Grid integration of renewable power generation

This thesis considers the use of three-phase voltage and current source inverters as interfacing units for renewable power, specifically photovoltaic (PV) into the ac grid. This thesis presented two modulation strategies that offer the possibility of operating PV inverters in grid and islanding modes, with reduced switching losses. The first modulation strategy is for the voltage source inverter (VSI), and exploits 3rd harmonic injection with selective harmonic elimination (SHE) to improve performance at low and high modulation indices, where the traditional SHE implementation experiences difficulties due to pulse dropping. The simulations and experimentation presented show that the proposed SHE allows grid PV inverters to be operated with less than a 1kHz effective switching frequency per device. This is vital in power generation, especially in medium and high power applications. Pulse dropping is avoided as the proposed modified SHE spreads the switching angles over 90°, in addition increasing the modulation index. The second proposed modulation strategy, called direct regular sampled pulse width modulation (DRSPWM), is for the current source inverter (CSI). It exploits a combination of forced and natural commutation imposed by the co-existence of an insulated gate bipolar transistor in series with a diode in a three phase current source inverter, to determine device dwell times and switching sequence selection. The DRSPWM strategy reduces switching frequency per device in a CSI by suspending each phase for 60°, similar to VSI dead-band, thus low switching losses are expected. Other benefits include simple digital platform implementation and more flexible switching sequence selection and pulse placement than with space vector modulation. The validity of the DRSPWM is confirmed using simulations and experimentation. This thesis also presents a new dc current offset compensation technique used to facilitate islanding or grid operation of inverter based distributed generation, with a reduced number of interfacing transformers. The proposed technique will enable transformerless operation of all inverters within the solar farm, and uses only one power transformer at the point of common coupling. The validity of the presented modulation strategies and dc current offset compensation technique are substantiated using simulations and experimentation.This thesis considers the use of three-phase voltage and current source inverters as interfacing units for renewable power, specifically photovoltaic (PV) into the ac grid. This thesis presented two modulation strategies that offer the possibility of operating PV inverters in grid and islanding modes, with reduced switching losses. The first modulation strategy is for the voltage source inverter (VSI), and exploits 3rd harmonic injection with selective harmonic elimination (SHE) to improve performance at low and high modulation indices, where the traditional SHE implementation experiences difficulties due to pulse dropping. The simulations and experimentation presented show that the proposed SHE allows grid PV inverters to be operated with less than a 1kHz effective switching frequency per device. This is vital in power generation, especially in medium and high power applications. Pulse dropping is avoided as the proposed modified SHE spreads the switching angles over 90°, in addition increasing the modulation index. The second proposed modulation strategy, called direct regular sampled pulse width modulation (DRSPWM), is for the current source inverter (CSI). It exploits a combination of forced and natural commutation imposed by the co-existence of an insulated gate bipolar transistor in series with a diode in a three phase current source inverter, to determine device dwell times and switching sequence selection. The DRSPWM strategy reduces switching frequency per device in a CSI by suspending each phase for 60°, similar to VSI dead-band, thus low switching losses are expected. Other benefits include simple digital platform implementation and more flexible switching sequence selection and pulse placement than with space vector modulation. The validity of the DRSPWM is confirmed using simulations and experimentation. This thesis also presents a new dc current offset compensation technique used to facilitate islanding or grid operation of inverter based distributed generation, with a reduced number of interfacing transformers. The proposed technique will enable transformerless operation of all inverters within the solar farm, and uses only one power transformer at the point of common coupling. The validity of the presented modulation strategies and dc current offset compensation technique are substantiated using simulations and experimentation

Renewable Power Generation Costs in 2017

Renewable energy has emerged as an increasingly competitive way to meet new power generation needs. This comprehensive cost report from the International Renewable Energy Agency (IRENA) highlights the latest trends for each of the main renewable power technologies, based on the latest cost and auction price data from projects around the world

A Real Options Evaluation Model for the Diffusion Prospects of New Renewable Power Generation Technologies

This study presents an investment planning model that integrates learning curve information on renewable power generation technologies into a dynamic programming formulation featuring real options analysis. The model recursively evaluates a set of investment alternatives on a year-by-year basis, thereby taking into account that the flexibility to delay an irreversible investment expenditure can profoundly affect the diffusion prospects of renewable power generation technologies. Price volatility is introduced through stochastic processes for the average electricity price and for input fuel prices. Demand for peak-load capacity is assumed to be increasingly price-elastic, as the electricity market deregulation proceeds, and linearly dependent on the extent of market opening. The empirical analysis is based on data for the Turkish electricity supply industry. Apart from general implications for policymaking, it provides some interesting insights about the impact of uncertainty on the diffusion of various emerging renewable energy technologies.Dynamic programming, Investment planning, Renewable energy technology diffusion, Real options, Learning curve, Turkey

Silicon in renewable power generation and storage: Decarbonizing the grid and automobile transport

