PROBLEMS OF SYSTEMS WITH DISTRIBUTED GENERATION

The problems of the development of modern production are related to the demand for electricity, which is ahead of the increase in generating capacity. Electric power industry in the 20 th century developed mainly by increasing the level of centralization of electricity supply in the creation of ever more powerful electric power facilities

Evaluating distributed generation impacts with a multiobjective index

Evaluating the technical impacts associated with connecting distributed generation to distribution networks is a complex activity requiring a wide range of network operational and security effects to be qualified and quantified. One means of dealing with such complexity is through the use of indices that indicate the benefit or otherwise of connections at a given location and which could be used to shape the nature of the contract between the utility and distributed generator. This paper presents a multiobjective performance index for distribution networks with distributed generation which considers a wide range of technical issues. Distributed generation is extensively located and sized within the IEEE-34 test feeder, wherein the multiobjective performance index is computed for each configuration. The results are presented and discussed

Reliability analysis of distribution systems with photovoltaic generation using a power flow simulator and a parallel Monte Carlo approach

This paper presents a Monte Carlo approach for reliability assessment of distribution systems with distributed generation using parallel computing. The calculations are carried out with a royalty-free power flow simulator, OpenDSS (Open Distribution System Simulator). The procedure has been implemented in an environment in which OpenDSS is driven from MATLAB. The test system is an overhead distribution system represented by means of a three-phase model that includes protective devices. The paper details the implemented procedure, which can be applied to systems with or without distributed generation, includes an illustrative case study and summarizes the results derived from the analysis of the test system during one year. The goal is to evaluate the test system performance considering different scenarios with different level of system automation and reconfiguration, and assess the impact that distributed photovoltaic generation can have on that performance. Several reliability indices, including those related to the impact of distributed generation, are obtained for every scenario.Postprint (published version

Operation of distributed generation under stochastic prices

The ongoing deregulation of electricity industries worldwide is providing incentives for microgrids, entities that use small-scale distributed generation (DG) and combined heat and power (CHP) ap- plications to meet local energy loads, to evolve independently of the traditional centralised grid in order to provide greater flexibility and energy efficiency to end-use consumers. We examine the impact of start-up costs on the option values and operating schedules of on-site DG installed by a microgrid in the presence of stochastic electricity and fuel prices. We proceed by formulating a stochastic dynamic programme (SDP) for the microgrid that minimises its expected discounted cost over a time horizon and solving it using least-squares Monte Carlo (LSMC) simulation. The expected cost saving that the microgrid realises by having gas-fired DG installed relative to meeting its entire electric load via off-site purchases is the implied option value of DG. Numerical examples indicate that although start-up costs do not significantly lower DG value, they, nevertheless, have a profound impact on the optimal DG operating schedule as the microgrid must incorporate not only current, but also future, expected start-up costs into its current decision-making process as an opportunity cost. As a consequence, the microgrid becomes more hesitant to turn DG units on (off), preferring to wait until the electricity price (natural gas generating cost) exceeds the natural gas generating cost (electricity price) by a significant margin before taking action. We demonstrate that ignoring this tradeoff and proceeding myopically as in the case without start-up costs results in drastically higher expected costs and fewer opportunities to use DG

Distributed entanglement generation from asynchronously excited qubits

The generation of GHZ states calls for simultaneous excitation of multiple qubits. The peculiarity of such states is reflected in their nonzero distributed entanglement which is not contained in other entangled states. We study the optimal way to excite three superconducting qubits through a common cavity resonator in a circuit such that the generation of distributed entanglement among them could be obtained at the highest degree in a time-controllable way. A non-negative measure quantifying this entanglement is derived as a time function of the quadripartite system evolution. We find that this measure does not stay static but obtains the same maximum periodically. When the qubit-resonator couplings are allowed to vary, its peak value is enhanced monotonically by increasing the greatest coupling strength to one of the qubits. The period of its peak to peak revival maximizes when the couplings become inhomogeneous, thus qubit excitation becoming asynchronous, at a relative ratio of 0.35. The study demonstrates the role of asynchronous excitations for time-controlling multi-qubit systems, in particular in extending entanglement time

Evaluating Distributed Time-Varying Generation Through a Multiobjective Index

In the last decade, distributed generation, with its various technologies, has increased its presence in the energy mix presenting distribution networks with challenges in terms of evaluating the technical impacts that require a wide range of network operational effects to be qualified and quantified. The inherent time-varying behavior of demand and distributed generation (particularly when renewable sources are used), need to be taken into account since considering critical scenarios of loading and generation may mask the impacts. One means of dealing with such complexity is through the use of indices that indicate the benefit or otherwise of connections at a given location and for a given horizon. This paper presents a multiobjective performance index for distribution networks with time-varying distributed generation which consider a number of technical issues. The approach has been applied to a medium voltage distribution network considering hourly demand and wind speeds. Results show that this proposal has a better response to the natural behavior of loads and generation than solely considering a single operation scenario

Distributed generation: definition, benefits and issues

This paper starts from the observation that there is a renewed interest in small-scale electricity generation. The authors start with a survey of existing small-scale generation technologies and then move on with a discussion of the major benefits and issues of small-scale electricity generation. Different technologies are evaluated in terms of their possible contribution to the listed benefits and issues. Small-scale generation is also commonly called distributed generation, embedded generation or decentralised generation. In a final section, an attempt is made to define the latter concepts more precisely. It appears that there is no consensus on a precise definition as the concept encompasses many technologies and applications.Distributed generation, embedded generation, electricity

Distributed multi-generation systems: energy models and analyses

Libro riguardante la caratterizzazione di sistemi per la produzione combinata di energia da sistemi di multi-generazione distribuita (Distributed Multi-Generation, DMG). Il libro tratta componenti, schemi e modelli di sistemi di multi-generazione distribuita, illustra concetti derivanti da proposte originali degli autori in merito all'analisi e alla pianificazione dei sistemi, con i corrispondenti indicatori energetici e ambientali approccio formulati secondo un approccio unificato. Numerosi esempi applicativi inclusi nel libro riguardano in particolare sistemi di cogenerazione e trigenerazion

Time-Series Analysis of Photovoltaic Distributed Generation Impacts on a Local Distributed Network

Increasing penetration level of photovoltaic (PV) distributed generation (DG) into distribution networks will have many impacts on nominal circuit operating conditions including voltage quality and reverse power flow issues. In U.S. most studies on PVDG impacts on distribution networks are performed for west coast and central states. The objective of this paper is to study the impacts of PVDG integration on local distribution network based on real-world settings for network parameters and time-series analysis. PVDG penetration level is considered to find the hosting capacity of the network without having major issues in terms of voltage quality and reverse power flow. Time-series analyses show that distributed installation of PVDGs on commercial buses has the maximum network energy loss reduction and larger penetration ratios for them. Additionally, the penetration ratio thresholds for which there will be no power quality and reverse power flow issues and optimal allocation of PVDG and penetration levels are identified for different installation scenarios.Comment: To be published (Accepted) in: 12th IEEE PES PowerTech Conference, Manchester, UK, 201