Jens Schmutzler

Network-centric Middleware for Service Oriented Architectures across Heterogeneous Embedded Systems

The increasing ubiquity of mobile embedded systems has been matched by the evolution of a variety of wireless network standards and technologies. The major constraints of wireless embedded systems are limitations of communication bandwidth, processing capabilities, and battery power. Remote wireless embedded systems often act as sensors, which provide data to a certain community. The exchange of data is nowadays usually realized through Web services. For standard Web services an XML parser is required, which demands a lot of processing power whereas embedded devices with their resource constraints provide only limited processing capabilities. Another drawback of standard Web services is the huge communication overhead due to the use of human readable XML. On the other hand using standard Web service technology enables service developers to easily integrate new embedded devices to their network or to the Internet. This paper reports on the on-going work of the key European research project MORE, which brings the embedded system world together with the Web services world. MORE introduces a new connector concept easing the handling of heterogeneous communication channels and muSOA for reducing the message size and processing demands for parsing XML messages.

Management of Distributed Energy Resources in IEC 61850 using Web Services on devices

The adoption of standardized Web Service communication protocols from manufacturing and automation industries carries a number of currently unused potentials for energy distribution processes. This work addresses potential advantages of such an approach, particularly highlighting benefits for medium-term, wide-spread use of Distributed Energy Resources (DER). Therefore a new communication protocol mapping for IEC 61850 is introduced based on the Devices Profile for Web Services (DPWS). Other than currently specified mappings, this approach benefits from intrinsic compliance to WS-* protocols. It brings along numerous advantages like plug and play field deployment of Intelligent Electrical Devices (IED) and more efficient asset management through seamless enterprise IT integration. Next to detailing this new mapping in theory, an increasingly important DER use case scenario based on fully electric vehicles (EV) is conducted as proof of concept. This use case also serves as evaluation scenario focusing on latency and scalability issues of the discovery process of dynamic DERs.

Analysis of message sequences and encoding efficiency for electric vehicle to grid interconnections

Grid compatibility is a major issue for charging infrastructures of electric vehicles especially in low voltage systems. In order to respect dynamic grid limitations during the charging process, electric vehicles and charging infrastructures have to negotiate charge and grid parameters autonomosly. The ISO/IEC Joint Working Group 15118 is working on the Vehicle to Grid Communication Interface enabling user-friendly plug & charge functionality and also allowing for grid compatible charging processes. This paper describes current efforts being conducted in the standardization group, discusses the current state of the protocol in terms of message specifications, and maps various V2G use cases to the current protocol draft. The evaluation focuses on the message exchange patterns between the electric vehicle and the charge spot. Due to the adoption of highly embedded devices in electric vehicles an analysis on the application layer protocol efficiency is provided in this work. It focuses on data encoding efficiency with respect to the current state of the protocol specification. Detailed investigations on physical and data link layers are not part of this work.

ICT Reference Architecture Design Based on Requirements for Future Energy Marketplaces

Todays Smart Grid initiatives propose highly decentralized power supplies with an increased number of providers utilizing renewable energy resources. This idea is driven by the imminent requirement for improved sustainability of power industries and also by the legislative demand for more competitive energy market structures. Due to these intentions the number of regional market participants will be increasing dramatically over the next few years. In order to coordinate and balance energy supply and demand under these new circumstances, major ICT related challenges need to be addressed. This paper introduces a reference architecture design offering a set of extensibility points to existing solutions for increased flexibility in moving energy markets. The architecture design is based on the idea for open energy marketplaces in regional power distribution networks enabling load management and transfer. By defining flexible high level interfaces, it respects potentially upcoming requirements, new evolving services, and - resulting from these services - integration and mediation of future market roles. Furthermore the architecture presented in this paper also considers various regulative requirements resulting in different operational modes for provisioning of clearing, monitoring and controlling data.

Distributed energy resource management for electric vehicles using IEC 61850 and ISO/IEC 15118

Research and development in the field of electric vehicles is evolving quickly based on global efforts reducing CO2 footprint and fossil fuel dependency for road vehicles. Standardized communication interfaces are a necessity for grid integration of electric vehicles, interoperability, and therefore mass market acceptance of E-Mobility. In extend to such base level of interoperability, the real opportunity of electric vehicles lies in demand and supply management. Such added value is provided through means like monitoring and control. IEC 61850-7-420 already addresses such means for distributed energy resources, like photovoltaic and combined heat and power systems. For such systems it defines appropriate object models as well as communication bindings in order to monitor and control a systems status. Based on these principles, this paper reviews relevant standards in electric mobility and points out particular requirements for electric vehicles. From that, it derives an extension to IEC 61850-7-420 in order to introduce a corresponding distributed energy resource information model for electric vehicles. The model is furthermore extended to various charging infrastructure scenarios in order to support aggregation over numerous electric vehicles. The proposed distributed energy resource provisioning mechanism for electric vehicles is validated with a proof-of-concept implementation. Hence, this work also provides validation of todays standardization efforts for electric vehicle in terms of grid integration.

