A method for evaluating the flexibility margin of power grid reactive voltage regulation

Abstract

The present application provides a kind of power grid reactive voltage regulation flexibility margin evaluation method, a kind of power grid reactive voltage regulation flexibility margin evaluation method, comprising the following steps: S1, evaluation index and evaluation system setting;S2, adjustable elastic resource modeling;S3, read in system configuration and real-time operation data;S4, model splicing and network topology analysis;S5, index calculation and grade evaluation, the reactive voltage adjustable resource in source, net, load, storage is quantitatively evaluated, finally multiple classification margin index, system overall margin index and grade classification are given, aims at accurately quantifying the reactive voltage adjustable resource flexibility margin of power grid, provides credible and powerful reference for the optimization planning of power grid, reactive voltage optimization control etc..

Description

Technical Field

[0001] This invention relates to the field of power system automation, and in particular to a method for evaluating the reactive power and voltage regulation flexibility margin of a power grid. Background Technology

[0002] With the continuous development of the social economy, new energy sources are developing rapidly, and a large number of distributed photovoltaic, natural gas power generation, and wind power are being connected to the grid. The safety red lines on the grid side are constantly being tightened. To ensure the grid connection of a large number of unstable power sources, reserve capacity is constantly increasing, and equipment and operational redundancy are also significant. On the load side, user load resources are dormant, and interaction mechanisms have not yet been established. On the energy storage side, facilities are scarce, difficult to utilize, and lack policy support. This means that the power grid faces four major problems: a lack of interaction between source and load, reliance on redundancy for safety, reduced balancing capacity, and a lack of efficiency improvement measures. The development of the power grid is under concentrated pressure from these four aspects: source, grid, load, and storage.

[0003] Currently, the data display of the four major elements of power generation, grid, load, and storage in power companies remains fragmented, failing to meet the development needs of "multi-dimensional integration." Grid resilience remains at the conceptual stage. If questions such as what grid resilience is, how it is specifically manifested, and how it is assessed cannot be clearly defined, they will inevitably become constraints on the construction of multi-dimensional integrated resilience control. Therefore, it is urgent to study multi-dimensional integrated grid resilience assessment technologies in conjunction with the characteristics of regional power grids to promote the allocation, construction, and access of regional source-grid-load-storage resources.

[0004] The Chinese patent document "A Method for Evaluating the Reactive Voltage Control Effect of Distribution Networks" (publication number CN110707714A) relates to the field of reactive voltage control effect evaluation technology in distribution networks, and more specifically, to a method for evaluating the reactive voltage control effect of distribution networks. The method includes the following steps: establishing an evaluation index system for the reactive voltage control effect of power grid operation; determining the acceptable range of evaluation indicators for voltage and power factors; collecting measured data; obtaining and ranking the weights of each evaluation indicator through analysis; and selecting the optimal reactive voltage control scheme based on the ranking. This invention can provide a comprehensive evaluation of the reactive voltage control effect of distribution networks and can obtain the optimal reactive voltage control scheme based on the evaluation. However, this invention does not involve a method for calculating and evaluating the reactive voltage regulation margin. Summary of the Invention

[0005] This invention addresses the lack of quantitative assessment of the adequacy of comprehensive reactive power and voltage adjustable resources in existing technologies. It proposes a method for assessing the elasticity margin of reactive power and voltage adjustment in power grids. This invention quantifies the adjustable reactive power and voltage resources in power sources, grids, loads, and storage, and ultimately provides multiple classification margin indicators, overall system margin indicators, and level classifications. The aim is to accurately quantify the elasticity margin of the adjustable reactive power and voltage resources in power grids, providing a reliable and powerful reference for power grid optimization planning and reactive power and voltage optimization control.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for evaluating the reactive power voltage regulation margin of a power grid, comprising the following steps:

[0007] S1, Evaluation indicators and evaluation system settings;

[0008] S2, adjustable and flexible resource modeling;

[0009] S3 reads in system configuration and real-time operating data;

[0010] S4, model splicing and network topology analysis;

[0011] S5, Indicator Calculation and Level Evaluation.

[0012] This invention calculates the reactive power elasticity margin value of adjustable reactive power and voltage resources in the power grid according to the source-grid-load-storage classification. By adjusting the weighting coefficients to account for the impact of different types of adjustable reactive power and voltage resources on the overall system margin, the invention ultimately derives the system's reactive power and voltage adjustable elasticity margin index and margin assessment level. This accurately quantifies the elasticity margin and margin level of the power grid's adjustable reactive power and voltage resources, providing a reliable and powerful reference for power grid optimization planning, reactive power and voltage optimization control, and new energy integration. Currently, no other research institutions, domestically or internationally, have conducted related technical research on the quantitative assessment method for reactive power and voltage regulation elasticity margin in multi-element integrated, highly elastic power grids. The method of this invention provides a reliable and powerful reference for power grid optimization planning and reactive power and voltage optimization control, promoting the allocation, construction, and integration of regional source-grid-load-storage resources.

[0013] Preferably, step S2 includes the following steps:

[0014] S21, Quantitative model of generator reactive voltage elastic adjustable margin;

[0015] The reactive power output Q of generator i Gi The following constraint must be satisfied:

[0016]

[0017] Among them, S G Represents the set of all generators. This represents the maximum permissible reactive power output under the current generator active power output on the power circle diagram. This represents the minimum permissible reactive power output under the current generator active power output on the power circle diagram.

[0018] When the current output of a single generator is Q Gireal At that time, its reactive power elasticity upper and lower adjustment margins are respectively:

[0019]

[0020]

[0021] Among them, R Giup and R Gidn These represent the upper and lower adjustment margins of reactive power flexibility for a single generator, respectively.

