Adaptive Under Frequency Load Shedding using PMU

Abstract

Under Frequency Load Shedding, UFLS, is the last step and the most extreme in protecting electric power systems from black outs and severe damages. Adaptive UFLS methods using df/dt are unreliable. SCADA is too slow to achieve a proper protection of the power system under severe over load condition. This paper presents an adaptive under frequency load shedding using Phasor Measurement Unit ,PMU, AUFLS, method depends on power measurement using the advantage of high speed wide area protection system. The simulation results demonstrate a considerable advantage to improve power system stability.

A Novel Approach to Extended System Frequency Response Model for Complex Power Systems (ESFR)

“…T r eq = n i=1 T r i P i n i=1 P i (13) where Tr i is the governor time constant of unit i, and P i is the nominal active power generation unit i. The analysis of the equivalent methods of various temporary droop for hydro governors (see Figure . the best formula to give a reasonable approximation of the equivalent Hydro Governor Temporary Droop (Delta) is as follows:…”

“…Adaptive [9] and semi-adaptive [10] Under Frequency Load Shedding (UFLS) are common protections to maintain power system stability by removing the overload in some part of the system and prevent system collapse and its catastrophic consequences. The successful design of these protection systems and the related system reliability impacts are closely dependent on the availability and accuracy of the system frequency response model [1], [2], [11], [12], [13], [14], [15]. However, a review of the literature on SFR model used in UFLS designs did not result of any finding of new idea for SFR model, as they employed the conventional approach or detailed models.…”

Methodology for a Security/Dependability Adaptive Protection Scheme Based on Data Mining

“…Other ideas for load shedding relays have been proposed in [49][50][51]. In [50] the problem is stated as a minimization problem where the protection system determines the minimum amount of load needed to maintain frequency and bus voltages within predefined margins.…”

“…In [51] a polynomial function in conjunction with phasor based indexes is used to determine the amount of load to be shed. In [49] intelligent schemes are discussed in general terms and field test measurements are used to highlight the importance of load characteristics.…”