In this paper,a new Distribution Management System(DMS)framework based on security region is proposed.First,the concept of Distribution System Security Region(DSSR)is introduced.DSSR is capable to describe the N-1 sec...In this paper,a new Distribution Management System(DMS)framework based on security region is proposed.First,the concept of Distribution System Security Region(DSSR)is introduced.DSSR is capable to describe the N-1 security boundary of the whole distribution network,including the secure output range of DGs.This new theoretic tool provides a chance for the implementation of real-time security analysis and active controls in DMS.Second,this paper proposes and describes five security states for distribution system.Third,an upgraded DMS enhanced with DSSR is proposed,which consists of advanced security functions such as preventive and predictive control of the trajectory of operating points.Finally,a practical case is presented to simulate the proposed DSSR-enhanced DMS,in which both the security region of network and the output range of DGs are calculated.Typical security functions are also demonstrated.In conclusion,the new DMS framework aims to help operate the system closed to its security boundary in order to improve the efficiency significantly within same security standard.This work is beneficial for future low carbon distribution systems with high penetration rate of DGs.展开更多
In order to overcome the shortages of diagnostic method for distribution networks considering the reliability assessment,this paper proposed a method based on power supply safety standards.It profoundly analyzed the s...In order to overcome the shortages of diagnostic method for distribution networks considering the reliability assessment,this paper proposed a method based on power supply safety standards.It profoundly analyzed the security standard of supply for urban power networks,and established quantitative indicators of load groups based on different fault conditions.Then a method suitable for diagnostic evaluation of urban distribution networks in China was given.In the method,“N-1”calibration analysis of the distribution network was conducted.Then the results are compared with quantitative indicators of load groups on different conditions deriving the diagnostic conclusions and the standard revision is discussed.The feasibility and accuracy of the method is finally verified in the case study.展开更多
An approach of transmission network expan-sion planning with embedded constraints of short circuit currents and N-1 security is proposed in this paper.The problem brought on by the strong nonlinearity property of shor...An approach of transmission network expan-sion planning with embedded constraints of short circuit currents and N-1 security is proposed in this paper.The problem brought on by the strong nonlinearity property of short circuit currents is solved with a linearization method based on the DC power flow.The model can be converted to a mixed-integer linear programming problem,realizing the optimization of planning model that considers the constraints of linearized short circuit currents and N-1 security.To compensate the error caused by the assump-tions of DC power flow,the compensation factor is pro-posed.With this factor,an iterative algorithm that can compensate the linearization error is then presented.The case study based on the IEEE 118-bus system shows that the proposed model and approach can be utilized to:opti-mize the construction strategy of transmission lines;ensure the N-1 security of the network;and effectively limit the short circuit currents of the system.展开更多
随着信息技术的不断发展,各种SQL注入攻击工具层出不穷,攻击类型多变万化,SQL注入问题一直是网络安全的主要问题。因此,针对SQL注入攻击提出一种基于N-Gram和TFIDF(term frequency inverse document frequency)的入侵检测方法。其核心...随着信息技术的不断发展,各种SQL注入攻击工具层出不穷,攻击类型多变万化,SQL注入问题一直是网络安全的主要问题。因此,针对SQL注入攻击提出一种基于N-Gram和TFIDF(term frequency inverse document frequency)的入侵检测方法。其核心思想是:首先在预处理阶段使用N-Gram技术选取特征词,再利用TFIDF技术进行SQL语句文本向量化处理,然后在此数据集基础上训练SVM分类器,最后通过与现有研究进行对比来检测分类效果。实验结果表明,与直接使用预先定义好的特征向量相比,此方法在保证召回率的基础上,准确率有所提高。展开更多
The region-based method has been applied in transmission systems and traditional passive distribution systems without power sources. This paper proposes the model of total quadrant security region(TQSR) for active dis...The region-based method has been applied in transmission systems and traditional passive distribution systems without power sources. This paper proposes the model of total quadrant security region(TQSR) for active distribution networks(ADN) with high penetration of distributed generation(DG). Firstly, TQSR is defined as a closed set of all the N-1 secure operation points in the state space of ADN. Then, the TQSR is modeled considering the constraints of state space,normal operation and N-1 security criterion. Then, the characteristics of TQSR are observed and analyzed on the test systems with different DG penetrations. TQSR can be located in any quadrant of the state space. For different DG penetrations,the shape and security features of TQSR are also different. Finally, the region map is discovered, which summarizes the features of different types of distribution networks.展开更多
