Download meeting notes - The California IDER and DRP Working Groups

Initial Draft: Notes from 1/17 Meeting – please send comments to [email protected]
Questions for PG&E, SCE and SDG&E Regarding
the Final Demo A (ICA) Reports
January 11, 2017
On January 10, 2017 a sub-group of stakeholders met to develop a list of questions for
the IOUs that would help stakeholders better understand the Demo A results and the possible
steps forward. These questions are not intended to reflect the views or positions of any one of
the participating organizations. The questions are roughly organized into categories for ease of
review.
A) Questions About the Assumptions and Calculations Used in the Methodologies
1) What alternatives to the operational flexibility limit (in both the streamlined and iterative
approach) did the IOUs consider? Why were these alternatives rejected? Are there other
alternatives that could be considered?
i) Other methodologies considered, including SCE method outlined in GRC (“planned
loading limit”)? Do any potential alternative methods lead to different results?
(1) WG: recommend continuing studies in long-term refinement. IOUs looked at one
approach that did not scale well. SCE will provide additional detail on how
operational flexibility is addressed within the methodology used in its recent
GRC.
ii) Using operational flexibility criteria as a limiting factor provides an unnecessary
constraint within interconnection/fast track process?
(1) Sahm: recommend that users can ID when reverse flow is the limiting criteria
within interconnection screen, and if that issue can be resolved, what the next
limiting criteria is (resolve in long-term refinement, need to ID specific timeline)
(2) Need to better understand operational flexibility (especially high operational
cases) within Rule 21 fast track/tariff discussions
(3) Understand how the issue is flagged within interconnection and what is the
mitigation option
2) How do the IOUs propose to move beyond the use of a heuristic approach for operational
flexibility?
i) IOU proposal: alternatives discussed within long-term refinement (Q2 2017)
(1) Within alternatives or modifications to methodology, need to also understand how
this would change the use of backflow criteria?
1
Initial Draft: Notes from 1/17 Meeting – please send comments to [email protected]
ii) Clarification: operational flexibility and reverse power flow constraints are not
synonymous. There are other instances where reverse flow may cause issues (ex:
some voltage regulators not equipped to operate in reverse flow). So, operational
flexibility limit (as “reverse flow limit”) would need to retain in normal configuration
situations.
(1) WG question: could run operational flexibility limit only for reconfiguration and
on certain devices?
iii) WG question: impact on computing time?
(1) Marginal savings if reduced, use does increase computational time for iterative
method
3) The operational flexibility criterion is intended to flag backflow across SCADA
controlled switching devices. See, e.g., SDG&E Demo A Report at 39. Do the IOUs
know the location of all SCADA-controlled devices for this modeling? Or do the IOUs
instead consider the criterion to be violated if there is backflow across any node,
irrespective of whether there is a SCADA device present?
i) Yes IOUs can ID location of SCADA controlled switches, reclosers, and voltage
regulators. Limitation criteria only applied to SCADA devices, and only limiting
when the switches are NOT capable of back flow.
4) Likewise, have the IOUs catalogued the SCADA devices that can distinguish backflow
from load/generation and tolerate backflow, and do the IOUs take this capacity into the
account in the operational flexibility criterion? If the IOUs do not have detail on the
location and capacity of all SCADA devices, what level of effort would it take to acquire
that detail?
i) WG follow-up: clarifying justification to replace relays. IOU justification is that it
adds a directional component to the relay, to better understand where the fault is.
5) Does any amount of backflow trigger a violation of the operational flexibility criterion, or
is there a limited amount of backflow that does not pose safety/reliability concerns (i.e.
what is the level of minimal risk that is tolerable)?
i) WG follow-up: does the operational flexibility criteria impact reliability?
(1) IOUs – limited impact to reliability
6) Can the utilities quantify how frequently abnormal feeder conditions occur that would
result in the type of feeder switching that the heuristic approach seeks to address?
i) IOUs (PG&E): ~5% at any given time?
ii) Can issue be bifurcated into 1) recommendations for initial system-wide roll out and
2) longer-term refinements?
