阅读说明：本技术 电压稳定性分析方法、装置、电子设备及存储介质 (Voltage stability analysis method and device, electronic equipment and storage medium ) 是由 丁涛 孙瑜歌 李立 王康 张青蕾 乔彦君 迟方德 曲明 穆程刚 于 2021-08-19 设计创作，主要内容包括：本发明提供一种电压稳定性分析方法、装置、电子设备及存储介质,该方法包括：依据电力系统中母线的类型和地理位置,将电力系统划分为至少两个区域；在每个区域中嵌入至少两个变量,至少两个变量包括对应区域的有功功率变化比率及无功功率变化比率；基于至少两个变量,采用多维全纯嵌入法,确定电力系统的潮流表达式,潮流表达式包括母线电压表达式和无功功率表达式；根据母线电压表达式,确定母线电压幅值表达式；根据母线电压幅值表达式和无功功率表达式,确定母线的V-Q灵敏度值；根据V-Q灵敏度值判断所述电压稳定性。该方案能够消除有功功率对V-Q灵敏度的影响,提高计算精度。(The invention provides a voltage stability analysis method, a voltage stability analysis device, electronic equipment and a storage medium, wherein the method comprises the following steps: dividing the power system into at least two areas according to the type and the geographical position of a bus in the power system; embedding at least two variables in each region, wherein the at least two variables comprise the active power change rate and the reactive power change rate of the corresponding region; determining a tidal current expression of the power system by adopting a multidimensional pure embedding method based on at least two variables, wherein the tidal current expression comprises a bus voltage expression and a reactive power expression; determining a bus voltage amplitude expression according to the bus voltage expression; determining a V-Q sensitivity value of the bus according to the bus voltage amplitude expression and the reactive power expression; and judging the voltage stability according to the V-Q sensitivity value. The scheme can eliminate the influence of active power on the V-Q sensitivity and improve the calculation precision.)

1. A method of voltage stability analysis, the method comprising:

dividing an electric power system into at least two areas according to the type and the geographical position of a bus in the electric power system;

embedding at least two variables in each of the zones, the at least two variables including a rate of change of active power and a rate of change of reactive power of the corresponding zone;

determining tidal current expressions of the power system by adopting a multidimensional all-pure embedding method based on the at least two variables, wherein the tidal current expressions comprise bus voltage expressions and reactive power expressions;

determining a bus voltage amplitude expression according to the bus voltage expression;

determining a V-Q sensitivity value of the bus according to the bus voltage amplitude expression and the reactive power expression;

and judging the voltage stability according to the V-Q sensitivity value.

2. The method of claim 1, wherein determining a bus voltage magnitude expression from a bus voltage expression comprises:

decomposing the bus voltage expression into a real part and an imaginary part;

and determining the bus voltage amplitude expression according to the relation between the voltage amplitude and the real part and the imaginary part.

3. The method of claim 2, wherein determining the bus voltage magnitude representation from the voltage magnitude versus the real and imaginary parts comprises:

listing a relationship between the voltage magnitude and the real and imaginary parts;

expanding the power series of the voltage amplitude, the power series of the real part and the power series of the imaginary part in the relation;

determining each power coefficient of the voltage amplitude expression according to the equality of the coefficients of the same power at the two sides of the relational expression;

and determining the bus voltage amplitude expression according to each power coefficient of the voltage amplitude expression.

4. The method according to any one of claims 1-3, wherein said determining a V-Q sensitivity value of the bus from the expression of the bus voltage magnitude and the expression of the reactive power comprises:

determining a V-Q sensitivity expression of the bus according to the bus voltage amplitude expression and the reactive power expression;

carrying out rational approximation on the V-Q sensitivity expression to obtain a diagonal rational approximation fractional expression of the V-Q sensitivity;

and determining the V-Q sensitivity value of the bus according to the diagonal rational approximation fractional expression of the V-Q sensitivity.

