CN106058876A - Dynamic reactive planning site-selection analysis method and system considering transient voltage stability - Google Patents

Abstract

The invention discloses a dynamic reactive planning site-selection analysis method and system considering transient voltage stability. The dynamic reactive planning site-selection analysis method comprises the steps of obtaining related data of a power grid firstly; then performing simulation analysis on the transient voltage stability of the power grid, analyzing the power grid faults to determine a transient voltage instability fault set, and dividing the transient voltage instability fault set into multiple transient voltage stable weak regions; next, calculating the dynamic reactive compensation sensitivity under each fault state, and determining the number and locations of the to-be-compensated points of one of the power grid fault weak region through a panning site-location combinational analysis method; and finally, outputting the position scheme of the dynamic reactive planning site-selection to-be-selected points of all the transient voltage stable weak regions. Compared with the prior art, the dynamic reactive planning site-selection analysis method and system are suitable for dynamic reactive planning site-selection in the alternating current/direct current hybrid power grid, have the advantages of high efficiency, simplicity, tight combination with engineering and the like; and in addition, the redundancy of the dynamic reactive planning site-selection to-be-selected compensation points can be effectively prevented.

Description

Dynamic reactive power planning site selection analysis method and system considering transient voltage stability

Technical Field

The invention relates to a reactive power compensation site selection method, in particular to a dynamic reactive power planning site selection analysis method and system considering transient voltage stability, and belongs to the technical field of reactive power compensation of power systems.

Background

The direct current transmission in China has a certain scale, and the extra-high voltage alternating current is also in vigorous development and continuous construction, a plurality of extra-high voltage alternating current projects (such as extra-high voltage alternating current projects of Jinsoutheast-south Yang-Jingmen, Huainan-Shanxi and the like) are built and put into operation, the grid structure in the areas of China east China, south China and the like is complex, the load is increased quickly, and a plurality of extra-high voltage accesses exist, so that the transient voltage stability of the load center area is greatly challenged along with the development of a future power grid. In order to enhance the transient voltage stability of the alternating current-direct current hybrid region, dynamic reactive power planning considering the transient voltage stability can be performed in a transient voltage stability weak region, and the number and the positions of nodes to be compensated in the weak region are determined, so that the dynamic reactive power supporting capability of the system after the power grid fails is improved.

The dynamic reactive power planning site selection analysis method for improving the transient stability of the system is mainly used for providing a transient voltage stability index reflecting the recovery capability of a power grid after a fault and establishing the dynamic reactive power planning site selection analysis method considering the transient voltage stability. At present, the voltage stability of a power grid is researched more, wherein the static voltage stability is researched more mature, and common static voltage stability indexes mainly comprise a PV curve method, a sensitivity index, a mode identification method and the like. However, the research on the weak voltage stability area of the power grid only by means of static voltage stability has certain limitation, and a plurality of transient voltage stability indexes are also provided in the current research, wherein the voltage drop index after the fault can reflect the transient recovery capability of the power grid, the maximum fault clearing time index can evaluate the longest time of the power grid under the fault, and the indexes are greatly influenced by the topology structure and the control system of the power grid and have certain limitation. In addition, the energy function method can be used for evaluating the voltage stability of the power grid after the fault, but because the energy function method is difficult to construct, the energy function method needs more research in the evaluation of the transient voltage stability. In order to more comprehensively and accurately reflect the recovery capability of the power grid after the fault, the novel transient voltage stability index is provided, and the method has important significance.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a dynamic reactive power planning site selection analysis method and system considering transient voltage stability.

The technical scheme adopted by the invention for solving the technical problems is as follows: the dynamic reactive power planning and site selection analysis method considering the transient voltage stability is characterized by comprising the following steps of:

step 1: acquiring relevant data of a power grid, wherein the relevant data of the power grid comprises transient parameters and control system parameters of a direct current transmission system, a dynamic reactive power compensation device and a generator;

step 2: carrying out simulation analysis on the transient voltage stability of the power grid, analyzing and determining a transient voltage instability fault set through the power grid faults, and recording the transient voltage instability fault set asAnd according toThe distribution of the voltage transformer divides a power grid with faults into a plurality of transient voltage stability weak areas;

and step 3: analyzing faults of the transient voltage stability weak area one by one, calculating dynamic reactive power compensation sensitivity in each fault state, determining the number and the position of points to be compensated of one power grid fault weak area by using a planning and site selection combined analysis method, and if 1 compensation point cannot meet the stability requirement, combining 2 or more compensation points to perform reactive power compensation on the weak area;

and 4, step 4: and (3) judging whether the dynamic reactive power planning site selection analysis of all the transient voltage stability weak areas is finished, if so, outputting a dynamic reactive power planning site selection to-be-selected point position scheme of all the transient voltage stability weak areas, otherwise, turning to the step (3) to continue the planning site selection analysis of the next weak area until the dynamic reactive power planning site selection analysis of all the transient voltage stability weak areas is finished.

The fault set comprises generator faults, extra-high voltage alternating current faults, extra-high voltage direct current transmission faults and line faults.

