Grid connection method and system based on double-synchronization device, electronic equipment and storage medium

Abstract

The invention relates to the technical field of new energy grid connection, and particularly provides a grid connection method and system based on a double-synchronization device, electronic equipment and a storage medium, and the method comprises the steps: obtaining the historical grid connection data of a power grid, and carrying out the preprocessing; extracting grid-connected load scene simulation data based on the preprocessed historical grid-connected data; based on grid-connected load scene simulation data, predicting an optimal grid-connected opportunity by taking minimization of power grid fluctuation as a target; constructing a grid-connected strategy adjustment model, and outputting an optimal grid-connected strategy according to the predicted optimal grid-connected opportunity and a preset working mode of the dual-synchronization device; and sending a switching-on command to the double-synchronization device according to the optimal grid-connection strategy to complete grid-connection operation. The invention aims to improve the grid-connected success rate of the generator set and reduce the grid-connected closing impact of the generator set.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy grid connection, and in particular to a grid connection method, system, electronic equipment and storage medium based on a dual synchronization device. Background Art

[0002] With the development of the power industry and the continuous improvement of power quality requirements, ensuring the power quality of generator sets at the moment of grid connection has become one of the key elements in power system design. In this process, the synchronization device plays a vital role, which ensures the precise synchronization between the generator and the grid in voltage, frequency and phase. Inaccurate synchronization will not only affect the safe and stable operation of the generator itself, but may also have a negative impact on the reliability and economy of the entire power system.

[0003] At present, a single synchronization device is usually used in the design of traditional power systems. A single synchronization device lacks redundant backup when encountering hardware or software failures. Once a failure occurs, it will not be able to provide accurate synchronization signals, resulting in the generator being unable to access the grid under the expected conditions. In some cases, even if the synchronization device works normally, due to the long system response time, it may also cause the synchronization conditions at the moment of grid connection to change, thereby reducing the success rate of grid connection. On the other hand, the synchronization error of the synchronization device and the inaccuracy of the grid connection condition assessment may cause a large impact on the unit's grid connection and closing, resulting in grid connection failure. Summary of the invention

[0004] The object of the present invention is to provide a grid-connected method, system, electronic device and storage medium based on a dual synchronization device, so as to improve the success rate of grid-connected generator sets and reduce the impact of grid-connected closing of generator sets.

[0005] The embodiments of the present invention are implemented by the following technical solutions:

[0006] The technical solution of the first aspect of the present invention provides a grid-connected method based on a dual synchronization device, comprising the following steps:

[0007] Obtain historical grid-connected data and perform preprocessing;

[0008] Extract grid-connected load scenario simulation data based on pre-processed historical grid-connected data;

[0009] Based on grid-connected load scenario simulation data, the optimal grid-connected timing is predicted with the goal of minimizing grid fluctuations;

[0010] Construct a grid-connected strategy adjustment model to output the optimal grid-connected strategy based on the predicted best grid-connected timing and the preset working mode of the dual-synchronous device;

[0011] According to the optimal grid-connected strategy, a closing command is issued to the dual synchronous device to complete the grid-connected operation.

[0012] Furthermore, obtaining historical grid-connected data and preprocessing the data include:

[0013] The historical grid-connected data of the power grid are obtained through the SCADA system, and the historical grid-connected data of the power grid at least includes power generation, load consumption, grid frequency and voltage level.

[0014] Furthermore, grid-connected load scenario simulation data is extracted based on the preprocessed historical grid-connected data, including:

[0015] Use the historical grid-connected data to build a simulation environment and extract grid-connected load scenario simulation data;

[0016] Perform uncertainty analysis on grid transient disturbance and frequency in grid-connected load scenario simulation data, and extract uncertainty analysis results.

[0017] Furthermore, based on the grid-connected load scenario simulation data, the optimal grid-connected timing is predicted with the goal of minimizing grid fluctuations, including:

[0018] Build and train prediction models based on grid-connected load scenario simulation data and uncertainty analysis results to extract future grid-connected scenario prediction data;

[0019] With the goal of minimizing grid frequency deviation and voltage deviation, an optimization algorithm is used to find the best grid connection timing.

[0020] Furthermore, the expression for minimizing the grid frequency deviation and voltage deviation is:

[0021]

[0022] Where J(t) represents the fluctuation degree of the power grid at time t+1; α represents the weight coefficient, which is used to balance the importance of frequency deviation and voltage deviation, α∈[0,1]; Represents the predicted value of frequency deviation; Indicates the voltage deviation prediction value.