2
Initial Draft: Notes from 1/17 Meeting – please send comments to [email protected]
iii) WG follow-up: does this have an impact on how frequently ICA results are updated
and mapped? (CYME models updated weekly, versus models updated in annual
planning process).
iv) WG follow-up: in what situations and at what levels of penetration is operational
flexibility limit triggered, when does it require a mitigation response?
v) WG follow-up: should the mapping display include an “optional display” option that
allows users to toggle limitation criteria on/off?
7) If there is a preexisting condition on a circuit that limits its hosting capacity, can the
IOUs still proceed with the ICA analysis to determine the next limit for that location? For
instance, it is our understanding that PG&E specifies a hosting capacity of zero when
there is a low voltage limitation but the other IOUs do proceed with the analysis. Why
does PG&E stop running the ICA when it reaches the first violation, even if it is
preexisting, whereas SCE and SDG&E continue to run the analysis when there is a
preexisting violation to identify what the next violation would be?
i) PG&E continues analysis to find limits for other criteria, but published limit is 0.
ii) When addition of DER aggregates pre-existing conditions, then should consider preexisting, but not all pre-existing conditions will limit ICA so should they should not
automatically limit ICA.
iii) Going forward, a few means to explore how to limit impact of pre-existing condition,
including better understanding hierarchy of circuits, means of changing limits when
you can expect certain conditions like low voltage (but how to do in most practical
means?)
iv) Can IOUs provide written explanation of current application (can be done jointly) so
we can refer to in WG final report?
8) In performing iterative calculations, are the IOUs modeling the substation bus? Do the
methodologies allow flow from one feeder to another?
i) SDG&E Yes, yes
ii) SCE: no-reverse flow, limit at breaker, in reverse flow allow
iii) PG&E: no limitations even in reverse flow simulation, but limited at substation
transformer
iv) What situations are necessary to use common bus calculation depending on existing
LTCs, others? Updated modeling also necessary in CYME/SYNERGI
(1) Can IOUs clarify differences with regards to modeling common bus? Include in
WG report to support WG recommendations
3
Initial Draft: Notes from 1/17 Meeting – please send comments to [email protected]
9) It is our understanding that SCE and PG&E’s methodologies have locked down the
voltage settings. SDG&E, however, allows them to change, and that appears to be one
reason why its iterative calculations are less efficient. Why does SDG&E do this, and not
the others? Does SDG&E have results that could help in evaluating the impacts of not
locking down voltage settings, both with respect to the accuracy of the results and the
computational time it entails?
i) SYNERGI allows to change (SDG&E to double check if locks as well), CYME
automatically locks
ii) SDG&E - allowing them to change simulates real time scenarios, more accurate
results
iii) PG&E – would like to work with CYME moving forward but with respect to Demo A
timeline/practicality of getting results, locked for Demo
iv) Likelihood that unlocking voltage settings will increase ICA, but increases
computational time as well
10) What PV load profile are the IOUs using, is it seasonally adjusted, and how did they
derive that profile?
i) To be answered in writing
11) The utilities have been asked to provide a more detailed comparison of their respective
methodologies and assumptions (preferably in table form). Do they intend to provide
these comparisons, and if so, when?
i) IOUs agree to provide assumptions table (including showing areas of common vision
but development differences between IOUs)
12) What accounts for the differences in voltage between the IOUs’ results on the IEEE 123
Feeder? According to Justin Fuller from IEEE, the voltage numbers should be the same
between CYME and Synergi.
i) To be answered in writing
13) What would be the key differences between the IEEE test feeder and more representative
California feeders? What are the IOUs’ plan for evaluating and comparing methodology
by using additional feeders?
i) To be answered in writing
14) How are the IOUs using AMI data in the ICA results?
i) To be answered in writing
4
Initial Draft: Notes from 1/17 Meeting – please send comments to [email protected]
15) Does part of the ICA development plan involve performing more accurate load
forecasting?
i) AMI data used to determine localized shapes, SCADA data at substation scales load
profile (load profile varies throughout the circuit)
ii) WG report: load forecast influences ICA and determined in DRP Track 3 (not
necessarily scope of work for ICA WG)
16) With respect to thermal limits, it is not clear from the reports whether the IOUs are
referring to a conductor or a transformer. Is there a tolerance for variation? Are they
using the specific capability of the unit or applying some blanket tolerance measure? Can
they be more specific on the device that is limited?
