Synchronization of multi‐machine power systems under disturbances and measurement errors

2022 ◽  
Author(s):  
Igor Furtat ◽  
Artem Nekhoroshikh ◽  
Pavel Gushchin
Keyword(s):  
Power Systems ◽  
Measurement Errors

scholarly journals Methodology for Implementing the State Estimation in Renewable Energy Management Systems

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2301
Author(s):  
Yun-Sung Cho ◽  
Yun-Hyuk Choi
Keyword(s):  
Renewable Energy ◽  
Power Systems ◽  
State Estimation ◽  
Measurement Errors ◽  
Large Scale ◽  
Test System ◽  
The State ◽  
Inner Function ◽  
Outer Function ◽  
Bad Data

This paper describes a methodology for implementing the state estimation and enhancing the accuracy in large-scale power systems that partially depend on variable renewable energy resources. To determine the actual states of electricity grids, including those of wind and solar power systems, the proposed state estimation method adopts a fast-decoupled weighted least square approach based on the architecture of application common database. Renewable energy modeling is considered on the basis of the point of data acquisition, the type of renewable energy, and the voltage level of the bus-connected renewable energy. Moreover, the proposed algorithm performs accurate bad data processing using inner and outer functions. The inner function is applied to the largest normalized residue method to process the bad data detection, identification and adjustment. While the outer function is analyzed whether the identified bad measurements exceed the condition of Kirchhoff’s current law. In addition, to decrease the topology and measurement errors associated with transformers, a connectivity model is proposed for transformers that use switching devices, and a transformer error processing technique is proposed using a simple heuristic method. To verify the performance of the proposed methodology, we performed comprehensive tests based on a modified IEEE 18-bus test system and a large-scale power system that utilizes renewable energy.

Error Considerations for Turbine-Generator Torsional Vibration Monitoring

2020 ◽  
Author(s):  
Jindrich Liska ◽  
Jan Jakl ◽  
Sven Kunkel
Keyword(s):  
Power Systems ◽  
Torsional Vibration ◽  
Gas Turbines ◽  
Measurement Errors ◽  
Power Plants ◽  
Signal To Noise Ratio ◽  
Vibration Monitoring ◽  
Turbine Generator ◽  
Turbine Generators ◽  
Incremental Encoder

Abstract Turbine-generator torsional vibration is linked to electrical events in the power grid by the generator air-gap torque. Modern power systems are subject to gradual transformation by increasing flexibility demands and incorporation of renewable resources. As a result, electrical transient events are getting more frequent and thus torsional vibration is getting more and more attention. Especially in the case of large steam and gas turbines torsional vibration can cause material fatigue and present a hazard for safe machine operation. This paper freely builds on previous work, where a method for torsional vibration evaluation using an incremental encoder measurement was presented, in that it supplements error considerations to this methodology. Measurement errors such as precision of the rotor encoder manufacturing, choice of the proper sensor, its signal to noise ratio and the error of instantaneous velocity computation algorithm are analyzed. The knowledge of these errors is essential for torsional vibration as there is an indirect and relatively complicated path from the measurement to the final torsional vibration results compared to other kinds of vibration. The characteristics of particular errors of the processing chain are validated both on experimental data from a test rig as well as field data measured on turbine-generators in power plants.

scholarly journals Mode diagnostics of pipeline systems of the energetics

2020 ◽  
Vol 216 ◽  
pp. 01001
Author(s):  
Mikhail Sukharev
Keyword(s):  
Mathematical Model ◽  
Power Systems ◽  
Flow Regime ◽  
Measurement Errors ◽  
Random Variables ◽  
Gas Pipeline ◽  
Pipeline System ◽  
Gas Pumping ◽  
Gas Pumping Unit ◽  
Standard Software

The paper proposes a method for diagnosing gradual failures in pipeline power systems, based on tracking the dynamics of flow regime parameters. The method also makes it possible to promptly adjust the coefficients of a mathematical model of the system objects. Conclusions are made based on the analysis of the entire set of measurements, which are considered random variables due to measurement errors. Conclusions are made based on the analysis of the entire set of measurements, which are considered random variables due to instrumental errors. Examples of a gas pumping unit and a complex looped gas pipeline system are given. Calculations are performed using standard software.