The dynamic reactive compensation sensitivity comprises a transient voltage recovery index TVRI-based compensation sensitivityAnd the compensation sensitivity based on the transient voltage fluctuation index TVFI

The compensation sensitivityThe calculation process comprises the following steps:

(11) the transient voltage recovery indicator TVRI is defined as:

${\mathrm{TVRI}}_i^{F_k}={\∫}_{t_{cl}}^{t_c}\frac{|U_{t,i}-U_{i0}|}{U_{i0}}dt---\left(1\right)$

in the formula: u shape_t,iIs the transient voltage at node i at time t; u shape_i0Is the voltage of the node i under the normal working condition; t is t_cIs the cut-off time in the transient recovery process; f_kFor fault classes of the power networkMolding; wherein, is a failure set;

(12) failure aggregationExpressed as:

in the formula: r_G，R_UHV，R_HVDC，R_BRRespectively representing a generator fault set, an extra-high voltage alternating current fault set, a direct current transmission fault set and a line fault set;

(13) the TVRI index of equation (1) is expressed as its differential definitional equation:

${\mathrm{TVRI}}_i^{F_k}=\underset{F_k,t\∈\[t_{cl},t_c\]}{\Σ}\frac{|U_{t,i}-U_{i0}|}{U_{i0}}{t}_s---\left(3\right)$

in the formula: t is t_sCalculating step length in time domain simulation analysis;

(14) by usingCalculating any node in the power grid, and obtaining a global transient voltage recovery index as follows:

${\mathrm{TVRI}}_s^{F_k}=\max \left({\mathrm{TVRI}}_i^{F_k}\right)=\max \left(\underset{F_k,t\∈\[t_{cl},t_c\]}{\Σ}\frac{|U_{t,i}-U_{i0}|}{U_{i0}}{t}_s\right)---\left(4\right)$

from equation (4), the global transient voltage recovery indexBy evaluating all nodes in the areaDetermining a maximum value;

the compensation sensitivity based on the TVRI index is expressed as:

$S_{{\mathrm{TVRI}}_s}^{F_k}=\frac{\∂{\mathrm{TVRI}}_s^{F_k}}{\∂Q_{svc}}---\left(7\right)$

converting formula (7) to:

$S_{{\mathrm{TVRI}}_s}^{F_k}=\frac{{\mathrm{\ΔTVRI}}_s^{F_k}}{{\mathrm{\ΔQ}}_{svc}}---\left(8\right)$

in the formula: TVRI_sCan be solved by equation (4), Q_SVCIs reactive compensation capacity.

The compensation sensitivityThe calculation process comprises the following steps:

(21) the transient voltage fluctuation index TVFI is defined as:

${\mathrm{TVFI}}_i^{F_k}=\frac{1}{2}\left(\frac{1}{N_T}\underset{p=1}{\overset{N_T}{\Σ}}{U}_{i,\max }^{F_k,N_p}-\frac{1}{N_T}\underset{p=1}{\overset{N_T}{\Σ}}{U}_{i,\min }^{F_k,N_p}\right)---\left(5\right)$

in the formula: n is a radical of_TThe frequency of the transient time domain simulation is; n is a radical of_pFor p th after grid fault_thA sub-cycle;are respectively F_kNode i is at Nth under fault_pMaximum and minimum voltage of the cycle;

(22) by usingCalculating any node in the power grid, and obtaining a transient voltage fluctuation index as follows:

${\mathrm{TVFI}}_s^{F_k}=max\left({\mathrm{TVFI}}_i^{F_k}\right)=max\left(\frac{1}{2}\right(\frac{1}{N_T}\underset{p=1}{\overset{N_T}{\Σ}}{U}_{i,\max }^{F_k,N_p}-\frac{1}{N_T}\underset{p=1}{\overset{N_T}{\Σ}}{U}_{i,\min }^{F_k,N_p}\left)\right)---\left(6\right)$

(23) the compensation sensitivity based on the TVFI index is expressed as:

$S_{{\mathrm{TVFI}}_s}^{F_k}=\frac{\∂{\mathrm{TVFI}}_s^{F_k}}{\∂Q_{svc}}---\left(9\right)$

equation (9) is simplified to:

$S_{{\mathrm{TVFI}}_s}^{F_k}=\frac{{\mathrm{\ΔTVFI}}_s^{F_k}}{{\mathrm{\ΔQ}}_{svc}}---\left(10\right)$

in the formula: TVFI_sCan be solved by equation (6), Q_SVCIs reactive compensation capacity.

The planning and site selection combined analysis method comprises the following steps:

(1) simulating and analyzing the transient voltage stability of the whole network by using a time domain simulation program, and dividing the transient voltage stability into a plurality of weak areas according to a fault set with a transient voltage stability problem;

(2) aiming at each transient voltage stability weak area, one or more points to be selected can be selected for compensation, and the principle of planning and site selection is to improve the transient voltage stability of the system by using the least compensation points;

(3) calculating and analyzing a fault set of each region of the transient voltage stability weak region one by one based on the compensation sensitivity, and if 1 dynamic reactive power compensation device cannot solve the problem of transient voltage stability, 2 or even more dynamic reactive power compensation devices are needed for compensation;

(4) and calculating and screening the site selection position of each weak area based on the dynamic reactive compensation sensitivity, and finally obtaining a dynamic reactive planning site selection to-be-selected position scheme of all transient voltage stabilization weak areas so as to improve the transient voltage stability of the whole network.

And the related data of the power grid are directly acquired from the power grid system or are input through an input device.

The invention also provides a dynamic reactive power planning and site selection analysis system considering the transient voltage stability, which is characterized by comprising the following components:

the data acquisition module is used for acquiring relevant data of a power grid, wherein the relevant data of the power grid comprises transient parameters and control system parameters of a direct current transmission system, a dynamic reactive power compensation device and a generator;

the simulation analysis module is used for carrying out simulation analysis on the transient voltage stability of the power grid, analyzing and determining a transient voltage instability fault set through the power grid fault, and recording the transient voltage instability fault set as

A region division module for dividing the region according toThe distribution of the voltage transformer divides a power grid with faults into a plurality of transient voltage stability weak areas;

the site selection analysis module is used for analyzing faults of the transient voltage stability weak area one by one, calculating dynamic reactive power compensation sensitivity in each fault state, determining the number and the position of points to be compensated of one power grid fault weak area by using a planning site selection combination analysis method, and if 1 compensation point cannot meet the stability requirement, combining 2 or even more compensation points to perform reactive power compensation on the weak area;

and the output module is used for outputting the dynamic reactive power planning addressing to-be-selected point position schemes of all transient voltage stability weak areas.

