Power grid equivalent model construction method, device and system, and storage medium

Abstract

The application relates to a power grid equivalent model construction method, device and system and a storage medium, and relates to the technical field of electric power. The method at least solves the technical problem that the power grid model in related technologies is too complex and cannot accurately reflect the dynamic characteristics of the power grid frequency. The method comprises the following steps: dividing the power grid into a plurality of first target sub-power grids according to the geographical distribution information of the power grid; performing secondary division on each first target sub-power grid in the plurality of first target sub-power grids according to the element type to obtain second target sub-power grids; simplifying each second target sub-power grid according to the power grid frequency response characteristics of each second target sub-power grid to obtain a plurality of third target sub-power grids; determining a first target element model composed of model parameters corresponding to second nodes and second branches in each third target sub-power grid; and integrating the first target element model corresponding to each third target sub-power grid into a target equivalent model.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of electric power, and particularly relates to a power grid equivalent model construction method, device, system and storage medium. BACKGROUND

[0002] With the development of new power systems, a large number of new energy is connected to the power grid, and the structure and operation characteristics of the power grid have changed significantly. The actual power grid load demand of its power consumption area is large and the structure is complex, and its frequency modulation faces many challenges under the condition of new power systems. The current power grid model is too complex to accurately reflect the dynamic characteristics of the current actual power grid in the frequency modulation process under the new power system, and cannot meet the needs of power system operation analysis, control strategy formulation, and planning and design. For example, the intermittency and volatility of new energy make the frequency fluctuation of the power grid more complex, and the related model cannot effectively consider the influence of new energy access on frequency modulation, resulting in poor effect in actual frequency modulation control and affecting the safe and stable operation of the power grid. SUMMARY

[0003] The present disclosure provides a power grid equivalent model construction method, device, system and storage medium to at least solve the technical problem that the power grid model in the related art is too complex to accurately reflect the dynamic characteristics of the power grid frequency. The technical solution of the present disclosure is as follows:

[0004] According to a first aspect of an embodiment of the present disclosure, a power grid equivalent model construction method is provided, applied to a power system, and the method comprises: dividing the power grid into a plurality of first target sub-power grids according to the geographical distribution information of the power grid; performing secondary division on each first target sub-power grid in the plurality of first target sub-power grids according to the element type, to obtain a plurality of second target sub-power grids; performing simplification processing on the first node and / or the first branch in each second target sub-power grid according to the frequency response characteristics of the power grid in each second target sub-power grid, to obtain a plurality of third target sub-power grids; one second target sub-power grid corresponds to one third target sub-power grid; determining a first target element model composed of model parameters corresponding to the second node and the second branch in each third target sub-power grid, and integrating the first target element model corresponding to each third target sub-power grid into a target equivalent model, the first target element model comprising one or more of the following: a new energy generator model, a load model and a power transmission line model.

[0005] As an implementation manner, the power grid is divided into a plurality of first target sub-power grids according to power grid geographical distribution information of the power grid, including: determining a region with a power grid distribution density greater than a preset density as a first power grid region; identifying a first load center of the first power grid region; clustering power transmission lines and substations in the first power grid region with the first load center to obtain at least one first target sub-power grid; determining a region with a power grid distribution density less than or equal to the preset density as a second power grid region; identifying a second load center of the second power grid region; and clustering power transmission lines and substations in the second power grid region with the second load center to obtain at least one first target sub-power grid.

[0006] As another implementation manner, each of the plurality of first target sub-power grids is divided into a plurality of second target sub-power grids according to a load type, including: identifying and marking a generator type and a power transmission line in each of the plurality of first target sub-power grids; determining generators of the same generator type in each of the plurality of first target sub-power grids as one second target sub-power grid, and determining output lines and power transmission equipment connected with the generators as another second target sub-power grid associated with the one second target sub-power grid; wherein the generator type includes a synchronous generator and a new energy generator, and the new energy generator includes a new energy engine and a photovoltaic generator.

[0007] As another implementation manner, the method further includes: for any second target sub-power grid, performing branch merging and deleting processing on branches in the any second target sub-power grid and performing node elimination processing on nodes in the any second target sub-power grid; wherein the branch merging and deleting processing includes: deleting a branch with a line length less than a preset length, merging at least two adjacent branches with consistent branch parameters into one equivalent branch, and the parameters of the equivalent branch are parameters converted in parallel from the parameters of the at least two branches; and the node elimination processing includes: eliminating a node with a load less than a preset load, and adjusting parameters of a branch where the node is located according to the load of the eliminated node.

[0008] As another implementation manner, the method further includes: determining that the second target sub-power grid includes a plurality of generators; determining dynamic characteristics of each of the plurality of generators; using a coherence analysis method, determining at least two generators with dynamic characteristics within a preset range as one equivalent generator from the plurality of generators, and weighting parameters of the at least two generators to obtain parameters of the equivalent generator.

[0009] As another implementation manner, the first nodes and / or the first branches in each second target sub-grid are simplified according to the power grid frequency response characteristics in the second target sub-grid, to obtain a plurality of third target sub-grids, including: inputting different preset disturbance signals into each second target sub-grid to obtain response changes of each first node and each first branch in the second target sub-grid; eliminating the first nodes with response changes less than a first preset change range; merging the first branches with response changes less than a second preset change range on the first branches serially adjacent or parallel to the first branches; the response changes include one or more of the following dimensions: performance parameters, vibration and noise, temperature and thermal characteristics, and control response.

