Program: 4th Session on Wednesday (15:20-17:00)

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W4-1 – Renewables Integration & Optimization – Solar

15:20 Power Integration for Solar Applications

Tanya Gachovska (Solantro Semiconductor Corp., Canada); Tudor Lipan (Solantro Semiconductor Corp, Canada); Gabriel Scarlatescu (Solantro Semiconductor Corp, Canada); Chris Gerolami (Solantro Semiconductor Corp, Canada); Nikolay Radimov (Solantro Semiconductor Corp, Canada); Mihai Varlan (Solantro Semiconductor Corp, Canada)

— Power integration in power electronic circuits is important for new circuit designs since it tends to decrease the bill of materials, cost, and size of an application, with the added benefit of an increase in reliability. A functional description of a novel architecture called a Micro-Inverter Controller (IXC64) integrated circuit is discussed. The IXC64 has a 32-bit RISC microcontroller core with 64 kB of RAM, as well as advanced switching timers and sensing features for control of different topologies for solar applications. These topologies may include stages such as an Active Clamp Forward converter, Buck converter, Unfolding Bridge, Dual Buck converter, Double Antiphase Buck converter, Chopper, and Current-fed Push-pull converter. Characterized test results and results of applications using the IXC64 is presented

15:40 Modeled Estimates of Solar Direct Normal Irradiance in Al-Hanakiyah,Saudi Arabia and Boulder, USA

Emad Abyad (University of Ottawa & Taibah University, Canada); Christopher Valdivia (University of Ottawa, Canada); Joan Haysom (Leidos Canada & University of Ottawa, Canada); Ahmad Atieh (University of Jordan, Jordan); Karin Hinzer (University of Ottawa, Canada)

Accurate knowledge of the solar resource is required for solar energy generation projects, including preferably data for both the direct normal (DNI) and diffuse horizontal (DHI) components of irradiance, but in many solar datasets, only a single global horizontal (GHI) may be available. This paper undertakes the evaluation of three models-Reindl*, BRL and DISC – which estimate DNI and DHI in such cases. The models are tested against actual data from Boulder, USA, and Al-Hanakiyah, Saudi Arabia. Generally, a good correlation between hourly measured or calculated DNI and hourly modeled DNI is observed for the three models in Boulder and Al-Hanakiyah. The three models overestimate DNI in Al_Hanakiyah while Reindl* and BRL model exhibit less bias for estimating DNI in Boulder. The results show that the BRL model outperforms other models in Boulder with RMSE of 121 W/m² and standard deviation (𝜎) of 121 W/m². Overestimation of DNI has been noticed in BRL and Reindl* models with values that exceed 1100 W/m². On the other hand, Reindl* model’s performance is better with MBE of -28 W/m², MAE of 63 W/m², and RMSE of 86 W/m² in Al-Hanakiyah. Other locations such as Ottawa, Canada and Ma’an, Jordan as well as DIRINT model will be included to evaluate the performance of each model under different weather conditions in the future.

16:00 Design and Application of a Photovoltaic Powered Domestic Solar Water Heating System in Regina, SK., Canada

Somkene Mbakwe (Memorial University of Newfoundland, Canada)

Canadians use an average of 75 Liters of hot water, per individual, at home every day for washing dishes and clothing, cleaning and personal hygiene. With the increasing cost of electricity, as well as the current and growing spate of environmental and climate change issues, the cost of heating domestic water that will meet this demand, through retail electricity, can add up quickly for the average family. This study presents a sustainable solution for domestic water heating – an indirect, non-pressurized, closed-loop with drain back tank domestic solar water heating system, driven by a photovoltaic-powered dc pump – which provides optimal techno-economic performance, reliability, availability, and maximized environmental performance. The analysis results of the proposed system show that the proposed system meets the performance criteria set for the project with annual savings of $744. The proposed system also demonstrates to be financially viable based on all key indicators assessed – NPV, IRR and yielding a simple payback period of approximately 12.8 years. A net annual GHG emission reduction of 3.1 tCO2/yr and cumulative net GHG reduction of 72 tCO2 over the duration of the project life is achieved, with a potential to even further improve both energy savings and emission reduction by up to 18% on an annual basis.

16:20 Power Variability Analysis of Megawatt-Scale Solar Photovoltaic Installations

Mohammad Sedighy (Hatch, Canada); Mark Mitchell (Hatch Ltd., Canada); Michael Campbell (Hatch, Canada); Kathryn Klement (Hatch, Canada)

Power output variability of solar PV installations is an increasingly important topic as more renewable power generation is connected to electrical grids. This paper presents a summary of solar power fluctuations for two solar installations in Eastern Ontario as measured over a two-month period. The installations use the same cell technology, and are in the same relative geographical area. In this analysis the 99.5th percentile value has been used to represent the maximum rate of change due to irradiance variability whereas the absolute maximum (100th percentile) rate of change would have included variability resulting from events such as curtailment step changes or breaker trips. Further analysis results are presented on the maximum dip from daily peak power output caused by weather conditions. The measurement setup allowed for the two 10 MW installations to be segmented and combined, giving a total of five different configurations subject to similar meteorological conditions. The results are also compared to other published studies on this topic.