The fault set comprises generator faults, extra-high voltage alternating current faults, extra-high voltage direct current transmission faults and line faults.

The site selection analysis module comprises a dynamic reactive compensation sensitivity calculation module and a planning site selection combination analysis module.

The dynamic reactive compensation sensitivity calculation module is used for calculating the compensation sensitivity based on the transient voltage recovery index TVRIAnd the compensation sensitivity based on the transient voltage fluctuation index TVFI

The compensation sensitivityThe calculation process comprises the following steps:

(11) the transient voltage recovery indicator TVRI is defined as:

${\mathrm{TVRI}}_i^{F_k}={\∫}_{t_{cl}}^{t_c}\frac{|U_{t,i}-U_{i0}|}{U_{i0}}dt---\left(1\right)$

in the formula: u shape_t,iIs the transient voltage at node i at time t; u shape_i0Is the voltage of the node i under the normal working condition; t is t_cIs the cut-off time in the transient recovery process; f_kThe fault type of the power grid; wherein, is a failure set;

(12) failure aggregationExpressed as:

in the formula: r_G，R_UHV，R_HVDC，R_BRRespectively representing a generator fault set, an extra-high voltage alternating current fault set, a direct current transmission fault set and a line fault set;

(13) the TVRI index of equation (1) is expressed as its differential definitional equation:

${\mathrm{TVRI}}_i^{F_k}=\underset{F_k,t\∈\[t_{cl},t_c\]}{\Σ}\frac{|U_{t,i}-U_{i0}|}{U_{i0}}{t}_s---\left(3\right)$

in the formula: t is t_sCalculating step length in time domain simulation analysis;

(14) by usingCalculating any node in the power grid, and obtaining a global transient voltage recovery index as follows:

${\mathrm{TVRI}}_s^{F_k}=\max \left({\mathrm{TVRI}}_i^{F_k}\right)=\max \left(\underset{F_k,t\∈\[t_{cl},t_c\]}{\Σ}\frac{|U_{t,i}-U_{i0}|}{U_{i0}}{t}_s\right)---\left(4\right)$

from equation (4), the global transient voltage recovery indexBy evaluating all nodes in the areaDetermining a maximum value;

the compensation sensitivity based on the TVRI index is expressed as:

$S_{{\mathrm{TVRI}}_s}^{F_k}=\frac{\∂{\mathrm{TVRI}}_s^{F_k}}{\∂Q_{svc}}---\left(7\right)$

converting formula (7) to:

$S_{{\mathrm{TVRI}}_s}^{F_k}=\frac{{\mathrm{\ΔTVRI}}_s^{F_k}}{{\mathrm{\ΔQ}}_{svc}}---\left(8\right)$

in the formula: TVRI_sCan be solved by equation (4), Q_SVCIs a reactive compensation capacity;

the compensation sensitivityThe calculation process comprises the following steps:

(21) the transient voltage fluctuation index TVFI is defined as:

${\mathrm{TVFI}}_i^{F_k}=\frac{1}{2}\left(\frac{1}{N_T}\underset{p=1}{\overset{N_T}{\Σ}}{U}_{i,\max }^{F_k,N_p}-\frac{1}{N_T}\underset{p=1}{\overset{N_T}{\Σ}}{U}_{i,\min }^{F_k,N_p}\right)---\left(5\right)$

in the formula: n is a radical of_TThe frequency of the transient time domain simulation is; n is a radical of_pFor p th after grid fault_thA sub-cycle;are respectively F_kNode i is at Nth under fault_pMaximum and minimum voltage of the cycle;

(22) by usingCalculating any node in the power grid, and obtaining a transient voltage fluctuation index as follows:

${\mathrm{TVFI}}_s^{F_k}=max\left({\mathrm{TVFI}}_i^{F_k}\right)=max\left(\frac{1}{2}\right(\frac{1}{N_T}\underset{p=1}{\overset{N_T}{\Σ}}{U}_{i,\max }^{F_k,N_p}-\frac{1}{N_T}\underset{p=1}{\overset{N_T}{\Σ}}{U}_{i,\min }^{F_k,N_p}\left)\right)---\left(6\right)$

(23) the compensation sensitivity based on the TVFI index is expressed as:

$S_{{\mathrm{TVFI}}_s}^{F_k}=\frac{\∂{\mathrm{TVFI}}_s^{F_k}}{\∂Q_{svc}}---\left(9\right)$

equation (9) is simplified to:

$S_{{\mathrm{TVFI}}_s}^{F_k}=\frac{{\mathrm{\ΔTVFI}}_s^{F_k}}{{\mathrm{\ΔQ}}_{svc}}---\left(10\right)$

in the formula: TVFI_sCan be solved by equation (6), Q_SVCIs reactive compensation capacity.

The planning and site selection combined analysis module firstly simulates and analyzes the transient voltage stability of the whole network by using a time domain simulation program and divides the transient voltage stability into a plurality of weak areas according to a fault set with the transient voltage stability problem; aiming at each transient voltage stability weak area, one or more points to be selected can be selected for compensation, and the principle of planning and site selection is to improve the transient voltage stability of the system by using the least compensation points; calculating and analyzing a fault set of each region of the transient voltage stability weak region one by one based on the compensation sensitivity, and if 1 dynamic reactive power compensation device cannot solve the problem of transient voltage stability, 2 or even more dynamic reactive power compensation devices are needed for compensation; and calculating and screening the site selection position of each weak area based on the dynamic reactive compensation sensitivity, and finally obtaining a dynamic reactive planning site selection to-be-selected position scheme of all transient voltage stabilization weak areas so as to improve the transient voltage stability of the whole network.