[0022] The reactive power flexibility margins for all generators are as follows:

[0023]

[0024]

[0025] Among them, R ALLGup and R ALLGdn These represent the upper and lower adjustment margins of reactive power flexibility for all generators, respectively.

[0026] S22, SVG reactive voltage elastic adjustable margin quantification model;

[0027] The reactive power output Q of the continuously flexible and adjustable reactive power SVG device i SVGi The following constraint should be satisfied, where capacitive reactive power is defined as positive and inductive reactive power as negative:

[0028]

[0029] Among them, S SVG Represents a collection of all SVGs. This represents the current capacitive reactive power capacity of the SVG device minus the emergency standby capacitive capacity. This represents the current inductive reactive power capacity of the SVG device minus the emergency standby inductive capacity.

[0030] The current output of a single SVG is Q. SVGireal At that time, its reactive power elasticity upper and lower adjustment margins are respectively:

[0031]

[0032]

[0033] Among them, R SVGiup and RSVGidn This represents the reactive power elasticity margin of a single SVG.

[0034] The upper and lower adjustment margins for reactive power elasticity of all SVGs are as follows:

[0035]

[0036]

[0037] Among them, R ALLSVGup and R ALLSVGdn These represent the upper and lower reactive power elasticity adjustment margins for all SVGs, respectively.

[0038] S23, a quantitative model for discrete elastic adjustable reactive power margin of capacitors, etc.

[0039] The reactive power output Q of the elastic reactive adjustable capacitor i Ci The following constraint should be satisfied, where capacitive reactive power is defined as positive and inductive reactive power as negative:

[0040]

[0041] Among them, S C Represents the set of all capacitors. This represents the maximum adjustable capacitive reactive power capacity of the capacitor bank under the current voltage value, and its calculation formula is:

[0042]

[0043] Among them, V breal and V bbase Q represents the current voltage value and the reference voltage value for the corresponding voltage level, respectively. Cap For the corresponding capacitor's rated capacity,

[0044] Q SVGimin =0,

[0045] The current output of a single capacitor is Q Cireal At that time, its reactive power elasticity upper and lower adjustment margins are respectively:

[0046] When the capacitor is in the closed position, the adjustment margin R is increased. Ciup The upper adjustment margin R is 0; when the capacitor is in the quantile position, the upper adjustment margin R is 0. Ciup equal

[0047] When the capacitor is in the cleavage position, the lower adjustment margin R Cidn The lower adjustment margin R is 0 when the capacitor is in the closed position. Ciup equal

[0048] The reactive power flexibility adjustment margins for all transformers are as follows:

[0049]

[0050]

[0051] Among them, R ALLCup and R ALLCdn These represent the upper and lower adjustment margins of reactive power flexibility for all transformers, respectively.

[0052] S24, a discrete elastic adjustable reactive power margin quantification model for reactors, etc.

[0053] The reactor model and the capacitor model are basically the same, but in opposite directions. The elastic reactive power controllability margin of the reactor is as follows:

[0054] When the reactor is in the vacancy position, the upper adjustment margin R Riup The upper adjustment margin R is 0 when the reactor is in the closed position. Riup equal

[0055] When the reactor is in the closed position, the lower adjustment margin R Ridn The lower adjustment margin R is 0 when the reactor is in the vacancy position. Ridn equal

[0056] The upper and lower adjustment margins of reactive power flexibility for all reactors are as follows:

[0057]

[0058]

[0059] Among them, R ALLRup and R ALLRdn These represent the upper and lower adjustment margins of reactive power flexibility for all reactors, respectively.

[0060] S25, quantitative model of reactive power voltage elastic adjustable margin of main transformer;

[0061] The main transformer does not have a direct reactive power adjustment margin parameter, but the adjustment margin can be calculated based on the voltage / reactive power sensitivity value and the transformer tap position.

[0062] S T The set of all adjustable transformers, with adjustable taps T Ti The following constraint should be satisfied:

[0063]

[0064] in, T TiminThis is the lowest adjustable tap of the transformer. This is the highest adjustable tap of the transformer.

[0065] Its voltage constraint range is:

[0066] V Ti -V b *V TRi *(T r -T Ti min )≤V Ti ≤V Ti +V b *V TRi *(T r -T Timax ) i∈S T

[0067] Among them, V Ti The measured voltage value (V) at the low-voltage side busbar node of the current transformer is shown. TRi V is the transformer tap change rate. b T is the reference voltage value for the bus node. r This represents the current real-time tap position value of the transformer.

[0068] Based on reactive voltage sensitivity, the elastic reactive power controllability margins of the transformer can be obtained as follows:

[0069] R Tiup =V b *V TRi *(T r -T Ti max )*S qv

[0070] R Tidn =V b *V TRi *(T r -T Ti min )*S qv

[0071] Among them, R Tiup and R Tidn S represents the reactive power flexibility upper and lower adjustment margins of a single transformer, respectively. qv This indicates the reactive voltage sensitivity of the corresponding bus node.

[0072] The upper and lower adjustment margins for all transformers are as follows:

[0073]

[0074]

[0075] Among them, R ALLT up and R ALLT dnThese represent the upper and lower adjustment margins of reactive power flexibility for all transformers, respectively.