Based on the diversified technology and the cross-validation mechanism,the N-variant system provides a secure service architecture for cloud providers to protect the cloud applications from attacks by executing multip...Based on the diversified technology and the cross-validation mechanism,the N-variant system provides a secure service architecture for cloud providers to protect the cloud applications from attacks by executing multiple variants of a single software in parallel and then checking their behaviors’consistency.However,it is complex to upgrade current Software as a Service(SaaS)applications to adapt N-variant system architecture.Challenges arise from the inability of tenants to adjust the application architecture in the cloud environment,and the difficulty for cloud service providers to implement N-variant systems using existing API gateways.This paper proposes SecIngress,an API gateway framework,to overcome the challenge that it is hard in the cloud environment to upgrade the applications based on N-variants system.We design a two-stage timeout processing method to lessen the service latency and an Analytic Hierarchy Process Voting under the Metadata mechanism(AHPVM)to enhance voting accuracy.We implement a prototype in a testbed environment and analyze the security and performance metrics before and after deploying the prototype to show the effectiveness of SecIngress.The results reveal that SecIngress enhances the reliability of cloud applications with acceptable performance degradation.展开更多
Multi-energy integrations provide great opportunities for economic and efficient resource utilization. In the meantime, power system operation requires enough flexible resources to deal with contingencies such as tran...Multi-energy integrations provide great opportunities for economic and efficient resource utilization. In the meantime, power system operation requires enough flexible resources to deal with contingencies such as transmission line tripping. Besides economic benefits, this paper focuses on the security benefits that can be provided by multi-energy integrations. This paper first proposes an operation scheme to coordinate multiple energy production and local system consumption considering transmission networks. The integrated flexibility model, constructed by the feasible region of integrated demand response(IDR), is then formulated to aggregate and describe local flexibility. Combined with system security constraints, a multi-energy system operation model is formulated to schedule multiple energy production, transmission, and consumption. The effects of local system flexibility on alleviating power flow violations during N-1 line tripping contingencies are then analyzed through a multi-energy system case. The results show that local system flexibility can not only reduce the system operation costs, but also reduce the probability of power flow congestion or violations by approximately 68.8% during N-1 line tripping contingencies.展开更多
基金This work was supported by the National Natural Science Foundation of China(51477112)National Natural Science Foundation of China(51277129).
文摘In this paper,a new Distribution Management System(DMS)framework based on security region is proposed.First,the concept of Distribution System Security Region(DSSR)is introduced.DSSR is capable to describe the N-1 security boundary of the whole distribution network,including the secure output range of DGs.This new theoretic tool provides a chance for the implementation of real-time security analysis and active controls in DMS.Second,this paper proposes and describes five security states for distribution system.Third,an upgraded DMS enhanced with DSSR is proposed,which consists of advanced security functions such as preventive and predictive control of the trajectory of operating points.Finally,a practical case is presented to simulate the proposed DSSR-enhanced DMS,in which both the security region of network and the output range of DGs are calculated.Typical security functions are also demonstrated.In conclusion,the new DMS framework aims to help operate the system closed to its security boundary in order to improve the efficiency significantly within same security standard.This work is beneficial for future low carbon distribution systems with high penetration rate of DGs.
文摘In order to overcome the shortages of diagnostic method for distribution networks considering the reliability assessment,this paper proposed a method based on power supply safety standards.It profoundly analyzed the security standard of supply for urban power networks,and established quantitative indicators of load groups based on different fault conditions.Then a method suitable for diagnostic evaluation of urban distribution networks in China was given.In the method,“N-1”calibration analysis of the distribution network was conducted.Then the results are compared with quantitative indicators of load groups on different conditions deriving the diagnostic conclusions and the standard revision is discussed.The feasibility and accuracy of the method is finally verified in the case study.
基金This work was supported by National Key Technology R&D Program of China(No.2013BAA01B02)National Natural Science Foundation of China(Nos.51325702,51407100).
