Economic Outage Evaluation

Woody Rickerson

ERCOT Outage Coordination Supervisor

5-9-2008

ISO Outage Coordination Workshops

– 10-7-2007 Folsom, CA– Attended by approximately 50 people from 8 NERC regions

– 1-8-2008 Austin, TX– Attended by approximately 45 people from 6 NERC regions

– 7-17-2008 Holyoke, MA

New England’s Electric Power Grid

– 6.5 million customer meters

– 350+ generators

– 8,000+ miles of high voltage transmission lines

– 5 local control centers

– 12 interconnections with approximately 5000 MW capability to three neighboring systems:

– New York

– New Brunswick

– Hydro Quebec

– 32,000 MW of installed generating capacity

– Peak load:

– Summer: 28,127 MW (8/06)

– Winter: 22,818 MW (1/04)

– Transmission Outage Requests Processed

– 2005 – 4800

– 2006 – 5000

– 2007 - estimated in excess of 5500

ISO

an

d Lo

cal C

on

trol C

en

ters

320 mi.

400 mi.650 km

ISO

an

d Lo

cal C

on

trol C

en

ters

520 km

ISO-NE Outage Coordination HistoryExtensive review of Outage Coordination processes in 2004

– Changes were necessary to respond to the greater demand for improved coordination

– Nearly doubled staff to facilitate increased studies and coordination

– Near-term Outage Evaluations (<21 days in advance)– 10 Positions (7x12 shift)

– Long-term Outage Evaluations (>21 days, up to 12 months ahead)– 5 Positions as 5 x 8 shift

– 6 degreed positions

– Historically received 90% of transmission outages less than 21 days notice

– Placed emphasis on increasing notice by use of the following:– Metrics– Economics– 60% now received with less than 21 days notice

ISO-NE Outage Coordination Study Tools

– Current– AREVA EMS Power Flow - Thermal

– AREVA Day Ahead Study System – Economic

– PSS/E - Voltage and Stability

– Future (Under Development)– Power World – Interface Limit Calculations

– Additional economic study software – RFP late 2007

ISO-NE Economic Evaluation History

– Move to consider Economics in outage coordination of transmission outages began 3 years ago

– Market driven– TSP opposed

– Generation Outages are generally denied based on capacity needs (compact system with definitive load pockets)

– Typically scheduled 6 to 18 months in advance

– TSPs elected to recover costs associated with economic coordination through rate annual rate adjustments

– A mechanism was designed for Load servers to share acceleration costs based on load ratio -- ultimately rejected by TSPs

– Report of Economic Savings issued each year to TSPs (not public)– 1st quarter 2008 shows $33 million in savings

ISO-NE Economic Overview

– Market Participant group maintains a list of “economically significant transmission elements”

– 20% of all transmission elements on list– List is dynamic and can be added or subtracted from at any time– Economic Evaluation of outages is not confined to list– List serves as a aid

– NEISO set threshold for economic consideration– $200,000 over a 1 week period

– Transmission vs Generation conflicts – Transmission usually gives way– Trend starting where transmission is scheduling important outages further in advance

– Outages flagged as “Economic” are subject to NEISO repositioning

– Historic load (similar day)

– Generator costs (historic bids – subject to outlier cleanup)– Virtual bids not used

– Outage-in vs Outage-out 1hr comparison of production cost– All other approved outages included

– False congestion analyzed by experience

– 1 hour costs extrapolated over outage period

– Unit commitment not considered

– Post Analysis Process being developed

ISO-NE Economic Evaluation Process

– Planned vs. Actual outage times become crucial

– Outage cancellations can invalidate results

– Personnel with experience in analyzing “typical” bids difficult to find

– Resistance to new Metrics – Number of cancellations– Reasons for cancellations– Planned vs Actual outage times

– TSP fear that realized savings could become public and result in pressure to decrease maintenance

ISO-NE Economic Evaluation Problems

KEY STATISTICSPJM member companies 500millions of people served 51peak load in megawatts 144,644MWs of generating capacity 164,905GWh of annual energy 729,000generation sources 1,271area served 13 states + DCInternal/external tie lines 247

PJM Power Grid

PJM Economic Evaluation History

Financial Transmission Rights (FTR) revenue inadequacy– Money is collected from loads to pay generators and FTRs.– Congestion on the system may not allow enough money to be collected.– Generators will be paid first, and then FTRs are paid.– If not enough money is collected to pay the FTRs, they are revenue inadequate.