[0076] S26, a quantitative model for adjustable margin of user-side dynamic capacity expansion devices, DPFC, electric vehicles, and central air conditioning variable loads; reactive power output Q of variable load i. Li The following constraint should be satisfied, where capacitive reactive power is defined as positive and inductive reactive power as negative:

[0077]

[0078] Among them, S L For the set of all variable load classes, This represents the maximum capacitive reactive load of the current variable load. Q Limin Given the maximum inductive reactive load of the current variable load, the current output of a single variable load can be calculated as Q. Lireal At that time, its reactive power elasticity upper and lower adjustment margins are respectively:

[0079]

[0080] R Lidn =Q Lireal - Q Limin

[0081] Among them, R Liup and R Lidn These represent the reactive power elasticity margins for a single variable load, respectively.

[0082] The adjustment margins for all variable loads are as follows:

[0083]

[0084]

[0085] Among them, R ALLLup and R ALLLdn These represent the upper and lower reactive power adjustment margins for all variable loads, respectively.

[0086] S27, Adjustable margin quantification model for energy storage devices;

[0087] The reactive power output Q of energy storage device i Ei The following constraint should be satisfied, where capacitive reactive power is defined as positive and inductive reactive power as negative:

[0088]

[0089] Among them, S E For the collection of all energy storage devices, This represents the maximum capacitive reactive power output capacity of current energy storage devices.Q Eimin The maximum inductive reactive power capacity of the current energy storage device is given. Clearly, the adjustability margin of the energy storage device is related not only to the current reactive power output but also to the total capacity of the energy storage device and its current state of operation. When the energy storage is fully charged, its reactive power absorption capacity is zero, while its reactive power output reaches its maximum. When energy storage is in an empty state, its margin for absorbing reactive power is at its maximum. Q Ei min However, it cannot output capacitive reactive power.

[0090] Therefore, the current state of a single energy storage device is P. E ireal The current reactive power output is Q. Eireal At that time, its elastic reactive power controllability margin indicators are as follows:

[0091]

[0092] R Eidn =Q Eireal -(1-P Eireal / P Eimax )* Q Eimin

[0093] Among them, R Eiup and R Eidn These represent the upper and lower reactive power adjustment margins of a single energy storage device, respectively.

[0094]

[0095]

[0096] Among them, R ALLEup and R ALLEdn These represent the upper and lower adjustment margins of reactive power flexibility for all energy storage devices.

[0097] In this invention, reactive power and voltage adjustable resources in the source, grid, load, and storage are uniformly modeled, including dynamic capacity expansion devices on the user side, DPFC, electric vehicles, central air conditioning variable loads, generators, centralized new energy sources, main transformers of the main distribution network, traditional discrete reactive power compensation equipment, dynamic SVG continuously adjustable equipment, distributed new energy power stations, and energy storage equipment. The main parameters include the upper and lower limits of resource capacity, availability status, availability coefficient, etc. The establishment of the reactive power and voltage adjustable resource model provides an important basis for model splicing, index calculation, and level evaluation.

[0098] Preferably, the index calculation specifically involves the quantitative calculation of the system's adjustable margin index: Considering the different priority levels of reactive power adjustable resources in the source, grid, load, and storage systems, reactive power adjustable resources of the same capacity have different margin weight coefficients to reflect this difference in priority. The weight coefficients for source, grid, load, and storage are specified as Ws = 1.5, Wg = 1, Wl = 0.8, and We = 0.5, respectively. The upper and lower adjustable margin values ​​of the system can then be obtained as follows:

[0099] S up =R ALLGup *W s +(R ALLSVGup +R ALLCup +R ALLRup +R ALLTup )*W g +R ALLLup *W l +R ALLEup *W e

[0100] S dn =R ALLGdn *W s +(R ALLSVGdn +R ALLCdn +R ALLRdn +R ALLTdn )*W g +R ALLLdn *W l +R ALLEdn *W e

[0101] Among them, S up and S dn These represent the upper and lower adjustable margin values ​​of the system, respectively.

[0102] In this invention, based on the zoning results and real-time operating data of the reactive voltage regulation elastic device, the upper and lower adjustable margin values ​​of the entire system are calculated according to the reactive voltage elastic margin index and weight calculation method determined in step S1, which facilitates the classification and evaluation of the levels.

[0103] Preferably, the rating assessment includes the following steps:

[0104] S51, set all discrete devices with adjustable reactive power and voltage in the system to be in the off state, and set the reactive power output of all continuous devices to maximum inductive value. Calculate the maximum upward adjustment margin value S of the system using the system's adjustable margin quantification index. upmax and the maximum downward adjustment elasticity margin value S dnmax ;

[0105] S52, from system 0-S upmaxThe range is divided into 6 regions according to the capacitive reactive power output state of the source generator: 0%, 20%, 40%, 60%, 80%, and 100%. Below 20% is considered severely excessive upward adjustment, 20%-40% is considered excessive upward adjustment, 40%-60% is considered suitable upward adjustment margin, 60%-80% is considered insufficient upward adjustment margin, and above 80% is considered severely insufficient upward adjustment margin.

[0106] S53, respectively, switches the system from 0 to S dnmax The regions are divided according to the inductive reactive power output status of the generator at the source end, which are 0%, 20%, 40%, 60%, 80%, and 100% respectively. Below 20% is considered severely excessive downward adjustment, 20%-40% is excessive downward adjustment, 40%-60% is suitable downward adjustment margin, 60%-80% is insufficient downward adjustment margin, and above 80% is severely insufficient downward adjustment margin.

[0107] In this invention, the maximum upward adjustment margin value and the maximum downward adjustment elasticity margin are obtained through the quantitative index of system adjustable margin. Based on the intervals corresponding to 0 of the two values, the intervals are divided according to the reactive power output state of the source generator and the inductive reactive power output state, respectively, to obtain the margin level evaluation result, which is convenient for differentiation and evaluation.

