FITNESS - Future Intelligent Transmission NEtwork SubStation

by Priyanka Mohapatra, Fraser Ainslie, and Craig McTaggart, SP Energy Networks, UK

FITNESS is a 4-year innovation project awarded funding under the Network Innovation Competition (NIC) mechanism by the GB Regulator, Ofgem, due to conclude in 2020.
SP Energy Networks (SPEN) is the part of Scottish Power UK plc, which owns and operates the electricity transmission and distribution network of southern Scotland and the electricity distribution network of Merseyside and North Wales, serving 3.5 million homes and businesses in three of the GB's largest cities (Liverpool, Glasgow & Edinburgh), as well as three large rural areas (North Wales, Scottish Borders and Dumfries & Galloway) (see page 46).

FITNESS Drivers & Benefits
The latest substations on the SPEN Transmission Network incorporate the IEC 61850 8-1 standard for the Station Bus. The deployment and demonstration of fully integrated control and protection across Station Bus and Process Bus represents a significant technological leap for SPEN but one that offers a reduced outage and low risk approach to future substation design and operation by enabling faster deployment, improved safety, greater availability and controllability, with a reduced footprint and at lower cost than conventional design.
The main goal of FITNESS is to pave the way for TOs and DNOs to adopt the IEC61850-9-2 sampled values (SV) approach to future new build and refurbishment to ultimately reduce overall life-cycle cost of system operation. The article focusses on the business case for digital substations in the GB; the final architecture for deployment is still under work and will be available by Q1 2017.

The experience of demonstrating interoperability between vendors will offer key learnings for industry stakeholders worldwide and identify any gaps in interpretation of standards for international standards committees. Through the pilot project, FITNESS will substantially de-risk the implementation of IEC 61850 for Transmission and Distribution Network Owners (TOs and DNOs) and System Operators (SOs) in the GB. (Figure 1).
The live pilot installation will bridge the gap between the limited trials completed to date and the full system integration and experience of the substation instrumentation system required to make a strategic step change of the business-as-usual practice to the design of substations in the near future.

This transition, however, will not be easy. The integration of a completely digital substation, particularly on the Process Bus, introduces many radical innovations in GB:
1. Integration of protection, monitoring and control functions in a digital substation using Process Bus architecture, in contrast to previous trials of individual subsystems that focused on protection only
2.Novel sensor technology including Non-Conventional Voltage Transformers (NCVTs) and distributed optical sensor technology, not yet commercially released, integrated with the sub-station instrumentation
3. Information coordination showing the use of novel measurement sources to satisfy current and emerging information services without the conventional constraints on connecting devices, and demonstrating new analysis capabilities in fields of synchrophasors, fault diag-nostics and harmonics
4. Wide area control infrastructure, providing the substation functionality to support emerging quality and latency requirements for frequency and stability controls, and constraint management

The widespread adoption of the practices and technologies demonstrated in FITNESS is expected to result in significant financial, operation, environmental and safety improvements.
Dependent on the level of uptake of the digital substation the predicted financial savings up to 2050 in GB alone are in the range of:

  • 10% of substation costs equating to £572m-£858m
  • 4.75% of network congestion costs due to planned outages equating £260m-£592m

Reduced Substation Size and Cost: Substation costs that are related to substation functionality and operation include primary and secondary equipment, cabling, and engineering and commissioning. Engineering and commissioning costs are reduced by maximizing the amount of testing at the factory and minimizing the amount of testing required on-site. Substation costs related to civil works, project management and design in new build or replacements require large investment, can be reduced by smaller physical size, fewer supporting structures, and smaller cable ducting and reducing engineering effort. A significant contribution to the minimization of these costs is through standardization of design, equipment and procedures.
Figure 2 highlights the projected reduction in substation bay costs based on the type of replacement.

Improved Operational Flexibility: FITNESS addresses a number of areas where operational costs can be reduced through reduction in the number and length of planned outages. Planned outages for maintenance and refurbishment constrain the network and power flow. Currently majority of the testing is done on site, unplanned delays in site commissioning and tests further add to the costs of the TO and DNO.

BeijingSifang June 2016