STER PMU portable phasor measurement unit is the integral part of the WAMSTER synchrophasor system.
STER PMU is an easy to use, portable (handheld) synchrophasor measurement unit (PMU) with a rechargeable battery backup and SD flash memory for more than 4 months of synchrophasor data. Contrary to a classic PMU unit, it needs no additional infrastructure to operate - it can use GPRS/UMTS to send data to a cloud server, or integrate with existing IEEE C37.118 equipment.
Portable PMU unit: Key features
- Small, lightweight (only 1.45 lb / 0.66 kg without accessories), easy to install, low-cost PMU device
- Battery backup for up to 5h of autonomy during power blackouts (or 8h if not communicating during the blackout)
- 4.5 months of full-speed synchrophasor measurements (with 32 GB SD cards), and 8 MB of installed flash memory for more than 1 hour of synchrophasor measurements during SD card replacement (up to 64 GB SD cards supported on demand)
- 10-min. harmonic/THD aggregates (min/max/avg)
- Up to 4 days of continuous waveform recording (3.2kHz, 8 channels)
- Base of the device is the handheld IEC 61000-4-30 A/S class analyzer
- Two 4-channel 16-bit A/D converters
- Three voltage ranges (150, 300 and 1000V), with configurable current/voltage transformer ratios
- Backlit 3.5" LCD display for configuration, measurements and diagnostics
- No additional infrastructure (no concentrator equipment, no cabling): data is sent over GPRS/UMTS to a cloud storage location
- Magnetic baseplate allows quick mounting of the device and accessories to the existing switchboard equipment
- No on-site configuration necessary
- Available as a single product (with IEEE C37.118 or other specific communication protocols on demand), or integrated with the WAMSTER service
For the end user, all the equipment necessary to start recording synchrophasors is included in a soft carrying bag: It takes only a couple of minutes to setup the wiring and signal ranges, as well as configure the SIM card settings and connect to the Internet. STER PMU can also be attached to the (optional) magnetic baseplate which is designed to pre-wire the device to the GPRS modem using as little area as possible, allowing instant attachment to switchboard doors and backplanes.
Equipped with a 3.5" backlit LCD display, all settings are easily visible and adjustable using the graphical user interface. This makes it simple to configure voltage and current transmission ratios, monitor real-time voltage and current synchrophasor measurements as well as diagnose and troubleshoot problems.
Wamster system is ideal for analyzing synchrophasor data during blackout conditions. Rechargeable battery can keep the portable PMU device operating for more than 4 hours without supply, including the supply for the GPRS modem. If the communication also breaks, device will continue storing measurements locally and report them to server when the connection is restored.
Up to 32 GB of SD flash memory
Without the SD card, internal flash memory is sufficient for storing around 2 hours of 4-phase synchrophasor data cyclically (at full reporting speed, 60Hz). If a 32 GB SD memory card is used, more than 4 months of synchrophasor measurements can be stored locally. This makes it even possible to use the device for offline scenarios and analyze data by retrieving it directly from the memory card.
Continuous Waveform Recording
Using a 32GB SD card, device can store 4 days of oscillograms (waveforms) for all channels, along with synchrophasor measurements at synchronous frequency. Additionally, the device records 10-min harmonic/THD aggregates (min/max/avg). Grouping multiple PMU devices into a single campaign using the WAMSTER system enables automatic retrieval of synchronized oscillograms from multiple locations in case of events, allowing detailed insight into the system operation.
A single STER PMU measurement set (Fig. 3) includes:
|3 phase 5A/1V measuring transformer||1|
|Test probe, red||3|
|Test probe, black||1|
|Crocodile clip, red||3|
|Crocodile clip, black||1|
|Voltage measurement lead, red||3|
|Voltage measurement lead, black||1|
|Voltage measurement lead, green||1|
|Power supply adapter||1|
|GPRS class 10 modem with connection cable||1|
|1.2 V NiMH rechargeable battery||6|
|Soft carrying bag||1|
|Basic measurement accuracy||
|Synchronized phasor measurements||
|Power quality measurements||
|Local non-volatile memory autonomy||
|Communication reporting rates||
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- WAMSTER Implementation Details (Whitepaper, 2012)
- WAMSTER Event Triggering Subsystem Details (Whitepaper, 2012)
- Measurement Campaigns: Typical Installations and References (Report, 2013)
- Other WAMSTER Whitepapers and Presentations