Transcript WECC-0100 Standards Briefing 4-7-2016

Project WECC-0100 Standards Briefing
WECC-0100 SDT
April 7, 2016
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R1.1 Steady State Voltage
• Applicability – All applicable BES buses.
• Criterion:
– At all applicable BES buses
– 95% to 105% of nominal for P0 event,
– 90 to 110% of nominal for P1-P7 events
• Discussion
– Steady state voltage range for P0 event originates in ANSI C84.1
standard. No difference for 500 kV for simplification.
– Wider range for P1-P7 events to allow for contingencies.
– Discussed definition of nominal. TP/PC can define nominal in
their individual criteria applicable to voltage limits in their system.
R1.2 Post-Contingency Voltage Deviation
• Applicability - At each applicable BES bus serving load.
Concerned with BES busses either feeding load directly
or busses feeding lower voltage system that serves load
• Criterion:
– Post-Contingency steady-state voltage deviation at each
applicable BES bus serving load shall not exceed 8% for P1
events
• Discussion
– The 8% for P1 events is based on some entities indicating a state
regulatory need, and some entities allowing 8% voltage deviation
for shunt reactive power device switching after an outage. The
main concern is voltage deviation in downward direction.
– For P2-P7 events it was concluded it would be acceptable to not
have voltage deviation criteria that is more stringent than allowing
the steady state voltage range in requirement R1.1.
R1.3-1.6 Transient Voltage Performance
• Applicability - At each applicable BES bus serving load.
• Applies to P1-P7 events
• R1.3 – Voltage recovery to 80% of pre-contingency
voltage within 20 seconds
– Consideration for FIDVR events based on comments and experience.
– Recognizes some load loss initiated during fault can’t be prevented.
• R1.4 – With a fault, following recovery above 80%,Vdip
below 70% for 30~, below 80% for 2 seconds.
– Guidance from IEEE 1668 Trial Use Recommended Practice for Voltage
Sag and Short Interruption Testing for End Use Equipment. Type I and
II tests seem reasonable, most transmission faults are non 3-phase.
– Helps minimize load loss for subsequent swings not due to fault.
– Also reviewed IEEE 1547 Interconnecting Distributed Resources.
– White paper developed with Posting 3.
• R1.5 – Same performance as R1.4 for contingencies
without a fault (event P2.1).
• R1.6 – Oscillations positively damped within 30 seconds.
R1.3 Example
R1.4 Example
R1.4 Example
Impacts to Other Systems
• WR2. – If an entity uses more stringent Criteria than
WR1 that Criteria applies only to their own system
unless otherwise agreed to by all Planning entities
involved.
• WR3 – If an entity uses less stringent Criteria than WR1
shall allow others to have same impact to that part of
system.
• These requirements carry over from the previous Criteria
requirement WR2 which allowed systems to apply
different requirements than Table W-1.
• Retains the philosophy of “allowable effects on other
systems”.
WR4. Cascading and Uncontrolled Islanding
• Threshold Criteria to identify potential for Cascading or
uncontrolled islanding.
• Criterion:
– Post contingency analysis results in steady-state facility loading
either exceeding 125% or the known trip setting.
– Transient stability voltage recovery to above 80% longer than 20
seconds.
– When unrestrained successive load loss or generation loss
occurs.
• Discussion
– Since Cascading or uncontrolled islanding would manifest itself
differently in different parts of the system, a threshold criteria
was developed where further investigation would be warranted.
– For unrestrained successive load or generation loss, it is
anticipated this would be an iterative study process as
determined by the entity.
WR5 Voltage Stability
• Positive reactive power margin for the following:
– For transfer paths 105% or 102.5% of path flow for P0-P1 or P2P7 events respectively.
– For load areas 105% or 102.5% of forecasted peak load for P0P1 or P2-P7 events respectively.
• Discussions
– Did not find good technical justification for changing existing real
power margins used in previous Criteria.
– Path or load area assumed to be voltage stable by at least
demonstrating the margins specified. Discussion this is a criteria
for transmission Planning over the Planning Horizon, not a
methodology to find system voltage stability limits beyond what
the system is planned for.
WR6 Make Criteria Available
• Entity that uses study criteria different from criteria in
WR1 shall make their criteria available upon request
within 30 days.
Frequency Dip Criteria
• Frequency dip criteria is not included in this Criteria. A
frequency dip criteria was included in Table W1 which
was retired.
• Drafting team did not find good technical justification for
frequency dip impact to load.
• Under frequency concern is to protect generators. UFLS
designed in coordinated fashion based on frequency
excursion to prevent excessive gen loss, not based on
frequency dip as defined by previous criteria.
• PRC-006 Automatic UF Load Shedding defines
requirements for PC’s developing UFLS Programs,
WECC Off Nominal Frequency Requirements.
• Generator frequency capability requirements defined in
NERC PRC-024
Next Steps
• Ballot Pool open 3/21 - 4/8
• Ballot open 4/12 - 4/28
• Next Board meeting June 2016
Questions?