[0010] As another implementation manner, the method further includes: inputting the historical operation data into the equivalent model to obtain an output test result; determining a result difference between the output test result and the historical actual measurement result; determining that the result difference exceeds a preset difference range, and adjusting model parameter coefficients of the equivalent model according to the result difference until the result difference is within the preset difference range.

[0011] According to a second aspect of the embodiments of the present application, an equivalent model construction device of a power grid is provided, which is applied to a power system, and the device includes: a division unit configured to divide the power grid into a plurality of first target sub-grids according to power grid geographic distribution information of the power grid; the division unit is further configured to perform secondary division on each first target sub-grid in the plurality of first target sub-grids according to an element type, to obtain a plurality of second target sub-grids; an optimization unit configured to perform simplified processing on first nodes and / or first branches in each second target sub-grid according to power grid frequency response characteristics in the second target sub-grid, to obtain a plurality of third target sub-grids; one second target sub-grid corresponds to one third target sub-grid; a construction unit configured to determine a first target element model composed of model parameters corresponding to second nodes and second branches in each third target sub-grid, and integrate the first target element model corresponding to each third target sub-grid into a target equivalent model, the first target element model including one or more of the following: a new energy generator model, a load model, and a power transmission line model.

[0012] According to a third aspect of the embodiments of the present application, an equivalent model construction device of a power grid is provided, which is configured to perform the equivalent model construction method of the power grid as in the first aspect and any possible implementation manner thereof.

[0013] According to a fourth aspect of the embodiments of the present application, a computer readable storage medium is provided, and instructions are stored on the computer readable storage medium, when the instructions in the computer readable storage medium are executed by a processor of an electronic device, the electronic device can perform the equivalent model construction method of the power grid as in the first aspect and any possible implementation manner thereof.

[0014] According to a fifth aspect of the embodiments of the present disclosure, a computer program product is provided, which includes computer instructions, when the computer instructions are run on an electronic device, cause the electronic device to perform the power grid equivalent model construction method of the first aspect and any possible implementation manner thereof.

[0015] The embodiments of the present application provide at least the following beneficial effects: first, the power grid is simplified into a plurality of first target sub-grids according to geographical distribution characteristics, so that each first target sub-grid can represent the state of the power grid under a certain type of geographical distribution characteristics, thereby reducing the influence of geographical distribution on the characteristics of the power grid. Then, based on the element type, each first target sub-grid is further divided to divide the power grid of the same element type in the first target sub-grid into the same second target sub-grid, so as to reduce the interference between different element types. At the same time, in order to make the equivalent model more fully reflect the frequency dynamic characteristics of the power grid, the branches and nodes in the second target sub-grid are simplified according to the frequency characteristics of the power grid, so as to further optimize the power grid structure to obtain a third target sub-grid, thereby determining the element model formed by each element of the third target sub-grid, and integrating the element models in each third target sub-grid into an equivalent model of the entire power grid.

[0016] The equivalent model constructed by the above construction method, on the one hand, reduces the influence of the difference between geographical distribution and load type, and on the other hand, focuses on the key characteristics, can fully reflect the dynamic characteristics of the branches and nodes, improves the accuracy of power system power grid operation analysis, improves the efficiency of power grid fault diagnosis, so as to formulate more accurate control strategy and planning design scheme.

[0017] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings incorporated into the specification and forming a part thereof, illustrate embodiments consistent with the present disclosure and, together with the specification, serve to explain the principles of the present disclosure, and do not constitute an undue limitation on the present disclosure.

[0019] Figure 1 is a flow chart of a power grid equivalent model construction method according to an exemplary embodiment;

[0020] Figure 2 is a block diagram of a power grid equivalent model construction device according to an exemplary embodiment;

[0021] Figure 3 is a schematic diagram of a power system device according to an exemplary embodiment. DETAILED DESCRIPTION

[0022] In order for those skilled in the art to better understand the technical solutions of the present disclosure, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings.

[0023] It should be noted that the terms "first", "second" and the like in the specification and claims of the present disclosure and the above-described drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. The implementation described in the following exemplary embodiments does not represent all implementations consistent with the present disclosure. Rather, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0024] Before the method for constructing the equivalent model of the power grid provided by the embodiments of the present application is described in detail, the application scenarios involved in the embodiments of the present application are briefly introduced.

[0025] First, the application scenarios involved in the present application are briefly introduced.

[0026] With the development of new power systems, a large number of new energy is connected to the power grid, and the structure and operating characteristics of the power grid have changed significantly. As economically developed areas, the power load demand in some regions is large and the structure is complex, and under the condition of new power systems, its frequency modulation faces many challenges. The traditional power grid model is difficult to accurately reflect the dynamic characteristics of the power grid in some regions in the process of frequency modulation under the condition of new power systems, and cannot meet the needs of power system operation analysis, control strategy formulation, and planning and design. For example, the intermittency and volatility of new energy make the frequency fluctuation of the power grid more complex, and the traditional model cannot effectively consider the influence of new energy access on frequency modulation, resulting in poor effect in actual frequency modulation control, affecting the safe and stable operation of the power grid.

