Published on May 8, 2014
©2014 Navigant Consulting, Inc. DISPUTES & INVESTIGATIONS • ECONOMICS • FINANCIAL ADVISORY • MANAGEMENT CONSULTING May 5, 2014 California Renewable DG Integration Study Gene Shlatz | Director, Energy Practice AWEA WINDPOWER 2014 AWEA Renewable Energy Workshop Las Vegas, NV
1©2014 Navigant Consulting, Inc. 1©2014 Navigant Consulting, Inc. Agenda • DG Study Objectives • Analytical Framework • Assumptions and Methods • Study Results • Key Findings
2©2014 Navigant Consulting, Inc. » Background – Governor’s Clean Energy Jobs Plan: Includes 12,000 MW of localized renewable energy (DG), generally defined as, o 20 MW or less o On-site or close to load o Constructed quickly w/ no new transmission » Study Purpose – Gain a better understanding of infrastructure costs and impacts associated with increased DG installations in California, and how they change based on: o interconnection location, distribution o feeder characteristics, load types o project size – Develop a framework for a DG planning tool applicable for use by all California electric utilities – Help achieve renewable DG goal of 12,000 MW by 2020 Project Overview: California Renewable DG Integration Study: Study Objectives
3©2014 Navigant Consulting, Inc. “ As variable and distributed energy resource adoption reach significant levels this decade, new engineering and operating paradigms are required. Resnick Institute, CalTech, Sept, 2012, Grid 2020 Towards a Policy of Renewable and Distributed Energy Resources. “Estimates for fully capable distribution circuits suggest an additional cost of between $2 million and $3.5 million per circuit for physical upgrade and intelligent control systems.” Electric Power Research Institute. April, 2011. Estimating the Costs and Benefits of the Smart Grid: A Preliminary Estimate of the Investment Requirements and the Resultant Benefits of a Fully Functioning Smart Grid. The addition of up to 12,000 MW of renewable DG is expected to transform electric grid operations and impose additional costs. . . . Accurate tools are needed to predict impacts and upgrades needed to ensure successful integration of renewable DG Notable remarks: California Renewable DG Integration Study: Background The methods and tools applied in the CEC framework are designed to predict DG impacts and integration costs with reasonable accuracy for California utilities
4©2014 Navigant Consulting, Inc. DG installation are based on estimated totals for the Southern California Edison system – DG capacity additions will vary by utility. Scenario DG Capacity Renewable DG 2020 Target (CA Clean Energy Plan) 12,000 MW Baseline DG Penetration (% DG assumed for SCE system) 4,800 MW Maximum DG Penetration (25% over baseline) 6,000 MW Minimum DG Penetration (50% below baseline) 2,400 MW California Renewable DG Integration Study: DG Capacity
5©2014 Navigant Consulting, Inc. Many of the preferred locations for DG are located in high load density urban areas, where distribution feeders typically are shorter. California Renewable DG Integration Study: Background (Utility System) Urban: 8‐10,000 sq. miles = 15‐20% Rural: 40‐42,000 sq. miles = 80‐85% (Nevada) (Los Angeles) Urban Customers: 75% Rural Customers: 25%
6©2014 Navigant Consulting, Inc. The framework is designed to contain the following features: 1. Has clear and easy to follow methods and assumptions 2. Contains sufficient analytical rigor to produce accurate results 3. Applies models and tools that are commonly used to simulate utility system operations 4. Uses processes that are understandable and repeatable for different scenarios 5. Includes Renewable DG technologies available to all California utilities and consumers 6. Uses evaluation criterion consistent with common industry practices and standards 7. Is expandable to include new DG technologies or solutions to address constraints 8. Produces results that clearly identifies all DG impacts and costs Analytical framework designed and structured to be applicable to electric utility distribution systems throughout California. California Renewable DG Integration Study: Analytical Framework
7©2014 Navigant Consulting, Inc. » Feeder selection – Based on statistical clustering approach » Integration costs – Interconnection costs based on historical averages and Navigant estimates – Includes DG interconnection and distribution system upgrades » Technology options – Mitigation/upgrades based on currently available technology – Near-term advanced technologies and solutions addressed (Smart Grid) » Simulation approach – Commercially available load flow model » DG interconnects to 33 kV, 16 kV, 12 kV, and 4 kV feeders » IEEE 1547 Standards/Guidelines* – Based on requirements as of January 1, 2013 – Includes series of standards under 1547, where applicable » Largest single DG unit is 20 MW – Most DG ≤ 10 MW because most feeders rated ≤ 10 MW Project team established guiding principles and assumptions to support the analytical framework. California Renewable DG Integration Study: Project Assumptions * IEEE Std 1547TM(2003)Standard for Interconnecting Resources with Electric Power SystemsP1547.1 DG benefits addressed in other ongoing studies
