Custom communication protocol enables WAMSTER to adapt to mobile network conditions. No data is ever lost during blackouts.
Using the GPRS/UMTS mobile (wireless) networks for synchrophasor data transmission, phasor measurement units can use existing mobile networks ad-hoc, with no need for additional networking infrastructure or on-site configuration. When communicating over GPRS, WAMSTER phasor measurement units utilize a custom optimized communication protocol which, compared to IEEE C37.118, allows dynamic reporting speed adjustments, skipped frames requests at different frame rates, enhanced diagnostics and full remote device control.
No need for network infrastructure
STER Phasor Measurement Unit does not need a IEEE C37.118 compliant PDC and additional equipment. Using a GPRS modem, it can connect to WAMSTER servers without additional infrastructure costs. Apart from configuring the GPRS modem connection settings (which can be done in the office), STER PMU starts transmitting synchrophasor measurements immediately after power up. EDGE/UMTS modem and wired Ethernet versions are also available on request.
Optimized protocol
Standard IEEE C37.118 protocol doesn't guarantee transmission of all recorded synchrophasors in case of communication problems or blackouts. To remedy this in low-bandwidth mobile (GPRS) networks, custom WAMSTER protocol introduces full-duplex device-to-server negotiation, which allows the server to request skipped frames from the phasor measurement unit, as well as adapt the real-time reporting speed to network conditions. STER PMU phasor measurement units are equipped with enough memory to store up to 5 months of full-resolution synchrophasors internally, which can be retransmitted to server at any time.
Remote firmware updates
When used with the Wamster service, firmware upgrades can be performed over GPRS to add new functionality according to customer's requests. Since the device is constantly connected to Wamster, this process is automated and the device continues measuring immediately after a reboot - with no need for human intervention.
IEEE C37.118 compatible
STER PMU phasor measurement unit can also directly communicate using the IEEE C37.118 protocol and be integrated with standard IEEE C37.118 compliant phasor data concentrators (PDCs) to reuse existing equipment. Additionally, Wamster server can act as a IEEE C37.118 client towards a third party phasor data concentrator, enabling STER PMU to use the benefits of the optimized GPRS protocol and still integrate with classic IEEE C37.118 PDC equipment.
