Transformer area side energy storage type electric energy quality comprehensive treatment method

Abstract

The invention discloses a transformer area side energy storage type electric energy quality comprehensive treatment method, which comprises the steps of monitoring and data analysis, voltage out-of-limit control, power out-of-limit control, reverse transmission prevention control, voltage reactive power control, source network load storage coordinated optimization, distributed photovoltaic absorption, comprehensive line loss reduction and the like. The transformer area operation parameters are monitored in all directions, the big data analysis technology is used for analyzing and processing real-time detection data, the functions of transformer area side voltage out-of-limit control, power out-of-limit control, reverse transmission prevention and the like are achieved, and the transformer area side electric energy quality can be effectively improved; the distributed photovoltaic bearing capacity and the access capacity of the alternating current charging pile of the electric vehicle are improved, the comprehensive line loss rate is reduced, the comprehensive line loss can be reduced by 10%, the distributed photovoltaic bearing capacity can reach 150%, the access capacity of the alternating current charging pile of the electric vehicle can be improved by 200%, and 100% consumption of the distributed photovoltaic is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of power quality management, and specifically relates to a comprehensive power quality management method for energy storage type power at the substation side. Background Art

[0002] The development of emerging loads such as electric vehicles has provided diversified control resources and capabilities for the coordinated control of distributed sources, grids, loads and storage. However, the bidirectional uncertainty of a high proportion of distributed power sources and loads currently makes the low-voltage distribution network face more prominent supply and demand matching and power balance problems. Distributed power sources are difficult to consume locally, resulting in power reverse transmission and reverse heavy overload, which seriously affects the safe and efficient operation of the distribution network. In order to solve the above problems, it is necessary to develop a comprehensive power quality management method for energy storage on the substation side. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and to provide a comprehensive management method for energy storage-type power quality on the substation side, which has the functions of substation side voltage over-limit control, power over-limit control, anti-reverse transmission, source-grid-load-storage coordination optimization, etc., which can improve the distributed photovoltaic carrying capacity and the access capacity of electric vehicle AC charging piles and reduce the comprehensive line loss rate.

[0004] The object of the present invention is achieved as follows: a method for comprehensive management of power quality of energy storage type at the substation side, comprising the following steps: (1) Monitoring and data analysis: Establish a real-time monitoring system to conduct all-round monitoring of the voltage, current, power, distributed power generation, and electric vehicle charging load in the substation area; use big data analysis technology to process the monitoring data, analyze the changing trends and uncertainty characteristics of distributed power sources and loads, and provide a basis for subsequent regulation and control decisions; (2) Voltage over-limit control: When the voltage on the substation side is detected to be over-limit, the intelligent control system automatically adjusts the charge and discharge status of the energy storage device and combines it with the reactive power compensation device to dynamically adjust the reactive power compensation amount according to the voltage situation to stabilize the voltage. (3) Power over-limit control: Continuously monitor the power on the substation side. When the power approaches or exceeds the limit value, adjust the output power of the distributed power source. If the power still exceeds the limit, control the energy storage device to adjust the charge and discharge, absorb or release power, and ensure that the power is within a safe range. (4) Anti-reverse power control: Install an intelligent reverse power monitoring device to monitor the power flow in the substation in real time. Once the power reverse power phenomenon is detected, immediately adjust the output power of the distributed power source to reduce it to a level where reverse power does not occur. At the same time, control the charging of the energy storage device to absorb excess power. (5) Voltage and reactive power control: By real-time monitoring of voltage and reactive power, the intelligent control system automatically calculates the required reactive power compensation amount and uses reactive power compensation equipment for dynamic compensation to maintain voltage stability and reactive power balance; (6) Coordination and optimization of sources, grids, loads and storage: Formulate an optimized dispatching strategy to reasonably arrange the output of distributed power sources, the charging and discharging of energy storage devices and the use of loads based on the generation forecast and load forecast of distributed power sources and the status of energy storage devices; (7) Distributed photovoltaic power consumption: Establish a coordinated control mechanism between distributed photovoltaic power generation and energy storage equipment. When photovoltaic power generation exceeds local load demand, the excess electricity will be stored in the energy storage equipment. At night or when photovoltaic power generation is insufficient, the energy storage equipment will be used to discharge electricity to achieve local consumption of distributed photovoltaic power. (8) Reduction of comprehensive line losses: Optimize the grid structure within the substation area, reduce line impedance, and reduce transmission losses. At the same time, by reasonably controlling the charging and discharging of energy storage equipment, balance the power distribution within the substation area, reduce reactive power flow in the line, and reduce line losses.

