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    Distribution System Planning in the Northwest Future Challenges,

    Deficiencies, and Solutions/OpportunitiesSolutions/Opportunities

    S. S. (Mani) VenkataNorthwest Energy System Symposium

    (NWESS)Seattle, WA

    February 22, 2007


    Overview of Distribution Systems

    Planning Objectives

    Future Challenges

    Distribution System Planning - 2 2007 KEMA Inc.

    Current Deficiencies


    Transmission and Distribution Electric Systems

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    Distribution System

    Distribution Substation

    Power Transformers: Single banked or doubled bank with 10/12.5 to 52/104 MVA ratings


    Switchgear: Breakers, switches,...

    Distribution Substation

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    Compensating Devices: Regulators, capacitors,...

    Control and monitoring Devices: CTs, VTs,....

    Computers and communications links

    Remote terminal units (RTUs)

    Distribution System Line EquipmentPrimary feeders three-phase) Laterals (three- or single-phase)Protective devices: Automatic Circuit Recloser (ACR),

    Distribution System Planning - 6 2007 KEMA Inc.

    ( ),sectionalizers, fuses, capacitors (150- to 1200-kvar) Distribution transformers (pole-mounted, padmount, commercial subsurface)Secondary services

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    3277 Electric Distribution System UtilitiesDistribution Systems is neglected step child Distribution System serves 131 Million Customersof Distribution lines 3.1 Million miles Electrical infrastructure is ageing rapidly

    U. S. Distribution System Size and impact

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    g g p yTotal Revenue $256 billion / yearAverage cost of retail energy sales $0.074 / kWhAverage cost of power generation $0.041 / kWhTotal cost of distribution losses $6.9 Billion / year

    U. S. Distribution System Size and impact

    Most of the customer complaints are on the distribution system since they are served directlyImpacts customer satisfactionAmount of data handled is at least 10 times higher L d id l di t ib t d

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    Loads are widely distributed Analysis and models needed are different for distribution systemsSystem losses (about 6%) are twice to four times higher than on the transmission Most of the infrastructure needed for delivery of power is on the distribution system

    The State of Washington Approximately 3.1 million customers served by:

    Investor Owned, Cities, Cooperatives, REAs, and Public Utility DistrictsFour Large PUDs

    Seattle City Light (374,000)Snohomish PUD (301,000)Clark Public Utilities (174,000)

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    Clark Public Utilities (174,000)Tacoma Power (163,000)

    Three IOUs AVISTA Corp (338,000), Pacific Corp (122,000), and Puget Sound Energy (1,002,000)

    46 remaining PUDs and Coop utilities Average: 14,312 customers eachRange: 46 to 52,015 customers each

    Distribution System Philosophical considerations

    Distribution systems are complex and capital intensive

    Distribution Planning is a very complex process

    Multiple objectives and constraints

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    Changes in customer base are occurring rapidly

    Opportunities that enhance planning capabilities

    How do we adapt to the changes?

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    Overall Planning ObjectivesMultiple objectives

    Affordable power delivery Adequate CapacityAdequate Reliability Acceptable Voltage quality

    Normal conditionsSystem efficiency, reliability, security

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    Cost-effective design solutions (minimized total costs)Minimum risk investmentsVoltage regulation/load balancingRe-configuration of system

    Emergency conditionsAdequate capacity and performanceLoad transferRestoration

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    Planning Constraints

    Multiple constraintsEconomic (long range total cost minimization)Technical (voltage quality, capacity & reliability)Societal (total consumer expectations)Environmental (UG dispersed generation)

    Distribution System Planning - 13 2007 KEMA Inc.