Outage Acceleration Process was developed to identify possible revenue inadequacy resulting from transmission outages (2007 first year for acceleration)

Year Congestion FTR revenue inadequacy

2005 2,070,038,758 177,842,265

2006 1,624,292,766 52,613,716

2007

(through 10/31)

1,405,308,639 0

New Outage Timelines added this year to enhance economic opportunities

Over last 2 years – 6 outages subject to acceleration (2 paid)

PJM Economic Outage Evaluation Overview

– Tools used– Energy Management System (EMS)– eDart (Dispatcher Application And Reporting Tool) – Internet-based outage management

system for generation and transmission

– Timelines– 9 to 12 months out – 6 months out (minimum for economic evaluation)– 1 month out– 1 to 3 days out

– Criteria for acceleration – Outage with significant market impacts

– Outage is five days or more– Estimated congestion revenue inadequacy in excess of $500,000

– Use the Transmission Adequacy and Reliability Assessment (TARA) tool– PowerGEM software for off line using PSSE Cases– Off line Application to run the Security Constrained Economic Dispatch to:

– Move minimum amount of generation to solve or– Solve on a least cost basis– Solution and cost for each hour of outage

– Create daily PSSE cases up to 365 days in advance– Loads incorporated based on forecasts– Outages automatically incorporated– Added functionality to the TARA application to handle the following network topology changing

events:– Split an existing bus– Add a new bus to the case– Add new pieces of equipment such as branches, transformers– Change the rating of an existing piece of equipment– Change the bus to which a branch, transformer, etc. is connected

– SCED used for two day out – 12 month out analysis

– Construct and evaluate all necessary snapshots spanning the duration of the outage (DC single contingency analysis)

– Benefit – Allows for a several outage snapshots – on peak, off peak, daily, weekends.– AC contingency analysis function to allow checking for the following:

– MVA and current line and transformer flow – Voltage deviations and voltage drop (change) violations – Voltage collapse conditions

– Perform a combined reliability and financial impact of proposed transmission outages Security Constrained Economic Dispatch

– Run with and without outage– Determine the production cost difference – Determine the FTR revenue inadequacy

PJM Economic Outage Evaluation Process

– “High Cost” Transmission outages posted four weeks prior to the FTR auction.

– Participant makes request to accelerate to PJM.

– If one or more requests to accelerate are received, PJM will request an estimate to accelerate from the transmission owner (TO).

– PJM provides participants the details of the estimate once it is received from TO.

– Actual costs to accelerate would be divided across the participants.– PJM acts as the middleman

PJM Economic Outage Evaluation Acceleration Process

– TSP acceleration costs unreasonable

– Capturing actual savings difficult

– Requires good metrics to handle “Planned vs Actual” planning

– Participants that benefit from acceleration not required to contribute to acceleration costs (only takes one willing to pay)

PJM Economic Outage Evaluation Problems

PJM and NEISO Comparison

NEISO PJMBreaker model Line Model

Independent of CRR Market Used in conjunction with CRR Market

Utilizes same RUC logic used in RT Utilizes Line Model “Generator Impact” tool

One hour analysis extrapolated over outage

Multi-hour or All-hour analysis

Acceleration/Repositioning/Cancellation decision up to NEISO

Acceleration decision up to Market

TSPs made whole through rates TSPs made whole by direct payments

Threshold $200K production cost increase over 1 week

5 day or greater outages that result in $500K of FTR revenue inadequacy

Annual Report of projected savings Monthly Report does not include dollar savings

ERCOT Economic Outage Analysis

Three Uses:

1. Avoiding high cost combinations of outages

2. Providing a dollars value for outage acceleration or repositioning savings (is there enough potential savings to warrant looking at acceleration or repositioning)

3. Capturing the cost of construction outages for proposed projects so that they can be included in the Planning Analysis

ERCOT Nodal Systems

ERCOT Nodal Market supported by multiple integrated systems and multiple vendors

– Outage Evaluation Tool = reliability based, multi-time, automatic outage assessment tool

– Vendor: AREVA

– Outage Scheduling – supports interactions with market participants, and a DB of outage requests’ statuses

– Vendor: ABB

– Model Source NMMS (in CIM). The same time-dependent source DB for all systems.

