Distribution Grid Monitor

Bitronics Distribution Grid Monitor

Packaged Solution for Distribution Automation Applications

NovaTech DGM on poleThe power distribution grid is undergoing unprecedented levels of change. The traditional one-way model of voltage regulation presumed voltages dropping predictably along feeders from substation to customers. The proliferation of larger scale Distributed Energy Resources (DERs) along feeders is rendering traditional models and regulation techniques incapable of maintaining delivered voltages within ANSI C84.1 guidelines. New approaches are required for grid measurement, monitoring and control.

Built around the Bitronics® M661P3, the Distribution Grid Monitor (DGM) can be deployed on the distribution feeder to interface with Lindsey and other pole top sensors. The DGM provides essential real-time measurements that enable Distribution Management applications to better manage voltages and maintain high power quality. The DGM calculates better than 0.5% accurate voltages, currents, power, energy, and fault data from raw sensor measurements. A typical DGM system, with a simple part number designation, consists of the M661P3 pole top monitor, a local PPXIITD detached display, a NEMA enclosure, and a shelf for utility supplied radio, all packaged as one offering with Lindsey GEN2 sensors and supporting cables.

Utilities Integrating DERs Face Several Voltage Control Problems:

  • Increasing integration of renewables means variable load and generation fluctuations which work against the constant voltage profile. Distribution lines with high integration of DER require more supervision to maintain a flat voltage profile.
  • Solar and wind DERs are, by nature, intermittent. Managing unpredictable intermittency without measurement, monitoring and control is becoming much more difficult.
  • In many cases, the utility cannot dispatch or monitor DERs.
  • When renewables are switched in and out, voltage levels local to the injection point may increase or decrease outside ANSI guidelines.
  • Voltage rises at injection points may create reverse systemic power flow. End-of-line voltage could be higher than other points on the line.
  • Intermittent behavior of DERs may result in oscillatory voltages in the system.
  • Combining Conservation Voltage Reduction (CVR) with DERs further complicates control scenarios.
  • Customer demands for high power quality are increasing.

Meeting the DER Integration Challenge

Advanced Distribution Management Systems (ADMS) and modern Integrated Volt-VAR Optimization systems (IVVO) can manage DER integration but need real-time data to implement their control strategies. The Bitronics DGM provides these data, including accurate voltages, loads, reactive power and fault data.

DGM: More than a Meter

The DGM is more than a meter in a box. The heart of the DGM – the M661P3 transducer – includes a preconfigured analog front-end that accepts the output from medium voltage sensors instead of from traditional CTs and PTs. These less-costly sensors provide safe, nominal 0-10V ac signals representing all measured voltages and currents and can be installed without taking an outage.

The combination of M661P3 and medium voltage sensors deliver average and instantaneous measurements via DNP3 to SCADA with an accuracy of 0.5%. The M661P3 updates measurements once per cycle and calculates both averaged and instantaneous values, accommodating slow poll rates. Reported voltages are “normalized” to 120.00V when the line is operating exactly at its nominal value. Load currents, fault currents, 51 pickup, power factor, and real and reactive power are all available as accessible DNP3 values, in addition to voltages.

Unique physical features include 12W power out (12V @ 1A) for the user-supplied radio, as well as an external, replaceable surge suppressor circuit, door switch, and security sleeves over sensor connectors.

Applications for DGM

The Bitronics DGM provides data to monitoring and control systems to better manage the Grid.

  • Provides voltage measurements to DMS and VVO systems, from the end-of-line and along the feeder
    • Supports applications with high integration of DERs where voltage delivery cannot be easily modeled, and where voltage control schemes require additional real time measurements
    • Supports applications requiring reported voltage to an accuracy of 0.5% or better, from sensor to DNP value
    • Supports applications where measurements must be rapidly presented to perform control
  • Provides fault detection to DA schemes for Fault Location, Isolation and Service Restoration (FLISR)
    • The Bitronics DGM provides a Definite Time Overcurrent protective relay element
  • Provides Peak Fault Currents to for Fault Location and Asset Management
    • The DGM records three-phase peak fault currents and presents data as DNP3 values
  • Provides real and reactive power measurements, and power factor, for capacitor control schemes

The Bitronics DGM Difference

The DGM Enclosure

The M661P3 is provided in an enclosure with the following:

  • Powder-coated steel ANSI 61 Gray 16”x14”x10” NEMA 4 or Stainless Steel NEMA 4X enclosure with brackets with bolt holes for mounting to pole
  • Bitronics PPXIITD display to provide local indication of measurement values
  • Door switch connected to binary input on M661P3 to provide alarm on door opening
  • Security sleeves (over bayonet connectors on sensor cables)
  • Polyphasers to protect antenna
  • Surge suppression board
  • Provision for accommodating user-provided radio on shelf

Lindsey GEN2 Post Insulator Sensors and Cables

  • Less than one half the weight of Lindsey Polysil-based sensors
  • Hotstick-friendly conductor keeper with washer-less bolts accommodate a wide range of conductor sizes
  • Glove-friendly cable with bayonet-style connectors that “snap” when properly tightened
  • 0.5% voltage accuracy, with flat harmonic response, and no phase shift. 1% current accuracy with no phase shift.
  • Voltage and current accuracy is independent of weather and conductor diameter
  • Safe, low voltage, low current outputs
  • Hydrophobic cycloaliphatic epoxy provides high performance in polluted and wet environments

Ordering a DGM

There are several DGM configurations installed.  The part number for the DGM is simple: DGM-60-XX-Y where:
XX = The sequential number corresponding to the specific elements requested by the customer
Y = The number of sensors (0 where the customer supplies the pole-top sensors, or 1, 2, or 3 depending upon the number of phases to be monitored)

Customization of the DGM can be provided.

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