The data acquisition module directly acquires the related data of the power grid from the power grid system or inputs the related data of the power grid through the input device.

The invention has the beneficial effects that: the dynamic reactive power planning method is divided into a plurality of transient voltage stabilization weak areas according to the distribution of the transient voltage instability fault set, and the reactive power compensation planning addressing is used as a subproblem to be solved in advance, so that the dynamic reactive power planning problem is simplified to a certain extent; the provided TVRI and TVFI indexes are used for transient voltage stability evaluation after a fault, the applicability is strong, and the dynamic reactive compensation sensitivity under the fault is highOrThe method is simple and easy to calculate, the established dynamic reactive power compensation planning site selection combination analysis method is high in practicability, and compared with the prior art, the method is suitable for the dynamic reactive power planning site selection problem in the alternating current-direct current hybrid power grid, has the advantages of being efficient, simple, closely combined with engineering and the like, and can effectively prevent redundancy of compensation points to be selected in the dynamic reactive power planning site selection.

The invention can solve the nearest compensation position of the reactive power planning problem considering the stability of the transient voltage, analyze the transient voltage instability area of the system by using time domain simulation software, analyze the number and the position of the optimal compensation points by using a reactive power planning and site selection combination method, simplify the problem by using the planning and site selection combination analysis method for each area, prevent the redundancy of dynamic reactive power planning and site selection by using the minimum compensation point position for a weak area, and efficiently enhance the transient voltage stability of the system.

In order to analyze dynamic reactive power planning site selection, the invention provides a transient voltage stability index capable of reflecting the voltage recovery capability after a power grid fault: transient voltage recovery index TVRI and transient voltage fluctuation index TVFI, so that the transient voltage deviation degree and the transient fluctuation degree after the grid fault are evaluated. The invention also provides a simple calculation method of compensation sensitivity based on TVRI indexes and TVFI indexes aiming at the weak transient voltage stability area.

Drawings

FIG. 1 is a schematic diagram of the addressing system of the present invention;

FIG. 2 is a flow chart of a method of the siting analysis method of the present invention;

FIG. 3 is a transient voltage curve after a large disturbance of the power grid;

FIG. 4 is a schematic diagram of a combined addressing method for a dynamic reactive power compensation device;

fig. 5 is a schematic diagram of an extended ac-dc hybrid system based on IEEE 39.

Detailed Description

In order to clearly explain the technical features of the present invention, the following detailed description of the present invention is provided with reference to the accompanying drawings. The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. It should be noted that the components illustrated in the figures are not necessarily drawn to scale. Descriptions of well-known components and processing techniques and procedures are omitted so as to not unnecessarily limit the invention.

Aiming at the weak area of transient voltage instability risk in the power grid, dynamic reactive power planning can be used as a precautionary measure. In the dynamic reactive power planning, firstly, a planning and addressing position needs to be determined, and two common modes of dynamic reactive power planning and addressing are determined, wherein one mode is to select an optimal planning and compensation point for establishing a proper transient voltage stability index, and the other mode is to establish a dynamic reactive power planning optimization model, and the planning and addressing position and the dynamic reactive power compensation capacity are both used as optimization variables to carry out optimization. The planning and site selection is simple in an optimization and optimization mode, but optimization variables are added when the method is used in an actual large power grid, so that the dimension of the control variable is obviously increased, therefore, the planning and site selection problem and the constant volume problem can be decomposed by providing an excellent dynamic reactive power planning and site selection analysis method based on the transient voltage stability index, and the dynamic reactive power planning problem is simplified to a certain extent. Therefore, the dynamic reactive power planning site selection analysis method considering the transient voltage stability is established, the dynamic reactive power planning method is decomposed and simplified, and the transient voltage stability of the system can be enhanced efficiently.

As shown in fig. 1, a dynamic reactive power planning and siting analysis system considering transient voltage stability of the present invention includes:

the data acquisition module is used for directly acquiring relevant data of a power grid from the power grid system or inputting the relevant data of the power grid through an input device, wherein the relevant data of the power grid comprises transient parameters and control system parameters of a direct current transmission system, a dynamic reactive power compensation device and a generator, and generator fault, extra-high voltage alternating current fault, extra-high voltage direct current transmission fault and line fault information can be acquired from the transient parameters and the control system parameters;

the simulation analysis module is provided with time domain simulation analysis software and is used for carrying out simulation analysis on the transient voltage stability of the power grid, analyzing and determining a transient voltage instability fault set through the power grid faults and recording the transient voltage instability fault set as a fault setThe set of faultsThe method comprises the following steps of (1) generating a generator fault, an extra-high voltage alternating current fault, an extra-high voltage direct current transmission fault and a line fault;

a region division module for dividing the region according toThe distribution of the voltage transformer divides a power grid with faults into a plurality of transient voltage stability weak areas;

the site selection analysis module is used for analyzing faults of the transient voltage stability weak area one by one, calculating dynamic reactive power compensation sensitivity in each fault state, determining the number and the position of points to be compensated of one power grid fault weak area by using a planning site selection combination analysis method, and if 1 compensation point cannot meet the stability requirement, combining 2 or even more compensation points to perform reactive power compensation on the weak area;

and the output module is used for outputting the dynamic reactive power planning addressing to-be-selected point position schemes of all transient voltage stability weak areas.

