Phasor measurement units(PMUs) can provide real-time measurement data to construct the ubiquitous electric of the Internet of Things. However, due to complex factors on site, PMU data can be easily compromised by inte...Phasor measurement units(PMUs) can provide real-time measurement data to construct the ubiquitous electric of the Internet of Things. However, due to complex factors on site, PMU data can be easily compromised by interference or synchronization jitter. It will lead to various levels of PMU data quality issues, which can directly affect the PMU-based application and even threaten the safety of power systems. In order to improve the PMU data quality, a data-driven PMU bad data detection algorithm based on spectral clustering using single PMU data is proposed in this paper. The proposed algorithm does not require the system topology and parameters. Firstly, a data identification method based on a decision tree is proposed to distinguish event data and bad data by using the slope feature of each data. Then, a bad data detection method based on spectral clustering is developed. By analyzing the weighted relationships among all the data, this method can detect the bad data with a small deviation. Simulations and results of field recording data test illustrate that this data-driven method can achieve bad data identification and detection effectively. This technique can improve PMU data quality to guarantee its applications in the power systems.展开更多
With more data-driven applications introduced in wide-area monitoring systems(WAMS),data quality of phasor measurement units(PMUs)becomes one of the fundamental requirements for ensuring reliable WAMS applications.Thi...With more data-driven applications introduced in wide-area monitoring systems(WAMS),data quality of phasor measurement units(PMUs)becomes one of the fundamental requirements for ensuring reliable WAMS applications.This paper proposes a doubly-fed deep learning method for bad data identification in linear state estimation,which can:(1)identify bad data under both steady states and contingencies;(2)achieve higher accuracy than conventional pre-filtering approaches;(3)reduce iteration burden for linear state estimation;(4)efficiently identify bad data in a parallelizable scheme.The proposed method consists of four key steps:(1)preprocessing filter;(2)online training of short-term deep neural network;(3)offline training of long-term deep neural network;(4)a decision merger.Through delicate design and comprehensive training,the proposed method can effectively differentiate the bad data from event data without relying on real-time topology information.An IEEE 39-bus system simulated by DSATools TSAT and a provincial electric power system with real PMU data collected are used to verify the proposed method.Multiple test scenarios are applied,which include steady states,three-phase-to-ground faults with(un)successful auto-reclosing,low-frequency oscillation,and low-frequency oscillation with simultaneous threephase-to-ground faults.The proposed method demonstrates satisfactory performance during both the training session and the testing session.展开更多
Due to its high accuracy and ease of calculation,synchrophasor-based linear state estimation(LSE)has attracted a lot of attention in the last decade and has formed the cornerstone of many wide area monitor system(WAMS...Due to its high accuracy and ease of calculation,synchrophasor-based linear state estimation(LSE)has attracted a lot of attention in the last decade and has formed the cornerstone of many wide area monitor system(WAMS)applications.However,an increasing number of data quality concerns have been reported,among which bad data can significantly undermine the performance of LSE and many other WAMS applications it supports.Bad data filtering can be difficult in practice due to a variety of issues such as limited processing time,non-uniform and changing patterns,and etc.To pre-process phasor measurement unit(PMU)measurements for LSE,we propose an improved denoising autoencoder(DA)-aided bad data filtering strategy in this paper.Bad data is first identified by the classifier module of the proposed DA and then recovered by the autoencoder module.Two characteristics distinguish the proposed methodology:1)The approach is lightweight and can be implemented at individual PMU level to achieve maximum parallelism and high efficiency,making it suited for real-time processing;2)the system not only identifies bad data but also recovers it,especially for critical measurements.We use numerical experiments employing both simulated and real-world phasor data to validate and illustrate the effectiveness of the proposed method.展开更多
