ELECTROMECHANICAL SYSTEM EQUIVALENT AND DYNAMIC LOAD AGGREGATION FOR TRANSIENT STABILITY OF ELECTRIC POWER SYSTEM
Creators: name: EL-Shimy, Mohamed
Publisher: name: figshare
Year: 2017
Subjects: subject: 90607 Power and Energy Systems Engineering (excl. Renewable Power)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: This research is aimed at enhancing the transient stability simulation of large-scale power systems by developing the power system model-reduction theory via (i) Development of accurate and fast coherency-based electromechanical reduction technique for large-scale power systems for use in transient stability studies. (ii) Development of dynamic load modeling and developing a generalized and an accurate technique for dynamic load aggregation. The considered load subsystem is constructed of interconnected induction motor loads (with different sizes and with different loading levels) and static loads. (iii) Enhancement of transient stability analysis of large-scale power systems through the integration of system electromechanical equivalent and dynamic load aggregation. <br><br>An electromechanical equivalent is proposed, applied, and evaluated on different large-scale systems. The power systems are divided, after selecting the study area, into two main regions: (i) A coherency-based external system that is subdivided into a set of external areas, each of which contains a group of coherent generators obtained from a proposed quasi-linear solution of the system differential equations and correlation factor analysis. (ii) A remote system that is considered electrically far enough from the study area to be represented by a very simple electromechanical model. The terminal buses of each group of generators are replaced by one common bus. The parameter of the new network interconnecting each of the common buses and each area terminal buses to the rest of the system is calculated by the proposed network reduction technique. The final stage of constructing the equivalent is obtained dynamic aggregation of each coherent group and the remote area generators. <br><br>A new developed technique for aggregating dynamic system loads is proposed, applied, and evaluated on different power systems. The proposed load aggregation technique overcomes the limitations placed on previous techniques as: (i) There are no limitations on the induction motors loading conditions. (ii) The effect of the network interconnecting dynamic load centers is considered in the aggregate model and not neglected. Moreover, the active/reactive loss in the equivalent network depends on the loading conditions of the equivalent load and not on the interface bus voltage as proposed in the LOADSYN program. (iii) There is no need of any measurements or applying parameter estimation techniques to estimate the parameters of the aggregate model. This allows avoiding the related problems facing researchers. (iv) The input/output data are in the standard engineering formats and output aggregate model parameters can be interfaced with any recent transient stability programs. (v) The proposed dynamic aggregation technique provides a load model that includes the voltage-dependency, frequency-dependency, and rotor-dynamics of power system loads. <br><br>An integrated-electromechanical-reduction algorithm, including equivalency of generators and dynamic load aggregation is developed and applied successfully to enhance transient stability analysis of large-scale power systems. The integrated reduction technique is recommended for effective application in the analysis of transient states of power systems. <br><br>The main outcome of this research is that it clarifies and improves the efficiency and accuracy of constructing electromechanical reduced-model of large-scale power systems effectively taking into consideration the aggregate effect of power system dynamic loads. Moreover, the proposed reduction techniques overcome most computing problems and limitations accompanying the construction of transient stability reduced power system model. <br>