    Environmental (UG, dispersed generation)

    Planning and Design Studies

    System performance and optimization studies

    Short- and long-range load forecasting

    Unbalanced three-phase power flow

    Fault or short-circuit analysis

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    Voltage Regulation

    Power quality (voltage sags and harmonics)

    Transient analysis

    Loss minimization and efficiency studies

    Motor starting (cold load pickup)

    Relay coordination

    Transformer load management

    Conservation voltage regulation analysis

    Planning and Design Studies

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    Reliability assessment

    Cost-benefit and risk analysis

    Operation contingency studies

    Small Area Forecasting

    Planning Challenges from Planners Perspective

    Evaluation of alternative futures Dispersed generationAuto-sectionalizing schemes.

    Efficient use of data base technologiesAM/FM/GIS systems

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    AM/FM/GIS systems Customer, system, planning and operational data

    information interfaces

    Compliance with RegulationsFERC, NERC, PUC, county, city, ...

    Compliance with standardsANSI, OHSA, UL, NEMA, IEEE, IEC, NESC and NEC,..

    Future Challenges for Distribution Planning

    Changing consumer load characteristics, consumer services, and reliability expectations.How to model and plan for the addition of more dispersed distribution generation?How to plan and model the addition of automatic metering interfaces?

    Distribution System Planning - 17 2007 KEMA Inc.

    gHow to use the new metering data to further improve distribution efficiency, reliability assessments, voltage modeling, and outage management?How to model, interface, and use the increase in size of data structures for consumer information like GIS and CIS?

    How to apply and analyze outage management data using remote SCADA sensing instead of phone calls?Higher efficiency standards enacted by the State of Washington (Initiative-937) require greater application of conservation and renewable resources

    Future Challenges for Distribution Planning

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    resources. The distribution system will be asked to pay more attention to system losses.Need for end-use load control devices and control (Grid Smart)

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    Conservation voltage regulation is becoming more popular and requires a higher degree of modeling, data collection, and monitoring.Performance penaltiesTime of use metering

    Future Challenges for Distribution Planning

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    Load control applicationsEvaluate reliability penalties for poor reliability as rebate to consumers How to optimize the total cost of the consumer for distribution system delivery for system losses, voltage control, and future infrastructure needs?

    Problems Unique to Pacific Northwest

    Variety of utilities: very small to large

    Mostly municipal utilities with unique issues

    Many of them deal with distribution only

    Distribution System Planning - 20 2007 KEMA Inc.

    Small utilities have very limited resources

    Each utility may have unique objectives and constraints to contend with

    How do utilities cooperate to solve common problems related to distribution planning?

    Current Planning Practices in Pacific Northwest

    1. Many small utilities have only one planning engineer

    2. Planning and design is performed by consultants and others.

    3. Few have GIS let alone GIS and CIS interfaces.

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    4. Distribution system load forecasting is based on historical trends and short term.

    5. T&D energy efficiency is routinely not addressed.

    6. System metering is mostly demand meters and seldom includes both watt and var 15 minute demands.

    7. Rates analysis is performed routinely but not used by planners.

    8. Distribution system modeling is simplified and typically does not incorporate the entire distribution system and is not interfaced with GIS.

    Current Planning Deficiencies in Pacific Northwest

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    9. Transformer load management and related applications are seldom realized.

    10. System reliability modeling is primarily a historical based approach.

    Current Planning Deficiencies in Pacific Northwest

    11. Few optimization applications of distribution system reliability, losses, and infrastructure

    12. Consumer load and dispersed generation 8760 hour profiles not addressed.

    13. Few model the total system voltage drop from th b t ti t th i t

    Distribution System Planning - 23 2007 KEMA Inc.

    the substation to the consumer service entrance (main feeders, laterals, distribution transformers, and secondary)

    14. No ability to evaluate alternative impacts on the distribution system for changing consumer load patterns, load densities, and cost of losses.

    15. No predictive reliability modeling

    Current Planning Deficiencies in Pacific Northwest

    16. Power flow analysis capable of radial feeder operation only

    17. Reliability, system efficiency, and capacity are modeled separately

    18 Long range distribution system expansion planning

    Distribution System Planning - 24 2007 KEMA Inc.

    18. Long range d


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