The problems of recovering the state of power systems and detecting the instances of bad data have been widely studied in literature.Nevertheless,these two operations have been designed and optimized for the most part...The problems of recovering the state of power systems and detecting the instances of bad data have been widely studied in literature.Nevertheless,these two operations have been designed and optimized for the most part in isolation.Specifically,state estimators are optimized based on the minimum mean-square error criteria,which is only optimal when the source of distortions in the data is Gaussian random noise.Hence,the state estimators fail to perform optimality when the data is further contaminated by bad data,which cannot necessarily be modeled by additive Gaussian terms.The problem of power state estimation has been studied extensively.But the fundamental performance limits and the attendant decision rules are unknown when the data is potentially compromised by random bad data(due to sensor failures)or structured bad data(due to cyber attacks,which are also referred to false data injection attacks).This paper provides a general framework that formalizes the underlying connection between state estimation and bad data detection routines.We aim to carry out the combined tasks of detecting the presence of random and structured bad data,and form accurate estimations for the state of power grid.This paper characterizes the optimal detectors and estimators.Furthermore,the gains with respect to the existing state estimators and bad data detectors are established through numerical evaluations.展开更多
快速准确的电力系统扰动检测能够为后续扰动分析提供有效的指导信息,而广域测量系统(wide area measurement system,WAMS)的广泛应用为扰动检测提供了有力的数据基础。基于PMU量测数据,该文提出一种考虑PMU不良数据的扰动事件检测方法...快速准确的电力系统扰动检测能够为后续扰动分析提供有效的指导信息,而广域测量系统(wide area measurement system,WAMS)的广泛应用为扰动检测提供了有力的数据基础。基于PMU量测数据,该文提出一种考虑PMU不良数据的扰动事件检测方法。首先分析PMU异常数据行为特性,揭示扰动事件与不良数据的差异性特征。进一步,提出一种基于差分Teager-Kaiser能量算子与3Sigma准则相结合的PMU异常数据初筛方法,避免了低强度扰动漏检和扰动的重复检测问题。接着,利用动态时间规整和最大互信息系数分别计算不同PMU间的时空相似性,以及同一台PMU内不同量测间的相关性,并以此作为表征扰动事件和不良数据差异的特征。最后,通过局部离群概率算法对得到的综合度量指标进行分析,可实现在含有不良数据场景下的扰动事件准确检测。基于IEEE39系统,实际电网模型以及PMU实测数据,验证所提方法具有较好准确性、实时性以及泛化能力。展开更多
In experimental tests, besides data in range of allowable error, the experimenters usually get some unexpected wrong data called bad points. In usual experimental data processing, the method of bad points exclusion ba...In experimental tests, besides data in range of allowable error, the experimenters usually get some unexpected wrong data called bad points. In usual experimental data processing, the method of bad points exclusion based on automatic programming is seldom taken into consideration by researchers. This paper presents a new method to reject bad points based on Hough transform, which is modified to save computational and memory consumptions. It is fit for linear data processing and can be extended to process data that is possible to be transformed into and from linear form; curved lines, which can be effectively detected by Hough transform. In this paper, the premise is the distribution of data, such as linear distribution and exponential distribution, is predetermined. Steps of the algorithm start from searching for an approximate curve line that minimizes the sum of parameters of data points. The data points, whose parameters are above a self-adapting threshold, will be deleted. Simulation experiments have manifested that the method proposed in this paper performs efficiently and robustly.展开更多
随着大数据、云计算、云会计等技术的发展,财务工作已经逐渐进入智能化时代,财务共享应运而生,已经成为集团企业进行日常财务工作管理的重要手段。近年来,部分集团公司试图通过建立财务共享中心以自动处理各子公司的繁杂的日常业务,并...随着大数据、云计算、云会计等技术的发展,财务工作已经逐渐进入智能化时代,财务共享应运而生,已经成为集团企业进行日常财务工作管理的重要手段。近年来,部分集团公司试图通过建立财务共享中心以自动处理各子公司的繁杂的日常业务,并制定一套规范的流程以进行管理,从而降低成本,但财务共享模式下应收账款管理中仍然存在着集成度与自动化程度不足的问题,而大数据技术的发展将有力地解决上述问题,该文研究企业日常应收账款管理工作中如何实际应用K-Means算法、人工神经网络中的反向传播算法(Backpropagation Algorithm,BP算法)结合机器人流程自动化(Robotics Process Automation,RPA)技术,借此帮助企业更好地管理其应收账款,满足其经营管理的需求。展开更多
基金supported by the National Key R&D Program (No.2017YFB0902901)the National Natural Science Foundation of China (No.51627811,No.51725702,and No.51707064)。
