Hyuk-Soo Jang

A survey of communication network paradigms for substation automation

In the realm of substation automation (SA), communication infrastructure plays a vital role in mediating between physical and virtual worlds of substation. Specification of data exchanges through standardized communication stacks is therefore an important issue for all substation equipment manufacturers seeking to provide vendor interoperability. Nowadays competitive electric utility marketplace, reliable and real-time information become the key factor for reliable delivery of power to the end- users, profitability of the electric utility and customer satisfaction. The operational and commercial demands of electric utilities require a high-performance data communication network that supports both existing functionalities and future operational requirements. As communication arena is changing day by day, the need for efficient and reliable communication infrastructure to address SA is evident. In this respect, a communication network constitutes the core of the SA, thus the design of cost-effective and reliable network architecture is a crucial task. Most of the existing communication networks claim to address the need of communication architecture for SA but in some regard these claims just could not fulfill the constraints imposed by highly available environment for SA. This paper presents a survey and analysis of the current state-of-the-art communication infrastructure in the SA. As Ethernet technology becomes more reliable and also widely available with fiber optical communication so this paper also examines the key issues and requirements for Ethernet in the substation environment and also opens some research challenges.

Optimized Security Algorithm for IEC 61850 based Power Utility System

As power grids are integrated into one big umbrella (i.e., Smart Grid), communication network plays a key role in reliable and stable operation of power grids. For successful operation of smart grid, interoperability and security issues must be resolved. Security means providing network system integrity, authentication, and confidentiality service. For a cyber-attack to a power grid system, which may jeopardize the national security, vulnerability of communication infrastructure has a serious impact on the power grid network. While security aspects of power grid network have been studied much, security mechanisms are rarely adopted in power gird communication network. For security issues, strict timing requirements are defined in IEC 61850 for mission critical messages (i.e., GOOSE). In this paper, we apply security algorithms (i.e., MD-5, SHA-1, and RSA) and measure their processing time and transmission delay of secured mission critical messages. The results show the algorithms satisfying the timing requirements defined in IEC 61850 and we observer the algorithm that is optimal for secure communication of mission critical messages. Numerical analysis shows that SHA-1 is preferable for secure GOOSE message sending.

Quality of service (QoS) of voice over MAC protocol 802.11 using ns-2

Transmitting voice through IP data network can provide significant cost savings. However if not managed properly, voice quality can degrade due to data network congestion. Voice over IP (VoIP) is gaining an ever increasing popularity. As such, it nowadays represents one of the most studied test applications in the performance evaluation of wireline and wireless networks in which the IEEE 802.11 distributed coordination function protocol or enhanced DCF protocol is used. However, since both DCF and EDCF are contention-based medium access control protocols, it is difficult for them to support the strict QoS requirement for VoIP. In this paper we will investigate QoS indications (for voice packets), Improvement of NS2 network simulator in order to simulate statistical QoS in 802.11 MAC and Show that Uplink/Downlink problem exists in EDCF and suggest different solutions using QoS parameters (DIFS, CWmin and PF).

A Path Based Internet Cache Design for GRID Application

Internet users are most likely opening multiple windows and surfing several sites concurrently with frequent site changes within a relatively short period of time. This work proposes a web cache organization algorithm, which can satisfy the frequent site changes effectively with low cost. The algorithm is based on the collected statistics of the visited sites and the pattern analysis of the site change. Our study suggests that the proposed path based cache scheme outperforms the existing algorithms in the hit ratio and response time dramatically.

QVT-Based Model Transformation to Support Unification of IEC 61850 and IEC 61970

A smart grid is an electrical power grid infrastructure for improved efficiency, reliability, and safety based on automated monitoring and control of data and communication. IEC 61850 and IEC 61970 are core standards in the smart-grid domain for substation automation and power operation management. There are significant data exchanges involved between the IEC 61850 level and the IEC 61970 level, which require high compatibility between the two standards. However, due to different perspectives and independent evolution, IEC 61850 and IEC 61870 are not compatible and practitioners have to come up with their own data mapping for the standards in an ad-hoc manner. This has led to significant issues on interoperability and data consistency in smart grids. An effective solution for this is to define a common semantic model of the standards and provide a systematic transformation method for transforming a model of the standards to a model of the common semantic model. In this paper, we present a metamodeling approach for unifying IEC 61850 and IEC 61970 and transforming models using query/view/transformation (QVT). We demonstrate the approach using a power transformer example.