[0027] To solve the above problems, the application provides a power grid equivalent model construction method. Under certain new power system conditions, the method for constructing a regional power grid equivalent model from the frequency modulation angle can accurately reflect the dynamic characteristics of the power grid in the frequency modulation process, and provide reliable basis for the operation analysis, control strategy formulation and planning design of the regional power grid. Specifically, the power grid is simplified into a plurality of first target sub-grids according to geographical distribution characteristics, so that each first target sub-grid can represent the state of the power grid under a certain type of geographical distribution characteristics, so as to reduce the influence of geographical distribution on the characteristics of the power grid. Then, based on the element type, each first target sub-grid is further divided, so that the power grids of the same element type in the first target sub-grid are divided into the same second target sub-grid, so as to reduce the interference between different element types. At the same time, in order to make the equivalent model more fully reflect the frequency dynamic characteristics of the power grid, the branches and nodes in the second target sub-grid are simplified according to the frequency characteristics of the power grid, so as to further optimize the power grid structure to obtain a third target sub-grid, so as to determine the element model formed by each element of the third target sub-grid, and integrate the element models in each third target sub-grid into an equivalent model of the entire power grid.

[0028] The equivalent model constructed by the above construction method can reduce the influence of regional distribution and load type differentiation on one hand, and focus on key characteristics on the other hand, so as to fully reflect the dynamic characteristics of the branches and nodes, improve the accuracy of power system grid operation analysis, improve the efficiency of power grid fault diagnosis, and facilitate the formulation of more accurate control strategies and planning design schemes.

[0029] In order to facilitate understanding, the power grid equivalent model construction method provided by the application is specifically introduced below in combination with the drawings.

[0030] Figure 1 is a flow chart of a power grid equivalent model construction method according to an example embodiment, as shown in Figure 1 The power grid equivalent model construction method includes the following steps.

[0031] S11, according to the power grid geographical distribution information of the power grid, the power grid is divided into a plurality of first target sub-grids according to the region.

[0032] Optionally, in order to maintain the integrity of the sub-grid in geography as much as possible, the adjacent and closely connected regions are avoided to be divided. For example, the power grid with the same and continuous natural geographical characteristics is divided into a sub-grid.

[0033] Optionally, the initially divided regions are adjusted according to the natural geographical features such as topography, rivers and mountains. For example, the regions separated by mountains or rivers are divided into different sub-grids.

[0034] Optionally, in combination with the topology of the power grid, regions with similar electrical characteristics and connection relationships are divided into a sub-power grid. For example, regions powered by the same substation are divided into a sub-power grid. Specifically, the topology of the power grid is analyzed, and regions with close electrical connections and relatively independent power transmission paths are combined or adjusted. For example, multiple power distribution regions powered by the same main substation and connected to each other are divided into a sub-power grid.

[0035] Optionally, considering the power demand and supply of each sub-power grid region, the power supply and demand in each sub-power grid are relatively balanced. The power demand can be evaluated according to historical electricity consumption data and load forecasting, and the above sub-power grids are adjusted according to the power demand to obtain multiple first target sub-power grids.

[0036] S12, according to the element type, the first target sub-power grid in each of the multiple first target sub-power grids is divided into multiple second target sub-power grids.

[0037] S13, according to the frequency response characteristics of the power grid in each second target sub-power grid, the first node and / or first branch in each second target sub-power grid are simplified to obtain multiple third target sub-power grids.

[0038] One second target sub-power grid corresponds to one third target sub-power grid.

[0039] The power grid structure includes the nodes and branches of the power grid. The power grid structure is optimized by simplifying the nodes and branches.

[0040] The third target sub-power grid obtained based on the frequency response characteristics of the power grid has the following two advantages.

[0041] First, focusing on key characteristics: the frequency response characteristics reflect the dynamic behavior of the power grid at different frequencies. Simplification based on this characteristic can highlight the key dynamic characteristics and main physical processes of the power grid, and ignore factors that have little effect on the overall frequency response of the system. This makes the equivalent model more accurately capture the essential features of the system, avoiding the interference that too many details in the detailed model may bring, thereby improving the accuracy of the analysis and prediction of the operating state of the power grid. For example, in the analysis of low-frequency oscillation problems of the power system, the equivalent model can more clearly show the dynamic characteristics of the key generators and lines, which helps to accurately diagnose the oscillation causes and develop appropriate control strategies.

[0042] Second, matching the actual operating conditions: the frequency response characteristics of the power grid are closely related to many problems in actual operation, such as power quality problems and system stability problems. The equivalent model constructed based on the frequency response characteristics can better reflect the dynamic behavior of the power grid in actual operation, making the analysis results more consistent with the actual situation and providing more reliable basis for the operation and control of the power grid.

[0043] S14, determine a first target element model composed of model parameters corresponding to the second nodes and the second branches in each third target sub-power grid, and integrate the first target element models corresponding to each third target sub-power grid into a target equivalent model.

[0044] The first target element model includes one or more of the following: a new energy generator model, a load model, and a power transmission line model.

[0045] The new energy generator model includes a power-wind speed model of wind power generation and a power-illumination intensity model of photovoltaic power generation.

