RiversidePublicUtilities.com Arts & Innovation RiversidePublicUtilities.com Challenges and Solutions for Large-Scale PV Integration on RPU’s Distribution System Ed Cortez, Principal Electrical Engineer In collaboration with Dr. Emma Stewart, Lawrence Berkeley National Laboratories

RiversidePublicUtilities.com Electric System Publicly Owned Electric and Water Utility Population - 311,896 Service Area - 82 square miles  Substations – 14  Transmission Lines – 91 Circuit Miles  Distribution Lines – 1,323 Circuit Miles  Electric Meters – 107,500 Record peak demand of 612 MW on 9/14/ – Total of 13 MW installed PV 2015 – Anticipating >10 MW of new PV

RiversidePublicUtilities.com Commercial PV Sites

RiversidePublicUtilities.com PV Interconnection Requirements RPU Rule 22 (CA Rule 21)  Point of Interconnection  Interconnection Equipment  Generating Capacity  Voltage Operating Range  Protective Functions

RiversidePublicUtilities.com PV Interconnection – RPU Rule 22 Interconnection requirements  Point of Interconnection  Point of Interconnection – Primary 12kV  Interconnection Equipment  Interconnection Equipment - RPU providing primary switchgear  Generating Capacity  Generating Capacity – 7.5 MW (AC)  Voltage Operating Range  Voltage Operating Range - SEL 351 Relay 59/27 implemented  Overvoltage/Undervoltage  Protection Functions  Protection Functions – Inverter is compliant with IEEE 1547/UL 1741  IEEE Trips automatically during voltage and frequency excursion  UL 1741 – Islanding detection  Fault Detection  Fault Detection – (Supplemental requirement)

RiversidePublicUtilities.com PV Interconnection Barriers From a distribution planning view, there are three barriers to the integration of large PV systems  Inadequate tools that simulate high-penetration levels  Inaccurate models, due to limited availability of data  Limited accuracy of measured data sources

RiversidePublicUtilities.com PV Studies - Data Comprehensive model  ESRI-based distribution network SCADA circuit load and voltage  Summer Peak  Winter Peak  Hourly  Minutes

RiversidePublicUtilities.com PV Studies Steady-State Analysis utilizing Synergi Electric  Modeling, Power flow, Voltage, Volt/VAR, Fault, Distribution Protection

RiversidePublicUtilities.com PV Studies - Modeling Modeling  Distribution model typically constructed assuming traditional power flow (one direction)  Distribution voltage usually represented by the blue line  In reality it looks like the red line

RiversidePublicUtilities.com PV Studies – Power flow Reverse power flow/high voltage  During off-peak daytime loads (winter), the 7.5 MW PV exceeds load on the circuit  Reverse power flow from the distribution system through the substation transformer RPU Solution  Currently improving the existing distribution infrastructure to limit the effects  Reconductor, transfer loads, relocate capacitor banks

RiversidePublicUtilities.com PV Studies – Protection Feeder relay / PV relay / short circuit current

RiversidePublicUtilities.com Analysis and Software Options

RiversidePublicUtilities.com Enhanced Modeling & Analysis LBNL and RPU collaborating to conduct dynamic and transient studies  Evaluate additional infrastructure improvements Install μPMUs at RPU  Use μPMUs as calibration and validation inputs to improve accuracy of the models

RiversidePublicUtilities.com Next Steps Model and simulate events to plan for future changes Simulate events to provide intelligence in reacting to outages and emergency conditions Utilize a combination of GIS, distribution planning tools and measured data to achieve objectives

RiversidePublicUtilities.com Conclusion No single software can achieve all analysis objectives Model data accuracy and standardization is essential Measured data is critical for validation Analyze in both steady-state and dynamic simulation