Solar PV Integration via

LCC HVDC

Transmission

Expansion

August 24, 2020

Bruno Leonardi, EPRI

Alberto Del Rosso, EPRI

Jonathan Ruddy, EPRI

R&D Approach

R&D Goal

PROGRAM

PROJECT

TASK FORCE

EPRI program P40.24-B: HVDC Transmission

Planning

• Increase planner’s knowledge on integration of HVDC technology

• Provide systematic approach, methods and tools for planning transmission expansions with HVDC

• Maintain knowledge base that can quickly be leveraged to support utility members through HVDC projects

• Complete HVDC planning case study in the Southwest Power Pool area

• Update HVDC Planning Guide

• Investigate technical performance issues with the integration of HVDC projects:

• 2019 will focus on sub-synchronous oscillations with increase of inverter-based resources

• [Tech Update] HVDC Planning Guide –2019 Edition

• [Tech Update] HVDC Planning case study

• [Tech Brief] HVDC Sub-Synchronous Oscillations in Transmission Systems (Joint deliverable of P40.024B and P173.03)

Deliverables 2019

40

24B

TP

R&D Objectives

R&D Approach

SPP Generation Interconnection requests by

type

• High number of interconnection requests of utility scale solar PV in the SPP generation queue

High solar irradianceregion

Credits: NREL

Case Study – 2GW LCC Bipole from SW to

Kansas City

Hypothetical future scenario of

large integration of solar

generation

Are of new solar

generation

2GW

Load Area

HVDC link

500 miles

Project scope:

• Feasibility analysis of the HVDC project

• Steady state analysis• Contingency analysis and reinforcement

evaluation

• Reactive Power and Voltage control requirements• QV analysis• Reactive compensation sizing

• Short Circuit strength • GSAT analysis• SSTI screening

• Dynamic performance (transient stability)

• Cost analysis

Area of new solar

generation (2GW)

Case study: Weak sending end

Blackwater (200 MW)

Artesia (200 MW)Sidney (200 MW)

Stegall(110 MW)

Rapid City DC(200 MW)

Miles City(200 MW)

IPP (2400 MW)

PDCI (3100 MW)

TBC (400 MW)

Eel River(320 MW)

Square Butte(500 MW)

Nelson River I(1620 MW)Nelson River II(1800 MW)

Coal Creek(1000 MW)

Oklaunion(200 MW)

Madawaska(350 MW)

Highgate(200 MW)

Quebec –New England(2000 MW)

Welsh(600 MW)

Eagle Pass(36 MW)

Cross SoundCable (300 MW)

Lamar (210 MW) Neptune(600 MW)

Sharyland(150 MW)

Chateauguay(1000 MW)

LCC HVDCVSC HVDC

WATL(1000 MW)

EATL(1000 MW)

Labrador –Island Link(900 MW)

Nelson River Bipole III(2000 MW)

Maritime Link(500 MW)

Hudson TransmProject (660 MW)

Mackinac(200 MW)

McNeill(150 MW)

Determining system strength at HVDC busses

CaseOriginal Case

No HVDC HVDC Added

SE Outage 0

SE Line Outage 1

SE Line Outage 2

SE Line Outage 3

Sending End (SE)

SCR 1.97 3.67 3.2 3.16 2.92 3.1

ESCR 1.39 3.09 2.62 2.58 2.34 2.53

▪ Sending end ESCR low

▪ Receiving end meshed and strong network ESCR 5+ even with outages

ESCR OK but low -Further investigation needed

Receiving End (RE)

SCR 6.45 6.13

ESCR 6.02 5.70

Sending end(rectifier)

Receiving end(inverter)

2 GW power transfer

Network reinforcements

Large load center

(Kansas City area)

Easter NM, NW Texas

Parallel AC grid

Parallel AC grid

LCC HVDC

Area one line diagram

Scenarios analyzed

1. HVDC Bi-pole trip

2. Solid Inverter fault

3. Solid Rectifier fault

HVDC Controls Enabled

1. AC-VDCOL• Aimed at improving stability, particularly voltage, during low

voltage recovery periods• Aimed at reducing risk of commutation failure

2. RAML• Aimed at avoiding firing angle rollback during low rectifier

voltages (e.g., faults)

3. Commutation failure emulation

HVDC Bipole trip

Sending end(rectifier)

Receiving end(inverter)

Parallel AC grid

Parallel AC grid

AC fault

Cleared element

LCC HVDC

2 GW power transfer

HVDC Bipole trip

Rectifier side

generators

speed

up/inverter side

slows down

Solar plants

scramble to

control voltage

under vastly

different

system flows

Steady state QV analysis

indicated that loss of harmonic

filters would lead to nearly zero

reactive margins – HVDC

bipole tripped as remediation

Inverter side AC fault

Sending end(rectifier)

Receiving end(inverter)

Parallel AC grid

Parallel AC grid

AC fault

Cleared element

2 GW power transfer

Inverter side AC fault

DC current

spike due to

AC fault can

be

troublesome

Generators

are stable

on both

ends

Solar plants POI

voltages

recover after

the fault

Rectifier side AC fault

Sending end(rectifier)

Receiving end(inverter)

Parallel AC grid

Parallel AC grid

AC fault

Cleared element

2 GW power transfer

Rectifier side AC fault

DC current

(and

power)

collapse

during fault

All generators

on both

sides are

stable

Conclusions

1. Case study evaluated system performance after integration of 2GW LCC HVDC line to export solar PV generation• Minor system reinforcements needed, mostly to allow exports

• Higher HVDC rating could require major reinforcements

2. No additional dynamic reactive power support needed• ** Under selected N-1 events **

• Transient voltages are reasonable (more thorough evaluation needed)

• In a real project, verify with OEM if HVDC controls can operate at identified SCR range (2-3)

3. Control settings/features of HVDC models is important in preliminary planning studies• May lead to incorrect conclusions (e.g., neglecting DC line dynamics

may lead to excessive dynamic VAR requirements)

• May not represent actual equipment performance in high fidelity

▪ Questions or follow up?

• bleonardi@epri.com

16

Thank you