The site selection analysis module comprises a dynamic reactive compensation sensitivity calculation module and a planning site selection combination analysis module; the dynamic reactive compensation sensitivity calculation module is used for calculating the compensation sensitivity based on the transient voltage recovery index TVRIAnd the compensation sensitivity based on the transient voltage fluctuation index TVFIThe planning and site selection combined analysis module firstly simulates and analyzes the transient voltage stability of the whole network by using a time domain simulation program and divides the transient voltage stability into a plurality of weak areas according to a fault set with the transient voltage stability problem; one or more points to be selected can be selected for compensating for each transient voltage stabilization weak areaThe principle of planning and site selection is to improve the transient voltage stability of the system by using the minimum compensation points; calculating and analyzing a fault set of each region of the transient voltage stability weak region one by one based on the compensation sensitivity, and if 1 dynamic reactive power compensation device cannot solve the problem of transient voltage stability, 2 or even more dynamic reactive power compensation devices are needed for compensation; and calculating and screening the site selection position of each weak area based on the dynamic reactive compensation sensitivity, and finally obtaining a dynamic reactive planning site selection to-be-selected position scheme of all transient voltage stabilization weak areas so as to improve the transient voltage stability of the whole network.

As shown in fig. 2, a schematic diagram of a system structure attached to the site selection analysis method is shown in fig. 1, and an analysis and screening scheme of the site selection method for the dynamic reactive power compensation equipment is provided.

The site selection analysis method can solve the nearest compensation position of the reactive power planning problem considering the transient voltage stability, analyzes the transient voltage instability area of the system by using time domain simulation software, and analyzes the number and the position of the optimal compensation points by adopting a reactive power planning site selection combination method, and the specific site selection process of dynamic reactive power planning is shown in figure 2.

The site selection analysis method can be assisted by time domain simulation analysis software, and mainly comprises the following steps:

step 1: acquiring relevant data of a power grid, wherein the relevant data of the power grid comprises transient parameters and control system parameters of a direct current transmission system, a dynamic reactive power compensation device and a generator;

step 2: the method comprises the steps of carrying out simulation analysis on the transient voltage stability of a power grid, analyzing and determining a transient voltage instability fault set through power grid faults such as generator faults, extra-high voltage alternating current faults, extra-high voltage direct current transmission faults and line faults, and recording the transient voltage instability fault set asAnd according toThe distribution of the voltage transformer divides a power grid with faults into a plurality of transient voltage stability weak areas;

and step 3: analyzing the faults of the transient voltage stability weak area one by one, and calculating the dynamic reactive power compensation sensitivity (in each fault state)Andcalculation can be carried out based on the formula (8) or (10), the number and the position of points to be compensated of one power grid fault weak area are determined by utilizing a planning and site selection combined analysis method, and if 1 compensation point cannot meet the stability requirement, 2 or even more compensation point combinations are needed to carry out reactive compensation on the weak area;

and 4, step 4: and (3) judging whether the dynamic reactive power planning site selection analysis of all the transient voltage stability weak areas is finished, if so, outputting a dynamic reactive power planning site selection to-be-selected point position scheme of all the transient voltage stability weak areas, otherwise, turning to the step (3) to continue the planning site selection analysis of the next weak area until the dynamic reactive power planning site selection analysis of all the transient voltage stability weak areas is finished.

The site selection analysis method of the invention can simplify the problem by utilizing a planning site selection combined analysis method for each area, and can prevent the redundancy of dynamic reactive power planning site selection by using the minimum compensation point position for the weak area.

The transient voltage response diagram of the power grid after the fault is shown in fig. 3, wherein U_NIs a rated voltage; t is t_FThe time of occurrence of the grid fault; t is t_clClearing time for grid faults; t is t_cThe cutoff time is calculated for the transient voltage stability indicator. After the fault, the voltage instability can be caused to occurThe area (2) can be improved by installing a dynamic reactive power compensation device.

In order to analyze the planning and site selection of the dynamic reactive power compensation equipment, a transient voltage stability index which can reflect the voltage recovery capability after the power grid fault needs to be provided at first, and therefore, a transient voltage recovery index TVRI (TVRI) and a transient voltage fluctuation index TVFI (TVFI) are provided, and the deviation degree of the transient voltage and the transient fluctuation degree after the power grid fault are evaluated.

The transient voltage recovery indicator TVRI is defined by the following formula:

${\mathrm{TVRI}}_i^{F_k}={\∫}_{t_{cl}}^{t_c}\frac{|U_{t,i}-U_{i0}|}{U_{i0}}dt---\left(1\right)$

in the formula: u shape_t,iIs the transient voltage at node i at time t; u shape_i0Is the voltage of the node i under the normal working condition; t is t_cIs the cut-off time in the transient recovery process; f_kThe fault type of the power grid; wherein, is a set of failures.

Wherein the fault setsIncluding generator faults, extra-high voltage ac faults, extra-high voltage dc transmission faults, line faults, etc., which can be expressed as:

in the formula: r_G，R_UHV，R_HVDC，R_BRAnd respectively representing a generator fault set, an extra-high voltage alternating current fault set, a direct current transmission fault set and a line fault set.

The transient voltage recovery index can be used for evaluating the degree of transient voltage deviating from the normal working condition after the power grid fault so as to measure the transient voltage recovery capability after the fault. In order to facilitate the calculation of the transient voltage recovery index after the fault by using a time domain simulation analysis program, the TVRI index of the formula (1) is expressed as a difference definition formula:

${\mathrm{TVRI}}_i^{F_k}=\underset{F_k,t\∈\[t_{cl},t_c\]}{\Σ}\frac{|U_{t,i}-U_{i0}|}{U_{i0}}{t}_s---\left(3\right)$

in the formula: t is t_sIs the calculation step size in the time domain simulation analysis.

Scalable node i fault setThe degree of transient voltage recovery at the time of the switching,any node can be calculated, in order to evaluate the transient voltage recovery capability of a certain area or the whole network, a global transient voltage recovery index is given, and the global transient voltage recovery index is defined as:

${\mathrm{TVRI}}_s^{F_k}=\max \left({\mathrm{TVRI}}_i^{F_k}\right)=\max \left(\underset{F_k,t\∈\[t_{cl},t_c\]}{\Σ}\frac{|U_{t,i}-U_{i0}|}{U_{i0}}{t}_s\right)---\left(4\right)$

global transient voltage recovery indicatorBy evaluating all nodes in the areaAnd (4) determining the maximum value. When the TVRI index is larger, the table is displayedThe power grid with the obvious fault does not have the automatic recovery capability, the greater the hidden danger that the voltage of the node is unstable after the power grid fails, the greater the hidden danger is, the node is the weak node with the transient stability, and a certain compensation measure needs to be taken to prevent the fault in the bud. The transient voltage recovery after a fault is associated with the grid structure and the control system of the dynamic conditioning element.