[0005] Preferably, big data technologies include data collection and preprocessing technology, load forecasting and distributed power generation forecasting technology, clustering analysis technology, correlation analysis technology and anomaly detection technology.

[0006] Preferably, the reactive power compensation device is a capacitor bank or a static reactive power compensator or a static reactive power generator.

[0007] Preferably, when it is detected that the voltage on the substation side exceeds the limit, the intelligent control system automatically adjusts the charging and discharging state of the energy storage device. If the voltage is too high, the energy storage device absorbs excess electrical energy for charging; if the voltage is too low, the energy storage device discharges to supplement the grid power.

[0008] Preferably, the source-grid-load-storage coordinated optimization scheduling strategy includes: storing excess electric energy in energy storage devices when the distributed power generation is at its peak and the load is low; releasing electric energy in energy storage devices to meet load demand when the load is peak and the distributed power generation is insufficient; for electric vehicle AC charging piles, an intelligent charging management system is used to dynamically adjust the charging power and time according to the power supply and demand situation in the substation area, thereby improving the access capacity of the charging piles.

[0009] Preferably, optimizing the grid structure within the substation area includes upgrading and transforming circuits and decentralized reactive power compensation.

[0010] Preferably, upgrading and reconstructing the circuit includes increasing the conductor area and adopting new conductor materials.

[0011] Preferably, decentralized reactive power compensation is that in addition to performing reactive power compensation at a centralized location, reactive power compensation equipment may also be installed at appropriate nodes of the substation line.

[0012] Due to the adoption of the above technical scheme, the beneficial effects of the present invention are as follows: on the basis of real-time all-round monitoring of the substation and big data analysis technology, the present invention adopts voltage over-limit control, power over-limit control, anti-reverse control, voltage reactive power control, source-grid-load-storage coordinated optimization, distributed photovoltaic consumption and comprehensive line loss reduction methods, which solves the more prominent supply and demand matching and power balance problems faced by the existing low-voltage distribution network, the problem that distributed power sources are difficult to consume on-site, and the problems of power reverse transmission and reverse heavy overload. It can improve the distributed photovoltaic carrying capacity and the access capacity of electric vehicle AC charging piles and reduce the comprehensive line loss rate. The comprehensive line loss can be reduced by 10%, the distributed photovoltaic carrying capacity can reach 150%, the access capacity of electric vehicle AC charging piles can be improved by 200%, and the distributed photovoltaic can achieve 100% consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic flow chart of the method of the present invention. DETAILED DESCRIPTION

[0014] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0015] like Figure 1 As shown, the present invention provides a method for comprehensive management of power quality of energy storage type at the substation side, comprising the following steps: (1) Monitoring and data analysis: Establish a real-time monitoring system to conduct all-round monitoring of parameters such as voltage, current, power, distributed power generation, and electric vehicle charging load within the substation area; use big data analysis technology to process monitoring data, analyze the changing trends and uncertainty characteristics of distributed power sources and loads, and provide a basis for subsequent regulation and control decisions.

[0016] Among them, big data technology adopts data collection and preprocessing technology, load forecasting and distributed power generation forecasting technology, clustering analysis technology, correlation analysis technology and anomaly detection technology, which are combined with subsequent functional modules for comprehensive power quality management in different directions on the substation side.

[0017] Data acquisition and preprocessing technology is used for multi-source data integration and time series data processing. Multi-source data integration is used to collect voltage, current, power, distributed power generation, electric vehicle charging load and other types of data from various smart meters, sensors, detection equipment, etc. in the substation area. Since these data come from different sources and have different formats, data cleaning, conversion and integration are required, noise and outliers are removed, and the data is unified in format for subsequent analysis; for example, for the power generation data of distributed power sources, data format conversion and calibration are required according to different types of power generation equipment and monitoring systems. Time series data processing is used for data related to power quality with obvious time series characteristics. Time series data needs to be preprocessed, including data interpolation and smoothing, to fill in data gaps and reduce data fluctuations, so that the data can better reflect the actual operation status of the power system; for data such as voltage and current that change over time, moving average method and other technologies can be used for smoothing.

[0018] Load forecasting and distributed power generation forecasting technology use machine learning algorithms and deep learning algorithms. Regression algorithms in machine learning algorithms, such as support vector machines, random forests, neural networks, etc., can be used to learn and train historical load data and distributed power generation data, establish a forecasting model, and predict load demand and distributed power generation in the future. Deep learning algorithms such as long short-term memory networks or gated recurrent units can be used to better handle the long-term dependencies of time series data to improve the accuracy of forecasts.