[0046] In the above embodiment, the power grid is first simplified into a plurality of first target sub-power grids according to geographical distribution characteristics, so that each first target sub-power grid can represent the state of the power grid under a certain type of geographical distribution characteristics, thereby reducing the influence of geographical distribution on the characteristics of the power grid. Then, based on the element type, each first target sub-power grid is further divided to divide the power grid of the same element type in the first target sub-power grid into the same second target sub-power grid, thereby reducing the interference between different element types. At the same time, in order to make the equivalent model more fully reflect the frequency dynamic characteristics of the power grid, the branches and nodes in the second target sub-power grid are simplified according to the frequency characteristics of the power grid, so as to further optimize the structure of the power grid to obtain the third target sub-power grid, thereby determining the element model composed of each element of the third target sub-power grid, and merging and integrating the element models in each third target sub-power grid into an equivalent model of the entire power grid.

[0047] The equivalent model constructed by the above construction method, on the one hand, reduces the influence of the differences in geographical distribution and load type, and on the other hand, focuses on the key characteristics, fully embodies the dynamic characteristics of the branches and nodes, improves the accuracy of power system power grid operation analysis, and improves the efficiency of power grid fault diagnosis, so as to formulate more accurate control strategies and planning design schemes.

[0048] As an embodiment, the step S11 of dividing the power grid into a plurality of first target sub-power grids according to regions specifically includes the following steps.

[0049] First, the region with a distribution density greater than a preset density is determined as a first power grid region, and a first load center of the first power grid region is identified, and the power transmission lines and substations in the first power grid region are clustered based on the first load center to obtain at least one first target sub-power grid.

[0050] Second, the region with a distribution density less than or equal to a preset density is determined as a second power grid region, and a second load center of the second power grid region is identified, and the power transmission lines and substations in the second power grid region are clustered based on the second load center to obtain at least one first target sub-power grid.

[0051] For example, considering natural geographical factors, such as mountains, rivers, and other natural barriers, which will affect the erection and connection of the power grid, the power grid area can be divided according to these factors. For example, the power grid in the mountainous area can be relatively independent, and the connection with the outside world is realized through a few power transmission lines crossing the mountains.

[0052] As an implementation, in the step S12, according to the load type, each first target sub-grid in the plurality of first target sub-grids is further divided to obtain a plurality of second target sub-grids, which specifically includes the following steps.

[0053] Firstly, the generator type and the power transmission line in each first target sub-grid are identified and labeled.

[0054] Secondly, the generators of the same generator type in each first target sub-grid are determined as a second target sub-grid, and the output line and the power transmission equipment connected with the generator are determined as another second target sub-grid associated with the second target sub-grid.

[0055] The generator type includes a synchronous generator and a new energy generator, and the new energy generator includes a new energy engine and a photovoltaic generator.

[0056] Optionally, the loads in the first target sub-grid are classified according to types (such as industrial load, residential load, commercial load, etc.) and characteristics (such as static load, dynamic load). For the static load in the first target sub-grid, a polynomial model or an exponential model can be used for equivalence; for the dynamic load in the first target sub-grid, such as a load containing a large number of motors, a dynamic model of an induction motor can be used for equivalence. The parameters of the load model are simplified, and the parameters of the equivalent load model are determined by field measurement data or statistical analysis method to reduce the number of unnecessary parameters.

[0057] In an implementation, for any second target sub-grid, the branches in the second target sub-grid are subjected to branch merging and deletion processing, and the nodes are subjected to node elimination processing; wherein the branch merging and deletion processing includes: deleting the branch with a line length less than a preset length, merging at least two adjacent branches with consistent branch parameters into an equivalent branch, and the parameters of the equivalent branch are the parameters converted by parallel connection of the parameters of the at least two branches; the node elimination processing includes: eliminating the node with a load less than a preset load, and adjusting the parameters of the branch where the node is located according to the load of the eliminated node.

[0058] As another implementation, the second target sub-grid is determined to include a plurality of generators. Based on this, further, dynamic characteristics of each of the plurality of generators are determined; using a homology analysis, at least two generators of the plurality of generators having dynamic characteristics within a preset range are determined as an equivalent generator, and parameters of the at least two generators are weighted to obtain parameters of the equivalent generator.

[0059] As an implementation, the specific process of obtaining the third target sub-grid through the simplification process in step S13 is as follows.

[0060] First, each second target sub-grid is input into different preset disturbance signals to obtain response changes of each first node and each first branch in the second target sub-grid, and different first nodes and different first branches are respectively provided with different first preset change ranges. Second, the first node with a response change less than the first preset change range in each first node is eliminated or merged with any one of the other first nodes with a response change greater than or equal to the first preset change range in the same branch as the first node (optionally, the first node with the lowest response change in the other first nodes is the first node for merging). Third, the first branch with a response change less than the second preset change range is merged on the first branch serially adjacent or in parallel to the first branch.

[0061] The response change includes one or more of the following dimensions: performance parameters, vibration and noise, temperature and thermal characteristics, and control response.

[0062] The response change can also be referred to as the response change amount.

[0063] In some embodiments, the element model in the second target sub-grid is simplified, and the simplification process includes generator equivalent simplification and load equivalent simplification.

[0064] The generator equivalent process is as follows: using homology analysis, generators with similar dynamic characteristics are divided into a homology group, and an equivalent generator is used to represent the group. The parameters of the equivalent generator are calculated by weighting the parameters of each generator in the group, such as the moment of inertia, which is calculated by dividing the sum of the products of the moment of inertia and the rated power of each generator by the total rated power of the group.

