Measured and predicted cold load pick up and feeder parameter determination using the harmonic model algorithm

Abstract

This paper presents theory of the "Cold Load Harmonic", CLHARM, model algorithm for SbUlatiOG of power feeder currents resulting from both Cold Load Pickup, CLPU, and the "Step Voltage Test", STEPV. The STEPV method is also presented.Feeder parmeters obtained from field STEPV measurement are used to predict CLPU on that feeder using the C L " algorithm. STEPV test measurements and actual measured CLPU currents on the same feeder are compared with computer prediction;. The CLHARM aggregates feeder thermostatically controlled load to simulate regain of diversity during outage restoration. All feeder weather sensitive load is lumped in CLHARM, using mean parameter values of a simple thermodynamic model. The ultimate objective of this work is experimentally obtained feeder "signatures" for CLPU prediction as e feeder design tool.

A Novel Dynamic Load Modeling for Power Systems Restoration: An Experimental Validation on Active Distribution Networks

“…7, the CLPU effect is clearly visible since most of the loads belongs to the L1 category, and it is possible to see that the sum of two exponential functions represents its shape better than a single exponential one. This experimental evidence can be noted also in the CLPU measurements reported in literature [7,8]. For this reason, in the above described CLPU modelling procedure the sum of two exponential functions is adopted instead of the commonly used single exponential function.…”

“…In [7], the harmonic model theory to predict the CLPU of the load supplied by a given feeder after an outage is described. This approach is based on experimental measurements performed on a feeder to derive several parameters representing its power demand during the reenergization of the load.…”

“…In technical literature [4][5][6][7], it is established that for such loads, in the first instants after a re-energization following an outage, the absorbed power is much higher than the power PSS absorbed in the steady state condition, which is gradually reached after some time with a monotonically decreasing trend. This is the above mentioned CLPU phenomenon.…”

“…By considering that k2=k1=k1,2 for residential loads, (5) can be rewritten as in (7) with k1,2 as the only unknown parameter. ( 7) can be solved numerically to obtain k1,2.…”

“…In order to identify the coefficients of (7), the data related to the active power measured at the sending-end of two feeders (A and B) of two real DNs (1 and 2) of the Italian network are exploited, as it is shown in the scheme of Fig. 6.…”