Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Grid oscillation
open-in-new
<p>The grid oscillations are <a href="/facts/Oscillations/6vSrm84a">oscillations</a> in an <a href="/facts/Electric_grid/RkWPqjmG">electric grid</a> manifesting themselves in low-frequency (mostly below 1 <a href="/facts/Hz/6Wshj5qm">Hz</a>) periodic changes of the <a href="/facts/Power_flow/QbMNhIbM">power flow</a>. These oscillations are a natural effect of <a href="/facts/Negative_feedback/G9byVgpN">negative feedback</a> used in the <a href="/facts/Power_system_control/R9mKeJL2">power system control</a> algorithms. During the normal operation of the power grid, these oscillations, triggered by some <a href="/facts/Contingency_(electrical_grid)/GI2Ap0HI">change in the system</a>, decay with time (are "damped" within few tens of seconds), and are mostly not noticeable. If the damping in the system is not sufficient, the amplitude of oscillations can grow eventually leading to a <a href="/facts/Power_outage/CBp7xY9w">blackout</a>. </p><p>For example, shortly before the <a href="/facts/1996_Western_North_America_blackouts/W8vvruh6">1996 Western North America blackouts</a> the grid after each disturbance was oscillating with a frequency of 0.26 Hz for about 30 seconds. At some point a sequence of <a href="/facts/Electrical_fault/QaCmxu1r">faults</a> and operations of automatic protection relays caused loss of damping, eventually breaking the system into disconnected <a href="/facts/Islanding/eDQFMz5e">"islands"</a> with many customers losing power. The other notable events involving oscillations were the <a href="/facts/Northeast_blackout_of_2003/N8NqLM3Y">Northeast blackout of 2003</a> and the 2009 subsynchronous oscillations in <a href="/facts/Texas/B987WHF0">Texas</a>. </p><p>While the theory and calculations tools for analyzing oscillations are available, pinpointing the source of instability in a real grid is frequently difficult as of the early 2020s. The oscillations are a normal occurrence, yet the difference in a flow as small as 10 MW is known to occasionally push the system from the stable mode with decaying oscillations into a situation where their amplitudes grow with time. The system operator frequently gets no warning that the grid is close to its damping limit. </p>