[0065] The load equivalent process is as follows: the load is classified by type (industrial, residential, commercial, etc.) and characteristics (static, dynamic). Static loads are equivalent using polynomial or exponential models, and dynamic loads (including a large number of motors) are equivalent using induction motor dynamic models.

[0066] In some embodiments, in order to improve the accuracy of the equivalent model, the equivalent model is tested and adjusted so as to call the adjusted equivalent model. Specifically, historical operation data is input into the equivalent model to obtain an output test result; a result difference between the output test result and the historical actual measurement result is determined; if it is determined that the result difference exceeds a preset difference range, the model parameter coefficient of the equivalent model is adjusted according to the result difference until the result difference is within the preset difference range; and if it is determined that the result difference is within the preset difference range, it is indicated that the equivalent model can be directly used.

[0067] In some embodiments, multiple engines with similar dynamic characteristics (i.e., the similarity of dynamic characteristics is less than a preset similarity) are equivalent to one generator. In order to determine whether the dynamic characteristics of multiple engines are similar, performance parameters, vibration and noise, temperature and thermal characteristics, control response, etc. can be used to make a comprehensive judgment by using measurement, analysis and comparison methods.

[0068] Firstly, the performance parameters are compared. Power and torque curves: measure the power and torque output of the engine at different speeds, and draw the power-speed curve and torque-speed curve. The curve shape and trend of the engines with similar dynamic characteristics should be basically consistent. For example, the peak position, rising and falling slope of the curve are similar. Fuel consumption rate: measure the fuel consumption rate of the engine under different working conditions, and compare the change relationship of the fuel consumption rate of each engine with load and speed. If the fuel consumption rates of the engines under the same working conditions are similar and the change trends are consistent, it indicates that the dynamic characteristics have similarity. Acceleration time: test the time required for the engine to accelerate from a certain speed to another speed, such as the time required to accelerate from idle speed to maximum speed. If the acceleration times of multiple engines are similar, it indicates that their dynamic characteristics in acceleration performance are similar.

[0069] Secondly, the vibration and noise are analyzed. Vibration frequency and amplitude: use vibration sensors to measure the vibration signals at different positions on the surface of the engine, and perform frequency spectrum analysis to obtain the vibration frequency and amplitude. The main vibration frequency components of similar engines under the same working conditions should be basically the same, and the vibration amplitudes should also be within a similar range. Noise characteristics: use a noise tester to measure the noise level of the engine during operation, and analyze the noise frequency distribution. If the noise frequency characteristics of each engine are similar, for example, there are obvious noise peaks at certain specific frequencies, and the overall noise level is similar, it indicates that their dynamic characteristics in noise generation and propagation are similar.

[0070] Third, detect temperature and thermal characteristics. Key location temperature: measure the temperature changes of key locations of the engine (such as cylinder head, piston, radiator, etc.), and observe whether the temperature rise rate and stable temperature value of these locations of different engines under the same working condition are similar. Heat transfer characteristics: analyze the heat transfer of the engine through techniques such as thermal imaging, and compare the heat flow distribution and heat dissipation characteristics of each engine. If the heat transfer mode and heat dissipation effect are similar, it means that their thermal dynamic characteristics are similar.

[0071] Fourth, evaluate control response. Throttle response: record the response of engine speed, torque, etc. when the throttle opening changes. Similar dynamic characteristics of engines, under the same throttle opening change, the response time and change amplitude of speed and torque should be similar. Speed regulation system response: test the regulation ability of the engine speed regulation system when the load changes, and observe the speed fluctuation and the time to recover to stable. If the response characteristics of the speed regulation system of multiple engines are similar, it means that they have consistency in control dynamics.

[0072] Fifth, carry out model analysis and simulation. Establish mathematical model: according to the physical structure and working principle of the engine, establish the mathematical model of the engine, and compare the parameters and output characteristics of the model to judge the similarity of dynamic characteristics. Simulation analysis: use professional simulation software to simulate the operation of the engine, input the same working condition, and compare the simulation results of each engine model. If the performance parameters and dynamic response obtained by simulation are similar, it can be considered that the dynamic characteristics of the actual engine are similar.

[0073] In some specific embodiments, the equivalent model is constructed by the following methods.

[0074] First, data collection and processing: collect the operation data of various power sources (such as thermal power, wind power, photovoltaic, etc.), loads and grid elements (such as lines, transformers, etc.) in the target area, including real-time power, frequency, voltage, etc. Preprocess the collected data to remove abnormal data and noise interference, and ensure the accuracy and reliability of the data.

[0075] Second, model parameter determination: according to the basic theory of power system and the actual structure of the target area power grid, determine the parameters of the equivalent model. Considering the characteristics of new energy power sources, establish the corresponding mathematical model, such as the power-wind speed model of wind power generation, the power-illumination intensity model of photovoltaic power generation, etc., and determine the parameters in the model. For loads, according to different load types (such as industrial load, residential load, etc.), establish load models, and determine the frequency regulation characteristic parameters of the load.