[0019] Cluster analysis technology is used to cluster user electricity consumption behavior and substation operation status. Perform cluster analysis on user electricity consumption data in the substation, and divide users into different types according to their electricity consumption habits, electricity consumption time, electricity consumption and other characteristics, and then formulate different electricity management strategies for different types of users. Cluster the substation operation status data, and divide the substation operation status under different time periods and different load conditions into different modes. By analyzing the power quality problems and power balance under different modes, optimize the charging and discharging strategies of energy storage equipment and the output control of distributed power sources, and formulate corresponding regulation strategies.

[0020] Correlation analysis technology is used for correlation analysis of power quality indicators and source-grid-load-storage synergistic correlation analysis. Power quality indicator correlation analysis is to analyze the correlation between power quality indicators such as voltage, current, power, harmonics, etc. in the substation area, and find out the key factors affecting power quality. For example, through correlation analysis, it is found that when a phase current in the substation is overloaded, the voltage of the phase will drop and the power factor will decrease, thereby determining an important factor affecting the power quality of the substation when the current is overloaded, and corresponding measures need to be taken to manage it. Source-grid-load-storage synergistic correlation analysis is to study the relationship and synergy between distributed power sources, power grids, loads and energy storage. By analyzing the power flow, energy conversion and time matching between them, the coordinated control strategy of source-grid-load-storage is optimized to improve the stability and efficiency of the system. For example, the time difference between distributed photovoltaic power generation and load demand is analyzed to determine the optimal charging and discharging time of energy storage equipment to achieve efficient use of electricity and power balance.

[0021] Abnormal detection technology is used for voltage and power over-limit detection and data anomaly monitoring. Based on historical data, a normal voltage and power range model is established. By comparing real-time detection data with the model, abnormal voltage and power over-limit situations are discovered in a timely manner. When real-time data exceeds the normal range, an alarm is triggered and corresponding control measures are initiated. For example, the normal voltage fluctuation range is set to ±5%. When the voltage is detected to be beyond this range, the charging and discharging state of the energy storage device or the output power of the distributed power source is immediately adjusted. Data anomaly monitoring is to detect abnormal values ​​and abnormal patterns in the data, such as sudden jumps in data, continuous abnormal fluctuations, etc. These anomalies may be caused by equipment failure, data collection errors, or abnormal operation of the power system. By timely discovering and processing these abnormal data, the accuracy and reliability of data analysis are improved. For example, when the power generation data of a distributed power source is monitored to fluctuate greatly in a short period of time, and the difference with historical data and other similar equipment is large, it is judged that there may be equipment failure or data collection abnormality, and the staff needs to conduct timely investigation and processing.

[0022] (2) Voltage over-limit control: When the voltage on the substation side is detected to be over-limit, the intelligent control system automatically adjusts the charging and discharging status of the energy storage device. If the voltage is too high, the energy storage device absorbs excess electric energy for charging; if the voltage is too low, the energy storage device discharges to supplement the grid power; at the same time, in combination with reactive compensation equipment, such as capacitor banks, the reactive compensation amount is dynamically adjusted according to the voltage conditions to stabilize the voltage.

[0023] Voltage over-limit on the substation side means that the voltage on the substation side exceeds the normal range. The normal voltage range is specified. If the voltage on the substation side is higher or lower than the normal range, voltage over-limit will occur. Excessive voltage may damage electrical equipment and shorten the service life of the equipment; too low voltage will cause electrical appliances to malfunction, such as lights will dim and motors will not start normally.

[0024] (3) Power over-limit control: Continuously monitor the power on the substation side. When the power approaches or exceeds the limit value, give priority to adjusting the output power of the distributed power source, such as reducing the output power of photovoltaic power generation. If the power still exceeds the limit, control the energy storage device to adjust the charge and discharge, absorb or release power, and ensure that the power is within a safe range.

[0025] The power limit on the substation side is when the power on the substation side exceeds the set limit. The power supply equipment (such as transformers) in the substation has a power capacity limit, which is generally determined by its design and manufacturing. When too many power devices of users in the substation are turned on and the total power demand exceeds the range that the transformer and other power supply equipment can bear, the power limit will be exceeded. Power limit may cause equipment overload, overheating of power supply equipment, accelerated insulation aging, and even equipment damage, power outages and other safety accidents.

[0026] (4) Anti-backflow control: Install an intelligent reverse power monitoring device to monitor the power flow in the substation in real time. Once power reverse flow is detected, immediately adjust the output power of the distributed power source to reduce it to a level where reverse flow does not occur. At the same time, control the charging of the energy storage device to absorb excess power. At the same time, control the charging of the energy storage device to absorb excess power.

