Predictive frequency stability control based on wide-area phasor measurements

Abstract

Wide-area phasor measurements provide a dynamic view of the power system in short-term intervals. The time synchronization and concentration of these measurements opens up a range for wide area applications for protection and control. For each kind of instability, related detection and action schemes can be defined to limit or prevent the system from severe disturbances or even collapses. This paper proposes a novel predictive method for emergency frequency control to be used on such occasions. The proposed method avoids the drawbacks of local underfrequency load shedding schemes, such as delayed response and overshedding, by basing control on synchronized phasor measurements. A single machine equivalent for each power system island including the frequency sensitivity of loads, is computed online using phasor measurements. Using this model the progression of frequency stability after a contingency is predicted and stabilizing load shedding is determined in a co-ordinated way for the supervised area of the power system.

A survey on the contributions of power electronics to smart grid systems

“…The measurement systems are not only utilized to determine the consumed energy by load plants but also used to observe the phasor, voltage and frequency values supplied to end-users [15,21,[31][32][33][34]. The security of electrical supply is a critical point for all nations.…”

“…The T&D section includes wide power control infrastructure such as remote monitoring and remote control of power circuits as inverters and converters in MG scale besides switches and breakers. The control elements of power electronics in a smart grid cover the power factor controllers, sensors, and other components of a SCADA-like system [33,[63][64][65][66]. The last section of the diagram consists of customers in where the advanced metering infrastructure (AMI) is installed to each node in order to perform monitoring and billing requirements.…”

Adaptive load shedding scheme to preserve the power system stability following large disturbances

“…The adaptive UFLS algorithms proposed in [14][15][16][17][18][19] try to overcome deficiencies of the conventional UFLS scheme. They estimate the active power imbalance following a disturbance, based on the equivalent system model suggested in [20].…”

Application of active power sensitivity to frequency and voltage variations on load shedding

“…Most of the earlier schemes were traditional schemes that relied heavily on local measurements for inputs and shed a preset amount of load when frequency or voltages reached a certain level. The traditional schemes were later replaced by semi-adaptive and adaptive under frequency load shedding schemes [1][2][3][4][5][6][7][8] that tried to overcome the problem of under shedding or over shedding of load by utilizing the rate of change of frequency along with the frequency value to make decisions about shedding load. Under voltage load shedding schemes [9][10][11][12][13][14][15][16][17][18][19][20][21] started making an appearance a few years ago as they proved to be an economical and effective technique to maintain voltage stability as against expensive and time consuming methods like shunt compensation, new additions to the main circuit, etc.…”