Phasor Measurement Techniques.- Phasor Estimation of Nominal Frequency Inputs.- Phasor Estimation at Off-Nominal Frequency Inputs.- Frequency Estimation.- Phasor Measurement Units and Phasor Data Concentrators.- Transient Response of Phasor Measurement Units.- Phasor Measurement Applications.- State Estimation.- Control with Phasor Feedback.- Protection Systems with Phasor Inputs.- Electromechanical Wave Propagation.

Synchronized Phasor Measurements and Their Applications

This paper proposes a hybrid particle swarm optimization (HPSO) for a practical distribution state estimation. The proposed method considers nonlinear characteristics of the practical equipment and actual limited measurements in distribution systems. The method can estimate load and distributed generation output values at each node by minimizing the difference between measured and calculated voltages and currents. The feasibility of the proposed method is demonstrated and compared with an original particle swarm optimization-based method on practical distribution system models. Effectiveness of the constriction factor approach of particle swarm optimization is also investigated. The results indicate the applicability of the proposed state estimation method to the practical distribution systems.

A hybrid particle swarm optimization for distribution state estimation

This paper presents a new smart grid infrastructure for active distribution systems that will allow continuous and accurate monitoring of distribution system operations and customer utilization of electric power. The infrastructure allows a complete array of applications. The paper discusses four specific applications: a) protection against downed conductors; b) load levelization; c) loss minimization; and d) reliability enhancement.

Smart Grid Technologies for Autonomous Operation and Control

This paper presents a linearized, three-phase, distribution class state estimation algorithm for applications in smart distribution systems. Unbalanced three-phase cases and single-phase cases are accommodated. The estimator follows a complex variable formulation and is intended to incorporate synchronized phasor measurements into distribution state estimation. Potential applications in smart distribution system control and management are discussed.

A Linear State Estimation Formulation for Smart Distribution Systems

A modified Newton method for radial distribution systems is derived in which the Jacobian matrix is in UDU/sup T/ form, where U is a constant upper triangular matrix depending solely on system topology and D is a block diagonal matrix. With this formulation, the conventional steps of forming the Jacobian matrix, LU factorization and forward/back substitution are replaced by back/forward sweeps on radial feeders with equivalent impedances. Tests on several large distribution systems ranged from 490 to 1651 in nodes, 0.15 to 5.48 in r/x ratio and 0.0004 /spl Omega/ to 3.07 /spl Omega/ in line impedance have shown that the proposed method is as robust and efficient as the back/forward sweep method. The proposed method can be applied to other applications, such as state estimation. The proposed method can also be extended to the solution of systems with loops, dispersed generators and three phase (unbalanced) representation.

A modified Newton method for radial distribution system power flow analysis

A power system state estimation based on (a) multiphase model, (b) voltage and current waveform measurements, (c) synchronized measurements and (d) multifrequency model (i.e. the approach accounts for waveform distortion or harmonics) is formulated. The paper focuses on the following: (a) modeling, (b) implementation, (c) observability and (d) performance. Sensitivity analysis is used to show how transmission line modeling and measurement schemes affect the performance of harmonic state estimation. The overall performance of the system is described in terms of confidence level versus error. These concepts are illustrated with simple systems. The overall harmonic measurement system is scheduled for installation and field evaluation on the NYPA/New York Power Pool transmission system by the end of 1993. >

Power system harmonic state estimation

A multiphase power flow model and state estimation for distribution systems are formulated and solution methods are presented. The multiphase power flow model is based on fully asymmetric modeling of the power distribution system. The state estimation uses this model in conjunction with synchronized measurements. The method provides an estimate of the total electric load for each distribution circuit without the requirement of knowledge of the individual loads along the circuit. The paper addresses the following issues: (a) modeling; (b) implementation; (c) observability; and (d) performance. The overall performance of the method is described in terms of confidence level versus error. The concepts are illustrated with a simplified distribution system.

Multiphase power flow and state estimation for power distribution systems

A technique for laboratory characterization of instrument transformers designed for transmission level voltage and current measurements is presented. The technique is also extended to transient event recorders (TERs). The objective of the method is to determine the suitability of existing substation instrument transformers for harmonic measurements, particularly in the frequency range of 60 to 1500 Hz covering the first 25 harmonics. Specifically, the following characteristics are of interest: transfer function magnitude and phase, linearity, and sensitivity of the frequency response to burdens. The measurement technique is based on exciting the instrument transformer primary with an impulsive waveform. Both input and output waveforms are recorded using laboratory grade probes and digitizers. Digital signal processing techniques are used to compute the instrument transformer frequency response. Several voltage transformers and current transformers in the 230 kV-765 kV voltage range were tested. The results are described. >

Transmission level instrument transformers and transient event recorders characterization for harmonic measurements

ABSTRCT This paper address issues related to hardware and software requirements for a H m o n i c Measurement System (HMS). It presents an overview of the requirements to achieve the goal of performing simultaneous measurements of harmonics at the various parts of the power system, providing for a common time reference with sufficient accuracy, processing the measurements with a harmonicstate estimator to determine harmonics at every point of the system, and a user interface to allow easy utilization of the system. The hardware consists of existing instrument transformers and Transient Event Recorders m), custom-built time triggering devices, personal computers (PCs) for loa1 processing of measured waveforms, a master workstation computer for data analysis and storage, and communications hardware. Software at the local PCs consists of data acquisition, waveform error correction algorithms, Fourier analysis, time tagging software, communications software, and user interface. Software for the master workstation consists of a harmonic state estimator, data base management, communications software, user interface, and statistical analysis.

Hardware And Software Requirements For A Transmission System Harmonic Measurement System

Two basic analysis problems are addressed for power systems with topology-changing components. The first problem is that of determining the periodic steady-state operation of such components. The second problem is that of determining the linearized models. The authors present a method which addresses both problems simultaneously. The method is based on state-space representations of the power system components and the theory of optimal control. The mathematical formulation of the method is presented. Results obtained from testing the algorithm on a single-phase AC controller are also presented. >

https://ieeexplore.ieee.org/iel2/622/6719/00271026.pdf

Fan Zhang

Papers

Power system harmonic state estimation

Multiphase power flow and state estimation for power distribution systems

Transmission level instrument transformers and transient event recorders characterization for harmonic measurements

Hardware And Software Requirements For A Transmission System Harmonic Measurement System

Modeling and analysis of power systems under periodic steady state conditions