Electricity + Control November 2016

ROUND UP

DRIVES, MOTORS + SWITCHGEAR

MPTC protects against gas supply interruptions

ABB has released the first variable speed drive control software that uses Model Predictive Control to regulate the drive’s torque.The MPTC software was initially developed to ensure the operation of compressor stations dur- ing voltage disruptions, caused by lightning strikes, winter storms or ice build-up on power lines. The stations use large compressors, up to 50 MW, to compress natural gas for travel through hundreds of miles of pipeline. Historically gas turbines pow- ered the compressors, today, more effi- cient large synchronous electric motors are used.The motors are controlled by variable speed drives, such as ABB’s largest drive, the MEGADRIVE-LCI.

When power supply disruptions hap- pen, protection systems quickly shut down the compressors. This halts the supply of gas. Restarting compressors lasts from a few hours to days. The resulting interruption in the gas supply can mean financial losses that range into the hundreds of millions USD per year for large facilities. Installed in the MEGADRIVE-LCI, the MPTC uses a control algorithm based on Model Predictive Control that en- sures the operation of the drive during power and grid disturbances in order to provide the compressor with partial torque, preventing the compressor from going into surge. The MEGADRIVE-LCI application is

the first where MPTC is used to control a commercial multi-megawatt drive system with much faster dynamic behaviour, where the underlying opti- mization problems need to be solved in less than a millisecond. Live testing of the software was done over the winter at two Statoil gas facilities in Norway. It was installed on ABB MEGADRIVE-LCIs used to power two 42,2 MW compressors at a gas processing plant in Kollsnes, and three 7,5 MWbooster compressors in Kårstø. The control software successfully protected the compressor operation during voltage dips. Enquiries: Vilma Lindell. Email vilma.lindell@fi.abb.com

Portable oscilloscopes

Mini subs mitigate against vandalism Electrical substations pose a number of unique challenges including vandalism and the theft of copper. This is especially true for mini substations, which are often located in residential areas and in remote rural areas, and applies to those owned by power utilities as well as private owners. While larger substa- tions are often protected using surveillance equipment, this is not always feasible with mini substations and apart from the unnecessary disruption of electrical services, the damage done to these installations could have potentially lethal consequences for maintenance personnel.Working in collaborationwith Eskom, WEG Transformers Africa (WTA), part of the Zest WEG Group , developed a vandal proof mini substationwhich is now approved by the power utility. Andre Mans, chief operating officer of WTA, says that this approval is very important as it confirms the functionality as well as reliability of the vandal proof mini substation. “This level of approval not only underpins that the mini substation meets all the criteria but also gives absolute assurance to the marketplace,” Mans says. Notably, the mini substations are targeted at both power utilities and private end users.TheWTA vandal proof mini substations are ideal for installation in high risk areas.The entire enclosure, including doors and lock protec- tion facilities, are constructed from 6 mm steel with the doors being specially reinforced.The four way locking mechanism is complemented by heavy duty door hinges.The transformer unit is sealed, further protecting the installation. Enquiries: Kirsten Larkan.Tel. +27 011 723 6000 or email marketing@zestweg.com

for harsh industrial

environments Fluke , represented locally by the Comtest Group , has on offer the first high- performance portable oscilloscopes with two or four independently insulated input channels, an IP51 dust and drip wa- terproof rating and a CAT III 1000V/CAT IV 600V safety rating. Users can choose from 500 MHz, 200 MHz, 100 MHz or 60 MHz bandwidth models. Especially designed for plant maintenance engineers, there is a choice of either a 2- or 4- channel scope for the harsh conditions or industrial electronics. A 5 000 count digital multimeter (DMM) is included in the 2- channel models. The 190 Series II has up to four independent floating isolated inputs, up to 1 000V and a real time sampling of up to 5 GS/s (depending on model and channels used). Frequency spectrum using FFT-analysis and automatic capture and REPLAY of 100 screens, as well as a deep memory of 10 000 points per trace waveform capture (scope mode), are all features of this new generation oscilloscope. 190 Series II software: • Connect-and-View triggering for intelligent, automatic triggering on fast, slow and even complex signals • ScopeRecord Roll mode gives 30 000 points per input channel for low frequency signal analysis • TrendPlot paperless recorder mode with deep memory for long- term automatic measurements Enquiries:Tel. +27 (0) 10 595 1821 or visit www.comtest.co.za

Electricity+Control November ‘16

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