Synchronized Measurement Technology Research Articles

The use of conventional measurements for the identification of bad PMU measurements

The maturity of the Synchronized Measurement Technology (SMT) in power systems along with the realization of the benefits that can be offered by the Phasor Measurement Units (PMUs) have increased the number of installed PMUs considerably in the last years. One of the control center applications that can benefit by the large deployment of the PMUs is the state estimator, whose formulation in a PMU observable system can be transformed into a linear one, avoiding the iterative procedure. Although there are numerous benefits from the application of a linear state estimator in the control center, the lack of PMU measurement redundancy can compromise the functionality of such an estimator, due to the possible presence of bad critical PMU measurements, which cannot be detected by the existing bad data identification procedures. In this paper, the difficulty for detecting bad PMU measurements in case of low measurement redundancy is first demonstrated, while a methodology that uses conventional measurements to detect the corresponding bad PMU measurements is proposed. The effectiveness of the proposed methodology is verified using the IEEE 14-bus system.

Phasor Estimation by EMD-Assisted Prony

The use of synchronized measurement technology leads to a more reliable and secure operation of the power system. Phasor calculation is needed for all buses where a phasor measurement unit is installed, and fast and precise estimation is necessary for accurate monitoring, protection and control. The Prony algorithm is one promising method due to its capability to estimate phasor adaptively with changing frequency. The algorithm projects the signal on <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$L$</tex-math></inline-formula> exponentially damped sine functions, where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$L$</tex-math></inline-formula> is the order of the Prony. However, the order under different conditions should be adapted automatically to reduce computation time. To adaptively specify the order, the empirical mode decomposition (EMD) method is proposed in this paper to be combined with the Prony and named EMD-Prony. The EMD decomposes a signal into finite single oscillatory modes, representing the number of modes in the signal. EMD is also used as a pre-processing step to filter noise from an input signal of Prony. Therefore, EMD is proposed here as an assistant of Prony in a phasor estimation. Finally, the proposed method is tested on the benchmark signals proposed in the IEEE standard, signals obtained from a simulated power system, and measured data from a real-world power system.

Synchronized Measurement Technology Supported Online Generator Slow Coherency Identification and Adaptive Tracking

In an electric power system, slow coherency can be applied to identify groups of the generating units, the rotors of which are swinging together against each other at approximately the same oscillatory frequencies of inter-area modes. This serves as a prerequisite-step of several emergency control schemes to identify power system control areas and improve transient stability. In this paper, slow coherent generators are grouped based on the direction and the strength of electromechanical coupling between different generators. The proposed algorithm performs low-pass filtering of generator frequency measurements. It adaptively determines the minimal number of the measurements to be processed in an observation window, and performs data selectivity to prevent mixing of interfering coherency indices. Finally, it adaptively tracks grouping changes of slow coherent generators and determines a finite number of groups for an improved affinity propagation clustering. The proposed algorithm is implemented as an online MATLAB program and verified in real-time using RTDS power system simulator with the integration of actual synchronized measurement technology components as hardware-in-the-loop. The obtained results demonstrate the effectiveness of the proposed algorithm for robust and near real-time identification of grouping changes of slow coherent generators during the quasi-steady-state and electromechanical transient period following a disturbance.

The algorithm with synchronized voltage inputs for islanding detection of synchronous generators

This paper presents a new algorithm for the islanding detection of synchronous generators. The algorithm uses synchronized phase voltages measured in all three phases on the main grid side and at the bus bars of the generator as input signals. Synchronized voltage measurement was performed using synchronized measurement technology (SMT). The algorithm based on digital phase comparison is the measured voltages and, based on the Islanding Detection Index (IDI), detects the occurrence of islanding operation. The algorithm testing was performed on the model of a radial distribution grid with two synchronous generators. The radial distribution grid is modeled in the MATLAB/Simulink software package. The test results show the good properties of the proposed algorithm.

Synchro-Measurement Application Development Framework: An IEEE Standard C37.118.2-2011 Supported MATLAB Library

Electrical power system monitoring, protection, operation, and control schemes are undergoing significant changes toward the next generation fully automated, resilient, and self-healing grids. At present, there still exists a lack of available user-friendly tools for the synchronized measurement technology supported application design. This paper presents a synchro-measurement application development framework (SADF) to promote a simplified design and thorough validation of synchro-measurement (IEEE Standard C37.118.2-2011) supported user-defined applications under realistic conditions. The proposed SADF supports online receiving of a phasor measurement unit (PMU) or phasor data concentrator (PDC) provided data stream and enables simultaneous use of processed machine-readable synchro-measurements in advanced user-defined applications. This paper fills the scientific gap between the IEEE Standard C37.118.2-2011 specifications and its implementation by proposing a novel robust communication technique and efficient synchro-measurement data parsing methodology. As a proof of concept, the proposed SADF is implemented as a novel open-source MATLAB library. Combining this library with MATLAB’s signal processing and visualization functions allows mastering the design and validation of complex wide-area monitoring, protection, and control applications, as well as PMU/PDC performance and compliance verification. Finally, this paper verifies the proposed library against the standard specifications, assesses its interoperability and performance via a cyber-physical simulation platform, and presents online voltage magnitude monitoring as an example application.

