Coherency and model reduction: state space point of view

Analytical connections are determined that relate coherent stability behavior of generators to redundancy in the controllability and observability gramians of the linear model of the power system. This redundancy is removed from the gramians of the reduced-order model generated by aggregating the coherent machines. Model reduction in large power systems is shown to be better if the order estimation information in the controllability and observability gramians is weighted properly by balancing the system. Perfect coherency of generators is related to the parameters of the linear model of the power system. Waveforms for generating the RMS coherency measures are compared. An algorithm for order reduction based on balancing is outlined and justified by testing on a 240-generator, 2500-bus system     

A general-purpose CMOS associative processor IC and system

An associative processor architecture that integrates the functionality of content-addressable memory (CAM), functional memory (FM), and associative parallel processors (APPs) in a single-chip architecture is described. The hardware design, environment and applications of the Coherent Processor, a microchannel memory device designed by combining 16 such chips, are discussed. It is shown that the processor's writable control store permits quick execution of application-specific microcoded operations     

Application of balanced realizations to power system equivalents

An algorithm is presented to accurately estimate the feasible order reduction of dynamic models used in power system analysis. Order estimates obtained by balancing a linear model of the power system are used to determine the proper aggregation level of power system models derived from modal-coherency analysis. Test results for the 39 bus New England system are presented.     

Reducing the order of very large power system models

Results are presented for reduced-order models of power systems as large as 254 generators and 2500 buses, using the modal-coherency method of model reduction. Extension of order estimation, based on balanced realizations, to larger systems is discussed. An alternative order-estimation approach based on the intergenerator coherency ranking table is introduced and compared to the balanced realization approach. The alternative approach is consistent with the balancing results and more than an order of magnitude faster