit of the function, g is the mapping, g _l is the lower limit of the function, is the square of the bus voltage.

S2: Formulate an optimization problem for power flow expansion with local voltage controllers.

min∑(u+v)

Among them, U _re and U _im are the real and imaginary parts of the bus voltage complex variable, t is the transformer tap position, t _min and t _max are the minimum and maximum limits of the transformer tap position, h is the mapping, v is a non-negative slack variable, and st is a constraint condition.

S3: Establish the zero-injection bus constraint equation.

where I _re and I _im are the real and imaginary parts of the injected current, respectively, Y _zero is the admittance row corresponding to the zero injected bus, U is the complex bus voltage, and are the real and imaginary parts of the equation, respectively.

S4: Establish the PV bus constraint equation.

in, is the voltage control target of the PV bus, the subscript PV is the corresponding vector or matrix row of the PV bus, diag is the diagonal matrix, * is the conjugate of the complex variable, and S _re is the real part of the injected complex power; is the real part of the equation, Y _PV is the admittance row corresponding to the PV bus, U _PV is the PV bus voltage, U is the complex bus voltage, is the real part of the square of the PV bus voltage, is the imaginary part of the square of the PV bus voltage.

S5: Establish the PQ bus constraint equation.

where S _re and _Sim are the real and imaginary parts of the injected complex power, respectively, and are the real and imaginary parts of the equation, respectively, diag is the diagonal matrix, * is the conjugate of the complex variable, subscript PQ is the corresponding vector or matrix row of the PQ bus, U _PQ is the PQ bus voltage, Y _PQ is the corresponding PQ bus The admittance row of the bus voltage, U is the complex bus voltage.

S6: Applying Matlab, solve the above optimization problem with IPM with constant Hessian matrix.

S7: According to [I.Kocar, J. Mahseredjian, U. Karaagac, G. Soykan, and O. Saad, "Multiphase Load-Flow Solution for Large-Scale Distribution Systems UsingMANA," IEEE Transactions on Power Delivery, vol. 29, no.2, pp.908–915, Apr.2014.], it can be seen that the step voltage regulator model is represented by a voltage-controlled voltage source and a current-controlled current source.

S8: Collect IEEE4 bus test feeder data in [W.H.Kersting, Distribution System Modeling and Analysis, Third Edition. Boca Raton, Florida: CRC Press, 2012.].

S9: Compare the power flow result adjusted by the step voltage regulator with the number of iterations of the method of the embodiment of the present invention, and verify that the method of the embodiment of the present invention has the advantage of fewer iterations.

S10: Multiply the C-phase load on the IEEE4 bus by 2 to obtain the infeasible voltage limit of the method of the embodiment of the present invention, and verify that the method of the embodiment of the present invention has the functionality of detecting the infeasible voltage limit and relaxation capability.

According to the extended power flow method based on the optimization method proposed in the embodiment of the present invention, the optimization model of the zero injection bus, the optimization model of the PV bus, and the optimization model of the PQ bus are solved by the IPM of the constant Hessian matrix, so as to obtain the integer tap positions, And perform functional tests under three-phase balanced and unbalanced conditions to achieve the purpose of expanding power flow based on the optimization method, and solve the nonlinear problem and heavy load of the distributed network power flow based on the sensitive method based on the local voltage controller under heavy load conditions. The problem of detecting and relaxing the infeasible voltage limit under heavy load conditions improves the convergence of the nonlinear sensitivity method under heavy load conditions, and is suitable for detecting and relaxing the infeasible voltage limit under heavy load conditions.

Next, the extended power flow device based on the optimization method proposed according to the embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a schematic structural diagram of an extended power flow device based on an optimization method according to an embodiment of the present invention.

As shown in FIG. 2 , the extended power flow device 10 based on the optimization method includes: a restriction equation establishment module 100 , an optimization problem establishment module 200 , an optimization model establishment module 300 and a power flow expansion module 400 .

Wherein, the restriction equation establishment module 100 is configured to establish a relaxed bus voltage restriction equation according to the restriction formula. The optimization problem establishment module 200 is used to establish a power flow optimization problem with a local voltage controller through an optimization formula. The optimization model establishment module 300 is used to establish an optimization model of the zero-injection bus, an optimization model of the PV bus, and an optimization model of the PQ bus through constraint equations. The power flow expansion module 400 is used to solve the optimization model of the zero-injection bus, the optimization model of the PV bus, and the optimization model of the PQ bus through the IPM of the constant Hessian matrix, so as to obtain the integer tap positions, and in the three-phase balanced and unbalanced conditions. functional test below. The apparatus 10 in the embodiment of the present invention can improve the convergence of the nonlinear sensitivity method under heavy load conditions, and is suitable for detecting and relaxing infeasible voltage restrictions under heavy load conditions, so as to ensure the solvability of power flow.

