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This paper studies voltage/reactive power coordination control between energy storage system and clean energy plant connected to AC/DC hybrid system. As energy storage power stations are widely integrated to grid, they pose larger influence on clean energy. It occurs that voltage/reactive power characteristic of energy storage plant and clean energy plant becomes complicated to control and analyze. For the sake of studying the energy storage system and clean energy plant’s voltage/reactive power characteristics, a model of energy storage and clean energy plant connected to AC/DC hybrid system is proposed, with a proper coordination control strategy of PCC voltage/reactive power. Then, the coordination control strategy is conducted under different conditions in time domain simulation to analyze voltage/reactive power dynamics of system. Lastly, the experiment on hardware-in-the-loop(HIL) system is finished to validate proposed voltage/reactive power coordination control above.

Biogeography-Based Optimization (BBO) algorithm, a novel optimizing algorithm, is applied in optimal tuning of multimachine Power System Stabilizer (PSS) parameters. The tuning of fixed-structure lead-lag type PSS parameters is formulated as a quadratic performance optimization problem. An eigenvalue-based objective function is chosen to maximize the damping ratio of the electromechanical modes at different system operating conditions. BBO algorithm, robust to the initial solution and computationally efficient compared with other meta-heuristic algorithms, such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Evolutionary Strategy (ES), is employed to search for optimal PSS parameters. Simulations are carried out on two typical multimachine power systems. Both frequency-domain eigenvalue analysis and time-domain dynamic simulation verify the effectiveness and robustness of the proposed BBO based PSSs under a wide range operating conditions. Moreover, the superiority of the proposed BBO algorithm is further illustrated by algorithm optimization performance evaluation and dynamic response damping characteristic compared with GA, PSO and ES. Keywords: Biogeography-Based Optimization (BBO), electromechanical oscillations, multimachine power system, parameter optimization, Power System Stabilizer (PSS).

In order to resolve the problem that the power industry is with a rigid expectation of energy storage, higher requirement is put forward for intelligent and precise dispatch control of energy storage. The historical abandonment scenarios of power grids is analyzed to explore the pain points of current renewable energy consumption, where the principle and technical scheme is proposed of precise control of energy storage power stations. The precise control system of pumped storage power stations is applied to the actual grid data of a province. From the perspective of "source-network-loadstorage", the precise regulation of energy storage is used to promote the effect of renewable energy consumption. Through the intelligent and precise energy storage precision control system, the energy storage up and down adjustment flexibility is fully utilized to help the power system reach a balance, which not only promotes the consumption of renewable energy, but also makes the system more flexible and resilient.

Sub-synchronous Oscillation (SSO) is a serious incident in power system, and has been occurred in wind farms many times during the past decade. In this paper, energy flow method is used to analysis the SSO interactions. Firstly, the relationship between oscillation energy and damping is explained. Then, the oscillation function between two nodes in a power system is presented. By calculating the SSO energy from the measureable signals, the SSO energy flows between different nodes in the power system can be revealed. Simulation shows how different wind turbine generators interact, and discusses the relationship between SSO energy flow and equivalent resistance of wind turbine generator.

Low frequency oscillation in power system may cause system failure and blackout. It is possible to avoid low frequency oscillation if we can detect the oscillation mode with low damping in early stage. This paper presents the Frequency Domain Decomposition (FDD) method, which can extract the low frequency oscillation modes from ambient measurement data of Phasor Measurement Units(PMU). The parameters of mode shape from poorly damped oscillation modes, such as damping ratio and modal frequency, can be directly determined from ambient PMU measurements. Then this paper presents the implementation of oscillation mode identification application with OpenPDC platform, which is an open-source platform and provides an easy-to-use test platform for phasor measurement application. The case study shows that the implementation of Oscillation Mode Identification module with FDD method and OpenPDC platform is very efficient for processing large quantity of PMU data and identify low frequency oscillation mode, which is key to take early actions avoiding low-frequency oscillation in power system.

It can avoid low frequency oscillation in power grid if we can detect the oscillation mode with low damping ratio and identify the source in early stage. This paper presents the Frequency Domain Decomposition (FDD) method, which can extract the low frequency oscillation modes from measurements of Phasor Measurement Units (PMU) in normal operation condition. The damping ratio, modal frequency and the mode shape of poorly damped oscillatory modes can be directly determined from ambient PMU measurements. After the oscillation modes are identified by FCC method, the next step is to identify the source of oscillation modes and the Pearson correlation coefficient (PCC) method is proposed. Combined with FDD and PCC from status data in energy management system (EMS) and the oscillation mode results, we can identify the source of oscillation mode with high correlations. The case study shows that the combination of FDD and PCC is a very efficient way to process large volume of WAMS data and EMS data, identifying low frequency oscillation mode source, and provide possible way to take early actions preventing low frequency oscillation in power system.

