10 ai impacts&settings_pvss2016_rylander_

© 2016 Electric Power Research Institute, Inc. All rights reserved.

Matthew Rylander, EPRI Jeff Smith, EPRI

Robert Broderick, SNL Barry Mather, NREL

May 10, 2016

Advanced Inverter Impacts and Methods to Determine

Recommended Settings

Analysis to Inform CA Grid Integration Rules for PV

2 © 2016 Electric Power Research Institute, Inc. All rights reserved.

Outline

California Solar Initiative project overview Explain simple methods to derive settings Illustrate distribution feeder response to settings

Today’s Key Takeaway: Simple methods to derive settings


Project Overview

Project Goal Determine advanced inverter

settings to accommodate more PV without system upgrades – Power factor, volt-var, volt-watt – Settings and/or methods to

determine settings

.3 1.01.9 2.7 2.5 3.2

4.6

.7.9

1.2 1.82.6

3.6

.3

.3

.5

.81.3

1.8

2.4

.9

1.9

3.3

4.75.6

7.6

10.6

2010 2011 2012 2013 2014 2015 2016

Utility Commercial Residential

Industry Challenge Landscape is changing

– Distributed resources New challenges for utilities

– Accommodate more PV – Use Advanced Inverters

Impact Below

Threshold

Impact Depends

Impact Above

Threshold

Setting 3

Setting 2

Setting 1

Unity Power Factor


Approach to Derive/Test Recommended Settings/Methods

Select Feeders

Develop Methods to

Derive Settings

Apply Methods and

Determine Feeder Impact

Final Deliverable

Summer 2016


Select Feeders


Feeders Selected from Previous Analysis*

Utility 1

Utility 2

Utility 3

Impact Below

Threshold

Impact Depends

Impact Above

Threshold

CPUC-CSI3 *Alternatives to the 15%

Rule: Final Project Summary. EPRI, Palo

Alto, CA: 2015. 3002006594.


Selected Feeder Details

Criteria for feeder selection Utility Feeder characteristics Hosting capacity

Feeder Name

Peak Load (MW)

Farthest 3-phase Bus (km)

PV Hosting Capacity

Nominal Voltage

683 3.6 17.9 Low 12 kV 631 3.4 11.7 Moderate 12 kV 888 2.2 2.8 Low 4 kV

2885 9.2 11.9 Low 12 kV 281 16.7 10.3 High 21 kV

2921 6.4 15.5 Moderate 12 kV 420 5.0 4.7 High 12 kV


Develop Methods to Derive Settings


Level Complexity Power Factor Volt-var Volt-watt

0 None Unity Power Factor Disabled, Unity Power Factor

Disabled, Unity Power Factor

1 Low Based on Feeder X/R Ratio Generic Setting Generic Setting

2 Medium Based on Feeder

Model and PV Location

Based on Feeder Model and PV

Location Not Applied

3 High Based on Feeder

Model and PV Location

Based on Feeder Model, PV Location,

and Service Transformer Impedance

Not Applied

Methods to Derive Settings


Power Factor Control

Level 1 settings: – Most simple method required to determine settings – Setting is feeder specific – Setting is based on the Median X/R ratio on the feeder

Level Method Data Requirements Power Factor Setting

1 Median X/R Ratio of all 3-phase MV nodes to determine power factor

Primary node X/R ratios on feeder, number of phases at each node

Single Setting on each feeder

𝑃𝑃𝑃𝑃𝑃 𝑓𝑓𝑓𝑓𝑃𝑃 ≅𝑋𝑅� 𝑚𝑒𝑒𝑒𝑒𝑒

𝑋𝑅� 𝑚𝑒𝑒𝑒𝑒𝑒

2+ 1


Volt-var Control

Level 1 settings: – Wide bandwidth (does nothing when within 2% from nominal) – Maximum reactive power output equivalent to 90% power factor when

real power is at full output (assumed that the inverter is 10% larger than the PV system rating)


Volt-watt Control

Level 1 settings: – Delayed control (does not curtail power when voltage is within ANSI

limits) – Reactive power control functions should be utilized before the inverter

voltage reaches the ANSI limit – Active power curtailed to Zero at 1.1pu voltage


Apply Methods and Determine Feeder Response


Feeder Response

Feeder response based on same hosting capacity analysis used in CPUC-CSI3 feeder analysis – The thousands of stochastic PV scenarios were converted from unity

power factor for each of the settings/methods derived PV scenario correlated to Median hosting capacity used to

compare settings/methods – Quantified by advanced inverter setting result minus result from unity

power factor

Median Hosting Capacity:

Defined when 50% of the analyzed scenarios have a

violation.

L1: Simple

L2: Moderate

L3: Complex


Quantifying Overall Impact from the Method/Setting

Overall feeder impact is quantified by: – Hosting Capacity – Reactive Power – Losses (assumed negligible)

Hosting Capacity

Reactive Power

Impact Ratio


Comparison of Overall Impact from Power Factor and Volt-var Power factor Level 1 and Level 2 have the least effective use of reactive power Level 3 power factor and Level 3 volt-var provided similar increase in hosting capacity

and also demand of reactive power, thus their overall ratio is comparable Volt-var Level 1 had low improvement in hosting capacity yet the control settings has

some of the most effective use of reactive power

Volt-

var

Pow

er F

acto

r


Conclusions

Power Factor Method Level 3 generally provides the most benefit with regards to hosting capacity while effectively using reactive power to do so Volt-var Method Level 1 is the least complex and has one of

the most effective uses of reactive power Volt-watt Method Level 1 should be used in conjunction with

power factor or volt-watt control while these reactive power control functions should prevent the unnecessary curtailment of active power when operated first


Together…Shaping the Future of Electricity

Robert Broderick

[email protected]

505.844.8161

Jeff Smith

[email protected]

865.218.8069

Matthew Rylander

[email protected]

512.351.9938

Barry Mather

[email protected]

303.275.4378

mailto:[email protected]





References

Public Link to Reports Online

CSI:RD&D. (2015). Analysis to Inform California Grid Integration Rules for PV. Available:

http://calsolarresearch.ca.gov/funded-projects/110-analysis-to-inform-california-grid-integration-rules-for-pv

Alternatives to the 15% Rule: Modeling and Hosting Capacity Analysis of 16 Feeders. EPRI, Palo Alto, CA: 2015. 3002005812.

Alternatives to the 15% Rule: Final Project Summary. EPRI, Palo Alto, CA: 2015. 3002006594.



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