Pricing Impact on Financial Management

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					                     October 1,2003

State Estimator Overview

   State Estimation - a generic definition
   State Estimation for power system operation
    – As a component in classical network security analysis
    – Typical data input/output descriptions
    – Summary of SE Functionality
   State Estimation for electricity market operation
    – As a component in market-based congestion
      management (e.g. LMP/Nodal pricing)
    – Impact of SE quality on financial settlement
       SE - A generic problem definition

   To obtain the best estimate of the state of the
    system based on a set of measurements of the
    model of the system. For example:
    – State variables: the weights of John (X) & Mary (Y)
    – Models & Measurements:
       • Model 1 - John stands on the scales alone
          – Measurements: X1, X2, X3….
       • Model 2 - Mary stands on the scales alone
          – Measurements: Y1, Y2, Y3, Y4...
       • Model 3 - John & Mary stand on the scales together
          – Measurements: Z1, Z2, ... ( Z = X + Y)
       • Different scales have different degrees of accuracy
       SE for Power System Operation

   Business Objectives:
    – To provide a view of real-time power system conditions
       • Real-time data primarily come from SCADA
       • SE supplements SCADA data: filter, fill, smooth….
    – To provide a consistent representation for power system
      security analysis
       • On-line dispatcher power flow
       • Contingency Analysis
       • Other applications (DTS, OPF/VVD…)
    – To provide diagnostics for modeling & maintenance
       SE Input & Output Data

   Input
    – Transmission network model (topology, impedance, limit)
    – Measurements (device, accuracy, SCADA-mapping.…)
    – Execution parameters (dynamic weight-adjustments…)
   Output
    – Bus voltages, branch flows, taps, generation, load
      …(state variables)
    – Measurement error processing results
       Functionality/Capability Summary

   Consistency across network security applications
    – Modeling: device (load, generation), schedule, limits...
    – User Interface: information presentation, maintenance
    – Data exchange: save cases, external import/export
   Estimation performance
    – Robust convergence (stability over wide range of
      measurement accuracy, time skew….)
    – Consistent treatment between internal & external areas
    – Error detection, processing, and management
      SE for Electricity Market Operation

   Reliable physical operation and robust market
    operation require convergence between real-time
    system operation and spot market delivery.
   Convergence most significantly affected by
    transmission congestion management.
    – Manage congestion in base case and in contingencies,
      i.e. Simultaneous Feasibility Test (SFT)
    – SFT is equivalent to SE & CA in EMS
    – Out-of-merit market dispatch in the RT Balancing market
      should be driven by RT constraints identified by SE/SA
Market Clearing
w/Congestion Management

               Market Data Base

            Data Importer / Exporter
            MktClearing Configurator
                DA             HA   RT
      SFT                           BidClear
        Market Clearing
        w/Congestion Management
RT SE/SA      Operator I/F
                             Bids & Offers
Constraints   (Constraint)
                             & Other Data



                                   MW Injections

Model (EMS)
                             (n-1 security)
       SE for LMP-Based Markets

   Dispatch Instructions
    – Real time dispatch targets: affected by critical (binding)
      constraints from SE/SA
   Settlement determinants (price & quantity)
    – LMP price: affected by bid/offer prices and by binding
      constraints from SE/SA.
    – Locational model: individual nodes and aggregated
      zones/hubs. Impact on binding constraints depends on
      relative effects of different types of measurements.
    – Quantity: profiling over time & location often based on
      relative pro-ration from SE results.

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