From a mathematical point of view, the evaluation of the open loop scheme of electromagnetic loop network is a multi-objective optimization problem. This paper combines subjective and objective weighting methods and takes fully into account the evaluation elements of electromagnetic loop network open-loop, and proposes an evaluation method based on comprehensive weighting for open-loop schemes of electromagnetic loop network. Firstly, the opening principle and mechanism of electromagnetic loop network are analyzed. On this basis, the comprehensive evaluation index system of the open loop scheme of the electromagnetic loop network is established by taking into account safety and stability of the system, current limiting effect and economic operation and so on. Then, in order to calculate the subjective and objective weight coefficient by using the analytic hierarchy process (AHP) and the coefficient of variation method and through the comprehensive evaluation calculation to obtain a comprehensive index to evaluate the advantages and disadvantages of the open-loop scheme. The rationality and validity of the method presented in this paper are verified through the example analysis of an actual grid in one province and the simulation analysis by using PSASP.

We experimentally and numerically demonstrate resonant behaviors of terahertz metamaterials can be tuned significantly by their asymmetry. In the asymmetric U-shaped structure, when terahertz electric-field is perpendicular to bottom bar, an interesting phenomenon comes up with three dips, which differs from the split-ring resonator which only has one dip in the transmission spectrum. By altering the position of the intermediate wire added in the asymmetric U-shaped structure, we could achieve and modulate resonant behaviors of the asymmetric samples, showing strong dependence on the polarization of the terahertz E-field. For the asymmetrically-cut double-ring structures, the mutual coupling between four arcs results in multi-resonance dips, especially a low-frequency Fano-like resonance accompanied with a sharp peak. Our asymmetric structures could offer potential applications in terahertz frequency selectors and bio-sensors.

In this paper, the safety, efficiency and cost (SEC) concept of asset life management are introduced into distribution network planning, and a multi-objective programming model considering safety, efficiency and cost is established. Subsequently, Strength Pareto Evolutionary Algorithm (SPEA2) is employed to seek the Pareto optimal frontier. At the same time, the original grid and the corridor information of distribution network are considered in the solving process. Afterwards, the planning program set of SEC of the grid structure is obtained, and the comprehensive benefit index is used to sort the Pareto non-inferior solution set in the second-level optimization decision-making so as to solve and select the optimal decision-making scheme. The simulation results based on the IEEE 33-bus system demonstrate the correctness and effectiveness of the proposed method.

This paper studies the influence of operation parameters on the coupling relationship of each region by perturbation method based on the study of source-network-load characteristics. The influence of any running parameter on the coupling relationship between nodes or regions can be obtained according to the method described in this paper. The influence of electrical parameters on source-network-load characteristic can be further decoupled by analyzing the influence of electrical parameters on the proposed coupling characteristic index. The practical operation system of a province proves the correctness and validity of the proposed method

The development of the wind power generation technology and the increasing penetration of the wind power to the power system make the wind power a considerable source to provide reactive power for voltage regulation of the power grid. A method to utilize the reactive power generation capability of wind farm to participate in the regional automatic voltage control is proposed in this paper. First, reactive power margin of the wind farm is evaluated by calculating reactive power consumption of the wind farm itself under various operating conditions and the reserving dynamic stability demand of the wind farm. And then an adaptive zone-division method is proposed to define the wind farms regulation range, which is based on the reactive power margin evaluation result, to coordinate the operation of the wind farms. The efficiency of proposed method is validated via a case study on a regional power system with high penetration of wind farms.

Since the research on probability density distribution model of wind power fluctuation is of great importance for wind power integration and operation, this paper proposes a novel modeling method for the wind power fluctuation probability density based on nonparametric kernel density estimation. Firstly, the fluctuation components of wind power are extracted by wavelet decomposition to build a model involved bandwidth optimization, which is based on nonparametric kernel density estimation. Then a bandwidth optimization model is built constrained by goodness of fit test. Finally, constrained ordinal optimization is adopted to solve the model. Simulation results show that the model constructed by nonparametric kernel density estimation is determined by sample data without a prior probability density distribution, therefore this modelling method features with higher accuracy and more general applicability. In addition, an improved strategy proposed in this paper for nonparametric kernel density estimation also greatly improves the modeling accuracy and computational efficiency.