5. The method of claim 4, wherein determining the V-Q sensitivity value of the bus according to a diagonal rational approximation fractional expression of the V-Q sensitivity comprises:

implementing acquisition of operating state data of the power system;

and substituting the running state data into the diagonal rational approximation fraction expression of the V-Q sensitivity to obtain the V-Q sensitivity value of the bus.

6. The method according to any one of claims 1-3, wherein said determining the voltage stability from the V-Q sensitivity value comprises:

if the V-Q sensitivity value is a positive number, determining that the voltage is stable;

and if the V-Q sensitivity value is changed from a positive number to a negative number, determining that the voltage is collapsed.

7. The method of claim 6, wherein if the V-Q sensitivity value is positive, the smaller the V-Q sensitivity value is, the more stable the voltage is.

8. A voltage stability analysis apparatus, comprising:

the system comprises a dividing module, a judging module and a judging module, wherein the dividing module is used for dividing the power system into at least two areas according to the type and the geographic position of a bus in the power system;

an embedding module, configured to embed at least two variables in each of the regions, where the at least two variables include an active power change rate and a reactive power change rate of the corresponding region;

the first determining module is used for determining tidal current expressions of the power system by adopting a multidimensional all-pure embedding method based on the at least two variables, wherein the tidal current expressions comprise bus voltage expressions and reactive power expressions;

the second determining module is used for determining a bus voltage amplitude expression according to the bus voltage expression;

the third determining module is used for determining the V-Q sensitivity value of the bus according to the bus voltage amplitude expression and the reactive power expression;

and the processing module is used for judging the voltage stability according to the V-Q sensitivity value.

9. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor implements the voltage stability analysis method of any of claims 1-7 when executing the program.

10. A readable storage medium on which a computer program is stored, which program, when being executed by a processor, is adapted to carry out the voltage stability analysis method according to any one of claims 1 to 7.

Technical Field

The invention belongs to the technical field of power systems, and particularly relates to a voltage stability analysis method and device, electronic equipment and a storage medium.

Background

In recent years, the increasing demand for electricity, and the lack of corresponding infrastructure extensions, has led to the risk that the power system will operate close to its voltage stability limits, thereby risking a voltage collapse. Other factors such as grid strength shortages, transmission capacity limitations, and the nature and limitations of reactive voltage control devices will also bring operating conditions closer to the voltage collapse point. The problem of unstable voltage becomes an important threat to the normal operation of a power system, and a large-scale power failure accident caused by voltage collapse causes huge economic and social losses. Therefore, the study of voltage stability is of great importance.

Voltage stability refers to the ability of the power system to maintain all bus voltages at acceptable steady state values after normal operation and after various disturbances. Conventionally, analysis methods of voltage stability can be roughly classified into a static method and a dynamic method. The static method takes the tidal current limit as a critical point of static voltage stability, and analyzes the voltage stability by utilizing a P-V curve or a Q-V curve. The static method mainly comprises three methods, namely a Continuous Power Flow (CPF) method, a V-Q sensitivity method and a modal analysis method. Wherein the V-Q sensitivity method uses a contracted Jacobian matrix to calculate the relationship between the voltage increment and the reactive power increment.

Most studies on voltage stability are based on iterative methods, such as Newton-Raphson (NR) and gaussian-Seidel (GS) iterations, which need to overcome their inherent non-convergence disadvantage. However, the proposed Method of recursive-based all-pure Embedding (HEM) can deal with this problem, ensuring that a feasible solution is found within the convergence region. Thus, the HEM-based voltage stability analysis eliminates the misconvergence problem.

However, most of the voltage stability analysis methods based on the HEM only embed one variable to uniformly control power generation and load change, and cannot accurately depict the situation that the load and the power generation change according to different proportions, and also cannot eliminate the influence of active power on the V-Q sensitivity.

Disclosure of Invention

An object of the embodiments of the present disclosure is to provide a voltage stability analysis method, device, electronic device, and storage medium, which can eliminate the influence of active power on V-Q sensitivity and improve calculation accuracy.