8©2014 Navigant Consulting, Inc. DG integration scenarios include a mix of mostly urban, mostly rural, and equal amounts of DG in each region Three case studies evaluated using the analytical framework: California Renewable DG Integration Study: Scenarios Urban/ Rural DG 70% Urban 30% Rural 50% Urban 50% Rural 30% Urban 70% Rural Urban DG (MW) 3,360 2,400 1,440 Rural DG (MW) 1,440 2,400 3,360 Total DG (MW) 4,800 4,800 4,800
9©2014 Navigant Consulting, Inc. » Navigant selected a subset of feeders that are representative of the entire system (~ 4,000 feeders) – Feeder selection based on a statistical “clustering” technique to group feeders according to the following attributes: o Urban and rural location o Lower voltage (4.16 kV) versus higher voltage feeders (12.47/16/33 kV) o Short and long feeders o Primarily residential versus primarily commercial/industrial customers o Light and heavy load density » This set of feeders was used to simulate DG impacts given differences in: – Feeder attributes – Location – Feeder loadings An analytical approach is used to select a subset of distribution feeders to accurately represent the entire SCE system for DG modeling. California Renewable DG Integration Study: Feeder Selection
10©2014 Navigant Consulting, Inc. Objective: » Collect and analyze data on all distribution feeders (~4,000 ), covering approximately 30 different attributes, e.g., customer counts, loading, energy usage by rate class, line length, existing DG, etc. » Goal: Identify a manageable set of feeders obtained from a ‘cluster’ of similar feeders, any of which can be represented by a single feeder Process: 1. Select key attributes, and apply mathematical algorithm to determine the similarity between feeders across these attributes 2. Group feeders into ‘clusters’, each of which has unique characteristics 3. Next, examine the resulting clusters, and settle on a group of 13 to represent the entire distribution system 4. Select an “average” feeder from each cluster to represent a population of comparable feeders for DG integration studies Feeder Selection Process California Renewable DG Integration Study: Feeder Selection
11©2014 Navigant Consulting, Inc. » Feeder groups are classified as urban or rural » Feeder groups include a combination of short and long, and mix of customers and voltages California Renewable DG Integration Study: Feeder Selection 7 Urban Classifications 6 Rural classifications 1. Urban ~4 kV (788 feeders) 2. Urban 12-16 kV Residential (536 feeders) 3. Urban 12-16 kV Commercial (397 feeders) 4. Urban 12-16 kV Industrial (332 feeders) 5. Urban 12-16 kV Residential-Commercial (1,160 feeders) 6. Urban 12-16 kV Long (20 feeders) 7. Urban 33 kV (13 feeders) 1. Rural ~4kV (82 feeders) 2. Rural 12-16 kV Short (113 feeders) 3. Rural 12-16 kV Medium (66 feeders) 4. Rural 12-16 kV Long (55 feeders) 5. Rural 12-16 kV Agricultural (65 feeders) 6. Rural 33 kV feeders (12 feeders) The analysis resulted in the selection of 13 feeders to represent the entire system of approximately 4,000 distribution feeders. Many urban feeders have similar characteristics and attributes. Urban Feeder 1 represents 788 urban feeders, whereas Rural Feeder 6 only represents 12 feeders.
12©2014 Navigant Consulting, Inc. Rules adopted for the study include: » DG output cannot exceed main line or lateral loading limits (load cannot offset DG output) » DG is assumed off-line for up to 5 minutes following a circuit interruption (IEEE 1547) » Inverter power factor is fixed; that is, not allowed to provide reactive support » Load Tap Changer (LTC) and regulator operations must not materially increase the number of voltage regulator or LTC operations » DG ride-through is not required for low voltage events » Total allowable DG should recognize limits associated with load transfers via feeder ties, either for maintenance of reliability; i.e., cannot exceed feeder loading or voltage limits Performance standards used to evaluate DG impacts based on industry standards, state regulations, and utility planning guidelines. California Renewable DG Integration Study: Impact Analysis The impact of intermittent renewable DG on bulk system generation load following and frequency regulation is not part of this study, but will be considered in future analyses and investigations.