The transient voltage fluctuation index TVFI is defined as follows:

${\mathrm{TVFI}}_i^{F_k}=\frac{1}{2}\left(\frac{1}{N_T}\underset{p=1}{\overset{N_T}{\Σ}}{U}_{i,\max }^{F_k,N_p}-\frac{1}{N_T}\underset{p=1}{\overset{N_T}{\Σ}}{U}_{i,\min }^{F_k,N_p}\right)---\left(5\right)$

in the formula: n is a radical of_TThe frequency of the transient time domain simulation is; n is a radical of_pFor p th after grid fault_thA sub-cycle;are respectively F_kNode i is at Nth under fault_pMaximum and minimum voltage of the cycle.

Similarly, the global index of TVFI under the whole network can be defined as:

${\mathrm{TVFI}}_s^{F_k}=max\left({\mathrm{TVFI}}_i^{F_k}\right)=max\left(\frac{1}{2}\right(\frac{1}{N_T}\underset{p=1}{\overset{N_T}{\Σ}}{U}_{i,\max }^{F_k,N_p}-\frac{1}{N_T}\underset{p=1}{\overset{N_T}{\Σ}}{U}_{i,\min }^{F_k,N_p}\left)\right)---\left(6\right)$

the TVFI index can measure the voltage recovery capability of the power grid through the average fluctuation of the voltage transient after the fault.

The dynamic reactive power planning site selection analysis method can be used for calculating and screening through compensation sensitivity, and provides a simple calculation method of compensation sensitivity based on TVRI indexes and TVFI indexes for transient voltage stability weak areas.

The compensation sensitivity based on the TVRI index can be expressed as:

$S_{{\mathrm{TVRI}}_s}^{F_k}=\frac{\∂{\mathrm{TVRI}}_s^{F_k}}{\∂Q_{svc}}---\left(7\right)$

in order to analyze and calculate the node to be selected of the dynamic reactive power compensation device by using the transient simulation analysis software, equation (7) can be converted into:

$S_{{\mathrm{TVRI}}_s}^{F_k}=\frac{{\mathrm{\ΔTVRI}}_s^{F_k}}{{\mathrm{\ΔQ}}_{svc}}---\left(8\right)$

in the formula: TVRI_sCan be solved by equation (4).

The compensation sensitivity based on the TVFI index can be expressed as:

$S_{{\mathrm{TVFI}}_s}^{F_k}=\frac{\∂{\mathrm{TVFI}}_s^{F_k}}{\∂Q_{svc}}---\left(9\right)$

also, to facilitate the transient simulation analysis calculation, equation (9) can be simplified as:

$S_{{\mathrm{TVFI}}_s}^{F_k}=\frac{{\mathrm{\ΔTVFI}}_s^{F_k}}{{\mathrm{\ΔQ}}_{svc}}---\left(10\right)$

in the formula: TVFI_sCan be obtained from the formula (6)And (5) solving.

And considering the problem of the nearest compensation point of the dynamic reactive power planning site selection of the transient voltage stability, and identifying the weak transient voltage stability area by a dynamic reactive power planning combined site selection analysis method.

The dynamic reactive power planning site selection combination analysis method can solve the problems of the number of points to be selected for site selection and the optimal combination, and aims to prevent excessive investment on compensation nodes in planning site selection. Because the actual area power grid network frame is complex and the buses are numerous, in order to enable the dynamic reactive power planning site selection analysis method to be applied to the actual power grid more quickly, conveniently and efficiently, a time domain simulation program can be used for simulating and analyzing the transient voltage stability of the whole grid, a plurality of weak areas are divided according to a fault set with the problem of transient voltage stability, one or more points to be selected can be selected for compensation aiming at each transient voltage stability weak area, and the planning site selection principle is that the transient voltage stability of the system is improved by using the minimum compensation points. As shown in fig. 4, the dynamic reactive power planning, site selection, combination and analysis method calculates and analyzes the fault set of each region of the transient voltage stability weak region one by one based on the compensation sensitivity, and if 1 dynamic reactive power compensation device cannot solve the problem of transient voltage stability, 2 or more dynamic reactive power compensation devices are required to compensate. The dynamic reactive power planning site selection method is based on dynamic reactive power compensation sensitivity analysis and screening, and the site selection position of each weak area is calculated and screened, so that the transient voltage stability of the whole network is finally improved.

The invention is now verified with reference to a specific application example.

In this embodiment, an extended ac/dc hybrid system based on IEEE39 standard calculation is used as an example, a structure diagram of the extended ac/dc hybrid system based on IEEE39 is shown in fig. 5, where the system has 3 dc power transmission accesses, the rectifying-side access points are nodes 2, 10, and 12, the inverting-side access points are nodes 8, 17, and 26, the dc power transmission system uses a constant-current constant-extinction-angle control mode, the initial dc power transmission current on the rectifying side is 1.0p.u., and the extinction angle on the inverting side is 8.0 °. The proposed dynamic reactive power planning and addressing analysis method considering the transient voltage stability is verified and analyzed through an IEEE39 standard calculation example.