In order to solve the above technical problem, the embodiments of the present application are implemented as follows:

in a first aspect, the present application provides a voltage stability analysis method, including:

dividing the power system into at least two areas according to the type and the geographical position of a bus in the power system;

embedding at least two variables in each region, wherein the at least two variables comprise the active power change rate and the reactive power change rate of the corresponding region;

determining a tidal current expression of the power system by adopting a multidimensional pure embedding method based on at least two variables, wherein the tidal current expression comprises a bus voltage expression and a reactive power expression;

determining a bus voltage amplitude expression according to the bus voltage expression;

determining a V-Q sensitivity value of the bus according to the bus voltage amplitude expression and the reactive power expression;

and judging the voltage stability according to the V-Q sensitivity value.

In one embodiment, determining the bus voltage magnitude expression according to the bus voltage expression comprises:

decomposing the bus voltage expression into a real part and an imaginary part;

and determining the expression of the bus voltage amplitude according to the relation between the voltage amplitude and the real part and the imaginary part.

In one embodiment, determining the bus voltage magnitude expression according to the relationship between the voltage magnitude and the real part and the imaginary part comprises:

listing a relation between the voltage amplitude and the real part and the imaginary part;

expanding the power series of the voltage amplitude, the power series of the real part and the power series of the imaginary part in the relational expression;

determining each power coefficient of the voltage amplitude expression according to the equality of the coefficients of the same power at the two sides of the relational expression;

and determining the bus voltage amplitude expression according to each power coefficient of the voltage amplitude expression.

In one embodiment, determining the V-Q sensitivity value of the bus according to the bus voltage amplitude expression and the reactive power expression comprises the following steps:

determining a V-Q sensitivity expression of the bus according to the bus voltage amplitude expression and the reactive power expression;

carrying out rational approximation on the V-Q sensitivity expression to obtain a diagonal rational approximation fractional expression of the V-Q sensitivity;

and determining the V-Q sensitivity value of the bus according to a diagonal rational approximation fractional expression of the V-Q sensitivity.

In one embodiment, determining the V-Q sensitivity value of the bus according to a diagonal rational approximation fractional expression of the V-Q sensitivity comprises:

acquiring running state data of the power system;

and substituting the running state data into a diagonal rational approximation fraction expression of the V-Q sensitivity to obtain a V-Q sensitivity value of the bus.

In one embodiment, determining the voltage stability according to the V-Q sensitivity value comprises:

if the V-Q sensitivity value is a positive number, judging that the voltage is stable;

and if the V-Q sensitivity value is changed from positive to negative, the breakdown of the voltage is judged.

In one embodiment, if the V-Q sensitivity value is positive, the smaller the V-Q sensitivity value, the more stable the voltage.

In a second aspect, the present application provides a voltage stability analysis device, comprising:

the dividing module is used for dividing the power system into at least two areas according to the type and the geographic position of a bus in the power system;

the embedded module is used for embedding at least two variables into each region, wherein the at least two variables comprise the active power change rate and the reactive power change rate of the corresponding region;

the first determining module is used for determining a tidal current expression of the power system by adopting a multidimensional all-pure embedding method based on at least two variables, wherein the tidal current expression comprises a bus voltage expression and a reactive power expression;

the second determining module is used for determining a bus voltage amplitude expression according to the bus voltage expression;

the third determining module is used for determining the V-Q sensitivity value of the bus according to the bus voltage amplitude expression and the reactive power expression;

and the processing module is used for judging the voltage stability according to the V-Q sensitivity value.

In a third aspect, the present application provides an electronic device, comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor executes the computer program to implement the voltage stability analysis method according to the first aspect.

In a fourth aspect, the present application provides a readable storage medium having stored thereon a computer program which, when executed by a processor, implements the voltage stability analysis method of the first aspect.

