Local Electrical Network Research Articles

Providing of electromagnetic compatibility in local electric networks

Main aspects of developing the principles of construction and technical solutions of the power part of parametric and regulated filter devices as well as hybrid filter-compensating converters on their basis, that made to provide electromagnetic compatibility and improve the power quality in local power supply systems (LPSS) with artificial neutral, are considered. The proposed three-phase networks with artificial zero points can be effectively applied for the creation of LPSS with a branch separated from the main network for the flow of currents of the zero sequence of the main and higher frequencies. It allows to comprehensively improve the quality of voltage on the clamps of critical loads, to ensure their electromagnetic compatibility and electrical safety, as well as to increase the reliability of electrical supply of electrical installations LSEP in fulfilling the requirements of standards with EMC and PUE. The original principles of construction and features of execution of power circuits of multifunctional devices for providing of electromagnetic compatibility and complex improvement of voltage quality in the composition of local networks are considered. It is shown that their main component is unregulated and regulated filtering devices based on a three-phase volt-adding autotransformer, which is executed as counter-zigzag on the three-phase core. Recommendations were given regarding to their practical use of the developed parametric and regulated filter devices, as well as local power supply sections on their basis in low voltage distribution networks with nonbalanced, nonlinear and variable loads to match the values of electricity quality parameters to the norms defined by the applicable standards DSTU EN 50160:2014 and GOST 13109-97

Adaptive system model of stabilization of the power factor of actuators of centrifuges for uranium enrichment with structural dynamic model of electric drive with parallel reactive power compensation

Presents an engineering model of adaptive system of automatic stabilization of the power factor Cos φ = 1 as the condition of resonance at the frequency of power supply with parallel compensation of reactive power of electric drive of centrifuges battery of capacitors. The resonance in the power circuit corresponds to an extremum (minimum) of total current was taken as the goal of the algorithm automatic search. The operation of the adaptive control system in conjunction with a structural dynamic model of the object of optimization is presented modeling in terms of a Simulink (MATLAB). It is shown that in the process of automatic stabilization Cos φ = 1 excluded “overcompensation” in the local electric power network, including when disconnect blocs of the centrifuges. The adaptive control system is insensitive to additive errors of the sensor current I, can be realized general technical means and applied in general power networks.

Real live demonstration of MPC for a power-to-gas plant

This paper presents the results – and the way towards them – for a field trial of a 120 kWel PEM electrolyser located within the city boundaries of Freiburg, Germany. The plant is equipped with on-site hydrogen storage and connected to the local gas and electricity network. Restrictions in gas feed-in and allowed peak electricity demand apply, and limit operation of the unit. Model predictive controls have been identified in simulations as a promising control strategy for such a case. However to move from simulation into practice few things, presented in this work, should be considered.A linear model predictive controller is successfully used in a field trial to optimise the operation of the power-to-gas unit in the presence of network restrictions and time varying electric prices. The impact of imperfect forecasts as well as deviations between the optimisation model and the real unit on controller performance are discussed. In the final part of the paper the lessons learned, improvements and potential solutions for integrating power-to-gas units into urban energy systems are presented. Additionally a modular controller design framework is introduced, which allows a rapid control development by interchanging historic time-series data with real-time values and simulation models with real components. In a separate testing sequence the power-to-gas unit is characterised regarding its dynamic properties, showing its potential for fast response, but also limitations in ramp-rates, tracking accuracy and losses due to warm stand-by.

An equitable and efficient energy management approach for a cluster of interconnected price responsive demands

