PRISM DERMS demonstration project is accepted

The results data is in for ACS’s EPIC distributed energy resources management system.

ACS successfully completed, installed and performed the site acceptance test of a full-function Distributed Energy Resource Management System (DERMS) solution on August 25, 2017 as part of the California Public Utilities Commission’s Electric Program Investment Charge (EPIC) program for “applied research and development, technology demonstration and deployment, for clean energy technologies and approaches”.

The demonstration project included two utility substations, selected to substantially improve electrical operations and power quality based on their historical performance. The selected feeders exhibited the following characteristics:

  • Poor operating performance and reliability
  • Large installed output of DER, such as PV, fuel cell and micro turbines
  • Significant energy storage capability
  • CentrixTM: the Autonomous DERMS Distributed Platform

PRISM DERMS is a suite of renewable, closed-loop automation applications delivered on the ACS Centrix platform, enabling the solution to be distributed anywhere in the utility environment. Centrix is a practical and cost-effective solution for islands of automation that can be deployed incrementally over time. PRISM DMS/ADMS offers an enhanced suite of DERMS supporting applications with operator supervision functions, injection forecast, visualization and mobile operations.

ACS successfully pioneered Centrix as a distributed automation platform. The first installation was deployed at Georgia Power, where Centrix provides autonomous fault detection, isolation and restoration (FDIR) independent of the centralized control center SCADA system. To date, Georgia Power has successfully deployed Centrix on over 750 feeders, saving 39 million customer minutes of interruption in the first two years of operation. During this time, two major ice storms hit Georgia, with the Centrix/FDIR technology effectively proving its mettle at both Georgia Power and Cobb EMC by flawlessly handling progressive outages with multiple outages per circuit.

The PRISM DERMS application suite combines and coordinates the Voltage and VAr control operations with the self-healing capability of FDIR. With DERMS, integrated Volt/VAr control includes the optimization of renewable PV and battery storage on the feeder.

Operator-less Use Cases

The PRISM DERMS application suite on Centrix is the base offering for autonomous operations. Centrix supports the following functions, which are designed to avoid feeder violations under all operating conditions:

  • Integrated Volt/VAr optimization with renewable DER control (IVVC/r)
  • Emergency Load Transfer (ELT)
  • Maximum Injection Capability (MIC) (curtailment)
  • Protection setting adjustment

When delivered as part of the PRISM Advanced Distribution Management System (ADMS), the DERMS suite offers additional optimization functions that are operator-directed for further “what-if” analysis, including a powerful 24-hour look-ahead feeder violation prognosis.

The primary objective of the DERMS applications is the safe operation of the feeder within acceptable operating limits. The secondary goal is to enable the maximum possible renewable injection. It employs a graduated degree of aggressiveness when voltage violations do occur.

Energy storage devices are operated as either an energy source or as a load (in charge mode). Multiple units on the same feeder may be simultaneously coordinated to operate in both source and load modes, to optimize the feeder’s operating conditions from substation to end of line.


The PRISM DERMS solution provides many benefits. Comparison of the feeder’s normal operation by independent controllers, with the Centrix integrated DERMS suite, has been proven to yield substantial benefits by every measurement:

Compared with typical uncoordinated voltage regulation, IVVC provided lower line drop voltage at lower ‘end of line’ voltage, with 26% fewer regulator control operations.

Capacitor switching was reduced 20% with IVVC/r. IVVC/r controlled the PV inverter to injection or absorb reactive power to provide VAr compensation at maximum real power output.

Unexpected disturbances were tested, such as tripping off-line a large 2500KW PV injection DER. IVVC/r demonstrated the ability to restore the feeder’s operation to an acceptable (green) operating zone three times more quickly than compared to traditional controls. The resulting steady state condition exhibited a flatter overall feeder voltage profile with IVVC/r (see Figure 1, which shows the voltage profile dip at the time of the PV trip—10 minutes after the start of the scenario).

The maximum Line Drop Voltage spread of 0.35 without IVVC/r, compared to 0.05 with IVVC/r, demonstrates superior operation.