State Estimation of Power Using the Whale Optimization Algorithm

2020 ◽  
Vol 11 (4) ◽  
pp. 194-213
Author(s):  
Suvabrata Mukherjee ◽  
Provas Kumar Roy
Keyword(s):  
Power Systems ◽  
State Estimation ◽  
Optimization Algorithm ◽  
Measurement Errors ◽  
Population Based ◽  
Whale Optimization Algorithm ◽  
State Variables ◽  
Optimal Point ◽  
Whale Optimization ◽  
Population Based Algorithm

In power systems, the process of attaining a better prediction from a set of variables from state variables is called state estimation (SE). These variables consist of magnitudes of bus voltage and the corresponding angles of all the buses. Because of the non-linearity and intricacy of ever-developing power systems, it has become important to apply upgraded techniques for the dissolution and supervision in practical environments. The discussed analysis evaluates the appositeness of a new metaheuristic technique called the whale optimization algorithm (WOA) which is a population-based algorithm, to reduce the measurement errors so as to gauge the optimal point of the power system when some susceptible values are inadequate. WOA displays admirable attainment in global optimization. It employs a bubble-net hunting approach and it mimics the social behaviour of humpback whales to get the best candidate solution. The approach is tested on IEEE-14, IEEE-30, and IEEE-57 bus test systems and the potency is validated by comparison with the biogeography based optimization algorithm (BBO).

scholarly journals Adaptive Tolerant State Estimation under Model Uncertainty in Power Systems

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2111
Author(s):  
Ruizi Ma
Keyword(s):  
Singular Value Decomposition ◽  
Power Systems ◽  
Model Uncertainty ◽  
Measurement Errors ◽  
Singular Value ◽  
State Estimator ◽  
Adaptive Estimator ◽  
Singular Value Decomposition Method ◽  
Value Decomposition ◽  
Tolerant State

In this paper an adaptive tolerant estimator using singular value decomposition is proposed for a distribution network under model uncertainty in power systems. The adaptive tolerant estimator was designed with adjusted parameters and adjusted weights to overcome the limitations of model uncertainty. The estimator that reduces the measurement errors is adaptive to fast parameter changes in complicated environments. The singular value decomposition method was combined into the state estimator, which extended the over-determined cases to under-determined cases under model uncertainty. The performance of the tolerant estimator was compared with the conventional adaptive estimator, and the tolerant estimator showed accurate estimations against model uncertainty in complicated measurement environments.

scholarly journals Thévenin Equivalent Parameter Adaptive Robust Estimation Considering the Erroneous Measurements of PMU

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4865
Author(s):  
Anan Zhang ◽  
Wenting Tan ◽  
Ming Cheng ◽  
Wei Yang
Keyword(s):  
Parameter Estimation ◽  
Power Systems ◽  
Measurement Errors ◽  
Measurement Data ◽  
Estimation Algorithm ◽  
Recursive Least Squares ◽  
Measurement Unit ◽  
External Interference ◽  
Equivalent Parameter ◽  
Thevenin Equivalent

Parameter estimation based on the measurement data of the phasor measurement unit (PMU) is an important approach for identifying the Thévenin equivalent parameters (TEPs) of power systems. However, in the process of acquiring or transmitting data in PMU, measurement errors due to external interference or internal system faults will affect the accuracy of parameter estimation. In this paper, a TEP estimation algorithm based on local PMU measurement is proposed. The algorithm considers the errors of the PMU and introduces Huber function and projection statistics (PS) to eliminate the effects of outliers and leverage measurements, respectively. Additionally, a variable forgetting factor (VFF) is used to quickly eliminate the historical data with measurement deviation and track the changes of the system. The regularization technique is used to solve the divergence problem in the inverse process of the ill-conditioned matrix, thereby improving the stability and generalization performance of the algorithm. Finally, by minimizing the cost function of this algorithm, a recursive formula for the equivalent parameter estimation is derived. The effectiveness of the algorithm is verified on the IEEE 118-bus and IEEE 30-bus systems, and compared with recursive least squares (RLS) and Huber’s M-Estimation; the mean relative errors decreased by 94.75% and 84.77%, respectively.