According to the technical scheme provided by the embodiment of the specification, the power system is divided into at least two areas, and the spatial relation of power generation/load in different areas can be represented. This approach does not require the power generation/load to change in a single direction and can simulate system changes over any operating range from the initial operating condition to the voltage collapse point. In addition, the reasonable embedding mode is selected, the influence of active power on the V-Q sensitivity index can be eliminated, the calculation precision is improved, and the actual planning and calculation requirements of a multi-region power system are met.

In addition, compared with the traditional voltage stability analysis method based on iteration, the voltage stability analysis method provided by the application can eliminate the problem of non-convergence, and the offline derivation of the V-Q sensitivity expression can avoid repeated load flow calculation, thereby greatly improving the calculation speed and reducing the calculation complexity.

Drawings

In order to more clearly illustrate the embodiments of the present specification or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only some embodiments described in the present specification, and for those skilled in the art, other drawings can be obtained according to the drawings without any creative effort.

FIG. 1 is a schematic flow chart of a voltage stability analysis method provided herein;

fig. 2 is a schematic structural diagram of a voltage stability analysis apparatus provided in the present application;

fig. 3 is a schematic structural diagram of an electronic device provided in the present application.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present specification, the technical solutions in the embodiments of the present specification will be clearly and completely described below with reference to the drawings in the embodiments of the present specification, and it is obvious that the described embodiments are only a part of the embodiments of the present specification, and not all of the embodiments. All other embodiments obtained by a person skilled in the art based on the embodiments in the present specification without any inventive step should fall within the scope of protection of the present specification.

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments described herein without departing from the scope or spirit of the application. Other embodiments will be apparent to the skilled person from the description of the present application. The specification and examples are exemplary only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

In the present application, "parts" are in parts by mass unless otherwise specified.

In the related art, only one variable is embedded in the voltage stability analysis method based on the HEM to uniformly control power generation and load change, the situation that the load and the power generation change according to different proportions cannot be accurately described, and the influence of active power on the V-Q sensitivity cannot be eliminated.

Based on the defects, the embodiment of the application provides a voltage stability analysis method, which can eliminate the influence of active power on the V-Q sensitivity and improve the calculation precision.

The present invention will be described in further detail with reference to the accompanying drawings and examples.

Referring to fig. 1, a schematic flow chart diagram of a voltage stability analysis method suitable for use in the embodiments of the present application is shown.

As shown in fig. 1, the voltage stability analysis method may include:

s110, dividing the power system into at least two areas according to the type and the geographical position of a bus in the power system;

s120, embedding at least two variables into each region, wherein the at least two variables comprise the active power change ratio and the reactive power change ratio of the corresponding region;

s130, determining a tidal current expression of the power system by adopting a multidimensional pure embedding method based on at least two variables, wherein the tidal current expression comprises a bus voltage expression and a reactive power expression;

s140, determining a bus voltage amplitude expression according to the bus voltage expression;

s150, determining a V-Q sensitivity value of the bus according to the bus voltage amplitude expression and the reactive power expression;

and S160, judging the voltage stability according to the V-Q sensitivity value.

Specifically, data of the power system is acquired, including information such as bus type and geographic position.

According to the bus type, the geographic position and the like of the power system, the power system is divided into at least two areas so as to accurately quantify the increment relation between the reactive power and the bus voltage and meet the actual planning calculation requirement of the multi-area power system. For example, into D zones, i.e. one power system comprises D zones.

HEM is a recursive method for solving a Power Balance Equation (PBE), which has the advantage of obtaining a bus voltage and reactive power series. It embeds a ratio control variable (i.e., power ratio) into the PBE and obtains the final solution through a recursive process starting from the physical initial solution. Physically, since there is only one embedded variable in the HEM, this allows all generators and loads to vary uniformly in the same direction. However, the generator/load characteristics of different regions may have significant differences, and the generator/load characteristics of the same region may have strong spatial correlation, and in practice, it is often necessary to analyze the load increase condition of a certain region. Therefore, we use Multi-Dimensional all-pure Embedding (MDHEM) to ensure that generators and loads in different regions vary in different directions at different scales. In addition, in order to eliminate the influence of active power on the V-Q sensitivity index in the subsequent solving process of the V-Q sensitivity, different control ratios should be adopted for the active power and the reactive power of each subarea.