[0023] Furthermore, a grid-connected strategy adjustment model is constructed to output the optimal grid-connected strategy according to the predicted optimal grid-connected timing and the preset working mode of the dual-synchronous device, including:

[0024] Select the working mode of the dual synchronization device based on the probability model;

[0025] Based on the optimal grid-connected timing, the grid-connected power ramp control is used to output the optimal grid-connected time point, power and circuit breaker closing time.

[0026] Furthermore, the expression of grid-connected power ramp control is:

[0027]

[0028] Where P(t) represents the grid-connected power; t grid Indicates the best time to connect to the grid; T r Indicates the power increase time period; P max Indicates the maximum grid-connected power.

[0029] The technical solution of the second aspect of the present invention provides a grid-connected system based on a dual synchronization device, including the grid-connected method based on a dual synchronization device according to the technical solution of the first aspect of the present invention, and the grid-connected system includes:

[0030] A data acquisition module is configured to obtain and preprocess historical grid-connected data of the power grid, and extract grid-connected load scenario simulation data based on the preprocessed historical grid-connected data;

[0031] A grid connection timing prediction module, configured to predict the best grid connection timing based on grid connection load scenario simulation data with the goal of minimizing grid fluctuations;

[0032] A grid-connection strategy adjustment module, configured to construct a grid-connection strategy adjustment model, and output an optimal grid-connection strategy according to the predicted optimal grid-connection timing and the preset working mode of the dual-synchronization device;

[0033] The grid-connected module is configured to issue a closing command to the dual synchronization device according to the optimal grid-connected strategy to complete the grid-connected operation.

[0034] The technical solution of the third aspect of the present invention provides an electronic device, comprising: a processor and a memory communicatively connected to the processor; wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor can execute the steps of the grid-connected method based on the dual synchronization device described in the technical solution of the first aspect of the invention.

[0035] The technical solution of the fourth aspect of the present invention provides a computer-readable storage medium, on which is stored a program for implementing a grid-connected method based on a dual-synchronous device. The program for implementing a grid-connected method based on a dual-synchronous device is executed by a processor to implement the steps of the grid-connected method based on a dual-synchronous device described in the technical solution of the first aspect of the invention.

[0036] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects:

[0037] The grid-connected method based on the dual synchronous device provided by the present invention improves the success rate of grid connection by predicting the best grid-connected time and optimizing the grid-connected strategy, and reduces the grid-connected failure caused by grid instability. The method considers the goal of minimizing grid fluctuations in the prediction process, and can effectively control the changes in voltage and frequency to maintain the stable operation of the grid. In addition, by adding a synchronous device to determine whether the adjustment is in place, the dual synchronous device further reduces the impact of the unit when the grid is connected and closed, further improves the grid-connected success rate of the generator set, ensures the efficiency and stability of the grid-connected operation, and promotes the reliability and stability of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic flow chart of a grid-connected method based on a dual synchronization device provided in an embodiment of the present invention;

[0039] Figure 2 A schematic structural diagram of a grid-connected system based on a double synchronization device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0041] See also Figure 1 As shown, the technical solution of the first aspect of the present invention provides a grid-connected method based on a double synchronization device, comprising the following steps:

[0042] Step S100: Obtain historical grid-connected data and perform preprocessing;

[0043] Step S100 specifically includes:

[0044] Step S110: Obtain historical grid-connected data of the power grid through the SCADA system, the historical grid-connected data of the power grid at least including power generation, load consumption, grid frequency and voltage level; obtain historical grid-connected data of the power grid according to a preset data collection cycle, wherein the power generation is the power generation data of each unit at different time nodes, the load consumption is the grid load consumption data in different time periods, and the voltage level is the voltage level data of the grid at different nodes;

[0045] Step S200: extracting grid-connected load scenario simulation data based on the pre-processed historical grid-connected data;

[0046] Step S200 specifically includes:

[0047] Step S210: Use the historical grid-connected data of the power grid to build a simulation environment and extract grid-connected load scenario simulation data; specifically, this embodiment uses MATLAB as a simulation tool to build a power grid simulation environment; import the historical grid-connected data obtained in step S110 into the simulation tool, define grid-connected load scenarios such as normal operation state, peak load state, valley load state, and fault state; run simulations under different load scenarios, extract grid-connected load scenario simulation data, and finally extract frequency deviation and voltage deviation from the grid-connected load scenario simulation data, which can be expressed as: Δf(t)=f(t)-f nom , ΔV(t)=V(t)-V nom , f(t) represents the grid frequency at time t; f nom represents the rated grid frequency; V(t) represents the grid voltage at time t; V nom Indicates the rated grid voltage;