[0076] Thirdly, equivalent model construction: based on the power system network simplification theory and frequency response characteristics, the equivalent model of the target regional power grid is constructed. The complex power grid structure is simplified, and the key nodes and branches that have important influence on frequency modulation are retained, while the interaction between elements is considered. The frequency regulation link is introduced in the model to accurately describe the dynamic characteristics of the power grid in the frequency modulation process, such as frequency change rate and frequency modulation power response, etc.

[0077] Specifically, according to the geographical distribution and electrical connection relationship of the target regional power grid, the power grid is partitioned and simplified. Then, according to the power system network simplification method, the non-key nodes and branches are combined or equivalently replaced, and the key nodes and branches that have greater influence on frequency modulation are retained. On the simplified power grid structure, the mathematical model of each element is established according to the determined parameters, and integrated into a complete equivalent model.

[0078] Further, a single machine-infinite system is built on the simulation software.

[0079] The target region is taken as the receiving end grid to undertake the task of secondary frequency modulation. Region A is taken as the sending end region, and region B is taken as the target region. Voltage disturbance and power disturbance are set in region A.

[0080] Actual operation data under different operating conditions are selected and input into the constructed equivalent model for calculation. The model calculation results are compared with the actually measured frequency, power and other data, and error analysis method is used to evaluate the accuracy of the model. If the error exceeds the allowed range, the possible problems in the model are analyzed, such as inaccurate parameters and unreasonable model structure, and the model is optimized and adjusted accordingly, and verified again until the model meets the accuracy requirements.

[0081] Fourthly, model verification and optimization: the actual operation data (such as when voltage disturbance and frequency disturbance occur) are used to verify the constructed equivalent model. The accuracy and reliability of the model are evaluated by comparing the model calculation results with the actually measured data. If the model has errors, the error reasons are analyzed, and the model parameters and structure are optimized and adjusted until the model can accurately reflect the dynamic characteristics of the target regional power grid in the frequency modulation process.

[0082] In the above specific embodiments, the equivalent model is constructed based on the power system network simplification theory and frequency response characteristics. Through reasonable partitioning and simplification of the complex power grid structure, key nodes and branches are selected according to sensitivity analysis and other methods, while retaining the key frequency modulation influencing factors and simplifying the model structure. The frequency regulation link is innovatively introduced in the model to accurately describe the dynamic characteristics of the power grid frequency modulation, which is not possessed by the traditional model.

[0083] And the equivalent model constructed can be directly applied to the operation analysis, control strategy formulation and planning design of the target regional power grid. The frequency modulation control strategy formulated based on the model effectively deals with the frequency fluctuation problem caused by the access of new energy, and improves the frequency modulation capability of the power grid. At the same time, the influence of different schemes on frequency modulation can be accurately evaluated in the planning stage of the power grid, and the layout of the power grid and the configuration of power sources are optimized, which reflects the foresight and practicality of the patent technology in practical application, and provides strong support for the development of the target regional power grid under the new type of power system.

[0084] In order to realize the above functions, the power grid equivalent model construction device contains the hardware structure and / or software module for executing each function. Those skilled in the art should easily realize that, in combination with the algorithm steps of each example described in the embodiments disclosed in the present application, the present application can be realized in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed in hardware or computer software driven hardware depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods for each specific application to realize the described functions, but such implementation should not be considered beyond the scope of the present application.

[0085] The present disclosure also provides a power grid equivalent model construction device as shown in Figure 2 The device is applied to a power system and includes a division unit 21, an optimization unit 22 and a construction unit 23.

[0086] The division unit 21 is configured to divide the power grid into a plurality of first target sub-power grids according to power grid geographic distribution information of the power grid.

[0087] The division unit 21 is further configured to perform secondary division on each first target sub-power grid in the plurality of first target sub-power grids according to an element type, to obtain a plurality of second target sub-power grids.

[0088] The optimization unit 22 is configured to perform simplification processing on first nodes and / or first branches in each second target sub-power grid according to frequency response characteristics of the power grid in each second target sub-power grid, to obtain a plurality of third target sub-power grids; one second target sub-power grid corresponds to one third target sub-power grid.

[0089] The construction unit 23 is configured to determine a first target element model composed of model parameters corresponding to second nodes and second branches in each third target sub-power grid, and integrate the first target element model corresponding to each third target sub-power grid into a target equivalent model; the first target element model includes one or more of the following: a new energy generator model, a load model and a power transmission line model.

[0090] As an implementation, the dividing unit 21 is specifically configured to: determine a region with a power grid distribution density greater than a preset density as a first power grid region; identify a first load center of the first power grid region; cluster transmission lines and substations in the first power grid region with the first load center to obtain at least one first target sub-power grid; determine a region with a power grid distribution density less than or equal to the preset density as a second power grid region; identify a second load center of the second power grid region; and cluster transmission lines and substations in the second power grid region with the second load center to obtain at least one first target sub-power grid.

[0091] As another implementation, the dividing unit 21 is specifically configured to: identify and label generator types and transmission lines in each first target sub-power grid; determine generators of the same generator type in each first target sub-power grid as one second target sub-power grid, and determine output lines and power transmission equipment connected with the generators as another second target sub-power grid associated with the one second target sub-power grid; wherein the generator types include synchronous generators and new energy generators, and the new energy generators include new energy engines and photovoltaic generators.