[0027] Reverse transmission on the substation side refers to the situation where the current direction flows in the opposite direction. Under normal circumstances, the current in the substation flows from the substation side through the transformer to the user side, but when reverse transmission occurs on the substation side, the current flows from the user side to the substation transformer and may even flow to the grid side. The main reason for reverse transmission on the substation side is usually that the electricity generated by distributed power sources (such as solar photovoltaic power generation, small wind power generation, etc.) exceeds the usage of local users, and the excess electricity will flow back into the grid. The reverse transmission will have a certain impact on the safe and stable operation of the power grid, such as causing the grid voltage to increase and the relay protection device to malfunction.

[0028] (5) Voltage and reactive power control: By real-time monitoring of voltage and reactive power, the intelligent control system automatically calculates the required reactive power compensation amount and uses reactive power compensation equipment such as capacitor banks for dynamic compensation to maintain voltage stability and reactive power balance.

[0029] Reactive power is mainly used to establish and maintain an alternating magnetic field. In the substation power grid, inductive loads such as motors and transformers require a large amount of reactive power during operation. When the reactive power is insufficient, the voltage on the substation side will drop. On the contrary, when the reactive power is excessive, it may cause the voltage to rise.

[0030] (6) Coordination and optimization of sources, grids, loads and storage: Formulate an optimized dispatching strategy to reasonably arrange the output of distributed power sources, the charging and discharging of energy storage devices and the use of loads based on the power generation forecast and load forecast of distributed power sources and the status of energy storage devices.

[0031] Specifically: when the distributed power generation is at its peak and the load is low, the excess electric energy is stored in the energy storage device; when the load is peak and the distributed power generation is insufficient, the electric energy in the energy storage device is released to meet the load demand; for electric vehicle AC charging piles, an intelligent charging management system is used to dynamically adjust the charging power and time according to the power supply and demand situation in the substation area, thereby improving the access capacity of the charging piles.

[0032] The coordinated optimization of source, grid, load and storage at the substation side refers to the comprehensive management of the power supply, grid, load and energy storage within the substation area to ensure the stable and efficient operation of the power system. In terms of coordinated optimization, the real-time status of the source, grid, load and storage is dynamically detected through the intelligent control system, and the power flow distribution of the grid is reasonably adjusted to reduce losses and ensure the voltage quality at the substation side.

[0033] (7) Distributed photovoltaic power consumption: Establish a coordinated control mechanism between distributed photovoltaic power generation and energy storage equipment. When photovoltaic power generation exceeds local load demand, the excess electricity will be stored in the energy storage equipment. At night or when photovoltaic power generation is insufficient, the energy storage equipment will be used to discharge electricity to achieve local consumption of distributed photovoltaic power.

[0034] (8) Reduction of comprehensive line losses: Optimize the grid structure within the substation area, reduce line impedance, and reduce transmission losses. At the same time, by reasonably controlling the charging and discharging of energy storage equipment, balance the power distribution within the substation area, reduce reactive power flow in the line, and reduce line losses.

[0035] Among them, optimizing the grid structure in the substation area includes upgrading and transforming the circuit and decentralized reactive power compensation. Upgrading and transforming the circuit includes increasing the conductor area and adopting new conductor materials; under conditional operation, replacing or adding conductors with larger cross-sectional areas, reducing conductor resistance, reducing line impedance, and thus reducing line losses, such as replacing thinner aluminum conductors in old communities with copper conductors or thick aluminum conductors. Decentralized reactive power compensation means that in addition to reactive power compensation at centralized locations such as substations, reactive power compensation equipment, such as capacitor banks, can be installed at appropriate nodes of the substation line, such as the end of long lines, load concentration points, etc., to balance reactive power on site, reduce the flow of reactive current in the line, and reduce line losses caused by reactive current.

[0036] During specific implementation, the reactive power compensation device may also be a static reactive power compensator or a static reactive power generator.