Equitable and efficient allocation is one of the basic principles in all energy management systems. Classic allocation methods tend to maximize the customers’ total surplus to achieve the maximum possible efficiency. From the perspective of equity, there are some elements of ambiguity in this approach. In this paper, a new approach is proposed to allocate consumed energy to the customers aimed at holding equity, while achieving maximum possible efficiency is taken into account. For this purpose, the energy consumption allocation is studied for a cluster of interconnected price-responsive demands (i.e., a group of loads, such as an industrial compound, which are interconnected to each other in a geographical area and also to the main network via a local electrical network). A centralized energy management for a cluster of members is a cooperative game. In this paper, the equilibria of the cooperative game are determined by solving a multi-objective optimization problem, constrained to the constraints of the local electrical network operation and also the demands constraints. The solution of this optimization problem results in a Pareto front of which each point represents an equilibrium of the cooperative game. Then, an equilibrium is selected based on the proposed equitable allocation. The nature of the proposed model is a bi-level optimization problem. In the first level, the optimization problem of selecting an equilibrium is formulated. In the second level, a multi-objective optimization problem is modeled to calculate all equilibria of the cooperative game. Accordingly, the energy consumed by demands is allocated through the proposed centralized energy management system which is established based on equity and efficiency. The results obtained from a test system show the advantages of the model in performing energy management for a cluster of price-responsive demands.

Stand Alone PV House Design for Maximum Power Output in Sydney Australia Metropolitan Area

Nowadays, a strong link exists between human comfort and electrical power. Abundant doings are not possible without the support of the electrical energy. Driven by the human obligation to save the environment, the installation of PV solar system increased dramatically in the past numerous years. The installation can be grid connected or standalone system. These micro-grid situations are installed world-wide and currently are contributing to the local electrical network. To maximize the use of the generated solar system, numerous system installed energy storage in the form of batteries. These energy storages harvest the sun power during daylight to support the household electrical demand after sunset. This paper linked the house roof design to the PV solar system for maximum generation condition. Furthermore the paper contains important information on the optimum location for the solar panel to ensure continuous and reliable system is achieved. An actual real case study is presented.

An innovation diffusion model of a local electricity network that is influenced by internal and external factors

Haynes et al. (1977) derived a nonlinear differential equation to determine the spread of innovations within a social network across space and time. This model depends upon the imitators and the innovators within the social system, where the imitators respond to internal influences, whilst the innovators react to external factors. Here, this differential equation is applied to simulate the uptake of a low-carbon technology (LCT) within a real local electricity network that is situated in the UK. This network comprises of many households that are assigned to certain feeders. Firstly, travelling wave solutions of Haynes’ model are used to predict adoption times as a function of the imitation and innovation influences. Then, the grid that represents the electricity network is created so that the finite element method (FEM) can be implemented. Next, innovation diffusion is modelled with Haynes’ equation and the FEM, where varying magnitudes of the internal and external pressures are imposed. Consequently, the impact of these model parameters is investigated. Moreover, LCT adoption trajectories at fixed feeder locations are calculated, which give a macroscopic understanding of the uptake behaviour at specific network sites. Lastly, the adoption of LCTs at a household level is examined, where microscopic and macroscopic approaches are combined.

TRANSFORMATION OF THE ORGANIZATIONAL STRUCTURE OF ENERGY COMPANY

Introduction. Country's economic growth and innovative changes of the enterprises are interdependent processes, therefore, enterprises should pay constant attention to the development management issues on the basis of innovative measures.complex of issues that is connected to management of process development and innovative changes requires acceptance of strategic management solutions in the area of enterprises of natural monopolies to increase the efficiency of their activities. Purpose. Justify the necessity and direction of the transformation of enterprises of natural monopolies and develop measures and ensure their implementation in order to provide development and increase the competitiveness in conditions of market formation and effective activity in the long prospect. Method (methodology). The theoretical and methodological basis of the research is the dialectical method of scientific knowledge, scientific works of domestic and foreign scientists. Results. The Paper highlights transformation of enterprises of natural monopolies in the direction of improvement organizational, legal and economic grounds of ensuring the increase of the efficiency of production, transmission and supply of electricity. The set of characteristics are determined for the construction of the model of improvement of management through the components coordination of the triad system, the structure of the organization of separate enterprises is substantiated. The implementation of the transformation program of the efficiency increasing of separate organizations for the transmission of electric energy by local electric networks and their supply on the regulated tariff of energy supply companies is proposed. It should consist of a certain sequence of steps.

