APPENDIX A CONNECTION ASSESSMENT Note: The conclusions and recommendations in this report are based on the results presented in Attachment A: Engineering Connection Assessment Results, which was prepared by a third party studies consultant in accordance with the AESO Connection Process. The AESO has reviewed Attachment A, and finds it acceptable for the purpose of assessing the potential impacts of the proposed connection on the performance of the AIES. 2 AESO Public Contents 1. Introduction ......................................................................................................................................... 5 1.1. Project............................................................................................................................................ 5 2. Assessment Scope ............................................................................................................................. 6 2.1. Objectives ...................................................................................................................................... 6 2.2. Existing System ............................................................................................................................. 6 2.3. AESO Long-term Transmission Plans ........................................................................................... 6 2.4. Study Area ..................................................................................................................................... 7 3. Connection Alternatives ..................................................................................................................... 9 3.1. Overview ........................................................................................................................................ 9 3.2. Connection Alternatives Examined ............................................................................................... 9 3.2.1. Connection Alternatives Selected for Further Studies .................................................................. 9 3.2.2. Connection Alternatives Not Selected for Further Studies ............................................................ 9 4. Assessment Approach ..................................................................................................................... 11 4.1. Standards, Criteria, and Assumptions ......................................................................................... 11 4.2. Scenarios ..................................................................................................................................... 11 4.3. Engineering Studies .................................................................................................................... 11 4.3.1. Power flow studies ....................................................................................................................... 11 4.3.2. Voltage Stability Studies .............................................................................................................. 12 4.4. Additional Engineering Studies ................................................................................................... 12 4.4.1. Transient voltage recovery studies .............................................................................................. 12 5. Interpretation of Results ................................................................................................................... 13 5.1. Pre-Project Studies ...................................................................................................................... 13 5.2. Post-Project Studies .................................................................................................................... 13 5.3. Proposed Mitigation Measures .................................................................................................... 14 5.3.1. Overview of Mitigation Measures ................................................................................................ 14 5.3.2. Impact of Ksituan River RAS ....................................................................................................... 15 5.4. Impact of Rycroft System Developments .................................................................................... 16 5.4.1. Overview of Rycroft System Developments ................................................................................ 16 5.4.2. Study Results with Rycroft System Developments ..................................................................... 16 5.5. Results Summary and Mitigation Measures ................................................................................ 17 6. Project Dependencies ....................................................................................................................... 20 7. Conclusions and Recommendations .............................................................................................. 21 7.1. Conclusions ................................................................................................................................. 21 7.2. Recommendations ....................................................................................................................... 21 3 AESO Public Attachments Attachment A Engineering Connection Assessment Results Report Figures Figure 2-1: Existing Study Area Transmission System ................................................................................. 8 Tables Table 2-1: 2017 LTP Developments in the Northwest Planning Region ...................................................... 7 Table 4-1: List of Connection Study Scenarios ........................................................................................... 11 Table 5-1: Project Impact and Mitigation Measures ................................................................................... 18 4 AESO Public 1. Introduction This Alberta Electric System Operator (AESO) Engineering Connection Assessment report describes the engineering studies that were completed to assess the impact of the Project (as defined below) on the performance of the Alberta interconnected electric system (AIES). This report also provides the AESO’s conclusions and recommendations based on the results of the engineering studies. Attached to this report are the results of the engineering studies (see Attachment A: Engineering Connection Assessment Results) and the scope and methodology used to perform the studies (see Attachment A1: AESO Engineering Connection Assessment Scope). These attachments provide details regarding technical criteria, assumptions, and methods for performing these engineering studies, and the results of the engineering studies. 1.1. Project ATCO Electric Ltd. (ATCO), in its capacity as the legal owner of an electric distribution system (DFO), submitted a system access service request to the Alberta Electric System Operator (AESO) to serve load growth in the Spirit River area. The DFO’s request for system access service includes a request for a Rate DTS, Demand Transmission Service, contract capacity increase of approximately 11.71 MW (from 26.29 MW to 38 MW) at the existing Ksituan River 754S substation, and a request for transmission development (collectively, the Project). Specifically, the DFO requested upgrades to the existing Ksituan River 754S substation. The scheduled in-service date (ISD) for the Project is February 1, 2019. 5 AESO Public 2. Assessment Scope 2.1. Objectives The objectives of the AESO Engineering Connection Assessment are as follows: • Assess the impact of the Project on the performance of the AIES • Evaluate Project connection alternatives and identify the AESO’s preferred alternative • Recommend mitigation measures, if required, to reliably connect the Project to the AIES • Identify Project dependencies, including any TFO projects or AESO plans to expand or enhance the transmission system that must be completed prior to connection 2.2. Existing System The Project is located in the AESO planning area of Grande Prairie (Area 20), which is part of the AESO Northwest Planning Region. Grande Prairie (Area 20) is surrounded by the planning areas of Peace River (Area 19), Valleyview (Area 23), and Grand Cache (Area 22). From a transmission system perspective, Grande Prairie (Area 20) consists of a 144 kV transmission system. Grande Prairie is connected to the Little Smoky 813S substation by the three 144 kV transmission lines 7L32, 7L45, and 7L46. The 144 kV transmission line 7L20 connects Grande Prairie (Area 20) to Grande Cache (Area 22), and the 144 kV transmission line 7L73 connects Grande Prairie (Area 20) to Peace River (Area 19). Existing constraints in the Northwest Planning Region are managed in accordance with the procedures set out in Section 302.1 of the ISO rules, Real Time Transmission Constraint Management. 2.3. AESO Long-term Transmission Plans The AESO 2017 Long-term Transmission Plan (2017 LTP) 1 includes system transmission developments in the vicinity of the Study Area.2 Table 2-1 summarizes the system transmission developments in the Northwest Planning Region in the near-term (five years). 1 The 2017 LTP document is available on the AESO website. 2 The 2017 LTP identifies the transmission developments in the Northwest Planning Region on page 48. The 2017 LTP also discusses the near-term developments in the Northwest Planning Region at page 54. 6 AESO Public Table 2-1: 2017 LTP Developments in the Northwest Planning Region Development