[0037] In summary, the present invention realizes the optimized scheduling and operation of the distribution network by reasonably allocating flexible resources such as energy storage and electric vehicle charging piles, improves the power supply capacity of the distribution network and the absorption capacity of distributed power sources, can effectively solve the problem of power quality, and has the functions of voltage over-limit control, power over-limit control, anti-reverse transmission, source-grid-load-storage coordinated optimization and other functions on the substation side. It can improve the distributed photovoltaic carrying capacity and the access capacity of electric vehicle AC charging piles, and reduce the comprehensive line loss rate. The comprehensive line loss is reduced by 10%, the distributed photovoltaic carrying capacity reaches 150%, the access capacity of electric vehicle AC charging piles is improved by 200%, and the distributed photovoltaic achieves 100% absorption.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the specific implementation modes of the present invention can still be modified or replaced by equivalents, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A comprehensive power quality management method for energy storage type power at the substation side, characterized in that: The steps include: (1) Monitoring and data analysis: Establish a real-time monitoring system to conduct all-round monitoring of the voltage, current, power, distributed power generation, and electric vehicle charging load in the substation area; use big data analysis technology to process the monitoring data, analyze the changing trends and uncertainty characteristics of distributed power sources and loads, and provide a basis for subsequent regulation and control decisions; (2) Voltage over-limit control: When the voltage on the substation side is detected to be over-limit, the intelligent control system automatically adjusts the charge and discharge status of the energy storage device and combines it with the reactive power compensation device to dynamically adjust the reactive power compensation amount according to the voltage situation to stabilize the voltage. (3) Power over-limit control: Continuously monitor the power on the substation side. When the power approaches or exceeds the limit value, adjust the output power of the distributed power source. If the power still exceeds the limit, control the energy storage device to adjust the charge and discharge, absorb or release power, and ensure that the power is within a safe range. (4) Anti-reverse power control: Install an intelligent reverse power monitoring device to monitor the power flow in the substation in real time. Once the power reverse power phenomenon is detected, immediately adjust the output power of the distributed power source to reduce it to a level where reverse power does not occur. At the same time, control the charging of the energy storage device to absorb excess power. (5) Voltage and reactive power control: By real-time monitoring of voltage and reactive power, the intelligent control system automatically calculates the required reactive power compensation amount and uses reactive power compensation equipment for dynamic compensation to maintain voltage stability and reactive power balance; (6) Coordination and optimization of sources, grids, loads and storage: Formulate an optimized dispatching strategy to reasonably arrange the output of distributed power sources, the charging and discharging of energy storage devices and the use of loads based on the generation forecast and load forecast of distributed power sources and the status of energy storage devices; (7) Distributed photovoltaic power consumption: Establish a coordinated control mechanism between distributed photovoltaic power generation and energy storage equipment. When photovoltaic power generation exceeds local load demand, the excess electricity will be stored in the energy storage equipment. At night or when photovoltaic power generation is insufficient, the energy storage equipment will be used to discharge electricity to achieve local consumption of distributed photovoltaic power. (8) Reduction of comprehensive line losses: Optimize the grid structure within the substation area, reduce line impedance, and reduce transmission losses. At the same time, by reasonably controlling the charging and discharging of energy storage equipment, balance the power distribution within the substation area, reduce reactive power flow in the line, and reduce line losses.

2. The method for comprehensive power quality management of energy storage type at the substation side according to claim 1 is characterized in that: Big data technologies include data collection and preprocessing technology, load forecasting and distributed power generation forecasting technology, cluster analysis technology, correlation analysis technology and anomaly detection technology.

3. The method for comprehensive power quality management of energy storage type at the substation side according to claim 1 is characterized in that: The reactive power compensation device is a capacitor bank or a static reactive power compensator or a static reactive power generator.

4. The method for comprehensive power quality management of energy storage type at the substation side according to claim 1 is characterized in that: When it is detected that the voltage on the substation side exceeds the limit, the intelligent control system automatically adjusts the charging and discharging status of the energy storage device. If the voltage is too high, the energy storage device absorbs excess electric energy for charging; if the voltage is too low, the energy storage device discharges to supplement the grid power.

5. The method for comprehensive power quality management of energy storage type at the substation side according to claim 1 is characterized in that: The source-grid-load-storage coordinated optimization scheduling strategy includes: when the distributed power generation is at its peak and the load is low, the excess electric energy is stored in the energy storage device; when the load is peak and the distributed power generation is insufficient, the electric energy in the energy storage device is released to meet the load demand; for electric vehicle AC charging piles, an intelligent charging management system is used to dynamically adjust the charging power and time according to the power supply and demand situation in the substation area, thereby improving the access capacity of the charging piles.

6. The method for comprehensive power quality management of energy storage type at the substation side according to claim 1 is characterized in that: Optimizing the grid structure within the substation area includes upgrading circuits and decentralized reactive power compensation.

7. The method for comprehensive power quality management of energy storage type at the substation side according to claim 6 is characterized in that: Upgrading circuits includes increasing the conductor area and using new conductor materials.

8. The method for comprehensive power quality management of energy storage type at the substation side according to claim 6 is characterized in that: In addition to performing reactive power compensation at a centralized location, decentralized reactive power compensation also involves installing reactive power compensation equipment at appropriate nodes of the substation line.

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