Circulating MW and Mvar flows in large systems

Abstract

Circulating power flows are possible in power systems and can lead to unnecessary power losses and voltage drops in the transmission system. The most common example is circulating Mvars caused by transformers with unbalanced tap ratios. This paper presents an algorithm to detect circulating real and reactive flows in a power system and also provides a metric to rank the severity of these circulating flows. Examples and causes of circulating flows are presented from large North American cases. The visualization of circulating flows is discussed, as well as the use of circulating flow information for bad data detection.

Maximum undergrounding degree of HV subtransmission networks as dictated by unscheduled power flows

“…In a meshed HV network supplied at different locations by the bulk power system, the decrease of series reactance will also cause an increase of 'loop' or 'parallel' active power flows [6][7][8][9][10][11] from the overlaid EHV system. At transmission level, control of parallel flows by means of phase-shifting transformers or flexible AC transmission systems (FACTS) control has been extensively studied [12][13][14][15].…”

A Case Study on the Effects of Predicted Wind Farm Power Outputs on Unscheduled Flows in Transmission Networks

“…USFs may be accommodated technically, [1], or in the market [3] - [9]. Technical accommodation methods involve managing USFs at the operational level such as rerouting power flow using flow control devices and curtailment of schedules at certain times.…”