13©2014 Navigant Consulting, Inc. DG integration studies include impact on feeder voltage performance capacity, operational factors, and other potential requirements. Category Description of Constraint or Requirement Over/Under voltage Exceeds +/- 5 % from nominal Line/equipment overloads Exceeds normal/emergency ratings Voltage regulation Excessive regulator or load tap changer operation Reverse power Reverse flow on mono-directional equipment Fault duty Exceeds equipment ratings Protection coordination Changes in settings or new devices Operational constraints Load transfer constraints (e.g., for maintenance or outage restoration) Power quality Voltage flicker Communications & SCADA For large DG or high penetration DG California Renewable DG Integration Study: DG Impact Analysis Additional analysis or data required to supplement feeder load flow studies
14©2014 Navigant Consulting, Inc. California Renewable DG Integration Study: DG Intermittency Highly intermittent renewable output may create power quality violations on longer feeders. LTC’s and voltage regulators typically do not respond quickly enough to stabilize voltage. 0 20 40 60 80 100 120 140 160 12:00AM 12:48AM 1:36AM 2:24AM 3:12AM 4:00AM 4:48AM 5:36AM 6:24AM 7:12AM 8:00AM 8:48AM 9:36AM 10:24AM 11:12AM 12:00PM 12:48PM 1:36PM 2:24PM 3:12PM 4:00PM 4:48PM 5:36PM 6:24PM 7:12PM 8:00PM 8:48PM 9:36PM 10:24PM 11:12PM Output(kW) Output Profile (10 MW Ground-Based PV) Minute-by-Minute PV Changes in Output Produces Significant Voltage Swings Output Profile (10 MW Ground-Based PV) Output(kW) Over 50% change in PV output results in highly variable voltages where PV is installed on the end of longer feeders
15©2014 Navigant Consulting, Inc. Study results must conform to utility design standards and operating practices, which includes non-static feeder configuration. California Renewable DG Integration Study: Operational Considerations Total connected DG after transfer is 16 MW, which exceeds 10 MW limit by 6 MW. (1) Normal conditions (feeder configuration) – Assume each feeder is able to interconnect 10 MW of DG (2) After sectionalizing and transfer for maintenance or outage restoration (A to B) How DG is Impacted by Standard Operating Practices S/S A B S/S B B DG DG Open Switch8 MW 8 MW S/S A S/S B X Open Bkr DG DG 8 MW 8 MW Switch Closed B
16©2014 Navigant Consulting, Inc. Voltage regulation equipment Automation / SCADA additions Overload mitigation (reconductoring) Additional switches and feeder ties Feeder breaker upgrades Additional protective devices Protection upgrades Additional communication / telecom New distribution lines or substations Most options for mitigating DG impacts are based on traditional distribution solutions. California Renewable DG Integration Study: Mitigation Options The applicability of non-traditional, forward-looking solutions such as active inverter controls and Smart Grid (Managed/Interruptible DG) will be critical in the future to enable greater amounts of DG capacity at lower cost.
17©2014 Navigant Consulting, Inc. California Renewable DG Integration Study: Integration Costs Estimated DG integration cost ranges from a low of $600 million to a high of about $1.4 billion, with higher costs for greater amounts of rural DG. Most costs are for upgrading rural feeders and the installation of voltage regulating devices. DG Distributed Uniformly on Feeders TotalCost($Millions) $- $200 $400 $600 $800 $1,000 $1,200 $1,400 70Urb/30% Rur 50Urb/50% Rur 30Urb/70% Rur Interconnection System Upgrades DG integration costs range from $190/kW to $270/kW for the distribution system
18©2014 Navigant Consulting, Inc. California Renewable DG Integration Study: Integration Costs The costs of integrating DG increases significantly if clustered in large quantities, particularly when located near the end of longer feeders. Most costs are for upgrading and installing new rural feeders, upgrading urban feeders, and installing voltage regulating devices. Clustered DG TotalCost($Millions) $- $500 $1,000 $1,500 $2,000 $2,500 70Urb/30% Rur 50Urb/50% Rur 30Urb/70% Rur Interconnection System Upgrades DG integration costs range from $260/kW to $420/kW for the distribution system
19©2014 Navigant Consulting, Inc. Key Takeaways: » Cost of DG integration is highly dependent on where DG is installed. Integration impacts and costs are lower for DG installed in urban areas. » DG integration costs vary as a function of key parameters and assumptions, including DG location on feeders and total installed capacity. » DG integration costs increase significantly as greater amounts of DG are installed near the end of distribution lines. » High penetration DG may require sophisticated communications and control systems to better manage DG impacts and reduce integration costs. » Policies that “guide” or encourage DG in areas with fewer impacts would help achieve state renewables goals at lower cost. The DG integration study produced a range of outcomes and integration costs. California Renewable DG Integration Study: Key Findings & Takeaways
20©2014 Navigant Consulting, Inc. » Expand analytical framework to include transmission integration costs » CEC to launch a state planning process pilot project that identifies and evaluates areas on the utility electricity system best suited to accommodate DG Next Steps (2014) California Renewable DG Integration Study: Next Steps
Key C O N T A C T S ©2010 Navigant Consulting, Inc. Confidential and proprietary. Do not distribute or copy. Key C O N T A C T S ©2010 Navigant Consulting, Inc. Confidential and proprietary. Do not distribute or copy. Key C O N T A C T S ©2010 Navigant Consulting, Inc. Confidential and proprietary. Do not distribute or copy. Key C O N T A C T S ©2014 Navigant Consulting, Inc. 21 Gene Shlatz | Director Burlington, VT +1.802.985.5216 direct email@example.com
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