[0108] Preferably, step S1 specifically involves decomposing the high-elasticity power grid reactive power and voltage regulation margin index into four categories: source, grid, load, and storage. The attribution of the reactive power and voltage adjustable equipment is determined according to its attributes, and the weighting coefficients of each category of source, grid, load, and storage index are set in the comprehensive power grid index.

[0109] In this invention, the elasticity margin index is divided into four categories: source, grid, load, and storage. The category to which the reactive power and voltage adjustable equipment belongs is determined according to the attributes of the equipment. Finally, the weight coefficients of the four categories of indexes are determined to facilitate subsequent model calculations.

[0110] Preferably, step S4 specifically involves assembling the read-in main network, distribution network, power grid model, and data to establish a comprehensive network model integrating sources, grid, load, and storage. Based on this, network topology analysis and power flow calculations are performed to determine the current power grid zoning and the real-time operating status and key measurement data of reactive power and voltage regulation flexible equipment.

[0111] In this invention, after the adjustable and flexible resource model is established, the model is spliced ​​together, including splicing together the main network, distribution network, power grid model and data. Then, network topology analysis is performed to obtain real-time data, which is beneficial for analysis.

[0112] The beneficial effects of this invention are: This invention quantifies and evaluates the reactive and voltage adjustable resources in the power source, grid, load, and storage, and finally provides multiple classification margin indicators, overall system margin indicators, and level classifications. It aims to accurately quantify the elasticity margin of the reactive and voltage adjustable resources of the power grid, and provide a reliable and powerful reference for the optimal planning of the power grid and the optimal control of reactive and voltage. Attached Figure Description

[0113] Figure 1 This is a flowchart of the present invention;

[0114] Figure 2 This is a flowchart of step S4 of the present invention. Detailed Implementation

[0115] Example:

[0116] This embodiment proposes a method for evaluating the elasticity margin of reactive power and voltage regulation in a power grid, referencing... Figure 1 and Figure 2 The process includes the following steps: Step S1, setting evaluation indicators and evaluation system; In this step, the high-elasticity power grid reactive power and voltage regulation elasticity margin indicators are specifically divided into four categories: source, grid, load and storage. The classification of these indicators is determined according to the attributes of the reactive power and voltage adjustable equipment, and finally the weight coefficients of the four indicators are determined.

[0117] Step S2, Modeling of Adjustable Elastic Resources: Define quantitative models and calculation methods for the elastic margin of all types of adjustable reactive and voltage resources in the power grid, determine the calculation method for the elastic margin index of the same type, and finally provide the calculation method for the quantitative model of the elastic margin of the system's adjustable reactive and voltage resources, mainly including seven types of modeling:

[0118] Step S21: First, establish a quantitative model for the elastic adjustable margin of the generator reactive voltage.

[0119] The reactive power output Q of generator i Gi The following constraints apply:

[0120]

[0121] In the above formula, S G This refers to the collection of all generators. This refers to the maximum permissible reactive power output under the current generator active power output on the power circle diagram. This refers to the minimum permissible reactive power output under the current generator active power output on the power circle diagram;

[0122] The current output of a single generator is Q. Gireal Under these circumstances, the upper and lower adjustment margins of the generator's reactive power elasticity can be calculated, as follows:

[0123]

[0124]

[0125] In the above formula, R Giup and R Gidn These refer to the upper and lower adjustment margins of reactive power flexibility for a single generator, respectively.

[0126] Therefore, the reactive power elasticity upper and lower adjustment margins of all generators are calculated:

[0127]

[0128]

[0129] In the above formula, R ALLGup and R ALLGdn These refer to the upper and lower adjustment margins of reactive power flexibility for all generators, respectively.

[0130] Step S22: Establish a quantitative model for the reactive voltage elastic adjustable margin of SVG;

[0131] In this step, the reactive power output Q of the continuously elastically adjustable reactive power SVG device i is... SVGi Under the following constraints, in this embodiment, capacitive reactive power is positive and inductive reactive power is negative:

[0132]

[0133] In the above formula, S SVG This refers to the entire collection of SVGs. This refers to the current capacitive reactive power capacity of the SVG device minus the emergency standby capacitive capacity. This refers to the current inductive reactive power capacity of the SVG device minus the emergency standby inductive capacity;

[0134] The current output of a single SVG is Q. SVGireal In this case, the specific upper and lower adjustment margins of reactive power elasticity for a single SVG can be calculated as follows:

[0135]

[0136]

[0137] In the above formula, R SVGiup and R SVGidn This refers to the reactive power flexibility upper and lower adjustment margins of the SVG.

[0138] From the above, the upper and lower adjustment margins of all SVG reactive power elasticity can be expressed as follows:

[0139]

[0140]

[0141] In the above formula, R ALLSVGup and R ALLSVGdn These represent the upper and lower adjustment margins of reactive power elasticity for all SVGs, respectively.

[0142] Step S23: Create a quantitative model of discrete elastic adjustable reactive power margin such as capacitors;

[0143] The main components include: the reactive power output Q of the elastic reactive power adjustable capacitor i. Ci Under the following constraints, in this embodiment, capacitive reactive power is positive and inductive reactive power is negative:

[0144]

[0145] In the above formula, S C This refers to the collection of all capacitors. This refers to the maximum adjustable capacitive reactive power of a capacitor bank under the current voltage value. Represented as:

[0146]

[0147] In the above formula, V breal and V bbase These refer to the current voltage value and the reference voltage value for the corresponding voltage level, respectively. Q Cap This refers to the rated capacity of the corresponding capacitor. Q SVGimin At this point, it equals 0.

