DRG Slides for PWG Update to COPS

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Highlights from the DGTFRecommendation - 3

• Small DRG applies to generation less than 50 kW– Profiling is applicable provided a readily available

profile has been accepted and validated by ERCOT– No consensus on specific methodology, but

• Excess generation should be profiled in a type-specific manner and

• The load profile should reflect solar output during daylight hours

– Recommended assigning solar profile development to PWG

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TAC Instructions to COPS/PWG

• At the January 3,2008 COPS reviewed the DGTF recommendations – TAC requested that PWG/COPs assess and

further develop profiling options for consideration to address small distributed renewable generation

– TAC members indicated that PWG should take into consideration the generation characteristics specific to the renewable technology

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Settlement of Outflow Only

Some possibilities for allocating the PV-generated outflows:

1. Spread the energy evenly over daylight hours

2. Spread the energy evenly over the peak PV generating hours

3. Spread the energy using a PV model

4. Spread the energy using both a PV model and the existing settlement load profile

How can the outflow for residential photovoltaic (PV) arrays as measured at the point of interconnection be settled?

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DGTF Attachment A

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RESHIWR NCENT load profile for 01/16/07, scaled to

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Suppose...Single Day Meter Read:

kWh in: 18.00 kWh out: 0.82

exported to grid

0.82 kWh

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DGTF Attachment B

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RESHIWR NCENT load profile for 01/16/07, scaled to

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Suppose...Single Day Meter Read:

kWh in: 18.00 kWh out: 0.82

exported to grid 0.82 kWh

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DGTF Attachment C

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Load shape used in settlement (18.00 kWh)

Suppose...Single Day Meter Read:

kWh in: 18.00 kWh out: 0.82

Gen shape used in settlement (inverted)

0.82 kWh

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DGTF Attachment D

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RESHIWR NCENT load profile for 01/16/07, scaled to

18.00 kWh

Suppose...Single Day Meter Read:

kWh in: 18.00 kWh out: 0.82

Load shape used in settlement (17.18 kWh)

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Distributed Renewable Generation (DRG)

TDSPs responded to ERCOT’s request for information on premises that have DRG with a generation capacity < 50 kW.

What is out there?

Five of the ESI IDs included above have PV and wind generation. This means there are currently 87 unique ESI IDs known to have one or more type of DRG (< 50 kW).

1. Photovoltaic (PV)A. Residential (RES) 52B. Business (BUS) 6

2. WindA. RES 30B. BUS 4

3. Other

58 ESI IDs

34 ESI IDs

0 ESI IDs

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How much energy will a PV array produce?

Given the currently known average Residential PV generation capacity of 3.5 kW (AC), at 100% capacity factor there would be (3.5 * 24 =) 84 kWh generated per day.

If we utilize the Interstate Renewable Energy Council’s irradiance estimate of 20% from its presentation to the DGTF on 12/04/07, the estimated yield would be 16.8 kWh per day.

Applying the above to the average Business PV generation capacity of 8.9 kW (AC) yields an estimated 42.7 kWh per day.

For simplicity, the energy produced by a PV array is presented in most of the slides as a sine wave spanning 9:00 AM to 5:00 PM.

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– Represented using Sine function– Begin/End Times for PV Generation are day of year & weather zone

specific• 1 hour after sunrise • 1 hour before sunset

– Daily kWh Generation for Residential is based on 3.5 kW with a 20% capacity factor

• Average daily PV Generation is 16.8 kWh • Average daily PV produces output for 10.2 hours (range: 7.9 – 12.4) • Daily PV Generation is prorated based on hours of generation for the

day compared to an average dayExample day with 8 hours of Generation:

2.138.162.10

8PVGenkWh

PV Generation Assumptions

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• Residential PV Model assumptions

– Standard Profile multiplied by 1.1215 to adjust to average usage level for PV ESIIDs

– Subtract PV Generation from scaled up Profile– if result in an interval is negative, set to zero

• Business PV Model assumptions

– Standard Profile multiplied by 2.7633 to adjust to average usage level for PV ESIIDs

– Subtract PV Generation from scaled up Profile– if result in an interval is negative, set to zero

• Residential and Business Wind/Other Model assumption

– Standard Profile used – the interaction between wind generation and load is unpredictable

DRG - KWh Load Models

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PV Gen PV Profile Standard Profile

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Residential HIWR North PV

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• Excess generation is the energy flowing into ERCOT from the premise

• PRR756 - Credit for excess generation handled as an adjustment to load in settlement process

– PV assumption: Flat line from 11am to 3pm

– Wind/Other assumption: Flat line for entire day

• Settlement adjustment is triggered by a DRG Profile ID assignment

Profiling Excess Generation

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Residential PV – Applying the Profile

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Suppose...

