Impact of Heat Pump Load on Distribution Networks

© The Institution of Engineering and Technology 2014. Heat pumps can provide domestic heating at a cost that is competitive with oil heating in particular. If the electricity supply contains a significant amount of renewable generation, a move from fossil fuel heating to heat pumps can reduce greenhouse gas emissions. The inherent thermal storage of heat pump installations can also provide the electricity supplier with valuable flexibility. The increase in heat pump installations in the UK and Europe in the last few years poses a challenge for low-voltage networks, because of the use of induction motors to drive the pump compressors. The induction motor load tends to depress voltage, especially on starting. The study includes experimental results, dynamic load modelling, comparison of experimental results and simulation results for various levels of heat pump deployment. The simulations are based on a generic test network designed to capture the main characteristics of UK distribution system practice. The simulations employ DIgSlILENT Power Factory to facilitate dynamic simulations that focus on starting current, voltage variations, active power, reactive power and switching transients

Undiagnosed Phenylketonuria Can Exist Everywhere: Results From an International Survey

peer reviewedMany countries do not have a newborn screening (NBS) program, and immigrants from such countries are at risk for late diagnosis of phenylketonuria (PKU). In this international survey, 52 of 259 patients (20%) with late diagnosed PKU were immigrants, and 145 of the 259 (55%) were born before NBS or in a location without NBS. © 2021 The Author

Network fault response of wind power plants in distribution systems during reverse power flows. Part II

Abstract—The ability of wind power park modules to control their response to transmission network faults allows for specification of new control features directed at stabilising the power system response during and after disturbances. However, the ‘effectiveness’ of these features in situations where wind power park modules are connected to ‘weak’ systems needs further clarification. The objective of the paper is to study the response of wind power park modules in distribution systems to transmission network faults during reverse power flows. The focus lies on the ‘effectiveness’ of their fast voltage control. A sensitivity analysis is performed to understand the differences made by the pre-fault operating point, the wind power park module’s fault and post-fault control modes and their settings, and the load modelling. The results show that correct load modelling is very important, the post-fault transmission system voltage recovery is worsened during reverse power flows, and that reactive current injection significantly affects the post-fault voltage recovery. Certain grid connection requirements worsened voltage recovery or even caused instability for some control settings

Response of low voltage networks with high penetration of photovoltaic systems to transmission network faults

Abstract—The power system is traditionally composed of large centralized synchronous generators (SG) serving loads connected directly to the network. In recent years, the share of convertercoupled, small-scale distributed generation (DG) and new types of loads that are connected to the electrical network by power electronics increased significantly. While wind power used to be the dominant DG technology in Germany, the installed capacity of photovoltaic (PV) systems has reached the same magnitude as installed wind power capacity, i.e. around 32 GW at the end of 2012. About 80% of the PV capacity in Germany is connected to low voltage networks. Consequently, the response of low voltage networks with high penetration of PV systems to transmission network faults could influence the overall power system performance. While DG was required to disconnect in the past, when their share in total generation was still negligible, nowadays DG is to a large extent required to ride-through low voltages (LVRT capability). That does not hold for small-scale DG, and especially PV, connected to low voltage networks. Given the strong development of such PV, LVRT requirements for the LV network level become of increasing interest. However, specifications of such future requirements depend on the outcome of an in-depth analysis that considers both the power system needs and the technological implications for the DG. This article describes the scope and methodology of a new research project that aims at investigating the future robustness of current network fault requirements for LV connected DG and proposing (where necessary) revisions

Contribution of negative-sequence controlled distributed generation to power system stability under unbalanced faults : a discussion paper

The transformation of the power system in terms of efficiency and sustainability will further lead to increasing converter-coupled generation and demand. This changes the system's characteristics and influences its stability. Despite these fundamental changes, the secure operation of the power system must be maintained at all times. DG and any converter-coupled generation of relevant size are requested to stay connected to keep power equilibrium and to support the voltage during faults. The balanced fast voltage control currently applied for all types of faults could be improved by an unbalanced injection of short-circuit current among the three phases depending on the fault. A technical solution is an active control of the negative-sequence during unbalanced faults. However, introducing a general requirement, e.g. in grid codes, for this new feature must be well justified. This paper is intended to start a structured discussion of unbalanced fast voltage control by converter-coupled generation for unbalanced faults from a system perspective

