After a heavy investment programme to expand the power network in Victoria, Australia, quality and reliability became an issue that demanded a new measurement and control system.
As Victoria’s largest electricity distributor, Powercor Australia owns and operates a distribution network that delivers electricity across 76 000 km of circuits to more than 600 000 premises throughout Western Victoria, from Melbourne’s western suburbs to the borders of South Australia and New South Wales.
Powercor recently embarked upon a major endeavour to upgrade 55 zone substations, plus several strategic customer related installations, with a network of intelligent energy meters and software. The goal of this upgrade was to provide Powercor engineers with the tools to remotely monitor and control conditions at each zone substation, and to help them optimize power quality and reliability across an entire distribution network spanning more than 74 000 distribution substations.
Out with the old
According to Joe Thomas, network planning manager for Powercor Australia, the decision to upgrade the company’s distribution network was motivated by several factors, not least of which was an industry regulator’s requirement to report any voltage fluctuations occurring at the 22 kV supply points of each zone substation. To align with annual network performance targets set by Victoria’s Essential Services Commission, Powercor maintains ’Guaranteed Service Levels’ as a commitment to provide its customers with a consistent level of reliable, high-quality service.
To help ensure a safe, reliable and high-quality electricity supply, the company’s Network Planning Group identified a need for remote access to detailed energy metering data from each zone substation, plus the tools to help pinpoint potentially damaging conditions such as excessive harmonic frequencies, sags and swells, transients, and phase unbalance. “Aside from a few protection relays, the zone substations originally offered very basic equipment for metering, and no capacity for monitoring power quality conditions such as transients or sags and swells,” explains Thomas. “We knew that a more comprehensive system for monitoring energy would provide our Network Planning Group with the type of detailed metering data necessary to make informed system-augmentation decisions.”
Powercor Australia’s network delivers electricity across 76 000 km of circuits from Melbourne to the border of New South Wales.
According to Thomas, the Network Planning Group also needed a way to gather accurate consumption data to better assess customer usage patterns, and proactively prepare for periods of increased power consumption. “Although energy consumption is high throughout Australia’s winter months (June through August), demand increases significantly in the summer (December through February) mainly due to the increased use of cooling equipment such as air conditioning and cooling storage units,” says Thomas. “We knew that creating a profile of energy consumption across the entire distribution network, and using this information for trending system quantities on an ongoing basis, would be invaluable for supporting decision making.”
To meet these requirements, Powercor installed an Ion Enterprise Energy Management (EEM) system from Power Measurement. With the assistance of Eltec Energy Services, Power Measurement’s regional representative, Powercor equipped its zone substations with Ion 7600 or Ion 7700 intelligent energy meters, and connected the meters to a centrally located computer workstation running Ion Enterprise energy management software. Each energy meter was then configured to collect detailed power quality and energy data at the source, and provide it to the Ion Enterprise software server located at Powercor’s head office. Once the EEM system was brought online, the software could automatically monitor each meter in the network, analyze the data, and notify personnel of any threats to power quality or reliability.
Because of the remote locations and considerable distances involved, each meter was equipped with an expanded onboard memory to accommodate additional data in the event of a communications interruption. Although the meters currently communicate with the head-end software via modem, Powercor is in the process of upgrading its communications network to Ethernet over fibre for improved speed and reliability.
With the use of the Enterprise Energy Management system, the network planning team is now able to develop a profile for each substation supply point enabling more efficient distribution.
At each zone substation, the Ion meters measure electricity delivered to the substation at 66 kV, and leaving the substation at 22 kV. Additionally, they monitor power quality parameters such as sags and swells, transients, harmonics, flicker, voltage unbalance and current unbalance. In order to monitor consumption across the entire distribution network, the system automatically records total kWh as interval data logs, and presents this information as monthly reports. In the near future, the company plans to install additional meters at the terminal stations that supply power to the Powercor network.
Challenge of harmonics
The end result is an enterprise-wide energy management system that provides real-time power monitoring and control capability across the entire distribution network. With 24-hour access to each zone substation, energy managers can now review real-time conditions and logged system data from multiple metering points to help determine effective maintenance strategies, or assess potential trouble spots. The system can also deliver alarm notifications to alert staff of any conditions requiring an immediate response. For example, the ability to trend harmonics is considered to be a key benefit of the system. If left unchecked, harmonics can cause severe damage to electrical equipment, overheating transformers, conductors, capacitors, and motors. “Due to the many new and varied technologies used by our customers, harmonics are an ever-increasing challenge,” confirms Thomas. “But with our improved power-quality monitoring capabilities, we can quickly identify potential trouble spots and take corrective action before reliability can be affected.”
The new system optimizes power quality and reliability across a network spanning 74 000 distribution substations.
The ability to remotely identify potential trouble spots has also helped Powercor improve reliability through enhanced awareness, increased efficiency, and reduced response time. Although Powercor employs comprehensive mitigation strategies to help minimize supply interruptions caused by bushfires, pole fires and wildlife, occasional damage or disruption along a line may occur, resulting in potentially damaging variations in voltage levels. By pinpointing the source of a problem and alerting staff, Powercor’s energy management network can help maintenance crews respond quickly and efficiently to minimize damage and correct any threats to reliability.
Powercor recently used its enhanced metering capability to monitor the effect of a hot water peak load which existed on a very weak network. “Our data illustrated how the distribution system tended towards voltage instability,” explains Thomas. “Using the system, we identified voltage regulators that were unable to coordinate or respond fast enough, and were able to quickly address the situation.” Although Powercor’s Network Planning engineers are among the EEM system’s primary users, the detailed energy information it provides has also proven useful to protection engineers, operations engineers, and regional managers throughout the organization. Additionally, the meters’ high sampling rate supports an increased level of power quality analysis that helps staff identify geographical areas that may be more susceptible to transient events. This capability also allows Powercor’s network planning team to view actual network voltages as a result of changing system conditions, and to develop a profile for each zone substation supply point. With this combined information on transients, sags and swells, personnel can better understand plant capability requirements across each segment of the network.
By upgrading its zone substations with advanced power monitoring and control technology, Powercor Australia now has the tools to track energy consumption, analyze power-quality conditions, and maximize reliability throughout its extensive distribution network. By investing in this sophisticated software, the company can offer a reliable and high quality electricity supply to its customers.
Anthony Tisot, Power Measurement, Australia