i)
No tolerance
17) In addition to the criteria already considered in the ICA methodologies, are any other
metrics or criteria considered in determining impact to operational flexibility in the
normal interconnection review process OR in the ICA?
i) See operational flexibility discussion notes
B) Questions Regarding the Data and Maps
1) When can we expect that PG&E and SDG&E will release functional maps and make
them available online?
i) PG&E: sometime this week, happy to share data in advance (USB)
ii) SDG&E: sometime this week
2) Is PG&E willing to offer downloadable KML files? If not, why not? Please be as
specific as possible regarding the precise concerns PG&E has, and if possible, why those
concerns are unique to PG&E.
i) No, due to physical security, infrastructure concerns
ii) PG&E to provide what specific concerns are in writing
C) Computational Processes and Power
1) To what extent are the differences in computational time between the iterative and
streamlined methods reported by SDG&E due to hardware differences (i.e. running the
analyses on server-based versus laptop computers)? Specifically can you quantify how
much of a difference is due to the different computer systems SDG&E used? See SDG&E
Demo A at 43.
5
Initial Draft: Notes from 1/17 Meeting – please send comments to [email protected]
i) Iterative method run on laptops, streamlined method run at server-level with multithread capabilities
ii) Estimate – iterative could be run 3-4x faster (estimate) if switched to similar serverlevel
iii) Going forward, likely CYME/SYNERGI likely to be better equipped to handle multiprocessing going forward, there is a multiple license issue
iv) WG follow up: which improvements incur what magnitude of cost? When could WG
potentially see cost and time estimates? Follow up needed with vendors (licensing
costs, server/cloud computing costs, etc.)before WG recommendation is possible.
v) Framing: Need to define under which conditions trigger re-run of ICA (which parts
are updated and how frequently should they be updated?)
2) To what extent is SDG&E’s computational efficiency limited by the software
(SYNERGI)? Please detail the possible solutions that have been explored to address these
software processing challenges. What software/hardware solutions is SDG&E intending
to use if it moves ahead with the iterative approach, and how does it propose to reduce
computational time and expense?
i) Can SYNERGI automate data input?
(1) Both CYME and SYNERGI can provide automatic updates but overrides whole
model; need to determine how to update section X without overriding section Y
ii) The WG would like to better understand which components of SYNERGI and which
methodological choices (locking voltage, computational efficiency choices, etc.)
impact processing time
3) How does computational time translate into costs for the utility? Have the utilities done
any cost assessment of running the iterative approach on the full distribution system as it
is currently formulated, and of what it would cost to run an improved iterative approach
(for instance, using cloud computing or other server-based approaches)? When PG&E
states that there are increased IT costs to using their current cloud-based approach, can
you quantify those costs?
4) What are the differential costs between running iterative, streamlined, and the proposed
blended approaches (taking into account computational time, differential IT resource
needs, etc.)?
5) Are there barriers to moving towards cloud computing (besides cost)? If so, what are
they and are there potential solutions to them that have been explored?
i) Data management/cyber security issue?
6
Initial Draft: Notes from 1/17 Meeting – please send comments to [email protected]
ii) Time/process of transferring data, synchronization issue when data exists in two
different places
6) Are there barriers to parallel computing? If so, what are they and are there potential
solutions to them that have been explored?
i) ICA analyses run in parallel processes (each hour is run in isolation)
D) Use Case Questions for Iterative and Streamlined Methodologies
1) How do the IOUs propose to use the results of the iterative approach to process
interconnection applications in the near term?
i) Many new limits developed through ICA can replace current fast-track limits (SCE,
PG&E, SDG&E)
(1) Existing screens F, G, L, M, N, O, P
ii) ICA should be updated based on interconnection applications, queue, existing
generation
(1) Updated monthly, potential longer-term goal of more frequent updates, and
replacing fast-track screens with a type of verification process
(2) Some questions regarding time lag, application to interconnection, more
applicable to Rule 21 discussion
iii) PG&E: ICA can help categorize whether a project can be fast tracked or go through
supplemental review. Specific components of fast track screens can be directly
answered/replaced with components of ICA. This also better informs projects going
through detailed study through better categorization of project issues.
iv) PG&E: potentially focusing iterative method done on demand, for example running
in supplemental review?
v) WG question: what is the marginal added cost of doing more frequent updates (ex:
weekly) or more intensive updates?
