Improving Power Delivery and Quality Through Secondary Voltage Control Aleksandar Vukojevic, Manager – Emerging Technologies Office

Duke Energy – About us

Secondary Voltage Control – Brief History Timeline Fall 2013 – first pilot project with Varentec 130 ENGO-V units installed on 4 feeders Use case: secondary voltage management in the vicinity of the 1.2MW PV Farm Summer 2014/Summer 2016 – pilot project with GridCo 5 IPR devices installed at 5 feeders Use cases: power quality improvements, residential solar high voltage mitigation, low voltage mitigation Spring 2015/Sumer 2016 – pilot project with GridCo (SVC-20) 25 devices installed on 5 feeders Use case: low voltage mitigation on CVR feeders and tobacco farm power quality improvement

In-Line Power Regulator (IPR) Diode Cell Technical Characteristics: Voltage: 240V, 1-phase Nameplate: 50 kVA Voltage Regulation: ±10% VAR Regulation: ±5 kvar Harmonic mitigation: 3rd, 5th and 7th String

Metal Shredding Facility Distribution Transformer Location Overview Inverter Metal Shredding Facility Distribution Transformer Traffic Lights

One Week Operational Data

Solar Array (IR) – First Inspection with IR camera

Voltages Before and After IPR Commissioning Grid-Co device turned on

Voltage % THD Before and After IPR Commissioning

Voltage Flicker Before and After IPR Commissioning

Static VAR Compensator – SVC-20 Technical Characteristics: Voltage: 240V, 1-phase VAR Rating: 4 steps of 4.3 kvar Control: Voltage or VAR

Project Objective – Low Voltage Mitigation Project with EPRI PI: Jason Taylor, PhD PI: Surya Santoso, PhD Professor at University of Texas

SVC and IPR Placement – 15 SVCs and 1 IPR (Optimal Solution) Siting Considerations Undervoltage violations Physical limitations Transformer rating Number and type of devices Iterative placement

Simulated Feeder Voltages Before and After IPR and SVC Implementation

SVC and Capacitor Switching Before After

SVC Node Analysis

Reactive Power Injection on Summer Peak Day

The D-VAR® VVO Solution What is it? A 15kV class power electronic compensator that is installed on primary distribution networks in communities, business parks, or wherever enhanced power quality is beneficial Why would a utility use it? To save time & money by avoiding costly alternatives to strengthen the distribution grid Example Applications Increasing feeder-level solar hosting capacity (e.g., mitigating flicker caused by cloud pass & variability) Balancing VARs in utility-owned microgrids Achieving mandated efficiency upgrades (e.g., CVR) Replacing voltage regulators to enhance power quality

The D-VAR® VVO Solution Shunt power electronics modules Continuous control of volt/VAR Absorbs and supplies reactive power 3ph or 1ph application Meets 15kV feeder standards Standard 15kV protection gear Pole mounted in feeders Pad mounted option (5’x6’) Acoustically Quiet Tamper proof enclosure (sealed) No routine maintenance (no mechanical switching, no pumps, fans, or filters)