Impact of fault ride-through and dynamic reactive power support of photovoltaic systems on short-term voltage stability

This paper investigates the impact of the Fault Ride-Through (FRT) capability and the dynamic reactive power support of large-scale PhotoVoltaic (PV) systems according to the newly proposed German Grid Code (GGC) on short-term voltage stability. The PV system is based on a generic model and realistic parameters are used that are determined in consultation with a manufacturer. In this context, improvements of the generic PV system model are stated. The GGC requirements are compared with several other control schemes for dynamic reactive power support, such as the adjusted control mode, i.e., the active and reactive current is calculated according to the grid impedance angle. The results show that the GGC requirements help the power system to avoid short-term voltage instability. Moreover, the requirements lead to an enhanced dynamic performance in terms of voltage support and recovery. Only the adjusted control mode shows a slightly better performance than the GGC. However, as this control scheme needs on-line information about the grid impedance angle, and therefore, additional infrastructure for the measurements, it is also more expensive. Hence, it can be concluded that the GGC requirements, with respect to FRT and dynamic reactive power support, are reasonable from a technical and economical point of view

A pesquisa participante na formação didático-pedagógica de professores de enfermagem La investigación participativa em la formación didáctico-pedagógica de professores de enfermería Participant-research in the didatic-pedagogical formation of faculty nurses

Neste relato a Pesquisa Participante é o referencial metodológico impulsionador para o trabalho coletivo empreendido por um grupo de enfermeiras-professoras da disciplina de Fundamentos de Enfermagem da Universidade Estadual de Londrina. Das discussões provenientes do processo participativo, que foram alicerçadas no referencial teórico da Pedagogia Histórico-Crítica, selecionou-se as concepções e práticas pedagógicas mais relevantes, através da apresentação e discussão das categorias Objetivos, Conteúdos, Metodologia e Avaliação. Concluiu-se que as reflexões produzidas no e com o grupo participante sobre os aspectos pedagógicos repercutiram na concepção e no fazer das docentes envolvidas e que o processo coletivo deve ser contínuo para o aperfeiçoamento pedagógico destes profissionais, agentes educativos preocupados com a formação de futuros enfermeiros críticos e transformadores da realidade.<br>En este relato la Investigación Participativa es la referencia metodológica impulsora para el trabajo colectivo emprendido por un grupo de enfermeras-profesoras de la asignatura de Fundamentos de Enfermería de la Universidad Estadual de Londrina. De las discusiones provenientes del proceso participativo, que se basaron en la referencia teórica de la Pedagogía Histórico-Crítica, se seleccionaron los conceptos y prácticas pedagógicas más importantes, a través de la presentación y discusión de las categorías Objetivos, Contenidos, Metodología y Evaluación, se llegó a concluir que las reflexiones producidas, en y con el grupo participante sobre los aspectos pedagógicos, repercutieron en la concepción y en el quehacer de las docentes comprometidas y que el proceso colectivo debe ser continuo para poder capacitar pedagógicamente estas profesionales, los agentes educacionales preocupados con la formación de futuros enfermeros críticos y transformadores de la realidad.<br>Through the participant-research framework, this collective study was carried out by a group of faculty nurses responsible for the course of Nursing Fundamentals at Londrina State University. Considering the discussion that emerged from the participative process and based on the Historical-Critical Pedagogy, the most relevant concepts and pedagogic practices were selected, through the presentation and discussion of the following categories: Goals, Contents, Methodology and Evaluation. Authors concluded that the reflections emerged by and with the group about pedagogic aspects effected the performance of the involved faculty as well as that the collective process must be continuous in order to support the pedagogic development of these professionals, who are educational agents concerned with the improvement of nurses' formation