Synchronized measurement technology supported AC and HVDC online disturbance detection

In electric power system, disturbance detection has become an important part of grid operation and refers to the detection of a voltage and current excursion caused by the wide variety of electromagnetic phenomena. This paper proposes a computationally efficient and robust algorithm for synchronized measurement technology (SMT) supported online disturbance detection, suitable for AC and HVDC grids. The proposed algorithm is based on the robust median absolute deviation sample dispersion measure to locate dataset outliers. The algorithm is capable of identifying the disturbance occurrence and clearance measurement sample based on the dynamic criteria, driven by present power system conditions. The effectiveness of the proposed algorithm is verified by real-time simulations using a cyber-physical simulation platform, as a co-simulation between the SMT supported electric power system model and underlying ICT infrastructure. The presented results demonstrate effectiveness of the proposed algorithm, making it suitable for an AC and HVDC online disturbance detection application or as a pre-step of backup protection schemes.

Detection and Protection of Distributed Generation From Island Operation by Using PMUs

Smart microgrids are small modern centralized power systems which contain all constituents as large power systems (production – usually Renewable energy sources (RES); power storage systems; transfer – from the source to the consumer; consumers). The basic characteristic is that the microgrid contains distributed generation and it can be in the island operation or connected to a large power system. Detection and protection from island operation of distributed generation, or in fact, protection of microgrid based on synchronized measurement technology (SMT) requires hardware (Phasor Measurement Unit –PMU) and the appertaining software support. This paper presents the solution for protection from island operation of distributed generation based on SMT. PMU devices transfer measurements to the central controller, which by applying certain algorithms that provide an image of the distributed generation condition in real time, and also make adaptive protection. The focus of the paper is on software algorithm for detection of distributed generation (microgrid) island operation, but it is open for implementation of various applications.

Study on dynamic deformation synchronized measurement technology of double-layer liquid surfaces

Accurate measurement of the dynamic deformation of double-layer liquid surfaces plays an important role in many fields, such as fluid mechanics, biomechanics, petrochemical industry and aerospace engineering. It is difficult to measure dynamic deformation of double-layer liquid surfaces synchronously for traditional methods. In this paper, a novel and effective method for full-field static and dynamic deformation measurement of double-layer liquid surfaces has been developed, that is wavefront distortion of double-wavelength transmission light with geometric phase analysis (GPA) method. Double wavelength lattice patterns used here are produced by two techniques, one is by double wavelength laser, and the other is by liquid crystal display (LCD). The techniques combine the characteristics such as high transparency, low reflectivity and fluidity of liquid. Two color lattice patterns produced by laser and LCD were adjusted at a certain angle through the tested double-layer liquid surfaces simultaneously. On the basis of the refractive indexes difference of two transmitted lights, the double-layer liquid surfaces were decoupled with GPA method. Combined with the derived relationship between phase variation of transmission-lattice patterns and out-of plane heights of two surfaces, as well as considering the height curves of the liquid level, the double-layer liquid surfaces can be reconstructed successfully. Compared with the traditional measurement method, the developed method not only has the common advantages of the optical measurement methods, such as high-precision, full-field and non-contact, but also simple, low cost and easy to set up.

Synchronized measurement technology: A blessing for power systems [Trends in Future I&amp;M

Synchronized measurement technology: A blessing for power systems [Trends in Future I&amp;M

An enterprise platform for wide area monitoring of load dynamics using Synchronized Measurement Technology

Abstract: This paper presents significant extensions of a vertically integrated platform, capable of real time processing of synchronized measurements obtained from a wide area monitoring system. Specific new contributions focus on including Matlab simulated load models into the real data processing chain, through the development of a virtual Phasor Measurement Unit functionality. Performance of the dynamic load model parameters estimation is assessed and compared for both simulated and real substation data. Automatically detected network disturbances are stored in a separate database, ensuring fast access to extracted knowledge. Additional developments include, but are not limited to intentional bad data injection, multiple simultaneous instances of virtual Phasor Measurement Units and automatic validation according to IEEE C37.118 standard. All new functionalities are implemented conforming to enterprise Java EE7 standards, thus ensuring a high level of scalability, concurrent access and reliability. These features are of particular importance in practical applications, which represent the actual target of this research: to use recently installed Great Britain (GB) wide area monitoring system, created in the Ofgem Network Innovation Competition VISOR project, for wide area monitoring of load dynamics.

Flexible Synchronized Measurement Technology-Based Fault Locator

This paper presents a flexible and robust numerical algorithm for fault location on transmission lines. The algorithm does not require line parameters to locate the fault, which is an advance over fault locators that do require such information. Line parameters are only approximately constant; they vary with different loading and weather conditions, which affects the accuracy of existing fault location algorithms. Thus, an approach which does not require line parameters would be more robust, accurate, and flexible. Accurately, locating faults on transmission lines is vital for expediting their repair, so the proposed solution could lead to an improvement in the security and quality of the energy supply. Development of the proposed algorithm was facilitated by new smart grid technologies in the field of wide-area monitoring, protection, and control. The proposed algorithm is based on emerging synchronized measurement technology, using synchronized data sampling at both line terminals; however, the “SynchroCheck” procedure is also proposed as a means of accurately locating faults when data sampling synchronization has been lost. This paper presents the algorithm derivation and the results of thorough testing using alternative transients program-electromagnetic transients program (ATP-EMTP) fault simulations.