Professor Kurt Kolasinski, Chemistry - Silicon in renewable power generation and storage: Decarbonizing the grid and automobile transport

Open source SCADA systems for small renewable power generation

Low cost monitoring and control is essential for small renewable power systems. While large renewable power systems can use existing commercial technology for monitoring and control, that is not cost-effective for small renewable generation. Such small assets require cost-effective, flexible, secure, and reliable real-time coordinated data monitoring and control systems. Supervisory control and data acquisition (SCADA) is the perfect technology for this task. The available commercial SCADA solutions are mostly pricey and economically unjustifiable for smaller applications. They also pose interoperability issues with the existing components which are often from multiple vendors. Therefore, an open source SCADA system represents the most flexible and the most cost-effective SCADA solution. This thesis has been done in two phases. The first phase demonstrates the design and dynamic simulation of a small hybrid power system with a renewable power generation system as a case study. In the second phase, after an extensive study of the proven commercial SCADA solutions and some open source SCADA packages, three different secure, reliable, low-cost open source SCADA options are developed using the most recent SCADA architecture, the Internet of Things. The implemented prototypes of the three open source SCADA systems were tested extensively with a small renewable power system (a solar PV system). The results show that the developed open source SCADA systems perform optimally and accurately, and could serve as viable options for smaller applications such as renewable generation that cannot afford commercial SCADA solutions

Power quality analysis for renewable power generation in household

Power quality is becoming essential part of Power Industry. The introduction of smarter and more sensitive equipment at both grid and residential level has created performance issues that need investigation. The cost of the power losses is rising due to power quality problems. The other significant factor that is proving vital is the customer dissatisfaction. The introduction of Renewable Energy (RE) into modern grids has also created Power Quality (PQ) problems. A study is required to narrow down the factors that can cause these PQ issues. The power companies are buying electricity back from the consumer produced by these RE sources. The power produced by RE sources coming into the electrical grid needs to be monitored. The research will focus on the factors that impact PQ especially the Total Harmonic Distortion in a electrical grid powered by renewable sources. The factors impacting power quality will be studied in detail by using an simulation approach aided by an experimental set up. The simulation approach will be used to test the hypothesis that total harmonic distortion increases by changing the nature and size of the load in the electrical system. The load type used for the research will be linear and nonlinear loads. The simulation will use single and three phase electrical system. The simulation results will be analysed and discussed. The experimental setup will be used to verify the simulation result. The experiment will be conducted on different set of load to observe the impact on the total harmonic distortion in particular. The experimental result will be collected over period of time enabling the researcher to study in detail the impact of weather, temperature, and inclination of solar panels. These factors will impact the research result. The collected data will be presented for discussion

Design Procedure of a Hybrid Renewable Power Generation System

© 2021 The Author(s). This is an open access conference contribution distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Electrification of small communities in districted off-grid area remains as a challenge for power generation industries. In the current study, various aspects of design of a standalone renewable power plant are examined and implemented in a case study of a rural area in Cape Town, South Africa. Estimating required electricity based on local demand profile, investment, operability, and maintenance costs of different generation technologies are studied in order to investigate their potential in an off-grid clean energy generation system. Several configurations of hybridization of solar system, wind, and micro gas turbine in combination with a battery are investigated. The Levelized Cost of Electricity (LCOE) and number of days with more than 3 h black out are compared

Power quality analysis for renewable power generation in household

Power quality is becoming essential part of Power Industry. The introduction of smarter and more sensitive equipment at both grid and residential level has created performance issues that need investigation. The cost of the power losses is rising due to power quality problems. The other significant factor that is proving vital is the customer dissatisfaction. The introduction of Renewable Energy (RE) into modern grids has also created Power Quality (PQ) problems. A study is required to narrow down the factors that can cause these PQ issues. The power companies are buying electricity back from the consumer produced by these RE sources. The power produced by RE sources coming into the electrical grid needs to be monitored. The research will focus on the factors that impact PQ especially the Total Harmonic Distortion in a electrical grid powered by renewable sources. The factors impacting power quality will be studied in detail by using an simulation approach aided by an experimental set up. The simulation approach will be used to test the hypothesis that total harmonic distortion increases by changing the nature and size of the load in the electrical system. The load type used for the research will be linear and nonlinear loads. The simulation will use single and three phase electrical system. The simulation results will be analysed and discussed. The experimental setup will be used to verify the simulation result. The experiment will be conducted on different set of load to observe the impact on the total harmonic distortion in particular. The experimental result will be collected over period of time enabling the researcher to study in detail the impact of weather, temperature, and inclination of solar panels. These factors will impact the research result. The collected data will be presented for discussion

UMN Morris and UMN WCROC launch the Center for Renewable Energy Storage Technology

UMN Morris and UMN WCROC are partnering to launch the Center for Renewable Energy Storage Technology, or CREST. In order to reach high levels of renewable power generation, efficient and economic energy storage systems are critically needed