A Software-based Low-Jitter Servo Clock for Inexpensive Phasor Measurement Units

This paper presents the design and the implementation of a servo-clock (SC) for low-cost Phasor Measurement Units (PMUs). The SC relies on a classic Proportional Integral (PI) controller, which has been properly tuned to minimize the synchronization error due to the local oscillator triggering the on-board timer. The SC has been implemented into a PMU prototype developed within the OpenPMU project using a BeagleBone Black (BBB) board. The distinctive feature of the proposed solution is its ability to track an input Pulse-Per-Second (PPS) reference with good long-term stability and with no need for specific on-board synchronization circuitry. Indeed, the SC implementation relies only on one co-processor for real-time application and requires just an input PPS signal that could be distributed from a single substation clock

Design and implementation of a low-cost phasor measurement unit: a comprehensive review

The complexity of the contemporary electrical power systems imposes challenges in aspect of monitoring, protection and control. In order to obtain high speed of response, wide area effect and prices synchronization, the grid control functions can be benefited by the implementation of Phasor Measurement Units (PMU). The paper is aimed to make a review of the commercial implementation of Phasor Measurement Units and then open source based implementations (open architecture hardware and software). This paper focuses on standard implementations; as a consequence the concept of virtual PMU is not discussed here

Development and implementation of an open-box distribution-level phasor measurement unit

Phasor measurement units (PMUs) are considered one of the most important measuring devices in power systems. PMUs are most commonly installed in substations, monitoring three-phase power. They provide synchronized measurements from any location where devices are installed. This synchronization is due to the micro-second Global Positioning System (GPS) time accuracy and is necessary for data to have meaning when compared across different locations. Among other purposes, data is used for post-mortem event analysis and system model validation. This thesis aims to provide a deep understanding of the PMU’s inner workings. Academia must know the inner workings of these devices in order to advance synchrophasor research and ensure standard compliance, as some devices do not fully comply with the existing IEEE (Institute of Electrical and Electronics Engineers) synchrophasor standards. Furthermore, it is difficult, if not impossible, to understand the causes of bad synchrophasor data since the software implementation of these devices is a mystery; although produced synchrophasors are all the same, as dictated by standards, the way these are calculated is undefined and varies depending on the PMU’s manufacturer. The chapters of this thesis explore the steps, challenges, and reasoning involved in the development of an open-box, distribution-level phasor measurement unit as well as the results obtained by deploying a network of these devices across the Urbana-Champaign distribution system.

Estudo de aplicação do conceito de OpenPMU para o desenvolvimento de PMU de baixo custo: módulo de aquisição de dados

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Engenharia Elétrica.Baseando-se nos desenvolvimentos tecnológicos das ultimas décadas e na desverticalização dos sistemas de energia elétrica, faz-se presente a necessidade de instrumentos capazes de garantir a segurança desses sistemas. Como a tecnologia dos sistemas de medição fasorial sincronizada é possível o monitoramento da dinâmica dos sistemas de energia elétrica a partir de dados adquiridos via unidades de medição fasorial. Dentre as iniciativas no Brasil para o fomento da tecnologia de medição de sincrofasores, destaca-se o Projeto Medfasee. Para a expansão do Projeto Medfasee, faz-se de interesse pesquisar a viabilidade do desenvolvimento de unidades de medição de baixo custo com o fim de aplicação em nível de baixa tensão. Neste contexto, o objetivo deste trabalho é apresentar conceitos do projeto OpenPMU, projeto este que visa o desenvolvimento de uma unidade de medição de código aberto utilizando componentes de relativo baixo custo. Neste trabalho, apresentam-se os componentes e módulos constituintes do projeto OpenPMU e desenvolve-se um diagrama de conexões físicas entre componentes para a implementação do primeiro módulo do projeto. Ademais, realiza-se um levantamento de custos relacionados a essa implementação.Based on the technological developments of the last decades and the unbundling of electric power systems, the need for instruments capable of guaranteeing the safety of these systems is present. As the technology of synchronized phasor measurement systems, it is possible to monitor the dynamics of electric power systems from data acquired through phasor measurement units. Among the initiatives in Brazil to promote synchrophasor measurement technology, the Medfasee Project stands out. For the expansion of the Medfasee Project, it is interesting to investigate the feasibility of developing low-cost measurement units for low voltage application. In this context, the objective of this work is to present concepts of the OpenPMU project, which aims to develop an open source measurement unit using relatively low cost components. This paper presents the constituent components and modules of the OpenPMU project and develops a diagram of physical connections between components for the implementation of the first module’s project. Furthermore, a survey of costs related to this implementation is carried out

Impact of prominent synchrophasor estimation algorithms on power system stability assessment

