By Dorothy Moryc, P.E.
Wholesale conversion is rarely an option for an established utility wanting to engage in substation automation. As any utility will agree, the equipment and installation cost associated with a complete conversion can be exorbitant. In addition, most will have an existing infrastructure that is far from reaching the end of its useful life. How can a utility transition to an automation scheme while preserving existing technology investments?
The answer is through integration.
This was the challenge facing Waterloo North Hydro Inc. in Waterloo, Ontario, Canada when we found ourselves managing a new 230-kV transformer substation project. Waterloo North Hydro is a municipally owned utility serving approximately 43,000 customers over 250 square miles. Peak load for the utility is 250 MW, comprising mainly residential and institutional loads. While we had two existing high-voltage transformer stations, rapid growth in the region led to the need for a third substation to handle anticipated load growth.
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Waterloo North Hydro’s transformer station #3.
Our short-term goal when engineering the new substation was to invest in full-scale automation capabilities at a reasonable cost at the site. At the same time, the long-term intent was to leverage the capabilities of this new substation to develop a network incorporating our two existing transformer stations. In doing this, we were able to achieve a fully integrated, fully redundant network flexible enough to handle ever-increasing load growth, while minimizing the capital costs normally associated with full-scale substation automation.
At the heart of Waterloo North’s new integration scheme was the desire to be able to control any point from more than one location in addition to traditional setups: at the control room via the SCADA master, locally via a human machine interface (HMI), and manually.
Facilitating this required as much soft control as possible. The premise was: If something can be controlled via software, then we would always have the option of configuring whatever system we chose now or in the future (in addition to, or perhaps instead of, the existing systems) to access that control point to operate it.
Our other objectives included having added functionality at both the SCADA and intelligent electronic device (IED) interfaces at the new site. We wanted the IEDs to be configurable from a local HMI or remote network connection at the central office using the IED software tools. We also needed the SCADA interface to ensure that there are no missed events from the IEDs or physical status inputs.
The local HMI needed to be capable of remote monitoring and control, alarm notification, systems communication, metering and data logging, and other functions. In other words, it needed to act as a mini SCADA master. Our vision was to have this local HMI accessible over Ethernet from the existing transformer substations or the office so we could operate the station remotely even if the SCADA master was not able to do so.
With Ethernet connectivity at all sites, we also wanted to be able to use the SCADA client software to monitor and control all stations connected to our SCADA master from any of the substations. This would allow us to set up a backup control room at any of the substations (provided that our SCADA masters remain operational at the head office location). Not only does this limit required equipment investment, it increases system reliability as well as our long-term cost savings, while adding considerable overall functionality.
Relay and Communications Technology
Relay and communications technology was an area where we knew we could increase functionality and keep costs in line. The challenge was finding equipment that would do that, as well as provide the modularity and flexibility to serve our interests over many years without having to be replaced.
Waterloo North chose to deploy Universal Relay (UR) and JungleMUX multiplexer technology from GE Multilin in Markham, Ontario. As microprocessor-based relays, URs provide microprocessor-based control and communications capabilities using open standards. We believed they could provide the flexibility, configurability and Ethernet accessibility we were seeking. Waterloo North was accustomed to working with older technology, including electronic relays, so this shift to an Ethernet-based approach was a new direction, but a necessary one given the anticipated demand for increased reliability and our need to guarantee that reliability while managing capital costs.
The URs’ programmability and expandability means we can increase I/O functionality simply by adding or switching cards. At the same time, the open communications allows us to maximize functionality through access to our existing fiber infrastructure.
Building an Integrated Network
This new design approach laid the groundwork for integration with Waterloo North’s other two transformer stations. Two sub-LANs in a mirror image configuration are located at the new site. Each set of relays communicates over the fiber-optic network via a hub to the remote terminal unit (RTU).
JungleMUX multiplexers at each site and head office provide optical transport of applications over the fiber-optic network to allow for communications between nodes in the field and the central office. The three transformer stations are fully connected over a redundant fiber-optic network, with the JungleMUX device acting as the bridge to connect the disparate LANs at the three sites to the SCADA LAN at the main office. A router at the head office manages network traffic to ensure secure communications between authorized users at the corporate LAN and remote users on the SCADA LAN and all three transformer sites. This set-up allows Waterloo North to facilitate transport of information between SCADA master and SCADA remote users; provide facilities for setting up a backup control room; and facilitate transport of information between the transformer station #3 (TS #3) HMI and remote users for remote control of TS #3 via the HMI WebClient software.
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Dorothy Moryc, Waterloo North Hydro’s stations and planning engineering supervisor, configures relays, RTU, and JungleMUX optical multiplexer from the local HMI at transformer station #3.
While many switching technologies are restricted to Ethernet-only products, the JungleMUX allows for multiple interfaces, including PBX, RS232 and Ethernet, to improve protective relaying communications. What makes this design so powerful is the combination of the IEDs and JungleMUX. Without the JungleMUX connections, operation or configuration could only be done at the station. With these connections, however, operation or configuration can be done from any Ethernet connection at any of the JungleMUX nodes (i.e. at the office or stations). Similarly, if we had the JungleMUX without IP-enabled relays, we could not access them over a high-speed link such as the Ethernet connection.
The new substation went live in July 2002, and integration of the two existing transformer stations over the fiber-optic network was completed. Now that the network is fully integrated, Waterloo North has realized a number of benefits beyond faster communications, improved equipment flexibility and systems reliability. The fiber optic-network also reduced substantially the amount of traditional wiring required inside the station, which translated into additional savings in associated construction time and costs.
Because the relays are modular, Waterloo North has reduced inventory and spare parts requirements, as well as maintenance costs and time. In the event of a repair or upgrade, we can simply interchange I/O cards between relays without removing the entire unit for repairs.
For any utility today, it is an ongoing challenge balancing innovation with available resources and customer needs. At the same time, the pace of technology makes it difficult for utilities to respond to market pressures, which is why it is crucial to build in as much flexibility as possible. Waterloo North is hoping that with the modularity and expandability offered by the technology we have chosen, we can extend the useful life of the products and protect our investment while enjoying all the benefits of full-scale substation automation.
Dorothy Moryc has been with Waterloo North Hydro Inc. for five years, initially as a stations designer and now as the stations and planning engineering supervisor. She is responsible for all design aspects of new or existing transformer substations, including project scheduling and management. Dorothy holds a degree in Electrical Engineering from University of Waterloo and is a member of Professional Engineers Ontario (PEO).