Robust multi-objective control of hybrid renewable microgeneration systems with energy storage

Microgeneration technologies are positioned to address future building energy efficiency requirements and facilitate the integration of renewables into buildings to ensure a sustainable, energy-secure future. This paper explores the development of a robust multi-input multi-output (MIMO) controller applicable to the control of hybrid renewable microgeneration systems with the objective of minimising the electrical grid utilisation of a building while fulfilling the thermal demands. The controller employs the inverse dynamics of the building, servicing systems, and energy storage with a robust control methodology. These inverse dynamics provides the control system with knowledge of the complex cause and effect relationships between the system, the controlled inputs, and the external disturbances, while an outer-loop control ensures robust, stable control in the presence of modelling deficiencies/uncertainty and unknown disturbances. Variable structure control compensates for the physical limitations of the systems whereby the control strategy employed switches depending on the current utilisation and availability of the energy supplies. Preliminary results presented for a system consisting of a micro-CHP unit, solar PV, and battery storage indicate that the control strategy is effective in minimising the interaction with the local electrical network and maximising the utilisation of the available renewable energy.

The impact of distributed power sources to the best of flow in electrical networks

Intensive implementing distributed generation sources from alternative energy sources leads to a situation where one feeder can connect several different types of distributed energy sources, including solar power plant and small hydropower plant. The system consists of distributed generation small-capacity power plants scattered throughout the energy system. They supply electricity to consumers in the near and in the case of excess energy can transfer its network centralized power. This paper discusses the reduction of active power losses in the local electrical systems that operate different types dispersed energy sources. The main goal is to develop a methodology for determining the point of power flow section the local electrical system of dispersed generation sources and develop a method for choosing the optimal place network disconnection criterion of active power losses. The article shows the computer model regime for local electricity system that allows to determined the place point of power flow section and calculated the power loss at section schemes in the respective nodes. The choice of multi sections is difficult optimization problems. It is proved that in the use of multiple distributed sources of energy in the local electrical system for optimum energy losses point of power flow section (several possible points of power flow section) is selected at the lower junction voltage. Regulation of power generated by small hydroelectric power plant affects the change point of power flow section local electric networks and reduces the active power losses in the local electrical system

The effects of electricity network development besides routine malaria control measures in an underdeveloped region in the pre-elimination phase.

BackgroundThe main purpose of this study was to investigate the effects of electricity network development on malaria transmission. The study was performed in the rural areas of three districts in Sistan-va-Baluchestan Province, Iran.MethodsFrom the mentioned districts, 122 rural communities were selected. The data of the years 2005–2009 were collected retrospectively from data banks of the district health centres and the offices of the local electricity network. Fixed and random effects panel data regression models were fitted to determine the effects of electrification and other variables on malaria transmission during the elimination phase.ResultsIt seems that access to electricity of rural communities, if not harmful, has no obvious effect on malaria control and prevention at least during the elimination phase in an underdeveloped region. Elevation above sea level and precipitation during spring and summer were found to be the other important, respectively, time-invariant and time-dependent variables associated with decreasing and increasing malaria transmission. Indoor residual spraying and the use of insecticide-treated mosquito nets were not found to be effective in decreasing malaria transmission in the elimination phase.ConclusionsThe introduction of electricity to a rural community does not guarantee an absolutely good effect on the reduction of malaria transmission.

Editorial Special Issue on Selected Papers from The 2nd IET Renewable Power Generation Conference (RPG2013), Beijing, China

This is the first IET Renewable Power Generation Special Issue from the 2nd IET Renewable Power Generation Conference organised by the Beijing Local Electrical Engineering Network. This conference focused on wind and solar power generation (both PV and solar thermal power) and integration into power systems.

Minimax Model Predictive Operation Control of Microgrids

Due to the steady growth of decentralised distributed generation, the operational management of small, local electricity networks (microgrids) is becoming an increasing challenge to meet: How to provide an operational control for microgrids with a high share of renewable energy sources (RES) that is robust to perturbations? In this paper we address an optimal control problem (OCP) that maintains all of the stated properties in the presence of an uncertain load and RES infeed in islanded operation. Assuming that the uncertainty is within a bounded region along a given load and RES trajectory prediction, the problem is posed as a worst-case hybrid OCP, where the RES output can be curtailed. We propose a minimax (MM) model predictive control (MPC) scheme that adjusts according to the present uncertainty and can be formulated as a mixed-integer linear program (MILP) and solved numerically online.

