Low-voltage Power Grid Research Articles

Power Line Communications for Low-Voltage Power Grid Tomography

Power line communications (PLC) has attracted considerable attention for supporting smart grid applications. Since it reuses the existing grid infrastructure, it offers cost advantages over alternative communications methods and gives electric utilities control over the communications medium. Furthermore, the through-the-grid property of PLC extends its possible use beyond mere communications. Since the PLC signals are bound to travel through the power grid, they can also be used for inference tasks, such as online diagnostics of power line integrity. In this paper, we consider such an inference application of PLC, enabled by modern signal processing. We assume a power grid at whose edges PLC devices are deployed to form a PLC network for purposes such as advanced meter reading. We are interested in retrieving the physical power-grid topology, i.e., the connections and lengths of power lines reaching to the locations of the PLC devices. To this end, we propose the combination of PLC-based ranging with inference based on end-to-end measurements. In the context of communication networks, the latter is known as tomography and hence, we refer to the developed method as power grid tomography. For the purpose of ranging we formulate a new super-resolution ranging algorithm specifically tailored for signal propagation through power lines. Numerical results for low-voltage distribution grid examples demonstrate the successful reconstruction of the grid topology by the proposed power grid tomography method.

Network constraints in techno-economic energy system models: towards more accurate modeling of power flows in long-term energy system models

Power systems are subject to extensive structural changes as a result of the fact that the share of renewable energies in power supply will increase significantly within the next decades. This requires the transport of large amounts of electricity, e.g. from the North Sea to the large load centres. Moreover, the decentralized installations for the generation of electricity (e.g. PV) need to be integrated in the lower voltage power grids without violating net-safety constraints. As a consequence, the grid load in the system will rise to an extent that is hardly manageable with existing power grid capacities. Therefore, while mostly neglected to date, the importance of considering the power grid in energy system models increases significantly. Within this paper, different examples will be given how network constraints can be considered in techno-economic energy system models with a focus on capacity expansion planning and a long-term time horizon. Firstly, a multi-period linear optimization model will be presented, which comprises the system equations for power generation and transmission. The latter is analyzed with the help of a DC power flow model. Secondly, the usage of an AC power flow modeling tool for a detailed representation of the medium and low voltage power grid will be described. Finally, we will present an illustrative example application of a new mathematical approach for grid modeling in techno-economic energy system models.

Research on OPPC Application in Low Voltage Circuit of Liaoning Power Grid

As a new kind of optical cable with high energy efficiency, low cost and high reliability, optical phase conductor (OPPC) cable has received widely concern in the industry area. In this paper, we consider the practical experience from the projects and take 10kV and 66kV circuit as examples. We analyze and discuss the important and difficult issues and problems of OPPC cable in design, construction and operation based on the requirement and circumstance of low voltage power grid communication network. After that, we provide a feasible and effective solution for low voltage grid of fiber optic coverage.

The Filtering Device under Improved Direct Current Control

This paper mainly describes the mechanism and elimination method of harmonic in low-voltage power grid. Improve direct current control method in the traditional filter method,filtering the harmonic and timely compensating reactive power in the grid. On this condition, it can make the power grid safe and stability. At the same time simulate the improved direct current control method, and the results verify the correctness and rationality of the control method.

Feasibility Analysis of Tripping in Small Current Grounding System

With the development of integrated automation systems and distribution automation technology, considering the safety of grid equipment, the voltage security of low-voltage power grid, personal safety and the characteristics of small current grounding system , this paper points out that still follow the old rules that run 0.5-2 hours allowed in dealing with ground fault of small current grounding system is unreasonable, elaborates the new philosophy that the protection function of small current grounding should be distributed to the feeder protection device and implemented tripping. Theoretical analysis shows that the scheme is accurate, reliable, and highly practical.

Towards Decentralization: A Topological Investigation of the Medium and Low Voltage Grids

The traditional power grid has been designed in a hierarchical fashion, with energy pushed from the large scale production factories towards the end users. With the increasing availability of micro and medium scale generating facilities, the situation is changing. Many end users can now produce energy and share it over the power grid. Of course, end users need incentives to do so and want to act in an open decentralized energy market. In the present work, we offer a novel analysis of the medium and low voltage power grids of the North Netherlands using statistical tools from the complex network analysis field. We use a weighted model based on actual grid data and propose a set of statistical measures to evaluate the adequacy of the current infrastructure for a decentralized energy market. Further, we use the insight gained by the analysis to propose parameters that tie the statistical topological measures to economic factors that influence the attractiveness of participating in such decentralized energy market, thus identifying the important topological parameters to work on to facilitate such open decentralized markets.

Learning Rate Updating Methods Applied to Adaptive Fuzzy Equalizers for Broadband Power Line Communications

This paper introduces adaptive fuzzy equalizers with variable step size for broadband power line (PL) communications. Based on delta-bar-delta and local Lipschitz estimation updating rules, feedforward, and decision feedback approaches, we propose singleton and nonsingleton fuzzy equalizers with variable step size to cope with the intersymbol interference (ISI) effects of PL channels and the hardness of the impulse noises generated by appliances and nonlinear loads connected to low-voltage power grids. The computed results show that the convergence rates of the proposed equalizers are higher than the ones attained by the traditional adaptive fuzzy equalizers introduced by J. M. Mendel and his students. Additionally, some interesting BER curves reveal that the proposed techniques are efficient for mitigating the above-mentioned impairments.

A Modular Approach to Distributed Control Implementations

Abstract The implementation of two distinct low-cost distribuited control schemes is discussed. Intended for projects on the fields of industrial automation and energy management, both systems were developed using a modular system conceived and executed previously. This modular system was designed for stand-alone control applications. The text discusses how additional hardware and software have been designed in order to allow its utilization as the standard outstation on the distribuited environments implemented. The physical connections differ substantially from each other. One is a twisted pair where high data rates are possible. The second is the low-voltage power grid, where a power-line carrier technique is used to code information by means of FSK, where comparatively low data rates are imposed. The software enveloped to support communications through the network is designed in such way as to provide the user with similar facilities in both implementations.