ferc – technical conference · 4/11/2018. dr. maya prica, assistant professor. case western...
TRANSCRIPT
4/11/2018
Dr. Maya Prica, Assistant ProfessorCase Western Reserve UniversityCleveland, OH
FERC – Technical Conference
Panel 5
Incorporating DERs in Modeling, Planning and Operations Studies
Transformation of the nation’s electric grid creates both challenges and opportunities
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CentralizedDispatchableGeneration
Predictable Load
Capacity Available
Distributed Intermittent Generation
Variable Net-Load and Customer Intervention
Capacity Constrained
Source: Dr. Sonja Glavaski, “NODES: Controlling the Grid Edge,” https://arpa-e.energy.gov/sites/default/files/Glavaski_FastPitch.pdf
Modeling DERs A model is a mathematical representation of a physical system
A model should only be detailed enough to provide needed information and answers to questions and not so detailed that the computation time is excessive
Main drivers for model development are voltage related or protection related issues
Type of models:o Economic o Steady-stateo Dynamic o Transient
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Modeling accuracy
The mathematical modeling DERs that include electrical features like harmonics, volt/freq ride through, dynamic response, etc. is mature and commercially available
Most of the time, the models have missing or unknown parameters that cause modeling inaccuracy
Software vendors are adding new models as new methodologies become available
Developed models need to be approved by utilities Aggregated models are mostly based on 3-phase balanced
representation of distribution circuits, for example, PVs may be connected by phase but their aggregated model for analysis assumes 3-phase balanced operation
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Most utilities are using commercially available modeling software packages Transmission modeling
o PTI-PSS-E (Siemens)o PSLF (GE Energy Consulting)o CYME (EATON)o PROMOD (ABB)
Distribution modeling o CYME (EATON) o Synergi (DNV GL)o MilSoft (Utility Solutions)o SINCAL (Siemens)o ASPEN (ASPEN)o DEW/ISM (Electrical Distribution Design)o OpenDSS (EPRI) – Open source, adopted by some commercial vendors
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The evolution load models
Static models – algebraic equation known as ZIP load model
CLOD – developed to simulate some dynamic behaviors of aggregated loads
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Source: https://ccaps.umn.edu/documents/CPE-Conferences/MIPSYCON-Papers/2017/CaseStudyonAggregateLoadModelinginTransientStabilityStudies.pdf
Evolution of load models (cont.)
CMLD – comprehensive dynamic model
Adaptation of the CLMD model to incorporate DER (under development)
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Source: https://ccaps.umn.edu/documents/CPE-Conferences/MIPSYCON-Papers/2017/CaseStudyonAggregateLoadModelinginTransientStabilityStudies.pdf
Modeling the interaction between T&D
There is no common methodology for analyzing the interaction between T&D systems
There is some research being done and several efforts to develop methodologies
T&D interaction modeling needs to be an “add on” rather than a replacement of existing systems
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T&D Interaction:1. Bundled 2. Iterative
Per phase model, balanced system 3-phase model, unbalanced system
1. Bundled, both systems are analyzed simultaneously as 3-phase, unbalanced2. Iterative, two step process, T&D are analyzed separately
Integrated T&D with PSS®SINCAL
Power utilities are able to analyze the impacts and benefits of DERs on their distribution system that could lead to issues on the transmission system
PSS®SINCAL can simulate:o Thermal loading of network equipmento Load and Generation Profileo Load Flowo Voltage Limitso Voltage Fluctuationso Reverse Power Flowo Protection Assessmento Short-circuit Assessment
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Source: https://www.siemens.com/content/dam/webassetpool/mam/tag-siemens-com/smdb/energy-management/services-power-transmission-power-distribution-smart-grid/consulting-and-planning/power-systems-simulation-software/pss-sincal-assets/10-psssincal-dertd-datasheet-intl-version.pdf
Integrated T&D with PSS®SINCAL and CYME SCE - DER modeling efforts Couple the distribution circuit model (e.g. CYME) to the load
at a certain bus in the bulk system and solve the coupled T&D system
10Sources: https://www.wecc.biz/Administrative/SCE%20DER%20Studies.pdf
New paradigm requires new models
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Enabling DERs to participate in the market without coordination with the distribution system operator may compromise distribution system reliability and power quality
Static Load flow analysis will not be sufficient; there will be a need to conduct load and generation profile simulation and to look at the entire system
Industry does not have the ability to study multiple resources aggregated across multiple circuits responding to an ISO/RTO signal
New paradigm: resources respond to an ISO/RTO signal that is different than a local reliability challenge of a distribution system.
More granular modeling of DERs at the edge of the network is needed
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Challenges:o System model sizeo Integrating DER control models
into the existing system modelso DER value - RTO/ISO price signals
are based on the transmission nodes. All resources below a transmission node receive the same value which does not consider the true value to the distribution system
New models that can capture control, coordination of DERs and their true value are needed
Communication and security
Detailed models of DERs at the bulk power system level would not provide better DERs visibility
Visibility of DERs may be achieved by adding real-time telemetry
Visibility and situational awareness of the system may be achieved by adding SCADA across distribution systems (presently only 1-2 percent of distribution system equipment has real-time telemetry)
Concern: reliable communication and cyber security Concern: security of modeling details and collected data –
physical security of data and models
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Evolving industry requires evolving models
IEEE 1547 is a system of options Each utility may have different options and settings
requirements Some settings will come from the bulk power system, some
will come from the distribution system IEEE 1547 will require the power industry to evolve New models will be needed for utilities to better understand
different options and their impact on system operation These models will evolve as industry evolves
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CWRU activities
CWRU is supporting utilities in developing and testing new models and tools
CWRU has worked on utility projects, both system studies and demonstration projects with EPRI and the US DOE:o SHINES – PV-energy storage model development and system control o Distributed energy storage for frequency regulation – methodology
development and impact studyo Energy storage/wind integrationo Grid demonstration project
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Summary Software vendors are adding new models as new
methodologies become available New models and tools are needed:
o Industry does not have the ability to study multiple resources aggregated across multiple circuits responding to an ISO/RTO signal
o Methodologies for DER impact studies needs to be developedo More granular modeling of DERs at the edge of the network is needed
Evolving industry requires evolving models Cyber, models and data security is a concern Economic value of DERs needs to be revisit
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