Powerlink Queensland

As part of a series of turnkey projects undertaken in 1999, Powerlink introduced an integrated substation design known as Intelligent Plug and Switch System - iPASS - an outdoor hybrid switchgear solution with intelligence built into the primary switchgear. This article will examine an IEC 61850 based SAS solution that is being considered as a favored upgrade option for Powerlink’s iPASS secondary system replacement project.

The Queensland – New South Wales Interconnector (QNI) included the establishment of four substations constructed as part of a series of turnkey projects commencing in 1999.  Under these projects an integrated substation design known as Intelligent Plug and Switch System – iPASS was introduced to Powerlink’s Transmission Network. These substations are now the backbone for an essential system interconnection, and the ongoing reliability and supportability of the substation design is imperative.  Subsequent to the QNI project, the use of the iPASS technology was extended to two more substations within Powerlink’s Transmission Network.  Powerlink is now planning the replacement of all iPASS secondary systems including the electronics mounted on the primary equipment prior to 2013.

The iPASS system is an outdoor hybrid switchgear solution with intelligence built into the primary switchgear.  There are different electronic modules used for the control and supervision of the switchgear (Circuit Breakers and Disconnector / Earthing switches) and the acquisition of the current / voltage samples (for control and protection functions) are derived from the Non-conventional Instrument Transformers (NCIT).   The electronic modules are an integral part of the Substation Automation System (SAS) that interface with the bay-level equipment using a proprietary fibre optic process bus. 

In 2004 the UCA Users Group released an Implementation Guideline for a digital interface standard using IEC 61850-9-2 process bus for the transmission of current/voltage samples.  This is also referred to as IEC 61850-9-2LE (Light Edition).  There have been several pilot projects implemented world-wide that support the new interface convention.  However, there are only limited automation devices available on the market which provide IEC 61850-9-2LE interface connectivity.  Since the release of the Implementation Guideline, companies have implemented the new interface standard in Merging Unit devices (MU) and bay-level devices of their current protection and SAS platforms.

This article focuses on the application of Sampled Value (SV) process bus according to IEC 61850-9-2LE using current MU technology for the transmission and distribution of SV data streams to control and protection applications.  It looks at different secondary system architectures and MU configuration options and analyzes the protection system reliability aspects in order to successfully deploy new technology in Powerlink’s future iPASS secondary system replacement projects.