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The evolving complexity of distribution networks with higher levels of uncertainties is a new challenge faced by system operators. This paper introduces the use of Gaussian mixtures models as input variables in stochastic power flow studies and state estimation of distribution networks. These studies are relevant for the efficient exploitation of renewable energy sources and the secure operation of network assets.

This paper presents a centralized voltage control scheme that uses pseudo-measurements to estimate lost voltage measurements. The controller automatically selects the bus voltages which best approximate the lost one according to dissimilarity indices computed from the system's voltage sensitivity matrix. Several computer simulations were carried out to test the performance of the controller subject to the loss of single and multiple measurements in a radial distribution network with dispersed generation. For single losses, the proposed approximation resulted in better performance of the controller as compared to simply considering the measurement unavailable. For multiple lost measurements, proper selection of association limits allowed for acceptable estimations and successful controller performance.

This paper presents a tool to automatically generate distribution network models for the power engineering software OpenDSS. The tool was developed in a free and open source Geographical Information System (GIS) software that allows a direct translation of GIS to OpenDSS files. The paper shows the potential of the developed piece of software and how it can help power engineers to carry out detailed studies of medium and low voltage networks. It also explains data requirements in the GIS database and all the steps followed to create the OpenDSS files. In order to demonstrate the capabilities of the model builder, the paper presents the translation of a real distribution circuit GIS model to OpenDSS.

This paper presents a novel method based on the Unscented Kalman Filter (UKF) to estimate the saturated parameters of synchronous machines. The proposed methodology uses voltage and current measurements taken from the stator and the field windings to update the parameters of the synchronous machine during steady state operation. The method also utilizes measurements of the power angle in order to relate the measurements (in abc components) with the voltage equations in the qd0 reference frame. The proposed methodology has been tested and validated for a saturated synchronous machine.

This paper reports a database of power delivery element model parameters required in specialized distribution network software packages. Based on the authors' experience, these parameters are seldom available or recorded by power utilities so that typical values must be used when modeling these elements. Due to space limitations, the parameters listed in this paper correspond to conductors, cables and distribution transformers mainly used in Costa Rica. To compensate this, an additional reference is presented to consider other power delivery elements and materials not included here.

A case study dealing with long-term voltage instability in systems hosting active distribution networks (DN) is reported in this paper. It anticipates future situations with high penetration of dispersed generation (DG), where the latter are used to keep distribution voltages within desired limits, in complement to load tap changers. The interactions between transmission and active DN are investigated on a 3108-bus test system. It involves transmission grid, large generators, and 40 DN, each with DG steered by a controller inspired by model predictive control. The reported simulations show the impact of distribution network voltage restoration, as well as the benefit of load voltage reduction actuated by the dispersed generators.

In this paper, we review the emerging challenges and research opportunities for voltage control in smart grids. For transmission grids, the voltage control for accommodating wind and solar power, fault-induced delayed voltage recovery, and measurement-based Thevenin equivalent for voltage stability analysis are reviewed. For distribution grids, the impact of high penetration of distributed energy resources is analyzed, typical control strategies are reviewed, and the challenges for local inverter Volt–Var control is discussed. In addition, the motivation, state-of-the-art, and future directions of the coordination of transmission system operators (TSO) and distribution system operators (DSO) are also thoroughly discussed.

This paper addresses the power system state estimation problem considering the correlations among instrument transformer signals. The correlations among processed measurements are estimated using the Unscented Transformation given the correlation and basic statistical information of internal measurements. In addition, the paper analyzes the impact of these correlations on the estimated states using the IEEE 118-bus test system under various operating conditions and measurement configurations.

Wide-area monitoring, protection, and control (WAMPAC) involves the use of system-wide information and the communication of selected local information to a remote location to counteract the propagation of large disturbances. Synchronized measurement technology (SMT) is an important element and enabler of WAMPAC. It is expected that WAMPAC systems will in the future reduce the number of catastrophic blackouts and generally improve the reliability and security of energy production, transmission, and distribution, particularly in power networks with a high level of operational uncertainties. In this paper, the technological and application issues are addressed. Several key monitoring, protection, and control applications are described and discussed. A strategy for developing a WAMPAC system in the United Kingdom is given as well.