[0048] Step S220: performing uncertainty analysis on transient interference and frequency of the power grid in the grid-connected load scenario simulation data, and extracting uncertainty analysis results; specifically, extracting transient interference and abnormal frequency fluctuation from the grid-connected load scenario simulation data, using probability density functions to describe the distribution of disturbance intensity and frequency, calculating the expected value and variance of disturbance intensity and frequency, and evaluating the degree of disturbance in different scenarios. These uncertainties may cause the dual synchronization device to be unable to correctly judge the synchronization condition;

[0049] In summary, step S200 can more accurately simulate the grid behavior under various operating conditions by constructing a grid simulation environment, thereby improving the accuracy of the simulation; by performing uncertainty analysis on transient interference and frequency fluctuations in the simulation data, the degree of these uncertainties can be quantified, which helps to better understand the dynamic characteristics of the grid. The results of the uncertainty analysis can help the dual-synchronous device better judge the synchronization conditions, reduce the possibility of misjudgment, and improve the success rate and reliability of grid connection.

[0050] Step S300: Based on the grid-connected load scenario simulation data, the optimal grid-connected timing is predicted with the goal of minimizing grid fluctuations; specifically, the optimal grid-connected timing is determined by predicting the state change trend of the grid state in the future; the optimal grid-connected timing provides a time window for adjusting the grid-connected strategy;

[0051] Step S300 specifically includes:

[0052] Step S310: Construct and train a prediction model based on grid-connected load scenario simulation data and uncertainty analysis results, and extract future grid-connected scenario prediction data; specifically, use a neural network to construct and train a grid-connected scenario prediction model, use the gradient descent method to minimize the loss function, use the trained neural network model to predict the future power grid state, and extract the predicted frequency deviation and voltage deviation

[0053] Step S320: extracting the best grid connection timing with the goal of minimizing the grid frequency deviation and voltage deviation; the objective function can be expressed as:

[0054]

[0055] Where J(t) represents the fluctuation degree of the power grid at time t+1; α represents the weight coefficient, which is used to balance the importance of frequency deviation and voltage deviation, α∈[0,1]; Represents the predicted value of frequency deviation; represents the predicted value of voltage deviation; specifically, a particle swarm algorithm is used to find the grid-connected timing with the minimum grid fluctuation; a group of particles is initialized, each particle represents a possible grid-connected timing; for each particle, its fitness value is calculated; the position and speed of the particle are updated according to the rules of the particle swarm algorithm until the preset maximum number of iterations is reached, and the grid-connected timing corresponding to the particle with the smallest fitness value is found as the optimal grid-connected timing;

[0056] Step S300 can more accurately select the timing of grid connection by predicting the changing trend of the future grid status, reduce the unstable factors that may occur during the grid connection process, and thus improve the success rate of grid connection; with the goal of minimizing the grid frequency deviation and voltage deviation, it ensures that the impact of the grid connection operation on the grid is minimal, which helps to maintain the stable operation of the grid; the optimal grid connection timing provides a time window for the subsequent grid connection strategy formulation, making the grid connection operation more flexible and efficient.

[0057] Step S400: constructing a grid-connection strategy adjustment model, and outputting an optimal grid-connection strategy according to the predicted optimal grid-connection timing and the preset working mode of the dual-synchronous device; the optimal grid-connection strategy includes: grid-connection time point, grid-connection power, circuit breaker closing time and the working mode of the dual-synchronous device; according to the predicted optimal grid-connection timing and grid-connection scenario prediction data in step S300, selecting the preset working mode of the dual-synchronous device;

[0058] Step S400 specifically includes:

[0059] Step S410: Select the working mode of the dual synchronization device based on the probability model; quantify the applicability of each working mode through the probability model, and select the mode that best suits the current situation; specifically, define a probability distribution for the working model of the dual synchronization device to represent the applicability under given conditions; the preset working modes of the dual synchronization device include: Mode 1: generator to bus or transmission line; Mode 2: synchronous or asynchronous power system or power line; Mode 3: synchronous or asynchronous power system or power line, similar to Mode 2, with additional terminal lines or terminal stations; Mode 4: synchronization detection of manual closing; Mode 5: fast switching of bus; Mode 6: measurement of circuit breaker closing time; The dual synchronization devices are configured with the same parameters, and mode 1 is selected as the final configuration according to the on-site conditions; on the other hand, the corresponding working mode can also be matched according to the actual on-site conditions. The preferred technical solution is to select the corresponding working mode of the dual synchronization device by inputting the device model.

