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Integrated Architecture and Programming Model for Distribution and Microgrid Automation

Short description
This idea proposes practices known as integrated architecture for the design and deployment of distribution automation computing and communication infrastructure. By giving parallels to the ongoing efforts with the AUTOSAR standard in the automotive industry, we argue that in order to keep increasing software development costs low, the power systems industry has to go beyond current standards such as IEC 61850. We identify a technical problem with these standards and suggest a solution based on a programming model with clearly defi ned semantics. We discuss business models and bene fits of the integrated architecture approach for all main stakeholders. We present data and references to the U.S. power market.

Please see the attached document for more detailed idea description.

Motivation and Market Drivers:
The introduction of advanced communication and control technologies, together with integration of new generation sources, loads, and power electronics, will soon have a strong impact on distribution automation (DA). According to [1] only about 10% of utility operated substations in North America have been fully automated and integrated by year end 2010. The North American spending for substation automation will grow from current $500 million to $10 billion. Moreover, the global investments in smart grid's DA are predicted to total $46 billion over the next five years [2].

However, this added functionality increases system complexity and introduces new sources of uncertainty. Utilities and equipment suppliers are faced with challenges to improve system reliability and restoration capability. For instance, in its recent DA project Sacramento Municipal Utility District put forward 25% reduction in SAIDI reliability indicator [3]. A truly reliable grid does not just react to emergencies, but predicts and prevents them. The Electric Power Research Institute animation shows how the virtual power plant concept can be leveraged to improve grid reliability as an alternative to installing additional grid infrastructure As the smart grid evolves, the substations will be upgraded as warranted, based on load growth and criticality to customers. In addition, software updates will be needed to maintain operation without infrastructure improvements.

Thus, the combination of the mentioned requirements (increased functional complexity, extensibility, and flexibility) demands advanced design methodologies for the underlying communication and computation architecture.

Technical Approach:
This idea proposes principles of Integrated Modular Architecture (IMA) for the design of DA computing infrastructure. IMA has been introduced in avionics [4], and has recently made inroads in other sectors such as automotive. As opposed to traditional Federated Architectures (FA) where each function has its own independent fault-tolerant computing resources, IMA architecture consists of a network of standardized computing modules each capable of supporting multiple functions at different criticality levels. Even though FA has inherent fault containment, it is often coupled with massive use of redundant resources which actually decreases reliability and increases costs. The IMA approach is scalable, and provides improvements in reliability, maintainability and size. Among important goals of IMA are that applications are neither impacted by the underlying hardware nor by the very process of upgrading the applications. In IMA the applications are moved from one computing module to another without loss of functional and time correctness, possibly even through a dynamic reconfiguration.

Consider substation communications standard IEC 61850. It allows the development of a new generation of substation protection, automation and control systems [5], and according to [1] is increasingly used among largest US utilities. In particular, IEC 61850-9-2 Process Bus concept proposes digitizing transformer outputs at the sources and communicating this process level data over the LAN to the protection and control devices. Some of the advantages of process bus technology are in reduction of copper cable costs and in elimination of safety related problems, e.g. open current circuit condition. However, the straightforward implementation of a process bus solution requires introduction of multiple computing components where previously only a single multifunction relay was used. Namely, it will consist of the following hardware components at each protection point: merging unit (digital interface to sensors), relay, breaker controller, network switch, and timing source. Such a solution will likely suffer from a decrease of reliability with each introduced dedicated component. Some applications such as differential protection schemes do require distributed solutions, but in many cases multiple functions can be mapped into a single physical device. In the Integrated Modular Architecture approach the process of mapping functions to devices can be optimized according to utility or user requirements. IMA offers such a partitioning through protection mechanisms that allow resources like memory to be shared by multiple applications potentially with multiple criticality level.

Some of the existing or prototype technology fits IMA approach well and could be further built upon. For instance, in test and measurements industry, it is becoming more common to have single computing boards comprising of a processor, programmable logic and high performance I/O. Beside other functions the processor offers networking and floating point computation. The programmable logic provides reconfigurable high-speed processing and low-level access to hardware with custom timing and triggering. On the communications side, recent networking protocols such as Ethernet-based IEEE 1588 time-synchronization protocol can be used to enable all communication be performed over a single local area network. IMA, with its common interface to access the hardware and network resources, simplifies hardware and software integration.

Please see the attached document for more detailed idea description.

[1] Newton-Evans Research Company, "Worldwide Market for Substation Automation and Integration Programs in Electric Utilities: 2011-2013",
[2] Pike Research, "Distribution Automation",
[3] Sacramento Municipal Utility District, "Distribution Automation Project",
[4] James W. Ramsey, "Integrated Modular Avionics: Less is More",
[5] Damien Tholomier and Denis Chatrefou, "IEC 61850 Process Bus - It is Real!",

Key benefits
- Technology vendors: IMA enables decoupling of software design from the hardware platform design. Reuse of software components. Vendors can serve as integrators, service providers, tool developers or conformance agency.

- Utilities: Increased functional complexity, reliability, extensibility and flexibility leads to improvements in operational efficiency. Working with (multiple) vendors to differentiate their services.

- Regulators: Better way to measure policy compliance and social benefits of utilities.

- Consumers: Increased reliability (e.g. industry, hospitals, military), service quality, and energy conservation. Innovative energy products offered on a deregulated market.

Keywords / TAGs:
Smart Grid Distributed Automation Microgrid Integration Reliability Hardware/Software Architectures

Virtual Powerplant , Microgrid, Other



Status: in discussion

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Number: 000703

Submitted on: 08.06.2011