[0092] As another implementation, the optimization unit 22 is further configured to: for any second target sub-power grid, perform branch merging and deletion processing on branches in the second target sub-power grid, and perform node elimination processing on nodes in the second target sub-power grid; wherein the branch merging and deletion processing includes: deleting branches with a length less than a preset length, merging at least two branches that are adjacent and have consistent branch parameters into one equivalent branch, and the parameters of the equivalent branch are parameters converted from the parameters of the at least two branches in parallel; and the node elimination processing includes: eliminating nodes with a load less than a preset load, and adjusting parameters of branches where the eliminated nodes are located according to the loads of the eliminated nodes.

[0093] As another implementation, the constructing unit 23 is further configured to: determine that the second target sub-power grid includes multiple generators; determine dynamic characteristics of each generator in the multiple generators; adopt a coherence analysis method to determine at least two generators with dynamic characteristics within a preset range as one equivalent generator in the multiple generators, and weight parameters of the at least two generators to obtain parameters of the equivalent generator.

[0094] As another implementation, the optimization unit 22 is specifically configured to: input different preset disturbance signals into each second target sub-power grid to obtain response changes of each first node and each first branch in the second target sub-power grid; eliminate a first node with a response change less than a first preset change range; merge a first branch with a response change less than a second preset change range on a first branch that is serially adjacent or parallel to the first branch; and the response change includes a change amount in one or more of the following dimensions: performance parameters, vibration and noise, temperature and thermal characteristics, and control response.

[0095] As another implementation, the optimization unit 22 is further configured to: input the historical operation data into the equivalent model to obtain an output test result; determine a result difference between the output test result and the historical actual measurement result; determine that the result difference exceeds a preset difference range; and adjust a model parameter coefficient of the equivalent model according to the result difference until the result difference is within the preset difference range.

[0096] As to the apparatus in the above embodiments, the specific manner in which each unit module performs operations has been described in detail in the embodiments of the method, and will not be described in detail here.

[0097] Figure 3 is a schematic diagram of a power system device provided by the present application. As Figure 3 , the power system device 50 can include at least one processor 501 and a memory 503 for storing processor-executable instructions. The processor 501 is configured to execute the instructions in the memory 503 to implement the power grid equivalent model construction method in the following embodiments.

[0098] In addition, the power system device 50 can also include a communication bus 502, at least one communication interface 504, an input device 506 and an output device 505.

[0099] The processor 501 can be a central processing unit (CPU), a micro processing unit, an ASIC, or one or more integrated circuits for controlling the execution of programs of the present application.

[0100] The communication bus 502 can include a path for transmitting information between the above components.

[0101] The communication interface 504 uses any transceiver-like device for communicating with other devices or communication networks, such as an Ethernet, a radio access network (RAN), a wireless local area network (WLAN), etc.

[0102] The input device 506 is used to receive input signals and the output device 505 is used to output signals.

[0103] The memory 503 can be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM), or other type of dynamic storage device that can store information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disk storage, a magnetic disk storage or other magnetic storage devices, or any other medium capable of storing desired program code in the form of instructions or data structures and that can be accessed by a computer, but is not limited to this. The memory can exist independently and be connected to the processing unit through a bus. The memory can also be integrated with the processing unit.

[0104] The memory 503 is configured to store instructions for implementing the solutions of the present application, and the processor 501 is configured to execute the instructions stored in the memory 503.

[0105] In a specific implementation, as an example, the processor 501 can include one or more CPUs, such as the CPU0 and the CPU1 in the Figure 3 In a specific implementation, as an example, the processor 501 can include one or more CPUs, such as the CPU0 and the CPU1 in the

[0106] In a specific implementation, as an example, the power system device 50 can include a plurality of processors, such as the processor 501 and the processor 507 in the Figure 3 In a specific implementation, as an example, the power system device 50 can include a plurality of processors, such as the processor 501 and the processor 507 in the

[0107] The power system device includes a processor 501 and a memory 503 for storing instructions executable by the processor 501, as shown in Figure 3 The power system device includes a processor 501 and a memory 503 for storing instructions executable by the processor 501, as shown in

[0108] The embodiment of the present application further provides a computer readable storage medium, when instructions in the computer readable storage medium are executed by a processor of a power grid equivalent model construction device or a power system equipment, the power grid equivalent model construction device or the power system equipment can execute the power grid equivalent model construction method of any possible implementation manner described above, and the same technical effects can be achieved. To avoid repetition, details are not described herein.

[0109] The embodiment of the present application further provides a computer program product, including a computer program or instructions, when the computer program or instructions are executed by a processor, the power grid equivalent model construction method of any possible implementation manner described above can be executed, and the same technical effects can be achieved. To avoid repetition, details are not described herein.

[0110] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

[0111] It should be understood that the application is not limited to the precise construction that has been described above and shown in the accompanying drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application is limited only by the appended claims.

