Integration of an IEEE Std. C37.118 compliant PMU into a real-time simulator

The simulation of Phasor Measurement Units (PMUs) into real-time simulators (RTSs) is typically limited by the complexity of the synchrophasor estimation (SE) algorithm. This is especially true when dealing with distribution network PMUs due to the more demanding accuracy requirement and, for the case of class-P PMUs, for the limited latency. In this respect, if the SE algorithm is too simplistic, the performances of the simulated PMU might not match the specific application needs. On the other hand, when higher precision of the synchrophasors estimations is required, an increased computational complexity of the SE algorithm is obtained and, as a consequence, few devices can be simulated into a RTSs at the same time. The work presented in this paper illustrates the design and the deployment of a C37.118 class-P compliant PMU into the Opal-RT RTS. The RTS-deployed PMU has demonstrated to match the requirements of both transmission and distribution networks. The simulated PMU has been experimentally validated and demonstrated to be well suited for its integration into any RTS

Design and Experimental Validation of an LTE-based Synchrophasor Network in a Medium Voltage Distribution Grid

We present and experimentally validate in a real-scale medium voltage (MV) grid a synchrophasor network that exploits the availability of a public 4G LTE communication infrastructure. An 18 buses, 10\,kV feeder located in Huissen, The Netherlands, has been equipped with 10 Phasor Measurement Units (PMUs) connected to the MV grid by means of dedicated voltage and current sensors. The PMUs stream synchrophasor data through a public 4G LTE network via an information-centric networking-based middleware, named C-DAX. The measurements are received and time-aligned at a phasor data concentrator and fed to a real-time state estimation application. The paper presents the various field-trial components and validates the feasibility of exploiting the 4G LTE technology for PMU-based applications. Specifically we assess the performance of the adopted wireless telecommunication infrastructure with and without the C-DAX middleware, as well as the accuracy of the real-time state estimation process

Architecture and Experimental Validation of a Low-Latency Phasor Data Concentrator

The paper presents the design principles of a Phasor Data Concentrator (PDC) that implements both the absolute and relative time data pushing logics together with a third one that aims at minimizing the latency introduced by the PDC without increasing the data incompleteness, as suggested in the IEEE Guide C37.244-2013. The performance of the aforementioned logics are assessed and compared in terms of reliability, determinism and reduction of the overall latency in two real Phasor Measurement Unit (PMU) installations adopting different telecom infrastructures. The first one is based on optical fiber links that transmit synchrophasor data measured by 15 PMUs installed in the sub-transmission network of the city of Lausanne, Switzerland. The second one adopts a 4G LTE wireless infrastructure to support the data streaming of 10 PMUs installed in a distribution network supplying the city of Huissen, in the Netherlands. The experimental results show that the proposed logic is characterized by the lowest latency, whereas the absolute time logic better mitigates the synchrophasor data latency variations

Probabilistic assessment of the process-noise covariance matrix of discrete Kalman filter state estimation of active distribution networks

The accuracy of state estimators using the Kalman Filter (KF) is largely influenced by the measurement and the process noise covariance matrices. The former can be directly inferred from the available measurement devices whilst the latter needs to be assessed, as a function of the process model, in order to maximize the KF performances. In this paper we present different approaches that allow assessing the optimal values of the elements composing the process noise covariance matrix within the context of the State Estimation (SE) of Active Distribution Networks (ADNs). In particular, the paper considers a linear SE process based on the availability of synchrophasors measurements. The assessment of the process noise covariance matrix, related to a process model represented by the ARIMA [0,1,0] one, is based either on the knowledge of the probabilistic behavior of nodal network injections/absorptions or on the a-posteriori knowledge of the estimated states and their accuracies. Numerical simulations demonstrating the improvements of the KF-SE accuracy achieved by using the calculated matrix Q are included in the paper. A comparison with the Weighted Least Squares (WLS) method is also given for validation purposes

Emprego e acidentes de trabalho na indústria frigorífica em áreas de expansão do agronegócio, Mato Grosso, Brasil