Evaluation of ground energy storage assisted electric vehicle DC fast charger for demand charge reduction and providing demand response

In 2012 there was approximately 2400 electric vehicle DC Fast Charging stations sold globally. According to Pike Research (Jerram and Gartner, 2012), it is anticipated that by 2020 there will be approximately 460,000 of them installed worldwide. A typical public DC fast charger delivers a maximum power output of 50 kW which allows a typical passenger vehicle to be 80% charged in 10–15 min, compared with 6–8 h for a 6.6 kW AC level 2 charging unit. While DC fast chargers offer users the convenience of being able to rapidly charge their vehicle, the unit's high power demand has the potential to put sudden strain on the electricity network, and incur significant demand charges.Depending on the utility rate structure, a DC fast charger can experience annual demand charges of several thousand dollars. Therefore in these cases there is an opportunity to mitigate or even avoid the demand charges incurred by coupling the unit with an appropriately sized energy storage system and coordinating the way in which it integrates. This paper explores the technical and economical suitability of coupling a ground energy storage system with a DC fast charge unit for mitigation or avoidance of demand charges and lessening the impact on the local electricity network. This paper also discusses the concept of having the system participate in demand response programs in order to provide grid support and to further improve the economic suitability of an energy storage system.

Algorithm for Adaptive Intelligent Agent Trading Electric Power in Decentralized Autonomous Smart Grid

In this paper, we propose a new learning model for decentralized autonomous smart grid involving adaptive trading agents which can sell and buy electric power effectively in a local electric power network. We name the electric power network i-Rene (inter intelligent renewable energy network). The trading agents manage the amount of electric power generated by solar panels or other renewable energies by trading electric power stored in a storage battery in a house. The agent learns a trading strategy by maximizing its utility. Based on the proposed system, we evaluated its price formation and effectiveness of the adaptive trading method through simulations. Additionally, we propose a new variable consumption model for decentralized autonomous smart grid involving living people consuming electric power and the adaptive trading agents. To model demand side management which can control the amount of electric power consumption, developing variable consumption model is essential. We added a variable consumption model to the i-Rene model. We evaluated its price formation and effectiveness of the decentralized autonomous smart grid to equalize fluctuating demand.

Simulating the household plug-in hybrid electric vehicle distribution and its electric distribution network impacts

This paper presents a multi agent-based simulation framework for modeling spatial distribution of plug-in hybrid electric vehicle ownership at local residential level, discovering “plug-in hybrid electric vehicle hot zones” where ownership may quickly increase in the near future, and estimating the impacts of the increasing plug-in hybrid electric vehicle ownership on the local electric distribution network with different charging strategies. We use Knox County, Tennessee as a case study to highlight the simulation results of the agent-based simulation framework.

A novel virtual instrument for power quality surveillance based in higher-order statistics and case-based reasoning

This paper presents the performance results of a Virtual Instrument (VI) based in Case-Based Reasoning (CBR), conceived to online monitor the power-quality. The PC-based instrument receives data through a DAQ board and a differential probe, while maintaining economy by eliminating the extra network construction and hardware. Being flexible, presents an user-friendly interface and a large data storage capacity, since it uses the hard disk. The computational guts of the instrument are based in third and fourth-order statistics (along with the variance), which enhance detection capability and reject noise influence. A time-domain sliding window sweeps the register under test and offers a time-variation pattern which reflects the deviation of the statistical estimator with respect to the steady state. This three-valued time-series comprises variance, skewness and kurtosis evolution, and constitutes a triple input to the innovative CBR module, which in turn is capable of distinguishing electrical anomalies among five categories (the sixth is reserved to the healthy signal): non-50Hz, 50-Hz-asymmetrical, 50-symmetrical non-sinusoidal, swell and sag. Online surveillance tests developed over the local electrical network show acceptable accuracy (96%).