[0148] The current output of a single capacitor is Q. Cireal Under the condition of [condition], calculate the upper and lower adjustment margins of reactive power elasticity for a single capacitor. Specifically, when the capacitor is in the closed position, the upper adjustment margin R is [value]. Ciup Equal to 0; when the capacitor is in the quantile position, the upper adjustment margin R is 0. Ciup The value and equal;

[0149] When the capacitor is in a quantile state, the lower adjustment margin R Cidn When the capacitor is closed, the lower adjustment margin R is equal to 0. Ciup The value and equal;

[0150] Therefore, the reactive power elasticity adjustment margins of all transformers can be obtained as follows:

[0151]

[0152]

[0153] In the above formula, R ALLCup and R ALLCdn These refer to the upper and lower adjustment margins of reactive power flexibility for all transformers, respectively.

[0154] Step S24: Establish a quantitative model for discrete, elastic, adjustable reactive power margin, such as that of reactors;

[0155] The reactor model is basically the same as the capacitor model, except that the directions are reversed. The upper and lower adjustment margins of the reactor are expressed as follows:

[0156] With the reactor in the shunt position, the upper adjustment margin R Riup Equal to 0; when the reactor is in the closed position, the upper adjustment margin R is 0. Riup The value and equal;

[0157] With the reactor in the closed position, the lower regulation margin R Ridn Equal to 0; when the reactor is in the vacancy position, the lower adjustment margin R is 0. Ridn The value and equal;

[0158] Therefore, the upper and lower adjustment margins of reactive power elasticity for all reactors can be obtained as follows:

[0159]

[0160]

[0161] In the above formula, R ALLRup and R ALLRdn These refer to the upper and lower adjustment margins of reactive power flexibility for all reactors, respectively.

[0162] Step S25: Establish a quantitative model for the reactive power voltage elastic adjustable margin of the main transformer.

[0163] The adjustable margin of the main transformer can be obtained directly from the voltage reactive power sensitivity value and according to the transformer tap:

[0164] Adjustable gear T Ti The following constraint should be satisfied:

[0165]

[0166] In the above formula, S T It refers to the collection of all adjustable transformers. T Timin This refers to the lowest adjustable tap of the transformer. This refers to the highest adjustable tap of the transformer;

[0167] The voltage constraint range can be obtained as follows:

[0168] V Ti -V b *V TRi *(T r -T Tim i n )≤V Ti ≤V Ti +V b *V TRi *(T r -T Timax ) i∈S T

[0169] In the above formula, V Ti This refers to the measured value of the low-voltage side bus node voltage in the current transformer, V. TRi This refers to the transformer tap change rate, V b This refers to the reference voltage value of the bus node, T. r This refers to the current real-time tap position value of the transformer;

[0170] Furthermore, the flexible reactive power controllability margin of the transformer is calculated from the reactive power voltage sensitivity, specifically as follows:

[0171] R Tiup =V b *V TRi *(T r -T Timax )*S qv

[0172] R Tidn =V b *V TRi *(T r -T Timin )*S qv

[0173] In the above formula, R Tiup and R Tidn These refer to the upper and lower reactive power adjustment margins of a single transformer, respectively. qv This refers to the reactive voltage sensitivity of the corresponding bus node.

[0174] From the above, the upper and lower adjustment margins of all transformers can be obtained, as shown in the following formula:

[0175]

[0176]

[0177] In the above formula, R ALLTup and RALLTdn These refer to the upper and lower adjustment margins of reactive power flexibility for all transformers, respectively.

[0178] Step S26: Establish a quantitative model of adjustable margin for user-side dynamic capacity expansion devices, DPFC, electric vehicles, and central air conditioning variable loads.

[0179] Reactive power output Q for variable load i Li Under the following constraints, in this embodiment, capacitive reactive power is positive and inductive reactive power is negative:

[0180]

[0181] In the above formula, S L This refers to the set of all variable load classes. This refers to the maximum capacitive reactive load of the current variable load. Q Limin This refers to the maximum inductive reactive load of the current variable load. As mentioned above, the current output of a single variable load is Q. Lireal In this case, the corresponding upper and lower reactive power elasticity margins are respectively:

[0182]

[0183] R Lidn =Q Lireal - Q Limin

[0184] In the above formula, R Liup and R Lidn These refer to the upper and lower reactive power adjustment margins of a single variable load, respectively. Therefore, the upper and lower adjustment margins for all variable loads are calculated as follows:

[0185]

[0186]

[0187] In the above formula, R ALLLup and R ALLLdn These refer to the upper and lower adjustment margins of reactive power flexibility for all variable loads, respectively.

[0188] Step S27: Finally, establish a quantitative model of the adjustable margin of the energy storage device.

[0189] The reactive power output Q of energy storage device i Ei Under the following constraints, in this embodiment, capacitive reactive power is positive and inductive reactive power is negative:

[0190]

[0191] In the above formula, S E It refers to the collection of all energy storage devices. This refers to the maximum capacitive reactive power output capacity of current energy storage devices. Q Eimin This refers to the maximum inductive reactive power capacity of current energy storage devices.

[0192] Clearly, the adjustability margin of an energy storage device is also related to its total capacity and current energy storage state. When the energy storage is fully charged, its reactive power absorption capacity is zero, while its reactive power output is at its maximum. When the energy storage is in an empty state, the margin for absorbing reactive power is at its maximum. Q Eimin However, it cannot perform capacitive reactive power output. In summary, the current state of a single energy storage device is P. Eireal Q is the result of no effort put in before. Eireal Under these circumstances, the elastic reactive power controllability margin index of a single energy storage device can be obtained, specifically:

[0193]

[0194] R Eidn =Q Eireal -(1-P Eireal / P Eimax )* Q Eimin

[0195] In the above formula, R Eiup and R Eidn These refer to the upper and lower reactive power adjustment margins of a single energy storage device, respectively.

