Bringing process and power together

Managing the process and the power systems that serve it through a single integrated control system offers significant benefits, writes Ramachandra Karamongikar:

Systems that serve process automation and power automation within the same plant are generally separated, both by a lack of common communication and architectural standards as well as differences between company departments.

Intelligent electronic devices (IEDs) - both those used for electrical protection and those used for control - are coupled by hard-wiring or serial interfaces. Because of the extensive cabling needed and the large number of available protocols, the bandwidth and cost-efficiency of this approach is very limited.

These complex set-ups can typically result in solutions having to be implemented on a project-by-project or even device-by-device basis. The multiple systems also require multiple databases, additional engineering tools, different operator stations, and more system administration and maintenance.

However, this costly reality for many industrial and power generation plants can be eliminated by integrating process automation and power automation into the same plant control system.

This creates a single automation environment that unifies the control of process-related equipment as well as protection, control and monitoring of substation equipment and power transmission and distribution.

Integrating the process automation system with the power automation system allows a single overall strategy in the areas of engineering, operations and maintenance. Whether you generate power or consume it, the economic benefits of electrical integration can run into millions of pounds, either through increased production or reduced operating costs.

Acknowledged as the global communication standard in substation automation, IEC 61850 represents a huge step forward in simplifying the integration of protection and control IEDs.

With its standardised model of the IED and its data and communication services, IEC 61850 ensures interoperability between electrical devices from different vendors and is able to replace all the typical protocols found in the substation automation domain.

Electrical integration extends the scope for asset management tools to include not only typical process automation equipment, instrumentation and field devices but also to include equipment, instrumentation and devices from electrical power generation and distribution as well.

The resulting architecture provides operators and maintenance personnel with current process information plus all relevant electrical asset information. This includes the potential for remote access to all equipment diagnostics from the same maintenance workplace.

To achieve this, IEC 61850 uses a mainstream communication technology, manufacturing message specification (MMS) over Ethernet for vertical communication with a higher level control system together with a second generic object orientated substation event (GOOSE) protocol for high speed horizontal peer-to-peer communication between IEDs.

Vertical communication uses the full MMS stack and is intended for the vast amount of data shared between the control system and the IEDs. Horizontal communication, using the special GOOSE messaging, allows high-priority data to go directly between the IEDs, replacing traditional hard-wired signals.

The benefits of electrical integration include reduced investment cost through one integrated system, improved operator effectiveness and collaboration across all areas of the plant and reduced maintenance costs through using one common maintenance strategy for the entire plant.

It can also provide an enhanced energy reduction program by improved visibility into power consumption. For industries such as oil and gas and power generation plants, 24/7 availability and reliable electrical supply are paramount, while for industries like pulp & paper, managing electricity as a raw material costs takes precedence.

The main objective of a power management system is to avoid blackouts in industrial plants, especially those with in-house generation, critical loads or insufficient supply from the electrical grid.

One critical functionality of a power management system is load-shedding; keeping critical loads running should incoming power be lost. Non-critical loads are shed to keep critical parts of the plant running.

With IEC60850 based electrical integration, load-shedding applications are now easier to implement particularly in situations where the Ethernet based GOOSE communications can be capitalised on such as situations where substations are physically separated over a wide area thus resulting in an even faster response time compared to hard-wired solutions.

The IEC 61850 integration allows the power management controller to behave like another IED on the station bus allowing it to communicate horizontally with other IEDs using GOOSE communications.

Load-shedding can be implemented using an Ethernet-based solution, which means faster trips, monitoring of trip data quality and reconfiguration of trip logic without re-wiring. This allows a faster response to power glitches, giving increased plant uptime by preventing blackouts.

With access to all critical electrical data, cost-sensitive producers can reduce their total consumption of electrical power significantly. An integrated system enables plant operators to see and understand power usage in a more coordinated manner, allowing new energy-saving opportunities and allowing existing reduction programs to be improved.

An increase in power consumption by a unit or area due to equipment malfunction and wear can quickly be remedied, while better visibility of power consumption and costs allows easier energy audits and benchmarking.
Intelligent motor starting, control and protection are a must if operators in heavy industrial segments are to stay competitive.

Their common aim is to secure power distribution at the same time as they reduce energy costs and greenhouse gas emissions.

The days of treating control and power as two separate entities are surely numbered and the progressive company seeking to cut costs and gain better visibility will increasingly come to see them as inextricably linked and part of a greater whole.

Ramachandra Karamongikar is electrical systems manager, oil, gas and petrochemical UK, at ABB Ltd