A mutual charge schedule information model for the vehicle-to-grid communication interface

The increasing market penetration of plug-in electric vehicles also brings along a rising number of mobility service providers. This results in various business models competing against each other for the customers favor. As a result various smart charging approaches will be pursued. This might lead to major interoperability issues for V2G communications, if standardization bodies do not wisely address them. Hence, this work derives a generic V2G information model allowing for mutual charge schedule negotiations between EVs and grid operators. Major requirements are derived from a holistic system model and respected by the proposed design. The proposed information model allows for efficient handling of multiple tariffs for charging EVs.

Dynamic web service orchestration applied to the device profile for web services in hierarchical networks

Based on the idea of Service Oriented Architectures (SOA), Web Services paved the way for open and flexible interaction between heterogeneous systems with a loose coupling between service endpoints. The Device Profile for Web Services (DPWS) implements a subset of WS-* specifications in order to make the advantages of the Web Service architecture available to a growing embedded systems market. In this paper we are proposing a service orchestration mechanism applied to services on top of a DPWS-based middleware. The approach is complementary to the rather complex and resource intensive Web Service Business Process Execution Language (WS-BPEL) and focuses on service orchestration on resource constrained devices deployed in hierarchical network topologies. We validate our service orchestration concept through its resource consumption and illustrate its seamless integration into the service development cycle based on the underlying DPWS-compliant middleware.

Interoperability Testing Based on TTCN-3 for V2G Communication Interfaces

A future widespread use of electric vehicles requires the deployment of reliable and comprehensive battery charging infrastructures. The communication between all systems, which are involved in order to control the battery charging processes or enable flexible billing of charging operations, becomes an important factor in acceptance of electric mobility. It will be a highly distributed infrastructure in a multi-vendor, multi-network and multi-service environment with spatially separated and partially mobile components. The challenge is to ensure interoperability of such systems, consisting of different charge point operators, electrical grid components and multitude electric vehicles, through standardized data structures and reliable communication protocols. This paper describes an approach for protocol-aware interoperability testing of standardized Vehicle to Grid (V2G) communication interfaces based on a TTCN-3 testing infrastructure. This approach allows to evaluate the interoperability of such communication systems with appropriate testing methods and to build an experimental Automatic Test Equipment.

Interference analyses of Electric Vehicle charging using PLC on the Control Pilot

For charging Electric Vehicles (EV) a communication between the EV and the Electric Vehicle Supply Equipment (EVSE) is inevitable. The Low Level Communication (LLC) protocol IEC 61851-1 is based on a Pulse Width Modulation (PWM) and provides safety to the customers by detecting errors very fast, e.g if the EV is disconnected from the EVSE. High Level Communication (HLC) Protocols are needed for authentication, clearing and coordination of charging processes to prevent local substation blackouts. Powerline Communication (PLC) is the proposed ISO/OSI layer 1 and 2 technology for the High Level Communication protocol ISO/IEC 15118, which describes the Vehicle-to-Grid Communication Interface in case of conductive charging. Both HLC and LLC use the same communication medium, the Control Pilot integrated into the charging cord. This work introduces an electric mobility test- and development-environment for communication systems and in particular an ISO/OSI layer 1 and 2 test bed. With this testbed the interferences on PLC, that are caused by the PWM signal and vice versa can be analyzed regarding PLC data rate and the limitations of IEC 61851-1. It is illustrated, that PLC has a performance loss of up to 66.3% for inappropriate PWM parameters. The interference analyses of PLC on the PWM signal for HomePlug AV has depicted, that the PWM signal with superposed PLC has a higher standard deviation but the limitations of 61851-1 are adhered.

An ISO/IEC 15118 conformance testing system architecture

A major goal for the ISO/IEC15118 standard for controlling the charging process for electric vehicles is the simplicity and reliability of use. Severe threats for a simple use are implementations of the standard which are not interoperable to each other. A traditional approach to reduce this threat is the setup of testivals between all implementations to explicit test interoperability. However this approach is complex and expensive as it requires extensive test and the coordination between all implementers. The project eNterop takes a different approach to enable a broad acceptance of the ISO/IEC 15118 and IEC 61851 specification on the market and to facilitate a large number of implementations. It defines conformance tests which can be fully automated. This is a quite new approach for machine to machine interface specifications which not only cover communication but also power interfaces. With that implementers can independently test their protocols including the power flow control and increase the likelihood of interoperable implementations without expensive testivals. This paper presents the approach of conformance tests for combined communication and power interfaces.