[0196]

[0197]

[0198] In the above formula, R ALLEup and R ALLEdn These refer to the upper and lower adjustment margins of reactive power flexibility for all energy storage devices, respectively.

[0199] Step S3: Read in the system configuration and real-time operation data; read in the system configuration, including the equipment type and weight coefficients involved in the index calculation; read in the variable load model and parameters; and finally read in the real-time operation mode and real-time operation data of the power grid, including the main grid, distribution network, transformer area and user-side resources.

[0200] Step S4, model splicing and network topology analysis; model splicing includes reading in the main network, distribution network, power grid model and data together to establish an integrated model including active, grid, load and storage. Then, the established model network topology analysis and power flow calculation are performed to clarify the grid partitioning and the real-time operation data of reactive power and voltage regulation flexible equipment.

[0201] Step S5, Index Calculation and Level Evaluation; In this step, index calculation is performed first. Since the priority levels of reactive power adjustable resources in the source, grid, load, and storage are different, reactive power adjustable resources with the same capacity will also have different weight coefficients. In this embodiment, W s It is 1.5, W g W is 1. l W is 0.8. e The value is 0.5. Based on the weighting coefficients and model data, we can obtain:

[0202] S up =R ALLGup *W s +(R ALLSVGup +R ALLCup +R ALLRup +R ALLTup )*W g +R ALLLup *W l +R ALLEup *W e

[0203] S dn =R ALLGdn *W s +(R ALLSVGdn +R ALLCdn +R ALLRdn +R ALLTdn )*W g +R ALLLdn *W l +R ALLEdn *W e

[0204] In the above formula, S up and S dn These refer to the upper and lower adjustability margins of the system, respectively.

[0205] Then, a rating assessment is conducted, which consists of three steps:

[0206] Step S51: Set all discrete devices with adjustable reactive power and voltage in the system to the off state, and set the reactive power output of all continuous devices to maximum inductive value. Calculate the maximum upward adjustment margin S of the system based on the indicators. upmax and the maximum downward adjustment elasticity margin value S dnmaxStep S52: Based on the capacitive reactive power output state of the source generator, the system is switched from 0 to S. upmax The range is divided into 6 ranges: 0%, 20%, 40%, 60%, 80%, and 100%. The ranges are as follows: Severely excessive upward adjustment: greater than 0 and less than 20%; Excessive upward adjustment: 20%-40%; Appropriate upward adjustment margin: 40%-60%; Insufficient upward adjustment margin: 60%-80%; Severely insufficient upward adjustment margin: greater than 80%.

[0207] Step S53: Based on the inductive reactive power output state of the source generator, the system is switched from 0 to S. dnmax The range is also divided into 6 ranges: 0%, 20%, 40%, 60%, 80%, and 100%. Severely excessive downward adjustment: greater than 0 and less than 20%; excessive downward adjustment: 20%-40%; moderate downward adjustment margin: 40%-60%; insufficient downward adjustment margin: 60%-80%; severely insufficient downward adjustment margin: greater than 80%.

[0208] This invention calculates the reactive power elasticity margin value of adjustable reactive power and voltage resources in the power grid according to the source-grid-load-storage classification. By adjusting the weighting coefficients to account for the impact of different types of adjustable reactive power and voltage resources on the overall system margin, the invention ultimately derives the system's reactive power and voltage adjustable elasticity margin index and margin assessment level. This accurately quantifies the elasticity margin and margin level of the power grid's adjustable reactive power and voltage resources, providing a reliable and powerful reference for power grid optimization planning, reactive power and voltage optimization control, and new energy integration. Currently, no other research institutions, domestically or internationally, have conducted related technical research on the quantitative assessment method for reactive power and voltage regulation elasticity margin in multi-element integrated, highly elastic power grids. The method of this invention provides a reliable and powerful reference for power grid optimization planning and reactive power and voltage optimization control, promoting the allocation, construction, and integration of regional source-grid-load-storage resources.

[0209] In this invention, reactive power and voltage adjustable resources in the source, grid, load, and storage are uniformly modeled, including dynamic capacity expansion devices on the user side, DPFC, electric vehicles, central air conditioning variable loads, generators, centralized new energy sources, main transformers of the main distribution network, traditional discrete reactive power compensation equipment, dynamic SVG continuously adjustable equipment, distributed new energy power stations, and energy storage equipment. The main parameters include the upper and lower limits of resource capacity, availability status, availability coefficient, etc. The establishment of the reactive power and voltage adjustable resource model provides an important basis for model splicing, index calculation, and level evaluation.

[0210] In this invention, based on the zoning results and real-time operating data of the reactive voltage regulation elastic device, the upper and lower adjustable margin values ​​of the entire system are calculated according to the reactive voltage elastic margin index and weight calculation method determined in step S1, which facilitates the classification and evaluation of the levels.

[0211] In this invention, the maximum upward adjustment margin value and the maximum downward adjustment elasticity margin are obtained through the quantitative index of system adjustable margin. Based on the intervals corresponding to 0 of the two values, the intervals are divided according to the reactive power output state of the source generator and the inductive reactive power output state, respectively, to obtain the margin level evaluation result, which is convenient for differentiation and evaluation.

[0212] In this invention, the elasticity margin index is divided into four categories: source, grid, load, and storage. The category to which the reactive power and voltage adjustable equipment belongs is determined according to the attributes of the equipment. Finally, the weight coefficients of the four categories of indexes are determined to facilitate subsequent model calculations.