The implementation of MDHEM is divided into three steps: the embedded equations are listed, recursive formulas are derived, and the entire power flow series is solved from the selected physical initial solution. Consider an N-bus power system with D partitions containing one slack bus, m PQ buses, and p PV buses. In general, there will be 2D variables (i.e., s)₁,s₂,…,s_2D) The variable-power-variable-ratio-based PBEs are embedded in the PBEs (namely two variables are embedded in each region, the change ratio of the active power and the change ratio of the reactive power are respectively controlled, and all the variables in the system are independently changed), and each variable represents the change ratio of the active power or the change ratio of the reactive power of the relevant region (actually, the embedding mode of the variable can be arbitrarily selected according to actual needs).

In the PQ bus, the initial PEBs formula (tidal current equation) is:

after embedding two variables in the initial PEBs of the PQ bus, the embedding equation is obtained as follows:

obtaining a recursion formula of the PQ bus according to the formula (1) and the formula (2):

in the PV bus, the initial PEBs formula (tidal current equation) is:

after embedding two variables in the initial PEBs of the PV bus, the embedding equation is obtained as:

obtaining a recurrence formula of the PV bus according to the formula (4) and the formula (5):

in the slack bus, the initial PEBs formula (tidal current equation) is:

V_i＝V_i ^sl，i＝m+p+1 (7)

after embedding two variables in the initial PEBs of the relaxed bus, the embedding equation is obtained as:

V_i(s₁,s₂,…s_2D)＝V_i ^sl (8)

obtaining a recursion formula of the slack bus according to the formula (7) and the formula (8):

C_i0＝V_i ^sl,C_i[n₁,n₂,…n_2D]＝0 (9)

and (3), a formula (6) and a formula (9) are combined to obtain tidal current expressions, wherein the tidal current expressions comprise a bus voltage expression, a reactive power expression and the like.

Wherein, Y_ikIs the element of the ith row and the kth column of the admittance matrix; p_iAnd Q_iIs the active and reactive power, P, injected into the bus i_i0And Q_i0Respectively, the initial values thereof;V_iis the voltage amplitude at bus i; v_i ^spAnd V_i ^slIs a given voltage amplitude on the PV bus and the slack bus; re (·) represents the operation of taking the real part of a complex number; (.)^*Represents a conjugate operation; x (i) represents the area index where the bus i is located; s_x(i)And s_D+x(i)Respectively representing the active power change rate and the reactive power change rate at the bus i. Voltage power series V_i(s₁,s₂,…,s_2D) And its reciprocal W_i(s₁,s₂,…,s_2D) And a reactive power series Q_i(s₁,s₂,…,s_2D) Are all multivariable expressions at the generatrix i, where C_i[n₁,n₂,…,n_2D]，R_i[n₁,n₂,…,n_2D]And U_i[n₁,n₂,…,n_2D]Is expressed inThe coefficient of the term.

In one embodiment, the step S140 of determining the bus voltage amplitude expression according to the bus voltage expression includes:

decomposing the bus voltage expression into a real part and an imaginary part;

and determining the expression of the bus voltage amplitude according to the relation between the voltage amplitude and the real part and the imaginary part.

Determining a bus voltage amplitude expression according to a relation between the voltage amplitude and the real part and the imaginary part, wherein the determining the bus voltage amplitude expression may include:

listing a relation between the voltage amplitude and the real part and the imaginary part;

expanding the power series of the voltage amplitude, the power series of the real part and the power series of the imaginary part in the relational expression;

determining each power coefficient of the voltage amplitude expression according to the equality of the coefficients of the same power at the two sides of the relational expression;

and determining the bus voltage amplitude expression according to each power coefficient of the voltage amplitude expression.

