Alberto, That's true. Measurement data is labeled with a time stamp, but how often is state estimation performed. To my understanding state estimation is done with an order of seconds or minutes, while PMU sends 60 measures per seconds. Apparently, the control center cannot draw an estimate for all received time-stamped data. Which set of data does the control center use for the estimation process? 

Hey Alireza,

In such scenarios, it is important to know whether one is oversampling or not.  

By oversampling, I mean, ideally, the sampling time is chosen to satisfy the Nyquist sampling Criterion (and is also dependent on the system bandwidth/time constant).  Your sensor might be capable of giving you measurements at a much faster rate, but the question to ask is, is the data informative?

(The observability analysis is also an alternative approach which would lead/aid you in determining whether you have oversampled or not).

If you happen to have oversampled, then I hope you would be able to compute the state estimates in your desired time.

If not, there are "computationally efficient" state estimator realizations available in the literature. You may consider employing them.

Also, do a search for state estimators using "irregularly sampled or multi-rate data". This theory would aid you in developing estimation schemes based on parallel computing.

There are solutions available depends on which area you wish to improve upon and whether you want to reconfigure your computational apparatus or not.

Hope this helps.

Regards,

Prashant