文摘An approach of transmission network expan-sion planning with embedded constraints of short circuit currents and N-1 security is proposed in this paper.The problem brought on by the strong nonlinearity property of short circuit currents is solved with a linearization method based on the DC power flow.The model can be converted to a mixed-integer linear programming problem,realizing the optimization of planning model that considers the constraints of linearized short circuit currents and N-1 security.To compensate the error caused by the assump-tions of DC power flow,the compensation factor is pro-posed.With this factor,an iterative algorithm that can compensate the linearization error is then presented.The case study based on the IEEE 118-bus system shows that the proposed model and approach can be utilized to:opti-mize the construction strategy of transmission lines;ensure the N-1 security of the network;and effectively limit the short circuit currents of the system.
文摘随着信息技术的不断发展,各种SQL注入攻击工具层出不穷,攻击类型多变万化,SQL注入问题一直是网络安全的主要问题。因此,针对SQL注入攻击提出一种基于N-Gram和TFIDF(term frequency inverse document frequency)的入侵检测方法。其核心思想是:首先在预处理阶段使用N-Gram技术选取特征词,再利用TFIDF技术进行SQL语句文本向量化处理,然后在此数据集基础上训练SVM分类器,最后通过与现有研究进行对比来检测分类效果。实验结果表明,与直接使用预先定义好的特征向量相比,此方法在保证召回率的基础上,准确率有所提高。
基金supported in part by National Key Research and Development Program of China (No. 2016YFB0900100)National Natural Science Foundation of China (No. 51877144)China Postdoctoral Science Foundation (No.2020M670668)。
文摘The region-based method has been applied in transmission systems and traditional passive distribution systems without power sources. This paper proposes the model of total quadrant security region(TQSR) for active distribution networks(ADN) with high penetration of distributed generation(DG). Firstly, TQSR is defined as a closed set of all the N-1 secure operation points in the state space of ADN. Then, the TQSR is modeled considering the constraints of state space,normal operation and N-1 security criterion. Then, the characteristics of TQSR are observed and analyzed on the test systems with different DG penetrations. TQSR can be located in any quadrant of the state space. For different DG penetrations,the shape and security features of TQSR are also different. Finally, the region map is discovered, which summarizes the features of different types of distribution networks.
基金the Foundation of the National Natural Science Foundation of China(62072467)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(61521003)the Foundation of the National Natural Science Foundation of China(62002383).
文摘Based on the diversified technology and the cross-validation mechanism,the N-variant system provides a secure service architecture for cloud providers to protect the cloud applications from attacks by executing multiple variants of a single software in parallel and then checking their behaviors’consistency.However,it is complex to upgrade current Software as a Service(SaaS)applications to adapt N-variant system architecture.Challenges arise from the inability of tenants to adjust the application architecture in the cloud environment,and the difficulty for cloud service providers to implement N-variant systems using existing API gateways.This paper proposes SecIngress,an API gateway framework,to overcome the challenge that it is hard in the cloud environment to upgrade the applications based on N-variants system.We design a two-stage timeout processing method to lessen the service latency and an Analytic Hierarchy Process Voting under the Metadata mechanism(AHPVM)to enhance voting accuracy.We implement a prototype in a testbed environment and analyze the security and performance metrics before and after deploying the prototype to show the effectiveness of SecIngress.The results reveal that SecIngress enhances the reliability of cloud applications with acceptable performance degradation.
基金supported by State Grid Corporation of China “Research on Multi-energy System Energy Conversion Simulation and Energy Efficiency Evaluation”(No.SGTYHT/18-JS-206)。
文摘Multi-energy integrations provide great opportunities for economic and efficient resource utilization. In the meantime, power system operation requires enough flexible resources to deal with contingencies such as transmission line tripping. Besides economic benefits, this paper focuses on the security benefits that can be provided by multi-energy integrations. This paper first proposes an operation scheme to coordinate multiple energy production and local system consumption considering transmission networks. The integrated flexibility model, constructed by the feasible region of integrated demand response(IDR), is then formulated to aggregate and describe local flexibility. Combined with system security constraints, a multi-energy system operation model is formulated to schedule multiple energy production, transmission, and consumption. The effects of local system flexibility on alleviating power flow violations during N-1 line tripping contingencies are then analyzed through a multi-energy system case. The results show that local system flexibility can not only reduce the system operation costs, but also reduce the probability of power flow congestion or violations by approximately 68.8% during N-1 line tripping contingencies.