[0060] Step S420: Based on the optimal grid-connected timing, the grid-connected power ramp control is used to output the optimal grid-connected time point, power and circuit breaker closing time; the expression of the grid-connected power ramp control is:

[0061]

[0062] Where P(t) represents the grid-connected power; t grid Indicates the best time to connect to the grid; T r Indicates the power increase time period; P max represents the maximum grid-connected power; the optimal grid-connected strategy can be expressed as: S = [t grid , P(t), t coise , M], where t grid Optimal grid-connected time; P(t) grid-connected power; t colse Indicates the circuit breaker closing time, t colse =t grid +Δt, Δt represents the optimal delay time; M represents the working mode of the dual synchronization device; by introducing the power ramp function, the grid connection process is made smoother, the impact on the grid is reduced, and the grid equipment is protected;

[0063] Step S400 combines the predicted optimal grid-connection timing, power control strategy, circuit breaker closing time optimization, and dual synchronous device working mode selection to form a comprehensive grid-connection strategy. This method can effectively improve the success rate of grid connection, reduce the impact on the power grid, and ensure the stable operation of the system. By introducing the power ramp function, the grid-connection process is smoother and the impact on the power grid is reduced; by optimizing the closing time, the impact of the grid connection moment is further reduced, and the safety and stability of the grid connection operation are improved; by selecting the most suitable working mode through the probability model, the decision-making process is more scientific and reasonable.

[0064] Step S500: issuing a closing command to the dual synchronous devices according to the optimal grid-connected strategy to complete the grid-connected operation; specifically, issuing a closing command to the dual synchronous devices according to the optimal grid-connected strategy; after receiving the closing command, one of the synchronous devices starts to measure the voltage difference, phase angle difference and frequency difference between the grid system side and the grid object side; the other synchronous device sends an increase / deceleration, increase / decrease voltage command according to the measurement result to adjust the state of the generator; when the voltage difference, phase angle difference and frequency difference meet the grid-connected conditions, both synchronous devices will send a closing pulse signal; only when the two synchronous devices send a closing pulse at the same time, will they send a closing pulse to the unit LCU (Local Control Unit) After receiving the closing command from the synchronization device, the LCU controls the circuit breaker to close and completes the grid-connected process. The voltage difference, phase angle difference and frequency difference data between the system side and the object side at the moment of grid-connected generator sets can be queried for multiple times, and the data can be analyzed. At the moment of grid-connected generator sets, the voltage difference between the system side and the object side is within ±1V, the phase angle difference is within ±2°, and the frequency difference is between ±0.1Hz, which fully meets the grid-connected requirements and effectively reduces the impact of grid-connected generator set closing. The experiment verified that the average time from the issuance of the PT command for starting synchronization by the self-monitoring system of each generator set to the issuance of the closing pulse by the synchronization device is less than 20s, that is, the grid-connected closing time of the generator set is less than 20s, which is far lower than the industry average.

[0065] This embodiment finally solves the problem of the impact of abnormal grid connection of generator sets caused by equipment failure that cannot be avoided by a single synchronization device; it avoids the technical problem of the complicated design method of transmitting the frequency and voltage regulation signals received by the switch station PLC to the unit LCU through the PLC communication network. In practice, this invention does not require long-distance cable laying, no modification or upgrade of existing equipment in the monitoring system, no large-scale modification of the current unit LCU program, and no need to add communication programs, which can effectively reduce the impact of unit grid connection and increase the success rate of generator set grid connection.

[0066] See also Figure 2 As shown, the technical solution of the second aspect of the present invention provides a grid-connected system based on a dual synchronization device, including the grid-connected method based on a dual synchronization device described in the technical solution of the first aspect of the present invention, and the grid-connected system includes:

[0067] A data acquisition module is configured to obtain and preprocess historical grid-connected data of the power grid, and extract grid-connected load scenario simulation data based on the preprocessed historical grid-connected data;

[0068] A grid connection timing prediction module, configured to predict the best grid connection timing based on grid connection load scenario simulation data with the goal of minimizing grid fluctuations;

[0069] A grid-connection strategy adjustment module, configured to construct a grid-connection strategy adjustment model, and output an optimal grid-connection strategy according to the predicted optimal grid-connection timing and the preset working mode of the dual-synchronization device;

[0070] The grid-connected module is configured to issue a closing command to the dual synchronization device according to the optimal grid-connected strategy to complete the grid-connected operation.

[0071] The technical solution of the third aspect of the present invention provides an electronic device, comprising: a processor and a memory communicatively connected to the processor; wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor can execute the steps of the grid-connected method based on the dual synchronization device described in the technical solution of the first aspect of the invention.