Further, in an embodiment of the present invention, the restriction formula in the restriction equation establishment module 100 is:

in, is the lower limit of the square of the bus voltage, is the upper limit of the square of the bus voltage, l and u represent non-negative slack variables, U _re and U _im are the real and imaginary parts of the bus voltage complex variable, g _u is the upper limit of the function, g is the mapping, and g _l is the lower limit of the function, is the square of the bus voltage.

Further, in an embodiment of the present invention, the optimization formula in the optimization problem establishment module 200 is:

min∑(u+v)

Among them, t is the transformer tap position, t _min and t _max are the minimum limit and maximum limit of the transformer tap position, h is the map, v is the non-negative slack variable, and st is the constraint condition.

Further, in an embodiment of the present invention, the optimization model establishment module 300 further includes:

For a zero-injection bus, the first constraint equation h is expressed as a pair of linear equations:

where I _re and I _im are the real and imaginary parts of the injected current, respectively, Y _zero is the admittance row corresponding to the zero injection bus, U is the complex bus voltage, and are the real and imaginary parts of the equation, respectively.

For the PV bus, the second constraint equation h is expressed in pairs as:

in, is the voltage control target of the PV bus, the subscript PV is the corresponding vector or matrix row of the PV bus, diag is the diagonal matrix, * is the conjugate of the complex variable, S _re is the real part of the injected complex power, is the real part of the equation, Y _PV is the admittance row corresponding to the PV bus, U _PV is the PV bus voltage, U is the complex bus voltage, is the real part of the square of the PV bus voltage, is the imaginary part of the square of the PV bus voltage.

For the PQ bus, the third constraint equation h is expressed in pairs as:

where S _re and _Sim are the real and imaginary parts of the injected complex power, respectively, and are the real and imaginary parts of the equation, diag is the diagonal matrix, * is the conjugate of the complex variable, subscript PQ is the corresponding vector or matrix row of the PQ bus, U _PQ is the PQ bus voltage, Y _PQ is the corresponding PQ bus The admittance row of the bus voltage, U is the complex bus voltage.

Further in one embodiment of the present invention, the integer tap positions are obtained by rounding off the fractional value of the tap positions.

It should be noted that, the foregoing explanations on the embodiment of the extended power flow method based on the optimization method are also applicable to the extended power flow device based on the optimization method in this embodiment, and details are not repeated here.

According to the extended power flow device based on the optimization method proposed in the embodiment of the present invention, the optimization model of the zero injection bus, the optimization model of the PV bus, and the optimization model of the PQ bus are solved by the IPM of the constant Hessian matrix, so as to obtain the integer tap positions, And perform functional tests under three-phase balanced and unbalanced conditions to achieve the purpose of expanding power flow based on the optimization method, and solve the nonlinear problem and heavy load of the distributed network power flow based on the sensitive method based on the local voltage controller under heavy load conditions. The problem of detecting and relaxing the infeasible voltage limit under heavy load conditions improves the convergence of the nonlinear sensitivity method under heavy load conditions, and is suitable for detecting and relaxing the infeasible voltage limit under heavy load conditions.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", " Rear, Left, Right, Vertical, Horizontal, Top, Bottom, Inner, Outer, Clockwise, Counterclockwise, Axial, The orientations or positional relationships indicated by "radial direction", "circumferential direction", etc. are based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying the indicated devices or elements. It must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as a limitation of the present invention.

In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature delimited with "first", "second" may expressly or implicitly include at least one of that feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically defined.

In the present invention, unless otherwise expressly specified and limited, the terms "installed", "connected", "connected", "fixed" and other terms should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection , or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between the two elements, unless otherwise specified limit. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

In the present invention, unless otherwise expressly specified and limited, a first feature "on" or "under" a second feature may be in direct contact between the first and second features, or the first and second features indirectly through an intermediary touch. Also, the first feature being "above", "over" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is level higher than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature has a lower level than the second feature.

In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples, without conflicting each other.

Although the embodiments of the present invention have been shown and described above, it should be understood that the above-mentioned embodiments are exemplary and should not be construed as limiting the present invention. Embodiments are subject to variations, modifications, substitutions and variations.

Claims (10)

