Dao Zhou

Wide-Area-Measurement System Development at the Distribution Level: An FNET/GridEye Example

Summary form only given. Electric power grid wide-area monitoring system (WAMS) have been extended from the transmission to distribution level. As the first WAMS deployed at the distribution level, the frequency monitoring network FNET/GridEye uses GPS-time-synchronized monitors called frequency disturbance recorders (FDRs) to capture dynamic grid behaviors. In this paper, the latest developments of monitor design and the state-of-the-art data analytics applications of FNET/GridEye are introduced. Its innovations and uniqueness are also discussed. Thanks to its low cost, easy installation and multi-functionalities, FNET/GridEye works as a cost-effective situational awareness tool for power grid operators and pioneers the development of WAMS in electric power grids.

Distributed Data Analytics Platform for Wide-Area Synchrophasor Measurement Systems

As synchrophasor data start to play a significant role in power system operation and dynamic study, data processing and data analysis capability are critical to wide-area measurement systems (WAMSs). The frequency monitoring network (FNET/GridEye) is a WAMS network that collects data from hundreds of frequency disturbance recorders at the distribution level. The previous FNET/GridEye data center is limited by its data storage capability and computation power. Targeting scalability, extensibility, concurrency, and robustness, a distributed data analytics platform is proposed in this paper to process large volume, high velocity dataset. A variety of real-time and non-real-time synchrophasor data analytics applications are hosted by this platform. The computation load is shared with balance by multiple nodes of the analytics cluster, and big data analytics tools such as Apache Spark are adopted to manage large volume data and to boost the data processing speed. Future data analytics applications can be easily developed and plugged into the system with simple configuration.

Impact of GPS Signal Loss and Its Mitigation in Power System Synchronized Measurement Devices

With the aid of global positioning system (GPS), synchronized measurement devices (SMDs) are increasingly deployed across power systems to monitor the status of electric grids by providing accurate measurement data along with unified time stamps. Unfortunately, GPS receivers tend to lose signal lock when certain uncontrollable and unpredictable factors arise. In order to investigate the presence of GPS signal loss (GSL) issues on measurement devices, analysis is performed on historical data from both phasor data concentrators and FNET/GridEye servers. Meanwhile, the impact of GSL on field measurement accuracy has not been previously explored in depth. Through analysis and experimental tests, this paper discovers angle drift caused by GSL, which consequently leads to the total vector error exceeding the IEEE standard C37.118.1-2011. Furthermore, a compensation method is proposed to rectify the angle drift and laboratory experiments demonstrate that the proposed method does effectively reduce angle drift and mitigate the impact of GSL in SMDs.

Improvement of timing reliability and data transfer security of synchrophasor measurements

Synchronized phasor measurements are becoming one of the key measurement elements of wide area measurement systems in advanced power system monitoring, protection, and control applications. Availability of global positioning system (GPS) provides the possibility of wide-area deployment of Phasor Measurement Unit (PMU) and Frequency Disturbance Recorder (FDR) in power system. GPS is the only timing source for PMU and FDR so far, and they will cease to work when GPS signal is lost or unstable. In addition, phasor data is transferred over the Internet without any encryption, which exposes data to cyber-attacks. The purpose of this paper is to develop an alternative GPS independent timing synchronization method for PMU and FDR, and to implement an encryption system without disrupting real-time data delivery. Primary test results confirm improvement of timing reliability and data transfer security of synchrophasor measurements.

Real-time power system electromechanical mode estimation implementation and visualization utilizing synchrophasor data

Wide area measurement systems (WAMS) could provide enough information to estimate the electromechanical modes which characterize the dynamic properties of the power grid. Utilizing the measured synchrophasor data from frequency monitoring network (FNET/GridEye), this paper proposes an approach to estimate the oscillation frequency and damping regardless of ring-down or ambient condition in real-time environment. The empirical mode decomposition (EMD) is used to detrend the frequency signal, and an auto-regressing moving-average (ARMA) model is used to describe the time series data and the modified yuler walker (MYW) algorithm is used to estimate the AR parameters. Additionally, this paper describes the details of the implementation of a real-time monitoring website showing the estimated dominant frequency and damping from the four interconnections in North America power grid.

A Distribution Level Wide Area Monitoring System for the Electric Power Grid–FNET/GridEye

The wide area monitoring system (WAMS) is considered a pivotal component of future electric power grids. As a pilot WAMS that has been operated for more than a decade, the frequency monitoring network FNET/GridEye makes use of hundreds of global positioning system-synchronized phasor measurement sensors to capture the increasingly complicated grid behaviors across the interconnected power systems. In this paper, the FNET/GridEye system is overviewed and its operation experiences in electric power grid wide area monitoring are presented. Particularly, the implementation of a number of data analytics applications will be discussed in details. FNET/GridEye lays a firm foundation for the later WAMS operation in the electric power industry.

Frequency-based real-time line trip detection and alarm trigger development

Wide-area measurement systems have made it possible for operators to monitor the dynamics of the whole power system in real time. By utilizing the FNET/GridEye system in the distribution network, many synchrophasor-based event detectors have been developed. This paper focuses on the development of a real-time application for line trip detection. A frequency-based algorithm is selected to identify line trip events by assembling low-pass filters and peak detectors. The detection and alarm trigger application is implemented using Adapters based on the openPDC platform. The performance of this application is tested with historical line trip events.

The impact of synchronized human activities on power system frequency

It has been demonstrated in previous studies that nation-wide or largely synchronous societal activities have impacts on the power grid frequency responses. This paper investigates NFL Super Bowl games as an example to evaluate the influence of synchronized human activities on the power system using data collected from a wide-area frequency monitoring network (FNET/GridEye). The statistics and plots of several frequency fluctuation phenomena and relevant analysis are presented. Featured characteristics drawn from the frequency data detected during the Super Bowl games are discussed.

Observation of inertial frequency response of main power grids worldwide using FNET/GridEye

Frequency monitoring network (FNET/GridEye), a wide-area monitoring system (WAMS) at distribution level, is known to be able to reveal many insights of power grid dynamics through the real time phasor measurement collected by frequency disturbance recorders (FDRs). A large number of FDR units are currently deployed in several power grids worldwide. This paper focuses on the inertial frequency responses of various bulk power grids over the world based on the observation of FNET/GridEye. It is the first time this kind of research is extended to main power grids worldwide. This paper discloses the frequency response characteristics for different sizes of power grids.

Frequency response analysis using automated tools and synchronized measurements

This paper describes the successes of using high resolution, time-synchronized phasor measurement data from across North America to perform frequency response analysis. The annual analysis is performed to determine the frequency response obligations for each interconnection and Balancing Authority (BA). This analysis utilizes R&D tools developed under industry guidance and Department of Energy (DOE) funding. An update to metrics used for comprehensive analysis for frequency response using high-resolution data is also described.