Guidelines For Electric System Planning - …

1 1 Guidelines For Electric System Planning (Transmission, Subtransmission, Distribution) Composed of Near Term System Development Guidelines & Methodology Standard Practices Document Operations Section of Planning Guidelines Document Line and Equipment Rating Summary 7/24/2007 2 Introduction These Guidelines are intended to be a guide for the development of the Transmission, Subtransmission and Distribution Plans. These Plans are completed during the fourth quarter of each calendar year and become the basis for the Transmission, Subtransmission, and Distribution budget and future facility construction. It is intended that these Guidelines be reviewed as needed as a part of the overall plans process. The Planning Guidelines Committee, composed of representatives from Electric System Engineering, System Design & Construction, Strategic System Planning , Transmission & Generation Operations, Electric System Operations & Maintenance, and Electric System Planning & Performance is responsible for performing this review.

2 Results of this review are summarized in this document. It is intended that the Guidelines not be used as a rigid rule for the development of future facility needs. It is recognized that alternative solutions may be developed for problems noted and evaluations and recommendations for these future facilities will be addressed as needed. It is possible that after considering all factors, including but not limited to economics, reliability and impact on System operations, exceptions could be made to the Guidelines . It is also recognized that certain parameters may change as a result of in-depth engineering design evaluations and the general evolution of our System . Existing facilities can be modified to meet the Guidelines , but should be done so on a cost effective basis. The Guidelines presented are for both Planning study and operating study purposes.

3 Separate sections of the document are devoted to each of these subjects. The Near Term Guidelines Section and the Standard Practices Section are directed toward the Planning process and the Operations Section is devoted to studies of that nature. The Line & Equipment Ratings Section of the document is applicable to both Planning and operating studies. The development of alternatives and exceptions to the Guidelines will be reviewed during the normal Planning process. At that time all affected parties will be made aware of any deviations. A glossary of terms has been provided at the end of the Near Term Guidelines Section and the Standard Practices Section of the document. The definitions contained in the glossary are an important factor in understanding the meaning and intent of these Guidelines .

4 3 NEAR TERM System DEVELOPMENT Guidelines & METHODOLOGY (ESA portion of Planning Guidelines document) guidelines_near_term GENERAL 3 STEADY STATE ANALYSIS 8 Normal Conditions (n-0) 8 Single Contingency Outage Conditions (n-1) 11 System DYNAMIC RESPONSE ANALYSIS 14 RELIABILITY ANALYSIS 16 FOLLOW UP 16 NEW ISSUES REQUIRING RESOLUTION 16 OLD ISSUES REQUIRING PERIODIC UPDATE 18 DEFINITIONS 18 REFERENCES 20 INDEX 22

5 FIGURES & TABLES 24 4 GENERAL The following paragraphs describe the near term System development Guidelines , assumptions & study methodology used to plan SRP s transmission, subtransmission and distribution systems. During all phases of the Bulk Electric System Planning process (100 kV and above), Transmission & Generation Operations will be involved as appropriate in the process to ensure that the studies take into account the operational perspective. LOAD FORECAST, ANNUAL: A peak load forecast corresponding to the local area forecast developed annually by Distribution Planning . This forecast is developed using historical local area loads and a per unit saturation curve methodology that defines likely area growth trends and growth knees and the associated Electric System expansion risk.

6 The coincident total load including mining and industrial loads is equal to the 10% Risk Forecast generated by Strategic Economic Services reflecting a 1 in 10 probability of extreme weather and economic conditions FORECAST, SATURATION: A peak load forecast designed to reflect the theoretical maximum or ultimate level possible in a given area. The recent development of a per unit saturation curve methodology has indicated that most areas will plateau at a load level of 11-12 MW/square mile, and will approach saturation at about 15 MW/square mile. The 2003 Saturation Forecast was developed by substation using 2000/01 load and land use information. The forecast includes load estimates by customer land use type, and since more accurate land use was available, a single saturated load estimate was developed for each substation service area.

7 GENERATION: Generation, sales and interchanges will be represented in Planning studies in accordance with the latest SRP corporate Loads & Resources. Generating units in power flow cases will be committed and scheduled according to SRP s planned scheduling practices after consultation with SRP s Supply and Trading/Power Coordination group. Construction recommendations will generally be based on the economic commitment and scheduling of generating units. Generation patterns will be varied in System studies to evaluate the results of planned or forced generator outages, seasonal commitment, seasonal scheduling of units, changes in fuel availability or prices, and/or economy interchanges. As a minimum test of the systems capability to accommodate different generation patterns, studies will investigate maximum and MINIMUM GENERATION 5 LEVELS for each normally scheduled valley plant (see TABLE A in Section for a description of MINIMUM GENERATION LEVELS).

8 Import and load serving nomograms shall be referenced to determine correct Generation patterns. The following will be considered prior to recommendation of construction for other than economic generating unit commitment and scheduling. 1. Annual hours for which System capability could limit maximum generation at a plant to less than rated output. 2. Cost of energy required above ECONOMIC UNIT COMMITMENT and schedule to avoid System problems without construction of new facilities. 3. Cost of constructing or advancing construction of new facilities. 4. PMax and Pmin for Power Flow Studies will be determined from Generation Services, O&M Capacity, Generation for Transmission Planning DISTRIBUTED GENERATION: Distributed generation options will be modeled as necessary to evaluate the impact on the Electric System plan.

9 LOOP FLOW: Power flow & stability studies are run with WECC full loop cases. Where unscheduled flow (loop flow) is a concern a reasonable amount of WECC loop flow will be simulated. The scheduling practices of phase shifting transformers which are intended to control major and minor loop flow will be considered in System modeling decisions. LEAD TIMES: Based on Line siting requirements and EHV equipment procurement goal in Planning is to keep the first three years of the 6-year plan fixed or unchanged if new lines are involved Otherwise, the two year guideline is acceptable. The equipment lead time, public involvement, permitting, right of way constraints, design considerations etc. all contribute to the necessity of this as discussed below. Please note that a 5 mw load addition in remote areas may result in an addition in the fixed 2 year plan.

10 LINES: For new lines at all voltages above 12kV the primary constraint for construction is acquisition of a route and right-of-way. This includes conducting a PUBLIC PROCESS and, in the case of 115kV and above, receiving a CEC (Certificate of Environmental Compatibility) from the Arizona Corporation Commission. The table below lists the earliest year that a new line shall be introduced into the 6 year construction plan for the first time based on whether or not a public process and/or CEC permit will be required. 6 TABLE BB YEAR OF 6-YEAR PLAN A NEW LINE CAN FIRST BE INTRODUCED SRP Public Process CEC Required? Voltage (kV) NO YES 12KV 1ST N/A 69KV 3RD N/A 115KV 2ND 4TH 230KV 2ND 4TH EXAMPLE: The preceding table is read in the following manner.