Handbook of Energy Storage for Transmission or ... - W2agz.com
Handbook of Energy Storage for Transmission or ... - W2agz.com
Handbook of Energy Storage for Transmission or ... - W2agz.com
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EPRI Proprietary Licensed Material<br />
energy st<strong>or</strong>age with a FACTS controller in damping low frequency oscillation that could<br />
not have been achieved with the STATCOM plus post oscillation damping (POD) alone.<br />
"The results illustrate that a STATCOM alone (i.e. no POD) will regulate voltage<br />
in the post contingency period but will not naturally add much damping to power<br />
oscillations. The STATCOM with POD signal applied to its voltage reference<br />
may damp swing oscillations following a disturbance however this is achieved at<br />
the expense <strong>of</strong> voltage regulation. The <strong>com</strong>bination <strong>of</strong> STATCOM plus SMES<br />
with POD modulating the SMES output will allow the system to both regulate<br />
voltage and provide oscillation damping." [2]<br />
Figure 20 Damping <strong>of</strong> Post Fault Oscillation with and without <strong>Energy</strong> <strong>St<strong>or</strong>age</strong><br />
The use <strong>of</strong> large-scale (100 MVAR <strong>or</strong> m<strong>or</strong>e) FACTS controllers to provide dynamic<br />
reactive <strong>com</strong>pensation has already been demonstrated through several landmark projects.<br />
However, because <strong>of</strong> high initial cost, the alternative <strong>of</strong> a smaller scale, modularized,<br />
distributed real, and reactive VAR injection has recently received considerable attention.<br />
The key to this application is the injection <strong>of</strong> real energy st<strong>or</strong>age to maintain the speed <strong>of</strong><br />
mot<strong>or</strong>s, which in turn reduces the inrush current <strong>f<strong>or</strong></strong> feeders heavily loaded with mot<strong>or</strong><br />
loads. This minimizes bus voltage depression and thus helps with both rot<strong>or</strong> angle and<br />
voltage stability. By providing a critical boost to the system both during faults and<br />
following the clearing <strong>of</strong> faults helps avert instability. This type <strong>of</strong> distributed dynamic<br />
reactive <strong>com</strong>pensation with energy st<strong>or</strong>age is particularly suitable <strong>f<strong>or</strong></strong> solving transient<br />
voltage stability problems in a weak p<strong>or</strong>tion <strong>of</strong> the netw<strong>or</strong>k with a high concentration <strong>of</strong><br />
induction mot<strong>or</strong> loads during peak loading conditions.<br />
The advantage <strong>of</strong> energy st<strong>or</strong>age under these conditions is mainly in reducing the<br />
maximum transient voltage dip, which is a measure <strong>of</strong> the dynamic per<strong>f<strong>or</strong></strong>mance <strong>of</strong> the<br />
system [3]. Based on Western Systems Co<strong>or</strong>dinating Council (WSCC) criteria as shown<br />
in Figure 21, the voltage at any load bus should not dip below 20% <strong>of</strong> the initial value <strong>f<strong>or</strong></strong><br />
m<strong>or</strong>e than 20 cycles.<br />
Electrochemical Capacit<strong>or</strong>s 42
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