Distributed photovoltaic systems: Utility interface issues and their present status. Intermediate/three-phase systems

The interface issues between the intermediate-size Power Conditioning Subsystem (PCS) and the utility are considered. A literature review yielded facts about the status of identified issues

Transactive energy system

The rising of distributed energy resource (DER) e.g. rooftop PV solar system, wind system and energy storage system, and load demand response bring both opportunities and challenges to the power grid. Coordinating decentralised DERs is important. The purpose of transactive energy (TE) system is to coordinate DERs at the distribution level and encourage consumers and prosumers to participate in electricity market by providing economic incentives. TE system enables customers and prosumers to sell the surplus energy to their neighbours. This thesis represents research on TE system in aspects of structure, technology, economics and participants. The impact of TE system in Australia’s electrical standard and electricity business mode is also explored. Moreover, based on research findings, a TE system model for Australia is proposed. The key findings of this project are: • TE System is a method to relieve electricity congestion. • The power flow (distribution level) and transaction in TE system are bidirectional. • TE system is customer-oriented and offers more choices to customers/prosumers. • The new distribution system operator (DSO) plays a key role in coordinating DERs and end-users. • Undertaking a TE system demonstration project in Australia is suggested

Multi-objective optimisation method for coordinating battery storage systems, photovoltaic inverters and tap changers

The many well-established advantages of distributed generation (DG) make their usage in active distribution networks prevalent. However, uncontrolled operation of DG units can negatively interfere with the performance of other equipment, such as tap-changers, in addition to resulting in sub-optimal usage of their potential. Thus, adequate scheduling/control of DG units is critical for operators of the distribution system to avoid those adverse effects. A linearised model of a multi-objective method for coordinating the operation of photovoltaics, battery storage systems, and tap-changers is proposed. Three objective functions are defined for simultaneously enhancing voltage profile, minimising power losses, and reducing peak load power. The formulated multi-objective problem is solved by means of the epsilon-constraint technique. A novel decision-making methodology is offered to find the Pareto optimality and select the preferred solution. To assess to proposed model's performance, it is tested using 33-bus IEEE test system. Consequently, tap-changers suffer lessened stress, the batteries state-of-charge is kept within adequate limits, and the DG units operation is at higher efficiency. The obtained results verify the effectiveness of this approach.fi=vertaisarvioitu|en=peerReviewed

Distributed photovoltaic systems: Utility interface issues and their present status

Major technical issues involving the integration of distributed photovoltaics (PV) into electric utility systems are defined and their impacts are described quantitatively. An extensive literature search, interviews, and analysis yielded information about the work in progress and highlighted problem areas in which additional work and research are needed. The findings from the literature search were used to determine whether satisfactory solutions to the problems exist or whether satisfactory approaches to a solution are underway. It was discovered that very few standards, specifications, or guidelines currently exist that will aid industry in integrating PV into the utility system. Specific areas of concern identified are: (1) protection, (2) stability, (3) system unbalance, (4) voltage regulation and reactive power requirements, (5) harmonics, (6) utility operations, (7) safety, (8) metering, and (9) distribution system planning and design

Dual-band microstrip loop antenna for wireless application

In recent years, microstrip and printed antennas are widely used in order to fulfill the commercial needs. The emergence of wireless applications requires compact antenna easy manufacture. The purpose of this project is to design of dual band microstrip loop antenna for wireless applications with a reduction in size. The aim of this antenna was to operate from 2 GHz to 4 GHz. A square microstrip patch antenna has been chosen as antenna design pattern due to its low-profile structure. The development of this project comprised two main stages where the first level is a software simulation (CST Microwave studio2012) and secondly is a hardware development. CST Microwave studio2012 has been used to simulate the antenna design for a purpose of preliminary design which the inherent of the advantages of the antenna can be identified, then the second stage is the development of the microstrip patch antenna which have been fabricated on FR4 substrate and tested using the network analyzer which has range between to 1GHz to 14GHz. Based on this project, the antenna parameters such as return loss, radiation pattern, voltage standing wave ratio (VSWR) and bandwidth have been investigated. For further investigation, a substrate material with higher dielectric constant can be used to reduce a microstrip antenna size. The dual band antenna performance shows agreement between both simulation and measurement results

Novel Controls of Photovoltaic (PV) Solar Farms

Solar Farms are absolutely idle in the night and even during daytime operate below capacity in early mornings and late afternoons. Thus, the entire expensive asset of solar farms remains highly unutilized. This thesis presents novel technologies for utilization of PV solar farm inverter in nighttime for providing multiple benefits to power systems, as well as accomplishing the same objectives during the daytime from the inverter capacity left after production of real power. The new technology transforms a solar farm inverter functionally into a dynamic reactive power compensator known as STATCOM, and termed PV-STATCOM. A novel coordinated control of PV-STATCOMs is proposed for loss reduction in a distribution network. The saved energy is substantial and can be used for powering several homes annually. The second novel PV-STATCOM control involves a temporary curtailment of real power production and utilization of the available reactive power capacity to prevent the instability of a critical induction motor load. The third novel PVSTATCOM control is employed to significantly enhance the power transfer limit of a long transmission line both in the nighttime and also during daytime even when the solar farm is producing a large amount of real power. A new technique for short circuit current management is developed for a conventional PV solar farm that can potentially solve the problem due to which several solar farms have been denied connectivity in Ontario. This thesis has contributed to two patent applications and presented first time implementations of another two filed patents. A generalized PV solar system model in EMTDC/PSCAD software has been developed and validated with manufacturer\u27s datasheet. Another contribution of this thesis is the first time harmonics impact study of the largest solar farm in Canada, in the distribution utility network of Bluewater Power, in Sarnia, Ontario. This thesis makes a strong case for relaxing the present grid codes to allow solar farms to exercise these novel controls. This technology can open up new avenues for solar farms to earn revenues apart from the sale of real power. This will require appropriate agreements between the regulators, network utilities, solar farm developers and inverter manufacturers

A Novel Cooperative Controller for Inverters of Smart Hybrid AC/DC Microgrids

This paper presents a novel cooperative control technique concerning fully-distributed AC/DC microgrids. Distributed generation based on inverters has two types, i.e., Current Source Inverter (CSI), also referred to as PQ inverter, and Voltage Source Inverter (VSI). Both inverter forms have a two-layer coordination mechanism. This paper proposes a design method for the digital Proportional-Resonant (PR) controller that regulates the current inside an inverter. The inverters will improve the voltage quality of the microgrid while maintaining the average voltage of buses at the same desired level. There is comprehensive detail on the computations specific to resonant and proportional gains and digital resonance path coefficients. The paper includes a digital PR controller design and its analysis in the frequency domain. The analysis is based on the w-domain. The main contribution of this paper is the proposed method, which not only focuses on the transient response but also improves the steady-state response which smoothens the voltage; furthermore, all inverters are effectively involved to increase the capacity of the microgrid for better power management. The suggested cooperative control technique is used on an IEEE 14-bus system having fully distributed communication. The convincing outcomes indicate that the suggested control technique is an effectual means of regulating the microgrid’s voltage to obtain an evener and steady voltage profile. The microgrid comprises distributed resources and is used as the primary element to analyse power flow and quality indicators associated with a smart grid. Lastly, numerical simulation observations are utilised for substantiating the recommended algorithm

Identification and development of microgrids emergency control procedures

Tese de doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 200