Claims

1. A method for constructing an equivalent model of a power grid, characterized in that, The method is applied to a power system, and the method comprises the following steps: According to power grid geographical distribution information of a power grid, the power grid is divided into a plurality of first target sub-power grids according to regions; According to element types, each first target sub-power grid in the plurality of first target sub-power grids is further divided to obtain a plurality of second target sub-power grids; According to power grid frequency response characteristics in each second target sub-power grid, a first node and / or a first branch in each second target sub-power grid are simplified to obtain a plurality of third target sub-power grids; one second target sub-power grid corresponds to one third target sub-power grid; First target element models of second nodes and second branches in each third target sub-power grid are determined, and the first target element models of each third target sub-power grid are integrated into a target equivalent model; the first target element models include one or more of the following: a new energy generator model, a load model and a power transmission line model; According to power grid frequency response characteristics in each second target sub-power grid, a first node and / or a first branch in each second target sub-power grid are simplified to obtain a plurality of third target sub-power grids, which comprises the following steps: Different preset disturbance signals are input into each second target sub-power grid to obtain response changes of each first node and each first branch in the second target sub-power grid; The first node with a response change less than a first preset change range is eliminated; The first branch with a response change less than a second preset change range is merged into a first branch adjacent to the first branch in series or in parallel; The response change includes a change amount in one or more of the following dimensions: a performance parameter, vibration and noise, temperature and thermal characteristics and a control response.

2. The power grid equivalent model construction method according to claim 1, characterized in that, According to power grid geographical distribution information of a power grid, the power grid is divided into a plurality of first target sub-power grids according to regions, which comprises the following steps: Regions with a power grid distribution density greater than a preset density are determined as first power grid regions; a first load center of the first power grid region is identified, and power transmission lines and substations in the first power grid region are clustered based on the first load center to obtain at least one first target sub-power grid; Regions with a power grid distribution density less than or equal to the preset density are determined as second power grid regions; a second load center of the second power grid region is identified, and power transmission lines and substations in the second power grid region are clustered based on the second load center to obtain at least one first target sub-power grid.

3. The method of claim 1, wherein, According to element types, each first target sub-power grid in the plurality of first target sub-power grids is further divided to obtain a plurality of second target sub-power grids, which comprises the following steps: Generator types and power transmission lines in each first target sub-power grid are identified and labeled; Generators of the same generator type in each first target sub-power grid are determined as one second target sub-power grid, and output lines and power transmission equipment in communication with the generators are determined as another second target sub-power grid associated with the one second target sub-power grid; The generator type includes a synchronous generator and a new energy generator, and the new energy generator includes a new energy engine and a photovoltaic generator.

4. The method of claim 3, wherein, The method further includes: For any of the second target sub-power grids, the branches in the any of the second target sub-power grids are subjected to branch merging and deleting processing, and the nodes are subjected to node elimination processing; The branch merging and deleting processing includes deleting branches with line lengths less than a preset length, merging at least two branches that are adjacent and have consistent branch parameters into an equivalent branch, and the parameters of the equivalent branch are parameters obtained by parallel conversion of the parameters of the at least two branches; The node elimination processing includes eliminating nodes with loads less than a preset load, and adjusting the parameters of the branches where the nodes are located according to the loads of the eliminated nodes.

5. The method of claim 3, wherein, The method further includes: It is determined that the second target sub-power grid includes a plurality of generators; The dynamic characteristics of each of the plurality of generators are determined; The at least two generators in the plurality of generators with dynamic characteristics within a preset range are determined as an equivalent generator by using a coherence analysis method, and the parameters of the at least two generators are weighted to obtain the parameters of the equivalent generator.

6. The power grid equivalent model construction method according to any one of claims 1 to 5, characterized in that, The method further includes: The historical operation data are input into the equivalent model to obtain an output test result; A result difference between the output test result and a historical actual measurement result is determined; When the result difference exceeds a preset difference range, the model parameter coefficients of the equivalent model are adjusted according to the result difference until the result difference is within the preset difference range.

7. A device for constructing an equivalent power grid model, characterized in that, The device is applied to a power system and includes: A division unit configured to divide the power grid into a plurality of first target sub-power grids according to power grid geographical distribution information of the power grid; The division unit is further configured to perform secondary division on each of the plurality of first target sub-power grids according to element types to obtain a plurality of second target sub-power grids; An optimization unit configured to simplify first nodes and / or first branches in each of the second target sub-power grids according to power grid frequency response characteristics in each of the second target sub-power grids to obtain a plurality of third target sub-power grids, one second target sub-power grid corresponding to one third target sub-power grid; A construction unit configured to determine first target element models composed of model parameters corresponding to second nodes and second branches in each of the third target sub-power grids, and integrate the first target element models corresponding to each of the third target sub-power grids into a target equivalent model, the first target element model including one or more of a new energy generator model, a load model, and a power transmission line model; The optimization unit is specifically configured to: Input different preset disturbance signals into each of the second target sub-power grids to obtain response changes of each of the first nodes and each of the first branches in the second target sub-power grids; Eliminate the first nodes with response changes less than a first preset change range; Merge the first branches with response changes less than a second preset change range on first branches that are serially adjacent or parallel to the first branches. The response changes include one or more of the following dimensions of change: performance parameters, vibration and noise, temperature and thermal characteristics, and control response.

8. A power system, characterized by The computer readable storage medium stores instructions which, when executed by a processor of an electronic device, cause the electronic device to perform the power grid equivalent model construction method as claimed in any one of claims 1-6.

9. A computer-readable storage medium having stored thereon instructions, the computer-readable storage medium comprising: The computer readable storage medium stores instructions which, when executed by a processor of an electronic device, cause the electronic device to perform the power grid equivalent model construction method as claimed in any one of claims 1-6.

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