Transformer inductive filtering technology is a new filtering method through elimination of harmonic flux of transformer's core, which has important practical value and application prospect. To improve the inductive filtering system and expand the application fields, the research of inductive filtering technology based on multi-winding transformer is done in this paper. Firstly, the implementation condition and filtering mechanism of inductive filtering technology based on multi-winding transformer are analyzed; Secondly, the mathematical model and equivalent circuit of multi-winding inductive filtering transformer is calculated; Finally, the practical application of the multi-winding transformer inductive filtering technology in 12-pulse industry rectifier systems is given and the testing results validate the good harmonic suppression effectiveness of multi-winding transformer inductive filtering technology and the correctness of the equivalent circuit.

The wide area measurement system (WAMS) is widely used in power system and it generates large volume of data. How to use WAMS data to identify the low-frequency oscillation (mode) source in power system remains a great challenge. This paper proposes the correlation data analysis including Pearson correlation coefficient (PCC) and classification decision tree methods, to use the correlation between WAMS and energy management system (EMS) data for low-frequency oscillation (mode) source identification. The case study shows these methods are very efficient and provides a new perspective for processing large volume of WAMS data with EMS data, for low-frequency oscillation (mode) source identification in power system.

The transient voltage stability issue is a well known problem in Hunan power grid, which the simulation shows the three-phase fault occurred at 500kV transmission line in eastern Hunan will cause the voltage collapse hundreds of kilometers away in southern Hunan. With the newly constructed Ultra High Voltage DC (UHV-DC) line in operation at 2017, located at eastern Hunan, the simulation reveals that the voltage issue is getting worse. This paper proposes a Transient Voltage Stability Probing Method and studies the transient voltage stability issue of Hunan power grid with UHV-DC in 2017. This study identifies the transient voltage stability weakness in Hunan power grid and helps to optimize the location of dynamic reactive power compensator installation. The simulation shows it improves transient voltage stability in Hunan power grid noticeably.

Fault Tree Analysis (FTA) is widely applied to evaluating failure probability related to complex engineering system. A large number of minimal cut sets (MCSs) may be involved in FTA when dealing with complex system, and searching for these MCSs may be time-consuming. Modules of fault trees have been employed to reduce the computational burden relevant to basic operations of fault trees. Based on the Graph Theory to find In-degree and Out-degree of the tree, this paper proposes an improved method to find modules of a fault tree, and the complexity associated with the proposed method is linear when the number of nodes and edges in the fault tree increases, which can remarkably reduce the module searching time. Comparisons between the proposed method and available ones are given. An experiment shows that the proposed method is efficient.

The traditional tie-line generation schedule is entirely based on the electricity transaction, hence it is independent of the generation schedule of local unit, and couldn't be changed by the load. These cause difficulties in resource allocation and safe and stable operation of power grid. Thus, this paper builds three optimal dispatch modes that are suitable for different scenes, whose objective functions are the maximization of grid safety margin, target tie line's absorption capacity and local wind power's absorption capacity. Based on this, the warning strategy models which are aimed at the possible safety problem during tie line connecting to the grid are proposed. At last, a case study based on practical data of a certain power grid is given to show that the models and the methods in this paper are validity and applicability.

Electromechanical oscillations are the major stability limits which constrain the power transfer in the interconnected system and influence the transmission line capacity. Power System Stabilizer (PSS) and Flexible AC Transmission Systems (FACTS) devices can be deploy to overcome these oscillations. In this paper the focus has been made on the damping of the inter-area oscillations and Unified Power Flow Controller (UPFC) which has been chosen to be installed at the midpoint of the tie-line between Pakistan and Iran. The region has been experiencing extensive blackouts due to oscillation. A comprehensive analysis for the control of power transmission and damping of inter-area oscillations has been performed with UPFC and PSS based on a dynamic control scheme. The complete system has been simulated in the Matlab/Simulink Environment for different fault conditions. The results verify the potency of the suggested control strategy.