– Vendor: Siemens

– Supporting systems: EMS & Market Management System

– Vendor: AREVA (EMS), ABB (MMS)

Nodal Outage Evaluation Process Steps

1) User– Selects all dates/hours for the study– Provides any resources that must be committed or scheduled at a particular value

2) OE pulls all the data corresponding to selected times, and automatically creates a power flow case for each selected hour (the user can manually edit any data):

– Network models– Forecasted loads– Approved outages– Forecasted temperatures– Expected resource status (within 7 days)

3) For each power flow case the OE separately and economically commits resources to match loads and then schedules the resources taking into account reliability (N-1 security)

– Not expected to run hourly analysis, e.g. no need to run similar or back-to-back hours, but it can if desired

4) OE computes sensitivity of the production costs to requested outages. If it can not find a secure operating point, it also finds sensitivities of overloads to requested outages. Outcomes:

– OE finds an N-1 secure operating point to accommodate all requested outages. It gives incremental cost of all outages, as well as contribution of each individual outage

– OE can’t find a secure operating point. It then computes contributions to the overload by each requested outage. No cost data produced in this case.

5) OE extracts and condenses the results, and presents a list of outages for approval to the user

6) If the user accepts approved outages list, OE sends the list to OS for status update.

Nodal Outage Evaluation Tools Challenges

– Automatic case setup - a big challenge to setup cases that are meaningful from the resource distribution standpoint, and also have adequate reactive resources to result in a solved power flow case

– Our approach: simplified Unit Commitment based on typical price curves. We are also expecting the need for some Voltage/Var scheduling considerations.

– Many study hours – computational burden to get N-1 (2000 contingencies) secure operating points for all the cases is enormous.

– Our approach: still in the design stage – maximize the use of in-memory information; design & try

– Sensitivity computations (cost and violations) with respect to requested outages very computationally intensive.

– Our position: trading the computer time for the analyst’s time. Without this info, the analyst would spend considerably more time to arrive at the needed conclusions.

Good Utility Practice and Nodal Protocols

3.1.1 Role of ERCOT(1) ERCOT shall coordinate and use reasonable efforts, consistent with Good Utility Practice, to accept,

approve or reject all Outage schedules for maintenance, repair, and construction of both Transmission Facilities and Resources within the ERCOT System. ERCOT may reject an Outage schedule under certain circumstances, as set forth in Section 3.1.5.6, Rejection Notice; Section 3.1.6, Outages of Resources Other Than Reliability Resources; and Section 3.1.7, Reliability Resource Outages.

3.1.5.6 Rejection Notice(2) ERCOT may reject a Planned Outage or Maintenance Outage of Transmission Facilities only:

(a) To protect system reliability or security;

(b) Due to insufficient information regarding the Outage; or

(c) Due to failure to comply with submittal process requirements, as specified in these Protocols.

ERCOT Nodal ProtocolsSection 2: Definitions and Acronyms

Good Utility Practice Any of the practices, methods, and acts engaged in, or approved by, a significant portion of the electric utility

industry during the relevant time period, or any of the practices, methods, and acts that, in the exercise of reasonable judgment in light of the facts known at the time the decision was made, could have been expected to accomplish the desired result at a reasonable cost consistent with good business practices, reliability, safety, and expedition. Good Utility Practice is not intended to be limited to the optimum practice, method, or act, to the exclusion of all others, but rather is intended to include acceptable practices, methods, and acts generally accepted in the region.

Dwr Translation -- A practice accepted by most ERCOT market participants to achieve a desired result in a timely manner without incurring exorbitant cost or compromising reliability and safety.

• Discussion