The electricity network is a critical infrastructure and its reliability is of paramount importance for the functionality of many critical systems in the modern society. Power system stability is one of the imperative aspects that impacts the reliability of electrical networks, hence power system stability needs to be observed in real-time for secure and reliable operation of the power grids. Conventionally, supervisory control and data acquisition (SCADA) based wide-area monitoring systems (WAMS) have been used for this purpose, however, they are predominantly designed to detect static changes in steady-state stability. In contrast, modern wide-area power networks pose significant challenges such as presence of power electronic switching loads and inductive motor loads, asynchronous distributed generation and dynamic fluctuations in demand and supply. Synchrophasor based WAMS is the next generation WAMS technology and offers great advantages over traditional SCADA systems such as precise time synchronisation, universally accepted standardisation and extremely fast and robust phasor estimation. A strategically placed network of phasor measurement units (PMUs) enables full visibility of the entire power network. Time synchronised PMU data can then be transferred to a phasor data centre (PDC) using efficient communication algorithms where multi facet analysis, including realtime stability assessment, could be performed. Despite significant benefits of the synchrophasor technology, several factors have hindered the widespread adoption ofthe synchrophasor technology. This research addresses such contemporary issues. The first phase of this research details an empirical study of existing synchrophasor estimation algorithms (SEAs) and considers the need for a benchmark in terms of robustness. Synchrophasor research is heavily populated with studies presenting diverse SEAs. Interestingly, not many studies have attempted to develop a robust SEA based on the mathematical technique proposed in the original Institute of Electrical and Electronics Engineers (IEEE) standardisation (i.e. IEEE std. C37.118.1-2011), the quadrature demodulation (QD) technique. Therefore, a verifiable benchmark algorithm is not currently available. This research presents comprehensive synchrophasor estimation models developed based on the QD technique and is then presented as the benchmark SEA. Proposed models are tested against all compliance requirements stipulated in the latest IEEE standardisation. Furthermore, a detailed comparison of prominent synchrophasor models is conducted against the proposed benchmark models, to understand the impact of the SEAs on the overall phasor estimation. Results establish a clear link between the accuracy/latency of the phasor estimation and the accompanying synchrophasor algorithm. The second phase of this research involves testing and comparison of synchrophasor models on hardware platforms. Even though development of SEA has been a prominent research area, only a few of these studies have been verified and validated with field tested results. This is a significant barrier to the advent of improved SEAs beyond academic literature, especially in industrial applications. A laboratory scale, hardware based synchrophasor test platform is proposed where any synchrophasor algorithm can be tested for any test condition or fault signal. Key highlights of this section include; global position system (GPS) time synchronisation of synchrophasors and a sinusoidal pulse width modulation (SPWM) technique based scalable input system capable of generating measurement conditions emulating any fault condition. Results establish the superiority of the proposed benchmark algorithm and identify key implementation issues in hardware implementation of some of the prominent synchrophasor models. The final phase of this research develops a synchrophasor based WAMS by using a bottom-up approach to evaluate real-time stability of wide-area networks under practical power network fault conditions. As part of this research the analyses and the impact of SEAs on the overall stability assessment has been evaluated. Development and testing of PMUs, and stability studies are historically conducted in two disjointed silos. As a result, stability analysis is often conducted based on the assumption that the PMU data delivered to the PDC are accurate and instantaneous. On the other hand, SEAs are tested against the compliance criteria listed in the IEEE standardisation which do not involve any practical power network faults. This study attempts to dive into this unexplored territory. Performance in realtime voltage and frequency stability of prominent SEAs is evaluated by employing a strategically placed PMU network on two standard power networks simulation models. The IEEE 9-bus system and New England 39-bus system are considered and consists synchronous generation sources, dynamic load centres and transmission links. By modelling practical transient fault conditions such as short circuit faults, loss of generation and addition of load centres, the real-time voltage and frequency stability have been studied. A modified highest Lyapunov exponent (HLE) based real-time stability assessment algorithm (RSAA) is proposed to suit implementation in practical power networks. Despite the full compliance against the IEEE standardisation, tested algorithms produce significantly different outcomes in the stability assessment that may directly impact on the subsequent activation of protection systems and overall network stability. Results of this study point to interesting findings and establishes a clear link between the reliability and the performance of the underlining SEA. In conclusion, key findings of this research contribute to two prominent areas within the synchrophasor research; SEA development and testing, and real-time stability assessment. This research has established a strong link between these disjointed research fields, thereby enabling future advancements synchrophasor based stability monitoring and control systems

Development and Hardware Implementation of a Phasor Measurement Unit using Microcontroller

As the world continues to move towards a Smarter Grid day by day, it has become the necessity to incorporate real-time monitoring of the grid wherein the instantaneous snapshot of the health of the grid can be made available. No other parameters than the Instantaneous Phasors, considered to be the heart-beats of the Electrical Grid, can represent the complete health status of the grid. This paper discusses how an Open Hardware Platform (Arduino Due with ARM Cortex M3 Micro-controller) can be used to estimate the phasors of a three phase system in real-time. The Pulse Per Second(PPS) signal from a GPS module is used to generate the sampling pulses. These pulses synchronise the sampling process by the Analog to Digital Converters(ADC), used by the PMU throughout the globe because of the high accuracy of the atomic clocks in the GPS satellites. The microcontroller uses a 64-Point DFT algorithm to estimate the phasors. The reference time is obtained from the GPS module which is the UTC time, with which the phasors are time stamped and displayed in a real-time Graphical User Interface(GUI) designed using Python(another open source programming language