North American Synchro-Phasor Initiative

							              North American Synchro-Phasor Initiative
                Planning Implementation Task Force
                                  Mid-term Workplan

                                     June 23, 2010

A number of utilities in the North America are involved in wide-scale deployment of
phasor measurement units and their applications under the Smart Grid Investment Grant
(SGIG) projects. NASPI Planning and Implementation Team (PITT) is taking steps to
align its workplan with the needs of the SGIG projects and NERC initiatives to better
serve the industry needs. This work plan will be periodically reviewed and updated based
on new information received and progress made.


   I.      Baselining

Baseline (noun) is a self-consistent set of measurements and performance metrics that
can be used as a reference for the evaluation of future observed and anticipated
conditions.
Baselining (verb) is comparing the data characterizing some condition of interest with an
appropriately chosen of baseline measurements. Baselining involves two processes (a)
getting and archiving the baseline and (b) using the baseline.

Getting and archiving the baseline:
   • Record system measurements that best indicative of system stress:
           – Total generation in an interconnection
                   • Percent of dispatchable load-following generation
                   • Percent of variable energy resource generation
           – Phasor angles
           – Generation clusters
           – Power flows on key flowgates
           – Reactive power reserves, etc
           – Status of critical lines and flowgates
           – Status of critical generators
           – Simultaneous phasor angles and power flows on different interfaces
               (especially bringing power to the same sink)
   • Calculate dynamic performance indicators:
           – Frequency response performance (pre-disturbance, dip and settling
               frequency, time of minimum dip, size of generation event, etc)
           – Oscillation performance (frequency, damping, energy, mode shapes)
           – Voltage stability and power-angle indicators
   • Correlate dynamic performance indicators with measurements

Using the baseline:
   • Tracking system performance over time


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   •   Detecting and acting upon acute changes in the system performance
   •   Comparing observed dynamic performance against the models


Baselining to be done at various levels:
   • Interconnection
           – Control area (Balancing Authority / Transmission Operator)
                   • Power Plant


Availability of a complete set of wide-coverage synchro-phasor data sets is a pre-
requisite for all tasks tasks below.

Objectives                     Tasks
1.1 Develop and maintain       Task 1-1a:
seasonal baselines for         Record phasor angles and develop norms for each
phasor angles in an            operating season / day of week / on- and off-peak.
interconnection
                               Task 1-1b:
                               Record phasor angles from seasonal and week ahead SOL
                               studies. Compare the angles with the norms established
                               during the baseline. Determine if phasor angles can be
                               used to back up operating nomograms.

1.2. Develop and maintain a    Task 1-2a:
frequency response baseline    For each qualified system frequency event, record the
for Eastern Interconnection,   following:
Western Interconnection             Disturbance size
and ERCOT.                                 include event details (generator breaker trip
                                               vs. turbine trip, simultaneous vs. staggered
                                               trip, other actions such as dynamic braking
                                               or load shedding during the event)
                                    Pre-disturbance frequency, system frequency dip,
                                       and settling frequency
                                           save system frequency profile
                                    On-line generation and generation capacity
                                           amount of synchronous generation
                                           amount of non-synchronous generation
                               A qualified event is the one when the system frequency
                               either drops below 59.9 Hz or raises above 60.06 Hz.

                               Task 1-2b:
                               Compare observed system frequency performance with
                               that produced by simulation models and advise modeling
                               work group.



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1.3. Develop and maintain a Task 1-3a:
baseline for inter-area power Based on system studies, identify critical factors that
oscillations in Eastern       affect inter-area oscillations, such as:
Interconnection, Western           Status of critical lines
Interconnection and                Phasor angle separation across the system
ERCOT.                             Flows on major flowgates
                                   Status and generation levels of generation
                                      injections groups
                                   Reactive support, etc

                               Task 1-3b:
                               Continuously calculate and archive the following
                               quantities from wide-area PMU data:
                                   Inter-area oscillation modes, including their
                                       frequency, estimated damping, energy, and mode
                                       shapes
                               Correlate damping indicators with the system conditions.

                               Task 1-3c:
                               Compare observed oscillatory performance with the
                               behavior observed by power system models and advise
                               modeling work group.

1.4. Disseminate the           Task 1-4a:
knowledge of baselining        Conduct regular updates at NERC and RRO meetings
studies



   II.     Model Validation

Decisions on power system operating limits are based on power system studies. The
studies rely on the accuracy of power system models in predicting system performance
for anticipated disturbances. Periodic system model validation is necessary to ensure that
the power system models are accurate and up to date. Actual disturbances present great
opportunities for model verification and model improvements. The need for a continual
system model validation is recognized in a white paper prepared by NERC Model
Validation Task Force under Transmission Issues Subcommittee in May 2010. The need
for generating unit model validation is addressed by NERC MOD-026-27 standards.