And analyzing the transient voltage stability of the extended system based on a time domain simulation analysis program, wherein the power grid fault type adopts a three-phase fault, the fault time is set to be 100ms, and the fault line tail end clearing time is delayed by 50ms to be cleared. After transient simulation analysis, it is known that the extended system of IEEE39 has two transient voltage stabilization weak areas, which are respectively the weak area 1 and the weak area 2 in fig. 5, and there are 8 line faults with voltage instability risk, and the voltage instability areas and the lines are shown in table 1.

Table 1: area and line with risk of transient voltage instability

Taking a 10-13 line fault of a transient voltage stabilization weak area 1 as an example, the calculation result of the compensation sensitivity of the transient voltage stabilization weak area is shown in table 2, and the compensation sensitivity result based on the TVRI index and the TVFI index can show that the transient voltage can be recovered after the fault is detected only by installing a dynamic reactive power compensation device at a node 10 or 11 in the area, and the optimal dynamic reactive power planning and addressing position of the area 1 is the node 11, and the planning and combination analysis method of the dynamic reactive power compensation device can show that only 1 dynamic reactive power compensation device is needed in the area.

Table 2: line 10-13 post-fault location compensation sensitivity

The analysis result of the compensation sensitivity after the fault of the lines 26-27 in the transient voltage stabilization weak area 2 is shown in table 3, it can be known through calculation that the purpose of improving the transient voltage stability cannot be achieved only by installing 1 dynamic reactive power compensation device in the area, a planning and site selection combined analysis method is used for installing 2 dynamic reactive power compensation devices for analysis, the result shows that the capacity of system recovery after the fault can be achieved by 2 devices, 3 point combination modes to be selected can improve the transient voltage stability, and the compensation sensitivity analysis result shows that the sensitivity of the effect of improving the transient voltage stability is the highest when the dynamic reactive power compensation devices are installed in the nodes 28 and 29.

Table 3: dynamic reactive compensation addressing compensation sensitivity after line 26-27 fault

Therefore, the optimal dynamic reactive addressing positions considering the transient voltage stability in this embodiment are the nodes 11, 28 and 29, and as can be seen from checking all faults in the weak area one by one, these 3 nodes have a good improvement effect as candidate points for dynamic reactive planning addressing.

Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims (10)

1. The dynamic reactive power planning and site selection analysis method considering the transient voltage stability is characterized by comprising the following steps of:

step 1: acquiring relevant data of a power grid, wherein the relevant data of the power grid comprises transient parameters and control system parameters of a direct current transmission system, a dynamic reactive power compensation device and a generator;

step 2: carrying out simulation analysis on the transient voltage stability of the power grid, analyzing and determining a transient voltage instability fault set through the power grid faults, and recording the transient voltage instability fault set asAnd according toThe distribution of the voltage transformer divides a power grid with faults into a plurality of transient voltage stability weak areas;

and step 3: analyzing faults of the transient voltage stability weak area one by one, calculating dynamic reactive power compensation sensitivity in each fault state, determining the number and the position of points to be compensated of one power grid fault weak area by using a planning and site selection combined analysis method, and if 1 compensation point cannot meet the stability requirement, combining 2 or more compensation points to perform reactive power compensation on the weak area;

and 4, step 4: and (3) judging whether the dynamic reactive power planning site selection analysis of all the transient voltage stability weak areas is finished, if so, outputting a dynamic reactive power planning site selection to-be-selected point position scheme of all the transient voltage stability weak areas, otherwise, turning to the step (3) to continue the planning site selection analysis of the next weak area until the dynamic reactive power planning site selection analysis of all the transient voltage stability weak areas is finished.

2. The dynamic reactive power planning, site selection analysis method considering transient voltage stability of claim 1, wherein the set of faults includes generator faults, extra-high voltage alternating current faults, extra-high voltage direct current transmission faults, and line faults.

3. The dynamic reactive power planning, siting and analysis method of claim 1 in which said dynamic reactive power compensation sensitivity comprises a transient voltage recovery indicator TVRI based compensation sensitivityAnd the compensation sensitivity based on the transient voltage fluctuation index TVFI

The compensation sensitivityThe calculation process comprises the following steps:

(11) the transient voltage recovery indicator TVRI is defined as:

in the formula: u shape_t,iIs the transient voltage at node i at time t; u shape_i0Is the voltage of the node i under the normal working condition; t is t_cIs the cut-off time in the transient recovery process; f_kThe fault type of the power grid; wherein, is a failure set;

(12) failure aggregationExpressed as:

in the formula: r_G，R_UHV，R_HVDC，R_BRRespectively representing a generator fault set, an extra-high voltage alternating current fault set, a direct current transmission fault set and a line fault set;

(13) the TVRI index of equation (1) is expressed as its differential definitional equation:

in the formula: t is t_sCalculating step length in time domain simulation analysis;

(14) by usingCalculating any node in the power grid, and obtaining a global transient voltage recovery index as follows:

from equation (4), the global transient voltage recovery indexBy evaluating all nodes in the areaDetermining a maximum value;

the compensation sensitivity based on the TVRI index is expressed as:

converting formula (7) to:

in the formula: TVRI_sCan be solved by equation (4), Q_SVCIs a reactive compensation capacity;

the compensation sensitivityThe calculation process comprises the following steps:

(21) the transient voltage fluctuation index TVFI is defined as:

in the formula: n is a radical of_TThe frequency of the transient time domain simulation is; n is a radical of_pFor p th after grid fault_thA sub-cycle;are respectively F_kNode i is at Nth under fault_pMaximum and minimum voltage of the cycle;

(22) by usingCalculating any node in the power grid, and obtaining a transient voltage fluctuation index as follows:

(23) the compensation sensitivity based on the TVFI index is expressed as:

equation (9) is simplified to:

in the formula: TVFI_sCan be solved by equation (6), Q_SVCIs reactive compensation capacity.

