Maximum undergrounding degree of HV subtransmission networks as dictated by unscheduled power flows. Issue 11 (1st November 2013)

• Record Type: Journal Article
• Authors: Lauria, Stefano; Palone, Francesco
• Is Part Of: IET generation, transmission & distribution. Volume 7:Issue 11(2013)
• Page Start: 1202
• Page End: 1209
• Publication Date: 2013-11-01
• Subjects: electric reactance -- load flow -- power overhead lines -- transmission networks -- underground cables; unscheduled power flow -- meshed HV subtransmission network -- active power flow -- EHV system -- underground cable -- HV line reactance -- UGC charging power -- maximum undergrounding degree -- optimum UGC shunt compensation requirement -- power flow simulation -- voltage 150 kV -- frequency 50 Hz; Electric power production -- Periodicals; Electric power transmission -- Periodicals; Electric power distribution -- Periodicals; 621.3105
• DOI: 10.1049/iet-gtd.2012.0295
• Languages: English
• ISSNs: 1751-8687

Abstract

Abstract : Meshed HV subtransmission networks are subject to undesirable parallel (unscheduled) active power flows from the EHV system. The phenomenon is worsened by conversion of HV overhead lines to underground cables (UGCs), which increases parallel flows through the HV network because of the attendant reduction in HV line reactance; the effect increase with network extension and are compounded by UGC charging power. The study deals with the assessment of the maximum undergrounding degree for a given subtransmission network. An analytical formulation of maximum HV line extension length as a function of EHV power flow and undergrounding degree is given; optimum UGC shunt compensation requirements are evaluated. Application to a typical 150 kV–50 Hz network is presented, showing a very good agreement with power flow simulation. In particular, the case study evidences that complete undergrounding of the HV network is possible if line length is under 50 km; the proposed shunt compensation effectively raises this limit to 70 km.