ESI ID's meter read for Aug. 1-31:kWh 'inflow to premise': 627 kWh 'outflow to grid': 88

RESHIPV NCENT for Aug. 1-31: 1,424.71 kWh

627 / 1,424.71 = 0.6

RESHIPV NCENT load profile for 08/26/07

scaled to this ESI ID's 'inflow to premise'

(22.01 kWh)

RESHIPV NCENT applied to a PV ESI ID and kWh 'Outflow to Grid'

exported to grid (88 kWh / 30) 2.93 kWh

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Breakdown of Proposed DRG Models

Profile Type PV Total1 RESHIWR 8 8 162 RESLOWR 8 8 163 BUSLOLF 8 8 164 BUSMEDLF 8 8 165 BUSHILF 8 8 166 BUSNODEM 8 8 167 BUSOGFLT 8 8 168 BUSIDRRG 8 0 89 RESIDRRG 8 0 8

72 56 128

Other DRG

• 8 Models per Profile Type to represent Weather Zones

• BUSIDRRG and RESIDRRG are not generation type specific:

Profile ID assignment is used to trigger settlement adjustment for excess generation

KWh Load and kWh Gen are settled with actual interval data

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DRG Profile ID Assignment

• TDSPs submit documentation to ERCOT to initiate a change to a DRG Profile ID assignment.

• ERCOT validates requests within 5 Business Days and notifies to initiate the 814-20

Information required from TDSP

• Affirmation of Interconnection Agreement with customer and effective date• Generation Type, and characteristics• Metering configuration• Inverter information if applicable (DC Generation)

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18.2.1 Guidelines for Development of Load Profiles

In developing Load Profiles, ERCOT shall strive to achieve an optimal combination of the following:(1) Give no unfair advantage to any Entity;(2) Maximize usability by minimizing the total number of Load Profiles without compromising accuracy and cost effectiveness;(3) Minimize the Load Profiles’ contribution to UFE over all Settlement Intervals, paying particular attention to higher cost periods;(4) Reflect reasonably homogenous groups, with respect to load shape and likely supply costs;(5) Develop Load Profiles that are distinctly different;(6) Develop Load Profiles for areas with incomplete load data utilizing data from other sources, taking into account similarities and differences in load;(8) Use the most accurate load research data available; and(9) Develop Load Profiles based on readily identifiable parameters that are not subject to frequent change.

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Distributed Renewable Generation Modifications LPGRR030

Pros: • Incorporates kWh load modifications resulting from PV Generation behind the meter

• PV and Non-PV DRG Profile ID assignments results in specific settlement cuts, and supports the reporting of load by Profile ID

• DRG Profile ID assignments trigger settlement for kWh Gen specific to the DRG type

• Allows forecasting systems to track customers by their DRG Profile ID to better forecast the balancing market schedules

• Shadow settlement systems perform the same basic evaluation as present

Cons:

• Large (128) increase in the number of Profile IDs used in ERCOT and Market Participants settlement and forecast systems

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Alternatives for DRG - LPGRR030

Concerns were raised at the March 26, 2008 PWG meeting about the large number of new Profile IDs being introduced for DRG

Several alternatives were discussed and then narrowed to three options:

1.LPGRR030 as drafted - 128 new Profile IDs2.DRG Profile IDs only for PV - 72 new Profile IDs 3.RESPV, BUSPV, RESWD, BUSWD, RESIDR, BUSIDR * 8 WZones – 48 new Profile IDs

PWG did not have consensus on a single option

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DRG Profile IDs only for PV Option 2:

Pros: • 72 Profile IDs instead of 128 – eliminated the requirement for Non-PV DRG Profile IDs• DRG Profile ID assignments trigger settlement for kWh Gen specific to PV

Cons:

• No settlement cuts for Non-PV ESIIDs with DRG; increases the difficulty to report NonPV DRG metrics

• No trigger for settlement for kWh Gen specific to Non-PV (requires an assumption that data in the meter-loop for ESIIDs with standard profiles are for Non-PV DRG)

• Increases the difficulty to perform required quarterly and annual validations for Non-PV ESIIDs

• Requires continuing manual validation of usage records with meter-loop information to confirm they are correctly associated with DRG ESIIDs and use of MarkeTrak to resolves discrepancies

• Increases the difficulty for forecasting systems to track customers by their DRG Profile ID

• Does not support Protocols Section 18

• PRR756 will need to be amended

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RESPV, BUSPV, RESWD, BUSWD, RESIDR, BUSIDROption 3:

Pros: • 48 Profile IDs instead of 128

• DRG Profile ID assignments trigger settlement for kWh Gen specific to DRG type

• Settlement cuts with DRG Profile IDs will be created

Cons:

• For some PV and Wind ESIIDs the Load shape will be inconsistent with the ESIIDs usage pattern (e.g. RESLOWR settled with RESHIPV)

• Increases possibility of gaming (e.g. Adoption of DRG to obtain a more advantageous settlement shape)

• Does not support Protocols Section 18

• Creates disincentives for some categories of ESIIDs to adopt DRG (e.g. Adoption of DRG would result in a less advantageous settlement shape)