Physical Model Of Power System Research Articles

Heterogeneity and Directionality Analysis of the Cyber Physical Power System

A cyber physical power system model based on the weighted tensor product is proposed in this paper to describe the interlayer and intralayer relationships of entities in both systems. The different functional attributes of nodes and the directivity of the energy flow in the system are respectively described as the heterogeneity of nodes and the directionality of edges. During failure propagation, the dynamic topology method is applied to convert the protection strategies and load redistribution measures into system connectivity rebuilding. The simulation results of fault propagation in the cyber physical power system under different initial failure ratios show that, compared with the undirected model, the directional interactions in the proposed approach can significantly improve the system survival rate during cascading failure. In addition, the physical system shows a lower vulnerability due to the protection provided by spare edges and power sources.

A Hybrid-Learning Algorithm for Online Dynamic State Estimation in Multimachine Power Systems.

With the increasing penetration of distributed generators in the smart grids, having knowledge of rapid real-time electromechanical dynamic states has become crucial to system stability control. Conventional Supervisory Control and Data Acquisition (SCADA)-based dynamic state estimation (DSE) techniques are limited by the slow sampling rates, while the emerging phasor measurement units (PMUs) technology enables rapid real-time measurements at network nodes. Using generator bus terminal voltages, we propose a hybrid-learning DSE (HL-DSE) algorithm to estimate the synchronous machine rotor angle and speed in real time. The HL-DSE takes the power system model into account and trains neuroestimators with real-time data in an online manner. Compared with traditional DSE methods, the HL-DSE overcomes limitations by using a data-driven approach in conjunction with the physical power system model. The time efficiency, accuracy, convergence, and robustness of the proposed algorithm are tested under noises and fault conditions in both small- and large-scale test systems. Simulation results show that the proposed HL-DSE is much more computationally efficient than widely used Kalman filter (KF)-based methods while maintaining comparable accuracy and robustness. In particular, HL-DSE is over 100 times faster than square-root unscented KF (SR-UKF) and 80 times faster than extended KF (EKF). The advantages and challenges of the HL-DSE are also discussed.

MODERNIZATION OF THE UNIVERSAL ANALOG MODEL OF THE ENERGY SYSTEM УРМЕС-2

Restoration and improvement of universal computational physical model of power system (УРМЕС-2) by application of modern electronic components and facilities of microcontroller technology. Results. Theprerequisites of such modernization for compatibility of parameters of modern microcontroller components with thenecessary characteristics of this calculated physical model of power system are considered. It has been shown thatyou do not even need to use specific software to achieve this. It is enough to use ready-made structural units, andtheir programs of operation far exceed the needs for restoration and improvement of the installation. As an example,an electrical circuit of a basic three-phase AC reference generator 200 Hz with the implementation of subsequentvoltage symmetry and power amplification. Generator design is developed. It is proposed to replace the oldgenerator, which gives a significant increase in the resource life. Originality. For the first time, the possibility ofupgrading the power system model (УРМЕС-2) by replacing a three-phase signal generator made by a slightmodification of a finished microcontroller unit with digital-to-analog converters, rather than by implementingsoftware pulse-width modulation of the microcontroller, is shown. Practical significance. The practical value of thework is to restore the possibility of using numerous laboratory works in the educational process with the use of thisuniversal analog model of the energy system.

Adaptive PSS using a simple on-line identifier and linear pole-shift controller

Implementation of an adaptive power system stabilizer (APSS) and experimental studies are presented in this paper. The APSS consists of an adaptive linear element (ADALINE) based identifier that identifies the power system as a third-order discrete auto-regressive moving average (ARMA) model and a pole-shift controller. The ADALINE is modeled so that its weights have a one-to-one relationship with the ARMA model parameters. The weights are updated at each sampling interval to track the dynamic characteristics of the actual system. The on-line updated ARMA parameters are used in the PS control algorithm to calculate the new closed-loop poles of the system that are always inside the unit circle in the z-plane. The calculated control is such that it achieves regulation of the system to a constant setpoint in the shortest interval of time. Experimental studies on a physical model of power system verify that the proposed adaptive PSS effectively damps the oscillations and improves power system stability.

Experimental test results for a parallel transmission lines protection scheme using wavelet transform

A scheme for the protection of parallel transmission lines using wavelet transform (WT) has been implemented and results of experimental tests on a physical power system model are described. The relaying scheme depends on the three line voltages and the six line currents of the two parallel lines at each end. Fault detection, fault discrimination and calculation of the phasors of the measured signals are done using WT. The performance of the proposed scheme has been investigated by a number of online tests. The results show that all types of shortcircuit faults can be correctly identified in less than one cycle of the fundamental frequency.

Implementation and laboratory test results of an Elman network-based transmission line directional relay

A transmission line fault direction identification module based on an Elman recurrent network has been implemented on a DSP board and its behavior is investigated on a physical power system model. Details of implementation and the experimental studies are given and analysed in the paper. Studies show that the proposed approach is able to identify the direction of a fault on a transmission line rapidly and correctly. It is suitable for realizing a fast transmission line directional comparison protection scheme.

Laboratory investigation of a digital recurrent network for transmission line directional protection

This paper presents a recurrent neural network-based technique to identify the direction of a fault on a transmission line. The network uses samples of voltage and current signals to learn the hidden relationship existing in the input patterns. The proposed small size recurrent network has been implemented on a digital signal processor board and its behavior is investigated on a physical power system model. Details of implementation and the experimental studies are given and analyzed in the paper. Performance studies results show that the proposed approach is able to detect the direction of a fault on a transmission line rapidly and correctly. It shows that the proposed network is robust, fast and accurate.