[0072] The technical solution of the fourth aspect of the present invention provides a computer-readable storage medium, on which is stored a program for implementing a grid-connected method based on a dual-synchronous device. The program for implementing a grid-connected method based on a dual-synchronous device is executed by a processor to implement the steps of the grid-connected method based on a dual-synchronous device described in the technical solution of the first aspect of the invention.

[0073] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A grid-connected method based on a double synchronization device, characterized in that: The steps include: Obtain historical grid-connected data and perform preprocessing; Extract grid-connected load scenario simulation data based on pre-processed historical grid-connected data; Based on grid-connected load scenario simulation data, the optimal grid-connected timing is predicted with the goal of minimizing grid fluctuations; Construct a grid-connected strategy adjustment model to output the optimal grid-connected strategy based on the predicted best grid-connected timing and the preset working mode of the dual-synchronous device; According to the optimal grid-connected strategy, a closing command is issued to the dual synchronous device to complete the grid-connected operation.

2. The grid connection method based on the double synchronization device according to claim 1 is characterized in that: Obtaining historical grid-connected data and preprocessing it includes: The historical grid-connected data of the power grid are obtained through the SCADA system, and the historical grid-connected data of the power grid at least includes power generation, load consumption, grid frequency and voltage level.

3. The grid connection method based on the double synchronization device according to claim 1 is characterized in that: The grid-connected load scenario simulation data extracted based on the pre-processed historical grid-connected data include: Use the historical grid-connected data to build a simulation environment and extract grid-connected load scenario simulation data; Perform uncertainty analysis on grid transient disturbance and frequency in grid-connected load scenario simulation data, and extract uncertainty analysis results.

4. The grid connection method based on the double synchronization device according to claim 3 is characterized in that: Based on grid-connected load scenario simulation data, the optimal grid-connected timing is predicted with the goal of minimizing grid fluctuations, including: Build and train prediction models based on grid-connected load scenario simulation data and uncertainty analysis results to extract future grid-connected scenario prediction data; With the goal of minimizing grid frequency deviation and voltage deviation, an optimization algorithm is used to find the best grid connection timing.

5. The grid connection method based on the double synchronization device according to claim 4 is characterized in that: The expression for minimizing the grid frequency deviation and voltage deviation is: Where J(t) represents the fluctuation degree of the power grid at time t+1; α represents the weight coefficient, which is used to balance the importance of frequency deviation and voltage deviation, α∈[0,1]; Represents the predicted value of frequency deviation; Indicates the voltage deviation prediction value.

6. The grid connection method based on a double synchronization device according to any one of claims 1 to 5, characterized in that: Construct a grid-connected strategy adjustment model to output the optimal grid-connected strategy based on the predicted optimal grid-connected timing and the preset working mode of the dual-synchronous device, including: Select the working mode of the dual synchronization device based on the probability model; Based on the optimal grid-connected timing, the grid-connected power ramp control is used to output the optimal grid-connected time point, power and circuit breaker closing time.

7. The grid connection method based on the double synchronization device according to claim 6 is characterized in that: The expression of grid-connected power ramp control is: Where, P(t) represents the grid-connected power; t grid Indicates the best time to connect to the grid; T r Indicates the power increase time period; P max Indicates the maximum grid-connected power.

8. The grid-connected system based on double synchronization device is characterized by: A grid-connected method based on a double synchronization device according to any one of claims 1 to 7, wherein the grid-connected system comprises: A data acquisition module is configured to obtain and preprocess historical grid-connected data of the power grid, and extract grid-connected load scenario simulation data based on the preprocessed historical grid-connected data; A grid connection timing prediction module, configured to predict the best grid connection timing based on grid connection load scenario simulation data with the goal of minimizing grid fluctuations; A grid-connection strategy adjustment module, configured to construct a grid-connection strategy adjustment model, and output an optimal grid-connection strategy according to the predicted optimal grid-connection timing and the preset working mode of the dual-synchronization device; The grid-connected module is configured to issue a closing command to the dual synchronization device according to the optimal grid-connected strategy to complete the grid-connected operation.

9. An electronic device, characterized in that: The electronic device includes: a processor and a memory communicatively connected to the processor; wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor can execute the steps of the grid-connected method based on a dual synchronization device as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a program for implementing a grid-connected method based on a dual-synchronous device, and the program for implementing a grid-connected method based on a dual-synchronous device is executed by a processor to implement the steps of the grid-connected method based on a dual-synchronous device described in any one of claims 1 to 7.

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