Kandahar City Long Term Transmission Plan

to support the medium to long term power transmission plan for Kandahar City, specifically for the Power Sector Master Plan completed by Fitchner in November 2012. The plan aimed to validate the findings of the Power Sector Master Plan, determine the in-service date of the 110 kV Kandahar City loop, identify system upgrades needed throughout the twenty year planning horizon, and provide a recommendation regarding the double circuit 110 kV transmission line between Kandahar East – Breshna Kot 110 kV substations. The Power Sector Master Plan identified necessary system upgrades required in the provinces to extend the coverage of the country's power supply. The plan was broken up into four stages to address near and long-term development, with several major projects identified for immediate implementation, including the finalization of the Salma HPP and Kajaki Expansion HPP (Unit 2, 18.5 MW) in 2016 and the NEPS to SEPS interconnector in 2017. The projected load growth for all provinces was calculated, and in-service years for additional transformer capacity were identified. Black & Veatch developed four network models of the SEPS, one for each year 2015, 2020, 2025, and 2032, consistent with the Power Sector Master Plan. Each model assumed that the entire SEPS was served by the NEPS-SEPS interconnection, represented by a fictitious generator at the Kandahar East 110 kV substation. The studies consisted of steady-state power flow analysis using Siemens PTI PSS/E version 32.1.2, a prominent software suite used widely in the field of transmission planning. The AC Contingency Calculation (ACCC) feature of PSS/E was used to conduct N-1 contingency analysis for each of the four network models. The results were reviewed in pairs (2015-2020, 2020-2025, and 2025-2032), and using linear interpolation of the results, Black & Veatch was able to identify an approximate "problem year" for observed thermal overloads and voltage violations. As needed, Black & Veatch identified system upgrades based on the results of the ACCC simulations. The 2015 network model was completed consistent with network data provided by Black & Veatch Special Projects Corp in-country staff, DABS, and the Power Sector Master Plan. In consultation with USAID, Black and Veatch confirmed the NEPS-SEPS tie has an expected in-service date of 2017. However, in order to ensure there were no thermal overloads or voltage violations prior to 2017, Black and Veatch used 2015 as the starting year for the analysis to provide greater resolution to the results. The 2015 network model identified unacceptable low voltages throughout SEPS primarily due to the system being radially fed from Kandahar East with long transmission lines between distribution substations. To mitigate the low voltage conditions, Black & Veatch added two 15 MVAR capacitor banks at Kajaki 110 kV and Durai Junction 110 kV respectively. This addition served two purposes: providing voltage support and reducing the voltage drop on the transmission lines by reducing the amount of reactive power flow at the NEPS-SEPS tie. The Kandahar City loop was required by 2017 to prevent overloading of the Kandahar East – Breshna Kot 110 kV transmission lines. Consequently, a revised 2020 base case was built with the Kandahar City loop in-service. A visual representation of the loop is provided in Figure 2.