The IEEE Standard C37.118.1 defines two performance classes, P and M, for phasor measurement units (PMUs), respectively for protection and monitoring oriented applications. The goal of this paper is to define an algorithm that allows the requirements of both classes to be met simultaneously, thus avoiding an a priori selection of either the fast response time of class P or the accuracy of the class M. The designed PMU consists of two digital channels that process in parallel the acquired samples with different algorithms: the first one allows accurate measurements of steady state signals, while the second one is better suited to follow the fast signal changes. Then, a detector identifies the possible presence of dynamic situations and selects the most appropriate output for the actual operating condition. The validation of the solution, performed by means of simulations in all the static and dynamic conditions defined in the standard, confirms that the method is able to comply with all the limits indicated for both classes for synchrophasor and frequency measurement. As for the rate of change of frequency, again the compliance to P-class is fully verified, while for the M-class the only exception is represented by the tests with out-of-band disturbances.

Effective monitoring and management applications on modern distribution networks (DNs) require a sound network model and the knowledge of line parameters. Network line impedances are used, among other things, for state estimation and protection relay setting. Phasor measurement units (PMUs) give synchronized voltage and current phasor measurements, referred to a common time reference (coordinated universal time). All synchrophasor measurements can thus be temporally aligned and coordinated across the network. This feature, along with high accuracy and reporting rates, could make PMUs useful for the evaluation of network parameters. However, instrument transformer behavior strongly affects the parameter estimation accuracy. In this paper, a new PMU-based iterative line parameter estimation algorithm for DNs, which includes in the estimation model systematic measurement errors, is presented. This method exploits the simultaneous measurements given by PMUs on different nodes and branches of the network. A complete analysis of uncertainty sources is also performed, allowing the evaluation of estimation uncertainty. Issues related to operating conditions, topology, and measurement uncertainty are thoroughly discussed and referenced to a realistic model of a DN to show how a full network estimator is possible.

Phasor measurement units (PMUs) are becoming one of the key issues of power network monitoring. They have to be able to perform accurate estimations of quantities of interest either under steady-state or transient conditions. Among all the sources which may contribute to the uncertainty introduced by PMUs, this paper analyzes the impact of the phasor estimation models on the accuracy of these devices, focuses on algorithms proposed in the literature for the estimation of dynamic phasors, and studies their performances under several different conditions.

This paper proposes a new distributed architecture to measure synchrophasors in power substations, inspired by the standards IEC 61850. The new scheme is implemented in the process bus, where a high performance merging unit (MU), synchronized by precision time protocol (PTP), according to the standard IEEE 1588-2008, sends the sampled values (SVs) to an intelligent electronic device (IED) enabled to behave as a phasor measurement unit (PMU). The synchrophasors are evaluated in the IED through an algorithm based on the Taylor Fourier Transform and suitably modified to have high performance also in terms of response time in presence of step change conditions. Different tests and considerations are presented to evaluate the various elements of uncertainty that a distributed architecture can introduce and, finally, to ensure the feasibility of the proposed approach.

Protection and measurement systems in electrical substations are required to have high availability. In an all-digital substation protection system, all the components (instrument transformers, processing units, merging units, intelligent electronic devices, communication network, and synchronization source) may affect the overall availability level. In this paper, a solution to enhance distributed PMU availability, during wired network failures, is presented. In the proposed scheme, the process bus has two parallel networks: 1) the classic wired Ethernet link and 2) a wireless link (implemented with industrial grade IEEE 802.11 devices), for sampled values packets, which carry measurement information. The time synchronization is carried out only through the wired Ethernet link, but the proposed solution is still able to compensate temporary failures of one of the communication links. Experimental tests have been performed to verify the performance of additional IEEE 802.11 link using different protocols and configurations. Communication parameters that can affect the PMU performance, like propagation latency, are characterized. It is shown that, if the measurement algorithm is opportunely designed, depending on the wireless link quality, it is possible to comply, with a single output, with M and P classes of the synchrophasor standard also during network restoration or, at least, to safeguard protection applications if higher latency occurs.

This paper proposes a modified version of the synchrophasor estimation algorithm which uses the non-orthogonal transform defined as a Taylor-Fourier Transform (TFT) and which is based on a Weighted Least Squares (WLS) approximation respect to a second order of Taylor model. The aim of the proposed changes is to improve the performance of the algorithm in presence of fast transient events. Several tests are presented, in different test conditions, to show the improvements achievable with the proposed method.