4. The dynamic reactive power planning and site selection analysis method considering transient voltage stability as claimed in claim 1, wherein the planning and site selection combination analysis method comprises the following steps:

(1) simulating and analyzing the transient voltage stability of the whole network by using a time domain simulation program, and dividing the transient voltage stability into a plurality of weak areas according to a fault set with a transient voltage stability problem;

(2) aiming at each transient voltage stability weak area, one or more points to be selected can be selected for compensation, and the principle of planning and site selection is to improve the transient voltage stability of the system by using the least compensation points;

(3) calculating and analyzing a fault set of each region of the transient voltage stability weak region one by one based on the compensation sensitivity, and if 1 dynamic reactive power compensation device cannot solve the problem of transient voltage stability, 2 or even more dynamic reactive power compensation devices are needed for compensation;

(4) and calculating and screening the site selection position of each weak area based on the dynamic reactive compensation sensitivity, and finally obtaining a dynamic reactive planning site selection to-be-selected position scheme of all transient voltage stabilization weak areas so as to improve the transient voltage stability of the whole network.

5. The dynamic reactive power planning, siting and analysis method considering transient voltage stability of claim 1, wherein the data related to the grid is obtained directly from the grid system or entered through an input device.

6. The dynamic reactive power planning and site selection analysis system considering the transient voltage stability is characterized by comprising the following components:

the data acquisition module is used for acquiring relevant data of a power grid, wherein the relevant data of the power grid comprises transient parameters and control system parameters of a direct current transmission system, a dynamic reactive power compensation device and a generator;

the simulation analysis module is used for carrying out simulation analysis on the transient voltage stability of the power grid, analyzing and determining a transient voltage instability fault set through the power grid fault, and recording the transient voltage instability fault set as

A region division module for dividing the region according toThe distribution of the voltage transformer divides a power grid with faults into a plurality of transient voltage stability weak areas;

the site selection analysis module is used for analyzing faults of the transient voltage stability weak area one by one, calculating dynamic reactive power compensation sensitivity in each fault state, determining the number and the position of points to be compensated of one power grid fault weak area by using a planning site selection combination analysis method, and if 1 compensation point cannot meet the stability requirement, combining 2 or even more compensation points to perform reactive power compensation on the weak area;

and the output module is used for outputting the dynamic reactive power planning addressing point selection position schemes of all transient voltage stability weak areas.

7. The dynamic reactive power planning and addressing system for transient voltage stability consideration of claim 6, wherein the set of faults includes generator faults, extra-high voltage ac faults, extra-high voltage dc transmission faults, and line faults.

8. The dynamic reactive power planning and siting system according to claim 6, wherein said siting analysis module comprises a dynamic reactive power compensation sensitivity calculation module and a planning and siting combination analysis module;

the dynamic reactive compensation sensitivity calculation module is used for calculating the compensation sensitivity based on the transient voltage recovery index TVRIAnd the compensation sensitivity based on the transient voltage fluctuation index TVFI

The compensation sensitivityThe calculation process comprises the following steps:

(11) the transient voltage recovery indicator TVRI is defined as:

in the formula: u shape_t,iIs the transient voltage at node i at time t; u shape_i0Is the voltage of the node i under the normal working condition; t is t_cIs the cut-off time in the transient recovery process; f_kThe fault type of the power grid; wherein, is a failure set;

(12) failure aggregationExpressed as:

in the formula: r_G，R_UHV，R_HVDC，R_BRRespectively representing a generator fault set, an extra-high voltage alternating current fault set, a direct current transmission fault set and a line fault set;

(13) the TVRI index of equation (1) is expressed as its differential definitional equation:

in the formula: t is t_sCalculating step length in time domain simulation analysis;

(14) by usingCalculating any node in the power grid, and obtaining a global transient voltage recovery index as follows:

from equation (4), the global transient voltage recovery indexBy evaluating all nodes in the areaDetermining a maximum value;

the compensation sensitivity based on the TVRI index is expressed as:

converting formula (7) to:

in the formula: TVRI_sCan be solved by equation (4), Q_SVCIs a reactive compensation capacity;

the compensation sensitivityThe calculation process comprises the following steps:

(21) the transient voltage fluctuation index TVFI is defined as:

in the formula: n is a radical of_TThe frequency of the transient time domain simulation is; n is a radical of_pFor an electric networkP th after failure_thA sub-cycle;are respectively F_kNode i is at Nth under fault_pMaximum and minimum voltage of the cycle;

(22) by usingCalculating any node in the power grid, and obtaining a transient voltage fluctuation index as follows:

(23) the compensation sensitivity based on the TVFI index is expressed as:

equation (9) is simplified to:

in the formula: TVFI_sCan be solved by equation (6), Q_SVCIs reactive compensation capacity.

9. The dynamic reactive power planning and addressing system considering the transient voltage stability of claim 8, wherein the planning and addressing combined analysis module firstly simulates and analyzes the transient voltage stability of the whole network by using a time domain simulation program, and divides a fault set with a transient voltage stability problem into a plurality of weak areas; aiming at each transient voltage stability weak area, one or more points to be selected can be selected for compensation, and the principle of planning and site selection is to improve the transient voltage stability of the system by using the least compensation points; calculating and analyzing a fault set of each region of the transient voltage stability weak region one by one based on the compensation sensitivity, and if 1 dynamic reactive power compensation device cannot solve the problem of transient voltage stability, 2 or even more dynamic reactive power compensation devices are needed for compensation; and calculating and screening the site selection position of each weak area based on the dynamic reactive compensation sensitivity, and finally obtaining a dynamic reactive planning site selection to-be-selected position scheme of all transient voltage stabilization weak areas so as to improve the transient voltage stability of the whole network.

10. The dynamic reactive power planning and addressing system considering transient voltage stability as claimed in claim 6, wherein the data obtaining module obtains the relevant data of the power grid directly from the power grid system or records the relevant data of the power grid through an input device.