(1) Can we quantify usefulness/accuracy of information if interconnection request
comes in near end of month?
(2) How to integrate into interconnection tariff?
(3) Which components are specific to an interconnection application versus solved
through monthly ICA update?
(4) Rethink hierarchy of screens (fast track, supplemental, detailed study?)
2) Do SDG&E and PG&E propose to reduce the hour profile and node volume for their
iterative calculations to improve computational efficiency, as SCE did? See SCE Demo A
Report at 76-78. Will this simplification be done for individual interconnection studies or
only for the purpose of running the iterative ICA on the entire distribution system?
i) SDG&E:
(1) Some node reduction applied
(2) Hour reduction: built-in SYNERGI application not optimal, would like to go back
and reprogram, similar to SCE strategy
ii) PG&E:
7
Initial Draft: Notes from 1/17 Meeting – please send comments to [email protected]
iii)
iv)
v)
vi)
(1) Node reduction not included in Demo but makes sense moving forward,
particularly with CYME Gateway (additional nodes)
(2) Hourly reduction: reducing hours (to 576) but ensure does not limit
understanding of situations
WG question: balancing level of reduction techniques with cost, time, accuracy of
results? Which are included in initial system-wide rollout?
Hourly reduction:
(1) Proposal to reduce from 576 to 24 hr profile, still applicable to interconnection
fast track use case (currently interconnection uses minimum loads), requirement
should develop in coordination/with modifications with Rule 21 process, and in
consideration of increasing IOU confidence in interconnection
WG question: from IOUs, what is the proposed optimal hourly profile to use within
each use case?
(1) One option: 48 hours (24 hours of minimum load, 24 hours of high/peak load) –
looking at both addresses different criteria limit issues (ex: thermal limit under
minimum load, voltage limit on peak load)
(2) If long-term goal to optimize design of systems providing solutions, need 576
profile? (ex: solar + storage solution)
(3) Consider solutions with respect to impact on range of technologies as well
Follow-up: IOUs can summarize different proposals they may be able to support,
with regards to hourly profiles (including benefits and trade offs)
3) How frequently does each IOU plan to update the iterative results for the entire
distribution system?
4) Will these system-wide results be used for Rule 21 interconnection proceedings, for
planning purposes, for both, or for neither?
5) Could the IOUs intend update the periodic iterative results with circuit-level
interconnection results that arise from Rule 21 interconnection results as those latter
results come in, and the make the updated ICA results publicly available?
6) Can the IOUs do a location-specific iterative analysis (i.e. circuit by circuit) instead of
doing an entire update of the analysis for the whole system?
7) How do the IOUs propose to use the streamlined approach for planning? SCE, for
instance, mentions that the streamlined method will provide information necessary for
“various uses cases” where it would be overly burdensome to use the iterative method.
SCE Demo A Report at 4. What specific “uses cases” do the IOUs envision using the
streamlined approach for?
Follow-up requests for IOUs:
8
Initial Draft: Notes from 1/17 Meeting – please send comments to [email protected]









Computing cost and time estimates: outline of IOU discussion strategy with
CYME/SYNERGI (priority for 1/20)
Specific discussion on planning use case (ex: targeted grid modernization
updates) (priority for 1/20)
More detail on operational flexibility alternatives (including for SCE - more detail on
"planned loading limit" described in GRC)
Development of common methodology table
PG&E specific: written explanation of policy on sharing KML file data
Proposed options for hourly profiles (24, 48, 576, etc.) – benefits and tradeoffs
Written explanation of current applications of preexisting conditions
Written explanation of differences among IOUs with regarding to modeling common bus
Written explanation of what other reasons a no-backflow screen might need to be used
beyond operational flexibility (Ex: for some voltage control devices, how the screen
would apply if it was used just for those cases) (priority for 1/20)
9