[0213] In this invention, after the adjustable and flexible resource model is established, the model is spliced ​​together, including splicing together the main network, distribution network, power grid model and data. Then, network topology analysis is performed to obtain real-time data, which is beneficial for analysis.

[0214] The main process of this invention is as follows: First, establish an evaluation index system and set an evaluation framework. On this basis, model each resource in the source, network, load and storage. Then, add configurations including weight coefficients and some important real-time data. After completing the model splicing, perform analysis and calculation. Finally, perform calculation and evaluation.

[0215] The above embodiments are further elaborations and descriptions of the present invention to facilitate understanding, and are not intended to limit the present invention in any way. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for evaluating the reactive power and voltage regulation margin of a power grid, characterized in that, Including the following steps: S1, Evaluation indicators and evaluation system settings; The reactive power and voltage regulation margin indicators of the high-elasticity power grid are divided into four categories: source, grid, load and storage. The classification is determined according to the attributes of the reactive power and voltage adjustable equipment, and the weight coefficient of the indicators is determined. S2, adjustable elastic resource modeling; resources include user-side dynamic capacity expansion devices, DPFC, electric vehicles, central air conditioning variable loads, generators, centralized new energy sources, main transformers of the main distribution network, traditional discrete reactive power compensation equipment, dynamic SVG continuously adjustable equipment, distributed new energy power stations and energy storage equipment; to obtain reactive power elasticity upper and lower adjustment margins; S3 reads in system configuration and real-time operating data; S4, model splicing and network topology analysis; S5, Indicator Calculation and Level Assessment; The priority levels of adjustable reactive power resources in the source-grid-load-storage system differ, therefore the margin weighting coefficients for adjustable reactive power resources also differ. The weighting coefficients for source-grid-load-storage are W... s =1.5, W g =1, W l =0.8 and W e =0.5, the upper adjustable margin value of the system. for *W s , , , , The sum multiplied by W g， *W l , *W e The sum; the system's lower adjustable margin value for *W s , , , , The sum multiplied by W g , *W l , *W e The sum; R ALLxxup and R ALLxxdn The reactive power elasticity adjustment margins for all resources, where xx represents the type of specific resource; All generators: and All SVGs: and All capacitors: and All reactors: and All transformers: and All variable loads: and All energy storage devices: and ; The maximum upward adjustment margin and the maximum downward adjustment elasticity margin are obtained by quantifying the adjustable margin of the system. Based on the intervals corresponding to 0, the intervals are divided according to the reactive power output state of the source generator and the inductive reactive power output state, respectively, to obtain the margin level evaluation result.

2. The method for evaluating the reactive power and voltage regulation margin of a power grid according to claim 1, characterized in that, Step S2 includes the following steps: S21, Quantitative model of generator reactive voltage elastic adjustable margin; Reactive power output of generator i The following constraint must be satisfied: , in, S G Represents the set of all generators. Given the current active power output of the generator, the maximum permissible reactive power output is determined based on its power circle diagram. This refers to the minimum permissible reactive power output determined based on the power circle diagram of the current generator's active power output; when the current output of a single generator is... At that time, its reactive power elasticity upper and lower adjustment margins are respectively: ， ， in, and This indicates the upper and lower adjustment margins of reactive power flexibility for a single generator; The reactive power flexibility margins for all generators are as follows: ， ， in, and , representing the upper and lower adjustment margins of reactive power flexibility for all generators, respectively; S22, SVG reactive voltage elastic adjustable margin quantification model; Reactive power output of continuously flexible reactive power adjustable SVG device i The following constraint should be satisfied, where capacitive reactive power is defined as positive and inductive reactive power as negative: i ∈ S SVG， in, S SVG Represents a collection of all SVGs. This represents the current capacitive reactive power capacity of the SVG device minus the emergency standby capacitive capacity. This represents the current inductive reactive power capacity of the SVG device minus the emergency standby inductive capacity. The current output of a single SVG is At that time, its reactive power elasticity upper and lower adjustment margins are respectively: ， ， in, and This represents the reactive power elasticity margin of a single SVG. The upper and lower adjustment margins for reactive power elasticity of all SVGs are as follows: ， ， in, and These represent the upper and lower reactive power elasticity adjustment margins for all SVGs, respectively. S23, a quantitative model for discrete elastic adjustable reactive power margin of capacitors, etc. The reactive power output of the elastically adjustable reactive capacitor i. The following constraint should be satisfied, where capacitive reactive power is defined as positive and inductive reactive power as negative: i ∈ S Ｃ， in, S Ｃ Represents the set of all capacitors. This represents the maximum adjustable capacitive reactive power capacity of the capacitor bank under the current voltage value, and its calculation formula is: ， in, and These represent the current voltage value and the reference voltage value for the corresponding voltage level, respectively. For the corresponding capacitor's rated capacity, The current output of a single capacitor is At that time, its reactive power elasticity upper and lower adjustment margins are respectively: When the capacitor is in the closed position, the adjustment margin R is increased. Ｃiup The upper adjustment margin R is 0; when the capacitor is in the quantile position, the upper adjustment margin R is 0. Ｃiup equal ; When the capacitor is in the cleavage position, the lower adjustment margin R Ｃidn The lower adjustment margin R is 0 when the capacitor is in the closed position. Ｃiup equal ; The reactive power elasticity adjustment margins for all capacitors are as follows: ， ， in, and These represent the upper and lower adjustment margins of reactive power flexibility for all capacitors, respectively.