Research on Power Measurement in Harmonics Disturbance Circumstances

2011 ◽  
Vol 403-408 ◽  
pp. 3253-3257
Author(s):  
Yu Xu
Keyword(s):  
Power Systems ◽  
Measurement Errors ◽  
Power Flow ◽  
Harmonic Wave ◽  
Electric Energy ◽  
Power Measurement ◽  
Current Status ◽  
Harmonic Pollution ◽  
Definition Of ◽  
Harmonic Power

Due to the rapid growth of non-linear loads in power systems, harmonic pollution is becoming more and more serious. Begin with the definition of harmonic power, the direction of power flow is analyzed from the sides of both fundamental and harmonic wave. Through a harmonic simulation circuit based on PSCAD/EMTDC, the conclusion that as a result of harmonic, harmonic-sources have their metered electric energy reduced, while non-harmonic-sources increased has been brought out. What's more, according to the result of simulation, the interactive influence of fundamental and harmonic wave on power measurement is proposed. Due to the above conclusion and the work principles of electromagnetic induction meter and electric meter, the reasons of measurement errors are found. And at the end of this paper, the development and current status of power definition which is a necessary key to the power measurement are discussed.

Precise on-line Measurement of Lattice Vectors

1990 ◽  
Vol 48 (1) ◽  
pp. 530-531
Author(s):  
W.J. de Ruijter ◽  
Sharma Renu
Keyword(s):  
Electron Microscope ◽  
Measurement Errors ◽  
Dynamic Range ◽  
Structural Information ◽  
Statistical Parameter ◽  
Systematic Errors ◽  
Geometric Distortion ◽  
Crystal Silicon ◽  
Camera System ◽  
On Line

Established methods for measurement of lattice spacings and angles of crystalline materials include x-ray diffraction, microdiffraction and HREM imaging. Structural information from HREM images is normally obtained off-line with the traveling table microscope or by the optical diffractogram technique. We present a new method for precise measurement of lattice vectors from HREM images using an on-line computer connected to the electron microscope. It has already been established that an image of crystalline material can be represented by a finite number of sinusoids. The amplitude and the phase of these sinusoids are affected by the microscope transfer characteristics, which are strongly influenced by the settings of defocus, astigmatism and beam alignment. However, the frequency of each sinusoid is solely a function of overall magnification and periodicities present in the specimen. After proper calibration of the overall magnification, lattice vectors can be measured unambiguously from HREM images.Measurement of lattice vectors is a statistical parameter estimation problem which is similar to amplitude, phase and frequency estimation of sinusoids in 1-dimensional signals as encountered, for example, in radar, sonar and telecommunications. It is important to properly model the observations, the systematic errors and the non-systematic errors. The observations are modelled as a sum of (2-dimensional) sinusoids. In the present study the components of the frequency vector of the sinusoids are the only parameters of interest. Non-systematic errors in recorded electron images are described as white Gaussian noise. The most important systematic error is geometric distortion. Lattice vectors are measured using a two step procedure. First a coarse search is obtained using a Fast Fourier Transform on an image section of interest. Prior to Fourier transformation the image section is multiplied with a window, which gradually falls off to zero at the edges. The user indicates interactively the periodicities of interest by selecting spots in the digital diffractogram. A fine search for each selected frequency is implemented using a bilinear interpolation, which is dependent on the window function. It is possible to refine the estimation even further using a non-linear least squares estimation. The first two steps provide the proper starting values for the numerical minimization (e.g. Gauss-Newton). This third step increases the precision with 30% to the highest theoretically attainable (Cramer and Rao Lower Bound). In the present studies we use a Gatan 622 TV camera attached to the JEM 4000EX electron microscope. Image analysis is implemented on a Micro VAX II computer equipped with a powerful array processor and real time image processing hardware. The typical precision, as defined by the standard deviation of the distribution of measurement errors, is found to be <0.003Å measured on single crystal silicon and <0.02Å measured on small (10-30Å) specimen areas. These values are ×10 times larger than predicted by theory. Furthermore, the measured precision is observed to be independent on signal-to-noise ratio (determined by the number of averaged TV frames). Obviously, the precision is restricted by geometric distortion mainly caused by the TV camera. For this reason, we are replacing the Gatan 622 TV camera with a modern high-grade CCD-based camera system. Such a system not only has negligible geometric distortion, but also high dynamic range (>10,000) and high resolution (1024x1024 pixels). The geometric distortion of the projector lenses can be measured, and corrected through re-sampling of the digitized image.

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