In order to analyze the voltage stability of a power system by using a V-Q sensitivity method, an analytic method for solving a bus voltage amplitude expression based on a recursion theory is provided. Through the MDHEM, a voltage expression on each bus can be obtained:

decomposing a bus voltage expression into a real part V_{i_R}(s₁,s₂,…,s_2D) And an imaginary part V_{i_I}(s₁,s₂,…,s_2D) As shown in formulas (11) to (13):

V_i(s₁，s₂，…，s_2D)＝V_{i_R}(s₁，s₂，…，s_2D)+jV_{i_I}(s₁，s₂，…，s_2D) (11)

wherein A is_i[n₁,n₂,…,n_2D]And B_i[n₁,n₂,…,n_2D]Are each V_{i_R}(s₁,s₂,…,s_2D) And V_{i_I}(s₁,s₂,…,s_2D) Is/are as followsThe term coefficient.

Assume that the voltage magnitude at bus i is expressed as (14), also expressed in a power series form, which Coefficient of term M_i[n₁,n₂,…,n_2D]. According to the recursive theory, we derive the unknown coefficients of the power series from low order to high order.

Based on the square sum relationship between the voltage magnitude and the real and imaginary parts of the bus voltage, equation (15) can be derived:

V_{i_R}(s₁,s₂,…,s_2D)²+V_{i_I}(s₁,s₂,…,s_2D)²＝V_{i_M}(s₁,s₂,…,s_2D)² (15)

substituting the expanded form of the power series in (12) - (14) into (15) can obtain:

power series V_{i_M}(s₁,s₂,…,s_2D) The series coefficients of (2) can be obtained by equaling coefficients of the same power on both sides of (16), giving the following recursion equations (17) - (19):

according to the recursion equations (17) - (19), coefficients of the voltage amplitude expression are derived from low-order coefficients to high-order coefficients.

To identify the voltage collapse point of the selected system and determine the weak bus bars in all operating conditions from the initial operating point to the voltage collapse point, the present application will use a voltage magnitude expression to calculate the V-Q sensitivity, representing it as a multivariable function with respect to the power ratio. Here, since only the PQ bus is focused on the study of voltage stability, the V-Q sensitivity of the PV bus is not discussed.

In one embodiment, the step S150 of determining the V-Q sensitivity value of the bus according to the bus voltage magnitude expression and the reactive power expression may include:

determining a V-Q sensitivity expression of the bus according to the bus voltage amplitude expression and the reactive power expression;

carrying out rational approximation on the V-Q sensitivity expression to obtain a diagonal rational approximation fractional expression of the V-Q sensitivity;

and determining the V-Q sensitivity value of the bus according to a diagonal rational approximation fractional expression of the V-Q sensitivity.

Determining the V-Q sensitivity value of the bus according to the diagonal rational approximation fractional expression of the V-Q sensitivity may include:

acquiring running state data of the power system;

and substituting the running state data into a diagonal rational approximation fraction expression of the V-Q sensitivity to obtain a V-Q sensitivity value of the bus.

Specifically, by definition, the V-Q sensitivity of the bus i is the ith diagonal element of the inverse of the contracted jacobian matrix, and the physical meaning is the incremental relationship between reactive power and voltage amplitude when the active power of the bus i is kept constant. In practical power systems, it is often necessary to study the incremental relationship between the regional reactive power and the bus voltage magnitude, i.e., the V-Q sensitivity, to reflect complete system information.

Unlike the traditional V-Q sensitivity method, since the bus voltage magnitude expression and the reactive power expression have been obtained, the multivariate V-Q sensitivity analysis method proposed in the present invention can re-express the V-Q sensitivity at bus i as:

wherein Z is_{i_sen}(s₁,s₂,…,s_2D) Is a multivariable V-Q sensitivity power series expression at a bus i; q_D+x(i)(s₁,s₂,…,s_2D) Representing the total reactive power expression of the area x (i) for which the sum of the initial reactive powers is Q_D+x(i),0. (20) May be further converted to (21).