A novel control method for a doubly-fed induction generator (DFIG) equipped with an energy storage Device (ESD) to enhance its transient voltage support capacity during grid faults. Specifically, the ESD connected to the DC-link capacitor of the DFIG is controlled to regulate the transient DC-link voltage. This is actually equivalent to absorb the power imbalance between the captured wind power and the power delivered to the grid by the DFIG during the fault so that the DC-link voltage and the rotor current dynamics can be greatly improved. Moreover, the rotor speed and the pitch angle are also controlled to initiatively react to the low voltage transient, which includes increasing the rotor speed to store the unbalanced energy as kinetic energy and augmenting the pitch angle to decrease the captured wind power. Thus, due to less unbalanced power flowing into the rotor, the DFIG dynamics can be further ameliorated and the required ESD capacity can be obviously saved. As the grid side converter (GSC) can be free from managing the transient DC-link voltage, it is manipulated to devote its whole capacity to inject reactive power to the grid for voltage support during the fault. By simulating a single-machine-infinite-bus power system, comparisons with other control methods are conducted to prove that the novel proposed control method can well ensure the DFIG LVRT capability but save the ESD capacity, and also significantly improve the terminal voltage dynamics during the grid fault.

The research on the modeling method of wind power fluctuation probability density is of great importance for wind power integration and operation. In this paper a novel modeling method is proposed for the wind power fluctuation probability density based on nonparametric kernel density estimation. First, wavelet decomposition is used to extract the fluctuation components of wind power to build a model which is based on nonparametric kernel density estimation. This modelling process involves bandwidth optimization. Then we built a bandwidth optimization model constrained by goodness of fit test. Finally, constrained ordinal optimization is utilized to solve the model. Simulation results show that the model constructed by nonparametric kernel density estimation is determined by sample data, therefore this modelling method features with higher accuracy and more general applicability. In addition, an improved strategy, which is proposed in this paper for nonparametric kernel density estimation, also greatly improves the modeling accuracy and computational efficiency.

This paper proposes a coordinated voltage control of synchronous condensers using wide-area measurements. The control is able to determine a coordinated control scheme of synchronous condensers to maintain stable post-fault voltages. A voltage control model with synchronous condensers has been established using wide-area measurements. By applying Networked predictive control (NPC), the time delay of a wide-area measurement system (WAMS) is compensated, and then, the relation between predicted voltage deviations and a sequence of controls is derived. The solution to the voltage control problem is formulated as a quadratic programming (QP) over a finite horizon. Finally, the proposed coordinated voltage control scheme is obtained by repeated procedures involving prediction of voltage deviations, solution of the QP problem, and step-by-step feedback correction. The New England 39-Bus system is used to validate the effectiveness of the proposed scheme.

Terahertz time-domain spectroscopy (THz-TDS) combined with emphatic orthogonal signal correction (EOSC) and least squares support vector machine (LS-SVM) has been applied to establishing qualitative analysis model for identifying 41 official and unofficial rhubarb samples. The correction factors of the model have been determined by bootstrapped Latin-partitions. The spectra were pretreated by autoscaling and Savitzky - Golay smoothing (the window size is 5, the polynomial order is 3), and a comparison of two pretreatment methods for the classified accuracy was implemented. The results showed that the identification accuracy of 97.84±1.62% could be accomplished by using the pretreatment methods of autoscaling and EOSC, which is higher than the classified accuracy of 87.45 ± 3.03% by using Savitzky - Golay smoothing method. The proposed method was proved to be a convenient, non-polluting, accurate, and nondestructive approach for identifying rhubarb samples. The developed procedure can be easily implemented for controlling quality in rhubarb production.

Terahertz time-domain spectroscopy has been used to analyze the mixed samples of different mass ratio of L-Tyrosine and L-Phenylalanine. The total dipoles of theses mixtures are given by absorption line shape function. Moreover, the statistical method of principle components analysis is employed to spectral recognition of these samples.

In this paper we use terahertz spectroscopy to study the concentration dependence non-linear absorption behaviors of the influenza virus hemagglutinin (HA) protein and effects of HA protein interacting with the neutralization antibody in the solutions. The thickness of the hydration shell around the HA protein was determined based on two and three components model. The absorption coefficient was measured over the frequency range 0.1-1.5THz. The terahertz properties of HA was strongly affected by the presence of a specific antibody. Therefore terahertz spectroscopy may be useful for label-free influenza virus detection in the future.

For the complex problem of cascade hydropower system optimal scheduling, a novel grouping differential evolution algorithm (GDE) is proposed in this paper by hybridizing differential evolution (DE) and shuffled frog leaping (SFL). In the proposed algorithm, the population is periodically executes grouping and shuffling operations, and the individuals are updated according to differential evolution in each memplex. Finally, the algorithm is applied to a case of cascade hydropower system mid-long term optimal scheduling. The results show its feasible and more efficient then dynamic programming. Thus it can be provided as an effective alternative for solving the complex hydropower system optimization problems.

