OPC UA Makes Smart Utility Distribution Systems Possible

Most of us don’t give much thought to the major utilities until one or more do not work or price goes up. In Poland 15% to 20% of generated heat is lost in transit from the manufacturer (Combined Heat & Power plants) to consumers, which gives a value of hundreds of millions of euro a year for several biggest national networks. In most cases, nonrenewable conventional fossil fuel must be used up in order to produce that heat, i.e. natural resources must be depleted and the environment must be polluted.

Following the concept of smart grids, more and more companies decide to start working on smart utility distribution systems (gas, water, chilly water, or even oil) to improve the performance and availability, and enable the consumers to monitor consumption and have effect on its economical use.

An example is the heating system of Warsaw that is the largest centralized district heating system in Poland and one of the largest in the world. Through the district heating network common for the whole city area, it provides heat to almost 19 thousand buildings in Warsaw, thus satisfying ca. 80% of the demand. This municipal heating system consists of almost 1700 km of network. Power transmitted from the sources amounts to ca. 5200 MW. Ca. 10000 GWh of heat is supplied to the consumers via the heating network.

Important components of the heating system that are involved in heat transmission to the customers are (read full case study):

  • Water pumping stations
  • Consumer exchanger substation
  • Heat chambers

Generally speaking, the task of the “smart distribution” is to support all processes that will make improvement in its operational performance possible. Therefore, with the aim of optimizing processes, the solution should provide:

  • Availability management
  • Costs management

Usually the above tasks are contradictory to some extent, e.g. when minimizing the cost we cannot ignore the consumer’s needs.

Optimization is a method of determining the best (optimal) solution. It is a search for an extreme of a certain function from the point of view of a specific criterion (index) (e.g. cost, temperature, time, etc.).

The selection of the indexes depends on many factors, but in any case we need real time and historical data gathered from highly distributed process control devices (PLC, distributed I/O, meters, etc.) to provide optimal process control. In the example described above up to 500 000 values is expected to be measured for this purpose.

In order to make a design and analysis of such an elaborate system possible, it is necessary to distribute certain function groups that are logically relevant to each other, using the compound system concept. A well-defined functionality boundary must be a distinguishing feature of each system of that type. To perform their functions, those systems must communicate creating mutual links.

To fulfill the above requirements of Smart Utility Distribution Systems we need the following subsystems:

  • Optimization: supervisory and optimal control of the real-time processes
  • Telemetry: remote control and data acquisition
  • Repository: database management systems to archive process data

To make this architecture deployable and, next, maintainable some critical issues must be addressed:

  • Openness – components communication is based on a common open standard
  • Unified data access – real-time, historical and metadata must be available to all clients using a common publishing mechanism
  • Complex data – with the goal to protect data integrity, complex process data must be supported
  • Security – the strategic nature of these systems requires appropriate security protection against malicious attack
  • Internet technology – it is obvious that Internet technology must be used on the data transportation level between the systems even if we are going to build a separated private network

In my opinion, the only answer to the question how to meet these requirements is OPC Unified Architecture (OPC UA). It is a set of specifications for the development of software connected such systems as ERP, SAP, GIS, MES or process control systems. These systems are designed for information exchange and they are used for the control and supervision of real-time industrial processes. OPC UA defines the infrastructure modeling concept in order to facilitate the exchange of process data. The whole architecture of the new standard improves and extends the previous OPC (now called classic) capabilities in the field of application security, stability, event tracking and data management, thus improving interoperability of the distributed architecture components.

OPC UA permits easier cooperation and data exchange between the process control and business management layers. It is designed so as to support a wide range of devices from the lowest level with PLCs to the distributed systems dealing with IT management in an enterprise.

It is worth noting that OPC UA technology is based on services and objects. For more than one decade the software authors have been using solutions based on objects and services but those solutions have never been transferred directly to industrial applications. OPC Unified Architecture has become the first standard close to the technological process that is of a dual nature, both object oriented (Object Oriented Architecture – OOA) and service oriented (Service Oriented Architecture – SOA).

The application of the OPC Unified Architecture standard as a foundation for the proposed architecture will enable us to:

  • Standardize communication between component systems
  • Create a consistent information model that is available to all systems and illustrates the system structure
  • Create a database model (metadata) based on a OPC UA information model, thus giving applications that use Repository access not only to process data but also to metadata describing the system objects
  • Provide open solutions, i.e. the possibility of free connection of the next components in the future
  • As OPC UA is Internet technology it could be used to build even global solution

The OPC UA standard allows us to get an open, interoperable and scalable architecture, thus making the development of the infrastructure and its use for other tasks in the future possible. As the proposed architecture is based on the open connectivity standards it provides a framework for the integration of highly distributed “islands of automation” with top-level applications employing the artificial intelligence idea to optimal control of the Distribution Network as a whole.

See also

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One thought on “OPC UA Makes Smart Utility Distribution Systems Possible

  1. […] OPC UA Makes Smart Utility Distribution Systems Possible: Following the concept of smart grids, more and more companies decide to start working on smart utility distribution systems (gas, water, chilly water, or even oil) to improve the performance and availability. The process is dispersed geographically and partially managed by independent operators. An active role of ultimate consumer is very important. […]

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