文摘Phasor measurement units(PMUs) can provide real-time measurement data to construct the ubiquitous electric of the Internet of Things. However, due to complex factors on site, PMU data can be easily compromised by interference or synchronization jitter. It will lead to various levels of PMU data quality issues, which can directly affect the PMU-based application and even threaten the safety of power systems. In order to improve the PMU data quality, a data-driven PMU bad data detection algorithm based on spectral clustering using single PMU data is proposed in this paper. The proposed algorithm does not require the system topology and parameters. Firstly, a data identification method based on a decision tree is proposed to distinguish event data and bad data by using the slope feature of each data. Then, a bad data detection method based on spectral clustering is developed. By analyzing the weighted relationships among all the data, this method can detect the bad data with a small deviation. Simulations and results of field recording data test illustrate that this data-driven method can achieve bad data identification and detection effectively. This technique can improve PMU data quality to guarantee its applications in the power systems.
基金supported by the Science and Technology Program of State Grid Corporation of China under project“AI based oscillation detection and control”(No.SGJS0000DKJS1801231)
文摘With more data-driven applications introduced in wide-area monitoring systems(WAMS),data quality of phasor measurement units(PMUs)becomes one of the fundamental requirements for ensuring reliable WAMS applications.This paper proposes a doubly-fed deep learning method for bad data identification in linear state estimation,which can:(1)identify bad data under both steady states and contingencies;(2)achieve higher accuracy than conventional pre-filtering approaches;(3)reduce iteration burden for linear state estimation;(4)efficiently identify bad data in a parallelizable scheme.The proposed method consists of four key steps:(1)preprocessing filter;(2)online training of short-term deep neural network;(3)offline training of long-term deep neural network;(4)a decision merger.Through delicate design and comprehensive training,the proposed method can effectively differentiate the bad data from event data without relying on real-time topology information.An IEEE 39-bus system simulated by DSATools TSAT and a provincial electric power system with real PMU data collected are used to verify the proposed method.Multiple test scenarios are applied,which include steady states,three-phase-to-ground faults with(un)successful auto-reclosing,low-frequency oscillation,and low-frequency oscillation with simultaneous threephase-to-ground faults.The proposed method demonstrates satisfactory performance during both the training session and the testing session.
基金This work was supported by SGCC Science and Technology Program under project“AI-based oscillation detection and control”(SGJS0000DKJS1801231)。
文摘Due to its high accuracy and ease of calculation,synchrophasor-based linear state estimation(LSE)has attracted a lot of attention in the last decade and has formed the cornerstone of many wide area monitor system(WAMS)applications.However,an increasing number of data quality concerns have been reported,among which bad data can significantly undermine the performance of LSE and many other WAMS applications it supports.Bad data filtering can be difficult in practice due to a variety of issues such as limited processing time,non-uniform and changing patterns,and etc.To pre-process phasor measurement unit(PMU)measurements for LSE,we propose an improved denoising autoencoder(DA)-aided bad data filtering strategy in this paper.Bad data is first identified by the classifier module of the proposed DA and then recovered by the autoencoder module.Two characteristics distinguish the proposed methodology:1)The approach is lightweight and can be implemented at individual PMU level to achieve maximum parallelism and high efficiency,making it suited for real-time processing;2)the system not only identifies bad data but also recovers it,especially for critical measurements.We use numerical experiments employing both simulated and real-world phasor data to validate and illustrate the effectiveness of the proposed method.