3. The method for evaluating the reactive power and voltage regulation margin of a power grid according to claim 2, characterized in that, Step S2 further includes: S24, a discrete elastic adjustable reactive power margin quantification model for reactors, etc. The reactor model and the capacitor model are basically the same, but in opposite directions. The elastic reactive power controllability margin of the reactor is as follows: When the reactor is in the vacancy position, the upper adjustment margin R Riup The upper adjustment margin R is 0 when the reactor is in the closed position. Ｒiup equal ; When the reactor is in the closed position, the lower regulation margin R Ｒidn The lower adjustment margin R is 0 when the reactor is in the vacancy position. Ｒidn equal ; The upper and lower adjustment margins of reactive power flexibility for all reactors are as follows: ， ， in, and These represent the upper and lower adjustment margins of reactive power flexibility for all reactors, respectively. S25, quantitative model of reactive power voltage elastic adjustable margin of main transformer; The main transformer does not have a direct reactive power adjustment margin parameter, but the adjustment margin can be calculated based on the voltage / reactive power sensitivity value and the transformer tap position. S T For the set of all adjustable transformers, their adjustable ranges The following constraint should be satisfied: i ∈ S T， in, This is the lowest adjustable tap of the transformer. This is the highest adjustable tap of the transformer; its voltage constraint range is: ， in, This represents the measured voltage value at the low-voltage side busbar node of the current transformer. This represents the transformer tap change rate. This is the reference voltage value for the bus node. This represents the current real-time tap position value of the transformer. Based on reactive voltage sensitivity, the elastic reactive power controllability margins of the transformer can be obtained as follows: ， ， in, and These represent the upper and lower adjustment margins of reactive power flexibility for a single transformer, respectively. This indicates the reactive voltage sensitivity of the corresponding bus node. The upper and lower regulation margins of all transformers are as follows: ， ， in, and These represent the upper and lower adjustment margins of reactive power flexibility for all transformers, respectively.

4. The method for evaluating the reactive power and voltage regulation margin of a power grid according to claim 2, characterized in that, Step S2 further includes: S26, Adjustable margin quantification model for user-side dynamic capacity expansion devices, DPFC, electric vehicles, and central air conditioning variable load types; Reactive power output of variable load i The following constraint should be satisfied, where capacitive reactive power is defined as positive and inductive reactive power as negative: ， in, S Ｌ For the set of all variable load classes, This represents the maximum capacitive reactive load of the current variable load. The maximum inductive reactive load of the current variable load. The current output of a single variable load can be obtained as follows: At that time, its reactive power elasticity upper and lower adjustment margins are respectively: ， ， in, and These represent the reactive power elasticity margins for a single variable load, respectively. The adjustment margins for all variable loads are as follows: ， ， in, and These represent the upper and lower reactive power adjustment margins for all variable loads, respectively. S27, Adjustable margin quantification model for energy storage devices; Reactive power output of energy storage device i The following constraint should be satisfied, where capacitive reactive power is defined as positive and inductive reactive power as negative: ， in, S Ｅ For the collection of all energy storage devices, This represents the maximum capacitive reactive power output capacity of current energy storage devices. The maximum inductive reactive power capacity of the current energy storage device is given. Clearly, the adjustability margin of the energy storage device is related not only to the current reactive power output but also to the total capacity of the energy storage device and its current state of operation. When the energy storage is fully charged, its reactive power absorption capacity is zero, while its reactive power output reaches its maximum. When the energy storage is in an empty state, its reactive power absorption margin is the largest. However, it cannot output capacitive reactive power. Therefore, the current state of a single energy storage device is: Currently, reactive power output is At that time, its elastic reactive power controllability margin indicators are as follows: ， ， in, and These represent the upper and lower reactive power adjustment margins of a single energy storage device, respectively. ， ， in, and These represent the upper and lower adjustment margins of reactive power flexibility for all energy storage devices.

5. The method for evaluating the reactive power and voltage regulation margin of a power grid according to claim 1, characterized in that, The rating assessment includes the following steps: S51, set all discrete devices with adjustable reactive power and voltage in the system to be in the off state, and set the reactive power output of all continuous devices to maximum inductive value. Calculate the maximum upward adjustment margin of the system using the system's adjustable margin quantification index. and maximum downward adjustment elasticity margin value ; S52, from system 0- The range is divided into 6 zones according to the capacitive reactive power output state of the source generator: 0%, 20%, 40%, 60%, 80%, and 100%. Below 20% is considered severely excessive upward adjustment, 20%-40% is considered excessive upward adjustment, 40%-60% is considered suitable upward adjustment margin, 60%-80% is considered insufficient upward adjustment margin, and above 80% is considered severely insufficient upward adjustment margin. S53, respectively, controls the system from 0- The regions are divided according to the inductive reactive power output status of the generator at the source end, which are 0%, 20%, 40%, 60%, 80%, and 100% respectively. Below 20% is considered severely excessive downward adjustment, 20%-40% is excessive downward adjustment, 40%-60% is suitable downward adjustment margin, 60%-80% is insufficient downward adjustment margin, and above 80% is severely insufficient downward adjustment margin.

6. The method for evaluating the reactive power and voltage regulation margin of a power grid according to claim 1, characterized in that, Step S4 specifically involves stitching together the read-in main network, distribution network, power grid model, and data to establish a comprehensive network model integrating sources, grids, loads, and storage. Based on this, network topology analysis and power flow calculation are performed to determine the current power grid zoning and the real-time operating status and key measurement data of reactive power and voltage regulation flexible equipment.

7. The method for evaluating the reactive power and voltage regulation flexibility margin of a power grid according to claim 6, characterized in that, After the adjustable and flexible resource model is established, the model is spliced ​​together, including the main network, distribution network, power grid model and data read in. Then, network topology analysis is performed to obtain real-time data.

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