Historically, workers' health problems have been increasing as the economy grows and the productive processes diversify. In the last three decades, the agribusiness has been expanding in the State of Mato Grosso (central region of Brazil). In this State, the intensification of the activities of the cattle sector meant the installation of the slaughterhouse industry, an increase in formal employment and also in the number of occupational accidents. This study aimed to characterize the occupational accidents in slaughterhouses located in the State of Mato Grosso in the period from 2000 to 2005, in light of the labor market and of manpower insertion. It used occupational accidents indicators provided by the Occupational Accident Reports of the Social Security Ministry, by RAIS (Annual Relation of Social Information), by the Ministry of Labor and Employment, and by PNAD (National Survey through Household Sample), conducted by IBGE (Brazilian Institute of Geography and Statistics). The results of the study point to the growth of jobs with expressive rotation, to a decrease in the admission salary (from 2.2 to 2.0 minimum salaries) and to the fact that the majority of workers have low schooling. The slaughtering sector occupied the second position in statistics of work-related diseases and accidents registered in the State. The incidence rate of occupational accidents increased from 41.2 to 46.5 per one thousand workers, with the highest incidence in the age group 18 - 24 years (49.8 accidents/one thousand workers), reaching mainly the employees working in the main steps of the productive process. The results suggest signs of precarious employment and work conditions in the slaughterhouse activities and insufficiency of the State's vigilance/inspection in the sector, as well as low investments from the employers into workers' health and safety.Os agravos à saúde do trabalhador vêm, historicamente, acompanhando o crescimento econômico e a diversificação dos processos produtivos. O agronegócio expandiu-se nas últimas três décadas no estado de Mato Grosso e nele a intensificação das atividades do setor pecuário traduziu-se na instalação de frigoríficos, aumento de empregos formais e acidentes de trabalho. Este estudo propôs-se a caracterizar os acidentes de trabalho em indústrias frigoríficas do estado de Mato Grosso no período de 2000 a 2005, contextualizando-os com o mercado de trabalho e a inserção da mão de obra, através da utilização dos indicadores de acidentes de trabalho oriundos das Comunicações de Acidentes do Trabalho do Ministério da Previdência Social, dados da RAIS, do Ministério do Trabalho e Emprego, e da PNAD, do IBGE. Os resultados apontaram para o crescimento de postos de trabalho com expressiva rotatividade, diminuição do salário de admissão (de 2,2 para 2,0 salários mínimos) e a maioria da mão de obra com baixa escolaridade. O setor frigorífico ocupou a segunda posição na estatística de doenças e acidentes de trabalho registrados no estado, cuja taxa de incidência cresceu de 41,2 para 46,5 acidentes de trabalho por mil trabalhadores, com maior incidência na faixa etária dos 18 aos 24 anos (49,8 acidentes/mil trabalhadores), atingindo principalmente os trabalhadores ocupados nas principais etapas do processo produtivo. Os resultados sugerem indícios de precarização do emprego e condições de trabalho na atividade frigorífica e insuficiência da ação de vigilância/fiscalização estatal no setor, bem como baixos investimentos dos empresários na saúde e segurança do trabalho

Definition and assessment of reference values for PMU calibration in static and transient conditions

The calibration of Phasor Measurement Units (PMUs) consists of comparing Coordinated Universal Time (UTC) time-stamped phasors (synchrophasors) estimated by the PMU under test, against reference synchrophasors generated through a PMU calibrator. The IEEE Standard C37.118-2011 and its amendment (IEEE Std) describe compliance tests for static and dynamic conditions, and indicate the relative limits in terms of accuracy. In this context, the paper focuses on the definition and accuracy assessment of the reference synchrophasors in the test conditions dictated by the above IEEE Std. In the first part of the paper, we describe the characterization of a nonlinear least-squares (NL-LSQ) fitting algorithm used to determine the parameters of the reference synchrophasors. We analyse the uniqueness and robustness of the solution provided by the algorithm. We assess its accuracy within the whole range of static tests required by the IEEE Std. In the second part, we discuss the appropriateness of synchrophasor model to evaluate the PMU performance in step test conditions. We compare the proposed algorithm against two synchrophasor estimation algorithms. Finally, we propose a time domain process for the better evaluation of PMU performances in transient conditions

A Hardware-in-the-Loop test platform for the performance assessment of a PMU-based Real-Time State Estimator for Active Distribution Networks

The paper describes the development of a Hardware- in-the-Loop (HIL) test platform for the performance assessment of a PMU-based sub-second linear Real-Time State Estimator (RTSE) for Active Distribution Networks (ADNs). The estimator relies on the availability of data coming from Phasor Measurement Units (PMUs) and can be applied to both balanced and unbalanced ADNs. The paper first illustrates the architecture of the experimental HIL setup that has been fully designed by the Authors. It consists of a Real-Time Simulator (RTS) that models the electrical network model as well as the measurement infrastructure composed by virtual PMUs. These virtual devices stream their data to a real Phasor Data Concentrator (PDC) suitably coupled with a Discrete Kalman Filter State Estimator (DKF-SE). By using this experimental setup, the paper discusses the performance assessment of the whole process in terms of estimation accuracy and time latencies. In the RTS, a real ADN located in the Netherlands has been modeled together with the associated PMUs

Fault Detection and Faulted Line Identification in Active Distribution Networks Using Synchrophasors-based Real-Time State Estimation

We intend to prove that PMU-based state estimation processes for active distribution networks exhibit unique time determinism and refresh rate that make them suitable to satisfy the time-critical requirements of protections as well as the accuracy requirements dictated by faulted line identification. In this respect, we propose a real-time fault detection and faulted line identification functionality obtained by computing parallel synchrophasor-based state estimators. Each state estimator is characterized by a different and augmented topology in order to include a floating fault bus. The selection of the state estimator providing the correct solution is done by a metric that computes the sum of the weighted measurement residuals. The proposed process scheme is validated by means of a real-time simulation platform in which an existing active distribution network is simulated together with a PMU-based monitoring system. The proposed process is shown to be suitable for active and passive networks, with solid-earthed and unearthed neutral, for low and high impedance faults of any kind (symmetric and asymmetric) occurring at different locations