Smart Overhead Lines Autoreclosure Algorithm Based on Detailed Fault Analysis

This paper presents a novel numerical algorithm implemented in a unique methodology for the control of smart single-phase autoreclosure and comprehensive fault analysis for overhead lines using synchronized measurement technology. The algorithm improves on existing methodologies for adaptive single-phase autoreclosure, fault location, detailed disturbance records analysis, and fault data management. It is based on line current and voltage data sampled at both line terminals and synchronized sampling of all analogue input variables is assumed in this paper. The proposed algorithm is derived in the spectral domain and based on the application of the Discrete Fourier Transform. The electrical arc as a source of higher harmonics is included in the complete fault model and represents the starting point for the development of the new algorithm. The algorithm's distinctive feature is that it can determine both the fault arc and the fault resistance. The presence or absence of an arc resistance is used to determine the nature of the fault. The algorithm can be applied to both short and long lines. The algorithm is thoroughly tested using electromagnetic transient simulations of an overhead line connected between two active networks, as well as with field data.

Embedding Synchronized Measurement Technology for Smart Grid Development

Present distribution networks have not been designed to accept extensive Distributed Generation (DG). The present framework may change in the near future impelled by a worldwide increase in DG penetration in distribution grids. The mutual dependency of energy distribution and communications on the same grid requires new means for effectively monitoring and controlling both systems in parallel. Relaying and control IEDs can also serve as measurement units for power quality. Synchronized Measurement Technology (SMT) has the potential of becoming the backbone of this paradigm. By using wide-area information systems, the data can be made available to all involved partners. This paper provides different outlooks about the possibilities of Embedded Systems to integrate the protection, control and monitoring functions in Distribution Automation Systems. To justify the choice of synchronization technology, we have scheduled a complete sequence of synchronism tests and measurement tests based on standard specifications.

Performance Assessment of Communication Network in WAMS

Wide Area Measurement Systems (WAMS) based on Synchronized Measurement Technology (SMT) is getting considerable attention worldwide from the power system engineers in last few years. The fast and synchronized measurements facilitate the real time Wide Area Monitoring and Control (WAMC) of the power system. The backbone of WAMS is high performance communication infrastructure. Network designer has vast variety of architecture, protocol and communication medium. The medium should be selected in such a manner that it provides guaranteed bandwidth for the utilities. In this paper, we have simulated Phasor Measurement Unit (PMUs) data traffic in OPNET, and then created scenarios with different routing protocols. The performance of WAMS has also been analyzed in presence of varying background traffic and main link failure. Simulation results have been pursued in such a way that under worst situation the ‘end to end delay’ is within an acceptable range.

The Research of Synchronized Phasor Measurement Unit Testing and Evaluation

Phasor Measurement Unit (PMU) devices, based on the synchronized measurement technology, are basic building blocks of Wide Area Monitoring System (WAMS) and Wide Area Monitoring Analysis Protection-control (WAMAP). Similar to the Remote Terminal Unit (RTU) in Energy Management System (EMS), PMU is becoming very important in the WAMS or WAMAP. This paper introduces the architecture of PMU testing and evaluation (T&E) in our laboratory. The integrated evaluation schemes include testing environment, performance testing method, conformance testing method and evaluation.

Wide-Area Monitoring, Protection, and Control of Future Electric Power Networks

Wide-area monitoring, protection, and control (WAMPAC) involves the use of system-wide information and the communication of selected local information to a remote location to counteract the propagation of large disturbances. Synchronized measurement technology (SMT) is an important element and enabler of WAMPAC. It is expected that WAMPAC systems will in the future reduce the number of catastrophic blackouts and generally improve the reliability and security of energy production, transmission, and distribution, particularly in power networks with a high level of operational uncertainties. In this paper, the technological and application issues are addressed. Several key monitoring, protection, and control applications are described and discussed. A strategy for developing a WAMPAC system in the United Kingdom is given as well.

Measurements get together

This article deals with the synchronized measurement technology that has the potential of becoming the backbone for real-time monitoring system. The secure and reliable operation of modern power systems is an increasingly challenging task due to the ever-increasing demand for electricity, the growing number of interconnections, penetration of variable renewable energy sources, and deregulated energy market conditions. Power companies in different parts of the world are therefore feeling the need for a real-time wide area monitoring, protection, and control (WAMPAC) system. Synchronized measurement technology (SMT) has the potential of becoming the backbone of this system. The major advantages of using SMT are that 1) the measurements from widely dispersed locations can be synchronized with respect to a Global Positioning System (GPS) clock, 2) voltage phase angles can be measured directly, which was so far technically infeasible, and 3) the accuracy and speed of energy management system (EMS) applications increases manifold.

電力システムにおける同期計測技術の応用動向

電力システムにおける同期計測技術の応用動向