Fast Power Reporting for PV Production Feed-In Limiting

Responding to new requirements from utilities, Continental Control Systems, LLC has released a new firmware version for the Modbus Revenue energy meter providing for a Fast Power register reading which updates every 200 milliseconds. Option FP (Fast Power) supports utility feed-in limit requirements for those utilities that have limits on the ac power that may be fed into the grid by PV and wind inverters. In order to avoid exceeding utility limits, and to read the power and energy production from the inverter, revenue-grade kW / kWh meters are installed to monitor the power flowing to and from the grid. The inverter converts direct current to alternating current that syncs with the grid. Taking the readings directly from the meter, the smart-inverter monitors the output of the meter and adjusts the generated power going to the grid to control line voltage accordingly.

The new Option FP (Fast Power) is implemented as a special firmware version. The WattNode Modbus provides true RMS power, reactive power, power factor, reactive energy, ac line frequency, rms voltage, computed RMS current, demand, peak demand, kW and kWh on all three phases and as an aggregate.

Option FP updates the fast power registers every 200 milliseconds – five times faster than the standard WattNode Modbus, allowing for a feed-in response time of 500 milliseconds. “The fact that we’ve been getting inquiries about faster response times from our power meters may partly be driven by the anticipation of recent developments where PV plants and producers are evolving into an asset for grid operators. Timely power reporting to the inverter is an important element in smart grid management,” said Cynthia A. Boyd, director of sales for Continental Control Systems.

The WattNode Revenue with Modbus interface is a revenue grade kilowatt hour (kWh) energy and power meter that communicates on an EIA RS-485 network, measures 1, 2, or 3 phases with voltages from 120 to 480 volts Vac. When used with Accu-CT Class 0.6 current transformers it meets the accuracy requirements of ANSI C12.1, and it is UL and cUL listed.