基金supported by the US NationalScience Foundation(No.ECCS-1554482).
文摘The problems of recovering the state of power systems and detecting the instances of bad data have been widely studied in literature.Nevertheless,these two operations have been designed and optimized for the most part in isolation.Specifically,state estimators are optimized based on the minimum mean-square error criteria,which is only optimal when the source of distortions in the data is Gaussian random noise.Hence,the state estimators fail to perform optimality when the data is further contaminated by bad data,which cannot necessarily be modeled by additive Gaussian terms.The problem of power state estimation has been studied extensively.But the fundamental performance limits and the attendant decision rules are unknown when the data is potentially compromised by random bad data(due to sensor failures)or structured bad data(due to cyber attacks,which are also referred to false data injection attacks).This paper provides a general framework that formalizes the underlying connection between state estimation and bad data detection routines.We aim to carry out the combined tasks of detecting the presence of random and structured bad data,and form accurate estimations for the state of power grid.This paper characterizes the optimal detectors and estimators.Furthermore,the gains with respect to the existing state estimators and bad data detectors are established through numerical evaluations.
文摘快速准确的电力系统扰动检测能够为后续扰动分析提供有效的指导信息,而广域测量系统(wide area measurement system,WAMS)的广泛应用为扰动检测提供了有力的数据基础。基于PMU量测数据,该文提出一种考虑PMU不良数据的扰动事件检测方法。首先分析PMU异常数据行为特性,揭示扰动事件与不良数据的差异性特征。进一步,提出一种基于差分Teager-Kaiser能量算子与3Sigma准则相结合的PMU异常数据初筛方法,避免了低强度扰动漏检和扰动的重复检测问题。接着,利用动态时间规整和最大互信息系数分别计算不同PMU间的时空相似性,以及同一台PMU内不同量测间的相关性,并以此作为表征扰动事件和不良数据差异的特征。最后,通过局部离群概率算法对得到的综合度量指标进行分析,可实现在含有不良数据场景下的扰动事件准确检测。基于IEEE39系统,实际电网模型以及PMU实测数据,验证所提方法具有较好准确性、实时性以及泛化能力。
文摘In experimental tests, besides data in range of allowable error, the experimenters usually get some unexpected wrong data called bad points. In usual experimental data processing, the method of bad points exclusion based on automatic programming is seldom taken into consideration by researchers. This paper presents a new method to reject bad points based on Hough transform, which is modified to save computational and memory consumptions. It is fit for linear data processing and can be extended to process data that is possible to be transformed into and from linear form; curved lines, which can be effectively detected by Hough transform. In this paper, the premise is the distribution of data, such as linear distribution and exponential distribution, is predetermined. Steps of the algorithm start from searching for an approximate curve line that minimizes the sum of parameters of data points. The data points, whose parameters are above a self-adapting threshold, will be deleted. Simulation experiments have manifested that the method proposed in this paper performs efficiently and robustly.
文摘随着大数据、云计算、云会计等技术的发展,财务工作已经逐渐进入智能化时代,财务共享应运而生,已经成为集团企业进行日常财务工作管理的重要手段。近年来,部分集团公司试图通过建立财务共享中心以自动处理各子公司的繁杂的日常业务,并制定一套规范的流程以进行管理,从而降低成本,但财务共享模式下应收账款管理中仍然存在着集成度与自动化程度不足的问题,而大数据技术的发展将有力地解决上述问题,该文研究企业日常应收账款管理工作中如何实际应用K-Means算法、人工神经网络中的反向传播算法(Backpropagation Algorithm,BP算法)结合机器人流程自动化(Robotics Process Automation,RPA)技术,借此帮助企业更好地管理其应收账款,满足其经营管理的需求。