The unsolvable power flow problem is one of the basic issues in dispatching automation, which frequently appears in the process of grid mode planning and Optimal Power Flow (OPF) analysis. To deal with this problem, a practical adjustment method based on grid weak point is proposed in this paper. This method use “lower power injection” method to calculate a similar power flow solution which also the system maximum load level in unsolvable case. According this solution, the system weak point can be found by the index based on local system operation parameters and external equivalent system model. Combined with sensitivity analysis to reschedule the active power of generators and reactive power compensation devices, so as to make the system maximum load level increase, eventually get the system power flow solution at the original load level. This method overcome the large calculation of optimize algorithm in unsolvable power flow problem and can be applied to large practical grid. In the meantime, this method has clear physical interpretation, operator can be involved during the process, have great value in application. The method is tested on IEEE14 nods system.

In line with China's accession to the World Trade Organization (WTO), largely due to the encouragement and support by the Chinese government, the last decades have witnessed a dramatic growing trend of Chinese construction companies making significant inroads into the international market. A Diamond Model is developed in this technical note to analyze the factors that have significant impacts on the competitiveness of the Chinese International Construction Companies (CICCs) in the Global Market. Data was collected from multiple sources including literature survey, statistics and policy review. The results show that Diamond Model is an effective method for the CICCs' self-competitiveness-assessment, which has great potential to be applied to any international contractor's competitiveness study in the global market. Refereed/Peer-reviewed

It is critically important for improving the wide area situation awareness of the operators or operational engineers and regional reliability coordinators of a large interconnected systems to prevent large scale cascading system outages. This paper describes an advanced wide-area power system visualization application (WAPSVA) for the real-time reliability monitoring using real-time synchrophasor measurements and for the post event analysis using historical synchrophasor measurements related to the large system events. This paper also presents a very useful feature which will allow a large number of users to perform the near real-time event replay a few seconds after a new large event occurs in a large interconnected power system. This wide area power system visualization application can also show the location, magnitude and the related event message on the visualization display in real-time by integration with the on-line event triggering and location of disturbance applications. The main performance challenges of the visualization application include how to efficiently handle large volume of synchrophasor measurements and how to support large number of concurrent users for performing real-time reliability monitoring, near real-time event replay or post event analysis. This paper describes the technologies used in the WAPSVA application to meet the challenging performance requirements. The technologies include the memory residence object oriented database, event oriented database and Smart Client. The system architecture, the technical approaches and the solution algorithms used in this visualization application are described in detail. This visualization application has been integrated and tested using the simulated synchrophasor measurements and the real time synchrophasor measurements of Eastern Interconnections at the TVA Super Phasor Data Concentrator (SPDC). The performance of the initial testing is very encouraging and the test results are presented in this paper.

In China, a large number of electric power projects are under construction as a result of huge energy demand. There is an increasing need of risks identification and management during the development and construction process of power projects. This paper selects Donghua-a typical heat and power combined project in Northern China as a case study. Using expert investigation method, the preliminary project risks list is obtained and key risk factors are identified. A questionnaire survey was conducted to gather views from experts with experience in power plant construction practice, and then the comprehensive evaluation of project risks is concluded. To deal with the identified high degree risk factors, a batch of risks controlling and monitoring measures and strategies are proposed. The application of the measures is tested effectively to resist and control the project risks. The research results offer a valuable reference of practices that electric power projects involved parties need to master in order to control risks in Chinese market.

With information and measurement technology evolving rapidly within the electric power industry, wide-area measurement, monitoring and control (WAMC) is deemed to be the key technology to improve power system reliability. Guided by this vision, the North American SynchroPhasor Initiative (NASPI) is a nation-wide project that collaborate various resources to build the infrastructure of WAMC across North American. As part of NASPI, Tennessee Valley Authority (TVA) is developing super phasor data concentrator (SuperPDC) which is the infrastructure hosting different measurement resources and providing platform for numerous WAMC applications, both real-time and none real-time. This paper outlines the SuperPDC architecture and demonstrates some real-time and close to real-time applications, developed by TVA and Virginia Tech based on SupersPDC platform.