1. an extended power flow method based on an optimization method, is characterized in that, comprises the following steps: Establish a relaxed bus voltage limit equation according to the limit formula; The power flow optimization problem with local voltage controller is established by the optimization formula; Build an optimization model for the zero-injection bus, an optimization model for the PV bus, and an optimization model for the PQ bus through constraint equations; and The optimization model of the zero injection bus, the optimized model of the PV bus, and the optimized model of the PQ bus are solved by the IPM of the constant Hessian matrix to obtain the integer tap positions, and the three-phase balanced and unbalanced conditions are obtained. functional test below. 2. The extended power flow method based on an optimization method according to claim 1, wherein the bus voltage restriction equation is established by a restriction formula, and the restriction formula is: in, is the lower limit of the square of the bus voltage, is the upper limit of the square of the bus voltage, l and u are non-negative slack variables, U _re and U _im are the real and imaginary parts of the bus voltage complex variable, g _u is the upper limit of the function, g is the mapping, and g _l is the lower bound of the function, is the square of the bus voltage. 3. the extended power flow method based on optimization method according to claim 2, is characterized in that, establish described power flow optimization problem by following optimization formula, and described optimization formula is: Among them, t is the transformer tap position, t _min and t _max are the minimum limit and maximum limit of the transformer tap position, h is the map, v is the non-negative slack variable, and st is the constraint condition. 4. the extended power flow method based on optimization method according to claim 1, is characterized in that, described establishing the optimization model of zero injection busbar, the optimization model of PV busbar and the optimization model of PQ busbar, further comprises: For the zero injection bus, the first constraint equation h is expressed as a pair of linear equations: where I _re and I _im are the real and imaginary parts of the injected current, respectively, Y _zero is the admittance row corresponding to the zero injection bus, U is the complex bus voltage, and are the real and imaginary parts of the equation, respectively. For the PV bus, the second constraint equation h is expressed in pairs as: in, is the voltage control target of the PV bus, the subscript PV is the corresponding vector or matrix row of the PV bus, diag is the diagonal matrix, * is the conjugate of the complex variable, S _re is the real part of the injected complex power, is the real part of the equation, Y _PV is the admittance row corresponding to the PV bus, U _PV is the PV bus voltage, U is the complex bus voltage, is the real part of the PV bus voltage, is the imaginary part of the PV bus voltage. For the PQ bus, the third constraint equation h is expressed in pairs as: where S _re and _Sim are the real and imaginary parts of the injected complex power, respectively, and are the real and imaginary parts of the equation, diag is the diagonal matrix, * is the conjugate of the complex variable, subscript PQ is the corresponding vector or matrix row of the PQ bus, U _PQ is the PQ bus voltage, Y _PQ is the corresponding PQ bus The admittance row of the busbar, U is the voltage of the complex busbar. 5 . The extended power flow method based on the optimization method according to claim 1 , wherein the integer tap positions are obtained by rounding off the decimal value of the tap positions. 6 . 6. An extended power flow device based on an optimization method, characterized in that, comprising: The restriction equation establishment module is used to establish the relaxed bus voltage restriction equation according to the restriction formula; The optimization problem building module is used to establish the power flow optimization problem with local voltage controller through the optimization formula; an optimization model building module for building an optimization model for a zero-injection bus, an optimization model for a PV bus, and an optimization model for a PQ bus through constraint equations; and The power flow extension module is used to solve the optimization model of the zero-injection bus, the optimization model of the PV bus, and the optimization model of the PQ bus through the IPM of the constant Hessian matrix, so as to obtain the integer tap positions, and in the three-phase balance and no Functional testing under equilibrium conditions. 7. The extended power flow device based on the optimization method according to claim 6, wherein the restriction formula in the restriction equation establishment module is: in, is the lower limit of the square of the bus voltage, is the upper limit of the square of the bus voltage, l and u represent non-negative slack variables, U _re and U _im are the real and imaginary parts of the bus voltage complex variable, g _u is the upper limit of the function, g is the mapping, and g _l is the function lower limit, is the square of the bus voltage. 8. The extended power flow device based on the optimization method according to claim 7, wherein the optimization formula in the optimization problem establishment module is: Among them, t is the transformer tap position, t _min and t _max are the minimum limit and maximum limit of the transformer tap position, h is the map, v is the non-negative slack variable, and st is the constraint condition. 9. The extended power flow device based on the optimization method according to claim 6, wherein the optimization model establishment module further comprises: For the zero injection bus, the first constraint equation h is expressed as a pair of linear equations: where I _re and I _im are the real and imaginary parts of the injected current, respectively, Y _zero is the admittance row corresponding to the zero injection bus, U is the complex bus voltage, and are the real and imaginary parts of the equation, respectively. For the PV bus, the second constraint equation h is expressed in pairs as: in, is the voltage control target of the PV bus, the subscript PV is the corresponding vector or matrix row of the PV bus, diag is the diagonal matrix, * is the conjugate of the complex variable, S _re is the real part of the injected complex power, is the real part of the equation, Y _PV is the admittance row corresponding to the PV bus, U _PV is the PV bus voltage, U is the complex bus voltage, is the real part of the PV bus voltage, is the imaginary part of the PV bus voltage. For the PQ bus, the third constraint equation h is expressed in pairs as: where S _re and _Sim are the real and imaginary parts of the injected complex power, respectively, and are the real and imaginary parts of the equation, diag is the diagonal matrix, * is the conjugate of the complex variable, subscript PQ is the corresponding vector or matrix row of the PQ bus, U _PQ is the PQ bus voltage, Y _PQ is the corresponding PQ bus The admittance row of the busbar, U is the voltage of the complex busbar. 10 . The extended power flow device based on the optimization method according to claim 6 , wherein the integer tap positions are obtained by rounding off the decimal value of the tap positions. 11 .