However, Z_{i_sen}(s₁,s₂,…,s_2D) Still a multivariable truncated series expression whose convergence domain often cannot be extended to the edges of the solution space, especially near the voltage collapse point.

Multidimensional rational approximation is used to extend the convergence region and provide analytic extension within the maximum range. Z_{i_sen}(s₁,s₂,…,s_2D) The diagonal rational approximation fractal expression of (a) may be expressed as (22). Coefficient m of numerator and denominator in diagonal rational approximation fraction expression_i[n₁,n₂,…,n_2D]And l_i[n₁,n₂,…,n_2D]Can be calculated by solving a system of linear equations by letting Z_{i_sen}(s₁,s₂,…,s_2D) And Z_{i_sen_M/N}(s₁,s₂,…,s_2D) Are equal and derived to a certain order.

Given a set of values of the embedded variables (i.e.Operating state data) into expression Z_{i_sen_M/N}(s₁,s₂,…,s_2D) To obtain an approximate value Z_{i_sen_M/N}(s^*) (V-Q sensitivity value of bus).

The voltage stability can be judged according to the V-Q sensitivity value. A positive V-Q sensitivity value indicates that the system is operating stably (i.e., the voltage is stable), and a smaller V-Q sensitivity value indicates that the system is more stable. The running state of the V-Q sensitivity value when the V-Q sensitivity value is changed from positive to negative can be judged as the occurrence of voltage collapse, namely the running point of the V-Q sensitivity value when the V-Q sensitivity value is changed from positive to negative is the voltage collapse point. Therefore, weak bus bars under any operating condition can be sequenced in the operating state change range of the power system for a period of time.

According to the voltage stability analysis method provided by the embodiment of the application, the power system is divided into at least two areas, at least two variables are embedded into each area, a multi-dimensional all-pure embedding method is adopted based on the embedded variables to determine a tide expression of the power system, a V-Q sensitivity value of a bus is determined according to the tide expression, and the voltage stability can be judged by utilizing the V-Q sensitivity value. The method can calculate the V-Q sensitivity expression in an off-line mode, and the V-Q sensitivity expression can be quickly solved by introducing the current power generation/load value into the expression under any operation condition, so that the situation that the traditional voltage stability analysis method based on iteration calculates the power flow for many times in an operation range is avoided. Furthermore, the method allows embedding multiple variables to simulate the variation of power generation/load in multiple directions in different areas of the power system; in particular, the method of embedding the variables into the active power and the reactive power respectively eliminates the influence of the active power on the calculation accuracy of the V-Q sensitivity.

Referring to fig. 2, a schematic structural diagram of a voltage stability analysis apparatus according to an embodiment of the present application is shown.

As shown in fig. 2, the voltage stability analysis apparatus may include:

the dividing module 210 is configured to divide the power system into at least two regions according to the type and the geographic location of a bus in the power system;

an embedding module 220 for embedding at least two variables in each region, the at least two variables including an active power change rate and a reactive power change rate of the corresponding region;

the first determining module 230 is configured to determine a tidal current expression of the power system by using a multidimensional all-pure embedding method based on at least two variables, where the tidal current expression includes a bus voltage expression and a reactive power expression;

a second determining module 240, configured to determine a bus voltage amplitude expression according to the bus voltage expression;

a third determining module 250, configured to determine a V-Q sensitivity value of the bus according to the bus voltage amplitude expression and the reactive power expression;

and the processing module 260 is used for judging the voltage stability according to the V-Q sensitivity value.

Continuing, the second determining module 240 is further configured to:

decomposing the bus voltage expression into a real part and an imaginary part;

and determining the expression of the bus voltage amplitude according to the relation between the voltage amplitude and the real part and the imaginary part.

Continuing, the second determining module 240 is further configured to:

listing a relation between the voltage amplitude and the real part and the imaginary part;

expanding the power series of the voltage amplitude, the power series of the real part and the power series of the imaginary part in the relational expression;

determining each power coefficient of the voltage amplitude expression according to the equality of the coefficients of the same power at the two sides of the relational expression;

and determining the bus voltage amplitude expression according to each power coefficient of the voltage amplitude expression.