Model validation needs to be performed at various levels:
  • Interconnection
          – Power Plant
          – Load center
          – Grid controllers like HVDC, SVC, etc



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Objectives                     Tasks
2.1 Conduct regular power      Task 2-1a:
plant model verification       Promote PMU installation at power plants
using disturbance data
                               Task 2-1b:
                               Develop requirements for the grid simulators to have
                               disturbance playback capabilities in their software
                               packages

                               Task 2-1c: develop automated tools that use disturbance
                               recordings for power plant model verification

                               Task 2-1d: develop processes and tools for managing data,
                               both model data and disturbance records, for power plant
                               model validation

                               Task 2-1e: develop understanding of the sensitivities of
                               power plant data and controls with respect to observed
                               dynamic performance

                               Task 2-1f: apply similar methods for validation of load
                               models and grid controllers

                               Task 2-1g: provide training for use of the tools for power
                               plant model verification

2.2 Conduct regular            Task 2-2a: Link state estimator power flow cases with
interconnection-wide model     planning dynamic model data base for system model
validation studies for large   validation studies.
disturbance events
                               Task 2-2b: put in place systems for disturbance data
                               collection and for system performance analysis

                               Task 2-2c: develop understanding of the sensitivities of
                               system model data with respect to observed dynamic
                               phenomena

                               Task 2-2d: continue developing tools for system-wide
                               model validation




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   III.    Load Characterization

Loads are usually represented at high side of bulk power delivery transformer (such as
69-, 115-, or 138-kV) in powerflow models. Loads are usually modeled as constant
power, active and reactive, in voltage stability studies. System tests indicate that loads
actually have a voltage sensitive component. Representing voltage sensitivities of loads
may result in higher reactive margins and, ultimately, unlocking capacity of voltage-
stability limited paths.

WECC has been engaged in the development of a composite load model for dynamic
simulations over the past several years. The development was motivated by severe
discrepancies observed between the dynamic simulations and the events of Fault-Induced
Delayed Voltage Recovery (FIDVR) that were recorded by PMUs in Southern California.
The development is almost complete, but extensive model validation against disturbance
events is required before the model can be used for production studies.

Objectives                     Tasks
3.1 Develop understanding      Task 3-1a:
of voltage sensitivity of      Expedite PMU installation in load centers at bulk power
loads for voltage stability    delivery substations.
studies
                               Task 3-1b:
                               Use bottom-up approach for estimating voltage
                               sensitivities from load composition information.

                               Task 3-1c:
                               Develop methods for determining load voltage
                               sensitivities using synchro-phasor data.

                               Task 3-1d:
                               Develop regional / seasonal / day of week / time of day
                               norms for voltage sensitivities of various loads

3.2 Support model              Task 3-2a:
validation studies for         Use PMU recordings of FIDVR events for load model
composite load model for       validation and tuning.
dynamic studies



   IV.     Data Mining

We are data rich, information poor. With tens of TB of data that expected to be generated
annually for each interconnection, there is a need for tools that can screen the data for
disturbances and unusual system conditions.




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Objectives                     Tasks
4.1 Develop “an engineering    Task 4-1:
tool” that automatically       Develop and implement an “engineering tool” that detects
detects grid disturbances      grid disturbances and unusual system conditions such as:
and unusual operating              - system events
conditions                                 o network faults and line outages
                                           o off-nominal frequency events
                                           o fault-induced delayed voltage recovery
                                              events
                                           o forced oscillations
                                   - changes in power plant controls
                                           o frequency response
                                           o voltage controls
                                           o power system stabilizers



   V.      Synchro-Phasor Data Validation

A production-grade synchro-phasor network is designed to the highest levels of reliability
and cyber security. Yet, the critical real time applications must be designed to tolerate
data dropouts and glitches, and must be capable of recognize corrupted data. A higher-
level data validation is required.

Objectives                     Tasks
5.1 Develop methods for on-    Task 5-1:
line validation of synchro-    Request NASPI Research Task Team to provide guidance
phasor data                    on methods that can be used for synchro-phasor data
                               validation. These should include data glitches, data
                               dropouts, CT-PT failures, stale data, loss of
                               synchronization, intrusion in the data system, etc.




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