Analysis of Electric Vehicles on Utility Networks

In order to satisfy the growing expectation for energy efficient eco-friendly transportation a number of vehicle concepts have emerged, including the hybrid electric vehicle (HEV) and battery electric vehicle (BEV). Vehicle dynamics necessitate careful sizing of onboard energy storage systems. As the penetration of electric vehicles, in both the public and private sector increases, the requirement to facilitate and utilize them becomes paramount. A particular class of vehicle, the plug-in hybrid-electric vehicle (PHEV) also poses a greater challenge to existing terrestrial based electrical supply systems. This paper of discusses the various future vehicle concepts and investigates the potential impact of PHEV’s and BEV’s fleets on the local electricity networks in the UK.

Economic evaluation of the dual mode CAES solution for increased wind energy contribution in autonomous island networks

Wind parks operating in autonomous island grids, such as those encountered in the Aegean Archipelago, face considerable wind energy curtailments, owed to the inability of local electricity networks to absorb the entire wind energy production. On the other hand, plans promoting the natural gas-based electricity generation in big islands (such as Crete) question the future of wind energy. To recover wind energy curtailments and benefit from the introduction of natural gas, the adoption of compressed air energy storage (CAES) systems suggests an appreciable energy solution. Furthermore, to improve the economic performance of the proposed system, it is decided that guaranteed energy amounts should be delivered to the local grid during peak demand periods. In an effort to obtain favourable negotiation conditions – for the selling price of energy delivered – and also improve the economic performance of the system, a dual mode CAES operation is currently examined. Proceeding to the economic evaluation of dual mode CAES configurations that ensure maximum wind energy recovery, the feasibility of the proposed system may be validated. Lower electricity production costs and considerable reduction of fuel consumption achieved – in comparison with the requirements of conventional peak demand power units – illustrate the system's advantages.

Optimal Design and Economic Evaluation of a Battery Energy Storage System for the Maximization of the Energy Generated by Wind Farms in Isolated Electric Grids

In this paper, a methodology for the optimal sizing of a Battery Energy Storage System (BESS) targeting to supply a predefined and constant (guaranteed) amount of power to an isolated electric grid during the peak load-demand hours is presented. The BESS battery bank is charged using that part of the energy produced by wind parks interconnected with the power system, which is rejected by the electric network due to grid stability limitations. Thus, using the proposed BESS configuration results in increment of the wind energy penetration in the isolated power system and reduction of the air pollution caused by the thermal power stations. The economic viability of the optimally sized BESS configuration is investigated by calculating the investment discounted payback period and internal rate of return. The proposed method has been applied for the optimal design of a BESS supporting the isolated electric network of a remote island with significant wind potential. According to the economic analysis results, the installation of the proposed BESS is economically beneficial for both the BESS investor and the local electric network operator.

Integrated electrification solution for autonomous electrical networks on the basis of RES and energy storage configurations

Most medium and small islands of the Aegean Archipelagos face serious infrastructure problems, strongly related with the limited electrical energy available at extremely high cost. On the other hand, the area is characterized by very high wind speeds and abundant solar energy, thus the exploitation of the available renewable energy sources (RES) may significantly contribute to the fulfillment of the local societies energy demand at minimum environmental and macroeconomic cost. However, the stochastic availability of wind energy and the variable availability of solar energy, the daily and seasonal electricity demand fluctuations, as well as the limited local electrical network capacity result in serious restrictions concerning the maximum renewable power penetration. In this context, the present paper investigates the possibility of creating a combined electricity generation facility based on the exploitation of wind or/and solar potential of an area as well as on the utilization of an appropriate energy storage configuration in order to replace the existing thermal power stations with rational investment requirements. For this purpose, the major parameters of the proposed integrated configuration are firstly calculated and its financial viability is accordingly analyzed. One of the main targets of the proposed solution is to maximize the RES exploitation of the area at a minimum electricity generation cost, while special emphasis is given in order to select the most cost-efficient energy storage device available. According to the results obtained the proposed solution is not only financially attractive but also improves the quality of the electricity offered to the local communities, substituting the expensive and heavily polluting existing thermal power stations.