Continuing, the third determining module 250 is further configured to:

determining a V-Q sensitivity expression of the bus according to the bus voltage amplitude expression and the reactive power expression;

carrying out rational approximation on the V-Q sensitivity expression to obtain a diagonal rational approximation fractional expression of the V-Q sensitivity;

and determining the V-Q sensitivity value of the bus according to a diagonal rational approximation fractional expression of the V-Q sensitivity.

Continuing, the third determining module 250 is further configured to:

acquiring running state data of the power system;

and substituting the running state data into a diagonal rational approximation fraction expression of the V-Q sensitivity to obtain a V-Q sensitivity value of the bus.

Optionally, the processing module 260 is further configured to:

if the V-Q sensitivity value is a positive number, judging that the voltage is stable;

and if the V-Q sensitivity value is changed from positive to negative, the breakdown of the voltage is judged.

Optionally, if the V-Q sensitivity value is a positive number, the smaller the V-Q sensitivity value is, the more stable the voltage is.

The voltage stability analysis apparatus provided in this embodiment may implement the embodiments of the method described above, and the implementation principle and the technical effect are similar, which are not described herein again.

Fig. 3 is a schematic structural diagram of an electronic device according to an embodiment of the present invention. As shown in fig. 3, a schematic structural diagram of an electronic device 300 suitable for implementing embodiments of the present application is shown.

As shown in fig. 3, the electronic apparatus 300 includes a Central Processing Unit (CPU)301 that can perform various appropriate actions and processes in accordance with a program stored in a Read Only Memory (ROM)302 or a program loaded from a storage section 308 into a Random Access Memory (RAM) 303. In the RAM 303, various programs and data necessary for the operation of the apparatus 300 are also stored. The CPU 301, ROM 302, and RAM 303 are connected to each other via a bus 304. An input/output (I/O) interface 305 is also connected to bus 304.

The following components are connected to the I/O interface 305: an input portion 306 including a keyboard, a mouse, and the like; an output section 307 including a display such as a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD), and the like, and a speaker; a storage section 308 including a hard disk and the like; and a communication section 309 including a network interface card such as a LAN card, a modem, or the like. The communication section 309 performs communication processing via a network such as the internet. A drive 310 is also connected to the I/O interface 306 as needed. A removable medium 311 such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, or the like is mounted on the drive 310 as necessary, so that a computer program read out therefrom is mounted into the storage section 308 as necessary.

In particular, the process described above with reference to fig. 1 may be implemented as a computer software program, according to an embodiment of the present disclosure. For example, embodiments of the present disclosure include a computer program product comprising a computer program tangibly embodied on a machine-readable medium, the computer program comprising program code for performing the voltage stability analysis method described above. In such an embodiment, the computer program may be downloaded and installed from a network through the communication section 309, and/or installed from the removable medium 311.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

The units or modules described in the embodiments of the present application may be implemented by software or hardware. The described units or modules may also be provided in a processor. The names of these units or modules do not in some cases constitute a limitation of the unit or module itself.

The systems, devices, modules or units illustrated in the above embodiments may be implemented by a computer chip or an entity, or by a product with certain functions. One typical implementation device is a computer. In particular, the computer may be, for example, a personal computer, a laptop computer, a mobile phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

As another aspect, the present application also provides a storage medium, which may be the storage medium contained in the foregoing device in the above embodiment; or may be a storage medium that exists separately and is not assembled into the device. The storage medium stores one or more programs that are used by one or more processors to perform the voltage stability analysis methods described herein.

Storage media, including permanent and non-permanent, removable and non-removable media, may implement the information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), Digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer readable medium does not include a transitory computer readable medium such as a modulated data signal and a carrier wave.

It is to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in the process, method, article, or apparatus that comprises the element.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is substantially similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.