Role-based access control for substation automation systems using XACML

There has been an increasing need for accessing data of internal equipment and devices of a substation system from external systems as power grids evolve. This has also introduced growing concerns on data security. In response to the concerns, IEC 62351 has proposed role-based access control (RBAC) for substation automation. In this work, we present a novel approach for implementing RBAC based on IEC 62351 for substation automation using eXtensible Access Control Markup Language (XACML). We integrate the approach with IEC 61850 by extending Abstract Communication Service Interface (ACSI), Manufacturing Message Specification (MMS), and System Configuration Language (SCL). A major advantage of the approach is that it fully conforms to both IEC 61850 and IEC 62351 and highly compatible with SCL as both XACML and SCL are XML-based. We implement the approach using OpenIEC61850 which is an open source library for ACSI services and demonstrate the implementation.

Baseline efficiency in EPON based architecture to inter-network substations

The design of cost-effective, interoperable, and efficient communication architecture is indeed one of the pressing needs not only for the realization of substation automation (SA) as per specification of IEC61850 but also to inter-connect different substations with minimum cost to bring data from all substations on the single information highway thereby paving a smooth way to centralize all the available information. Ethernet technology has dramatically changed the communication trend because of its availability, efficiency, cost effectiveness, proven interoperability, and capability to drive on-demand bandwidth as per incremental growth and expansion of the network and on the other hand optical fiber communication system is one of the technically attractive communication medium due to its high capacity, efficiency, and security. Therefore, EPON (Ethernet Passive Optical Network) is the desired communication paradigm for the SA as it is shipped with the two most demanding communication trends, i.e., Ethernet and Fiber Optics in a single package. EPON underscores the importance of not only last-mile operability for inter-connecting different substations but can also play a vital role when ATM is replaced with GPON (Gigabit Passive Optical Network) for the long-haul communication thereby saving the cost of protocol conversion. In this paper we propose EPON as the desired communication architecture for inter-connecting substations and present analysis related to the significant importance of EPON with respect to the deployment in the substation environment both internally and externally. Finally we show the result of simulations to validate the deployment and effectiveness of our purposed communication paradigm for substation.

A metamodeling approach to unifying IEC 61850 and IEC 61970

A smart grid is an electrical power grid infrastructure for improved efficiency, reliability, and safety based on automated monitoring and control of data and communication. IEC 61850 and IEC 61970 are core standards in the smart grid domain for substation automation and power operation management. Significant data exchange is involved between the IEC 61850 level and the IEC 61970 level. However, due to different perspectives on smart grid and independent evolution, IEC 61850 and IEC 61970 are not compatible. This forces practitioners to come up with their own data mappings between the standards in an ad-hoc manner, which leads to significant issues on interoperability and data consistency. An effective solution for this is to define a common semantic model for both substation automation and operation management. In this paper, we present a metamodeling approach for unifying IEC 61850 and IEC 61970 to provide a common semantic model and demonstrate the approach using a power transformer example.

Parallel implementation of a financial application on a GPU

The architecture of the latest Graphic Processing Unit (GPU) has surpassed the previous application-specific stream architecture. They consist of a number of uniform programmable units integrated on the same chip which facilitate the general-purpose computing beyond the graphic processing. With the multiple programmable units executing in parallel, the latest GPU shows superior performance for many different applications. Furthermore, programmers can have a direct control on the GPU pipeline using easy-to-use parallel programming environments, whereas they had to rely on specific graphics APIs in the past. These advances in hardware and software make General-Purpose GPU (GPGPU) computing widespread. In this paper, using the latest GPU and its software environment, we parallelize a computationally demanding financial application based on Monte-Carlo methods and optimize its performance. Experimental results show that a GPU can achieve a superior performance, greater than 190x, compared with the CPU-only case.

Gigabit Ethernet based substation under IEC61850 standard

Communication architecture for substation automation is one of the challenging and subtle tasks to address in order to visualize the substation into digital world under the umbrella of IEC61850. Communication paradigm for substation automation demands critical importance because of two reasons; as communication arena is changing day by day so it is convenient to opt for something that is simple to deploy and incur a less cost in terms of time and asset when migration is to be considered since data-intensive applications drive the incremental demand for bandwidth as per growing need with the expansion of concerned network and last but not least the interoperability as it is one of the core constrained put by IEC61850 for substation automation. So it is viable to consider Ethernet as the most promising solution for the communication architecture of substation automation as Ethernet technology has changed the trend of communication network because of its availability, efficiency, and cost effectiveness on the other hand interoperability is assured based on the proven and highly deployed industrial Ethernet. This paper presents analysis and the crucial need for the deployment of Gigabit Ethernet in the substation and also presents how Ethernet technology can help in the substation automation as a long run solution in the changing arena of communication as Ethernet is one of the most pervasive communication technologies. In the end we have performed simulations in NS-2 to prove that our suggested communication paradigm is optimal in various regards by keeping into consideration the constraints imposed by IEC61850.