Frequency is one of the most important parameters for determining the performance of an electrical power system. To study and gain a better understanding of the power system dynamics, the concept of building a frequency monitoring network (FNET) was proposed in 2000 and now has been realized. The FNET system consists of many high dynamic precision frequency estimation devices, also known as frequency disturbance recorders (FDR). These FDRs can be used at any 110 V or 220 V wall outlet and transmit measured frequency data remotely via the Ethernet. There are currently more than 40 FDRs placed strategically in different locations within the United States to monitor the entire power network. This paper summarizes the implementation of several FDR design and discusses some of ongoing hardware developments conducted in FNET.

Taking advantages of proportional-integral-differential (PID) control in voltage regulation, and those of linear optimal control in dynamic stability, a new excitation control scheme based on fuzzy logic control is proposed. The method adjusts the weights of voltage regulation tunnel and auxiliary stabilizing tunnel on-line according to different operating conditions by a fuzzy controller, aiming to improve the performance of excitation controller by the coordination of voltage control and stability control. The requirements of excitation control in different circumstances are studied, and the fuzzy rules of the coordination are presented also. Numerical simulation results demonstrate the effectiveness and robustness of the proposed method.

This paper discusses the latest developments in wide-area frequency-based event location using FNET. FNET, meaning ldquoInternet based frequency monitoring networkrdquo, is a low cost and quickly deployable wide-area frequency measurement system with high dynamic accuracy. This project demonstrated the feasibility of using information from FNET to estimate the location of events in the electric grid. An on-line real time event detection tool using least squares methods was developed and tested on data from FNET. This paper outlines the methods used along with an examination of implementation feasibility.

It is very important to understand system dynamics during disturbances in order to improve control measures to ensure power system security and reliability. Power system disturbances are examined in this paper based on wide-area frequency data from a nation-wide frequency monitoring network (FNET). Frequency characteristics of events in three major North America power grids are investigated. Typical frequency patterns of generation loss and load drop events are analyzed for Eastern Interconnection system, Western Electricity Coordinating Council system, and Electric Reliability Council of Texas system. The recovery patterns following disturbances are also studied to evaluate control performances of the interconnections.

Disturbance location information in power system is critical information to power system operator. Fast and accurate event location estimation may help operators respond promptly to restore the system to a normal operating condition. With the help of the Internet based real-time, GPS synchronized, wide-area frequency monitoring network (FNET) , Virginia Tech has patented and implemented the event location estimation approach based on the previous study of the electromechanical wave propagation in power systems. This paper addresses the problem from another prospective-using the oscillations that occur during the frequency perturbation to improve the event location estimation. Generally, we found that the frequency measurements taken in close proximity to the event will have a more severe swing compared with measurements that are more distant from the event. This information can be used to improve the accuracy of the event location estimation.

System-wide frequency is one of most important vital signs of power system. To better understand the dynamics of large power systems, wide-area, synchronized monitoring of system frequency is needed. The concept of an Internet based, real-time, GPS synchronized, wide-area frequency monitoring network (FNET) was proposed in 2000. Today, FNET consists of more than 30 frequency disturbance recorders (FDRs) throughout the US with an information management system (IMS) based at Virginia Tech. In the near future, more FDRs will be deployed. With the help of FNET, a wide-area power system disturbance event filter has been developed. The filter helps pick out the disturbances from massive amounts of daily monitoring data and collect valuable information for the disturbance analysis.

Field-measured frequency data from a nationwide frequency monitoring network (FNET) are examined in this paper. Wavelet-based denoising signal processing technique is applied to filter out spikes and noises from measured frequency data. System's frequency statistics of three major U.S. power grids are investigated. Comparison between phasor measurement unit (PMU) and FNET data illustrates the close tracking between the two. Several generator trip events in the Eastern Interconnection System and the Western Electricity Coordinating Council system are recorded and the frequency patterns are analyzed. Sample results are shown for a 13 month period of time. In addition to transient states' observation, the quasi-steady-state, such as oscillation, can also be observed by FNET.

Frequency is an important parameter in the operation of power systems. Dynamic visualization provides a quick and direct way to view the state of the system. Tools are being developed to help to observe frequency behavior from both simulations and field real-time measurements. Frequency replay from simulation data provides some insights of how the frequency electromechanical waves propagate when major events occur. Several examples are given to show some characteristics of the wave propagation. Visualization from frequency disturbance recorder (FDR) measurement provides a real-time view of the system's status.

This paper reports an application of the k-out-of-n and the consecutive-k-out-of-n system reliability models in a petro-chemical company. The models are used to represent the relationship between the functioning of the furnace system and its tubes. The remaining life of the furnace system is estimated based on the remaining lives of the tubes. The models are also useful for decision making regarding the optimal furnace replacement time.