16:40 A Predictive Direct Power Control Technique for Transformerless Grid Connected PV Systems Application

Nima Safari (University of Saskatchewan, Canada); Osama Aslam Ansari (University of Saskatchewan, Canada); Chi Yung Chung (University of Saskatchewan, Canada)

Transformerless grid-connected PVs are more economical and efficient compared to transformer connected PVs. However, in this type of connection high leakage current flows between the PV arrays and the grid due to the parasitic capacitances of the system. This leakage current is one of the main culprits in causing electromagnetic interference in power system, saturation of distribution transformers and poses safety issues. Common mode voltage (CMV) is primarily responsible for the existence of this leakage current. To cope with issues which arise from omitting galvanic isolation (transformer), in this paper a predictive direct power control (PDPC) with reduced common voltage (CMV) called active zero predictive direct power control (AZ-PDPC) is proposed. Both theory and simulation show that the proposed method reduces the level of CMV along with general good performance. The proposed method’s characteristics are compared with the PDPC technique.

W4-2 – Modeling & Computing Methods

15:20 Comparing Bisection Numerical Algorithm with Fractional Short Circuit Current and Open Circuit Voltage Methods for MPPT Photovoltaic Systems

Muamer Shebani (Memorial University of Newfoundlan, Canada); Tariq Iqbal (Memorial University of Newfoundland, Canada); John Quaicoe (Memorial University of Newfoundland, Canada)

The maximum power produced by a photovoltaic (PV) system varies according to the variation in the solar irradiance and temperature. Maximum power point tracking (MPPT) algorithms are implemented to extract maximum power from PV system. This paper presents a bisection numerical algorithm (BNA) based MPPT, and it compares the algorithm’s tracking accuracy and performance to Fractional Short-Circuit Current (FSCC) and Fractional Open Circuit Voltage (FOCV) methods. This comparison uses the same DC-DC boost converter, PI controller, and load to examine the tracking accuracy for each method. The mathematical model for the PV system is developed using a single diode model, and it is implemented in Matlab/Simulink environment to examine each method. Simulation results for different solar irradiations are presented. The results show that the BNA has the best maximum power tracking accuracy in comparison with the FSCC and FOCV methods.

15:40 A Study on Power-Flow and Short-Circuit Algorithms Capable of Analyzing the Effect of Load Current on Fault Current Using the Bus Impedance Matrix

Insu Kim (Alabama A&M University, USA); Ronald Harley (Georgia Institute of Technology, USA)

In short-circuit studies, load makes difficult to determine fault current that flows in positive-, negative-, and zero-sequence networks. Therefore, it is often ignored because the magnitude of load current is much less than that of fault current that flows from generators when a fault occurs. As distributed generation resources such as photovoltaic systems, wind farms, and non-linear generators based on power electronics have being deployed into power system networks, load current that flows from them may affect a magnitude of fault current. Thus, the objective of this study is to develop a short-circuit algorithm that analyzes the effect of load current on fault current. For this purpose, this study initially develops a power-flow analysis algorithm that iterates to calculate current to be injected and determines voltage using the bus impedance matrix. Then, the proposed short-circuit algorithm uses as input data the results of the proposed power-flow algorithm. To verify the algorithms developed in MATLAB, a distribution system with a distributed generator is presented in a case study. Then, this study (a) calculates the power flow of a distribution system, (b) generates a single line-to-ground fault on the case study, and (c) changes the capacity of load, the capacity of a distributed generator, and the location of a fault. Finally, it examines the effect of load and distributed generation on a magnitude of fault current.

16:00 MATLAB/Simulink Modelling and Experimental Results of a PEM Electrolyzer Powered by a Solar Panel

Mohamed Albarghot (Memorial University of Newfoundland, Canada); Luc Rolland (Memorial University of Newfoundland, Canada)

Abstract – in this paper, the solar panels are used to power an electrolyzer to separate the water into hydrogen and oxygen gas. The electrical equivalent circuit for the proton exchange membrane electrolyzer was developed and implemented in MATLAB/Simulink along with the atmospheric hydrogen storage tank. The voltage (2 volt) and current (1 ampere) were supplied in a similar manner in order to compare the simulated and experimental results. The hydrogen amount is calculated to be 7.345 (ml/min A) from the model as well as the experimental set up. The experimental and simulation results were matched.

16:20 Analysis of Transients in a Micro-grid Using Wavelet Transformation

Yunqi Wang (University of New South Wales, Australia); Jayashri Ravishankar (University of New South Wales, Australia); Phu Le (University of New South Wales, Australia); Toan Phung (University of New South Wales, Australia)

The increasing penetration of distributed generation (DG) into the electrical network presents new challenges to reliable operation of system due to the special characteristics of DG units and their low inertia. Transient in the micro-grid causes more serious disturbances in the reliable operation of the network. The transients only occur for a few cycles, which are difficult to detect and cannot be identified by using digital measuring and recording instruments. This paper utilises wavelet transformation method to detect and analyze the transient signals in the micro-grid. The results show that disturbances are successfully observed by applying wavelet transform. The variation of coefficients is found to be much smaller in grid-connected mode.

16:40 An AC Power Flow Linearization for Power System Optimization Using Linear Programming

Torsten Sowa (RWTH Aachen University & Institute for High Voltage Technology, Germany); Alexander Stroband (RWTH Aachen University, Germany); Wilhelm Cramer (RWTH Aachen University, Germany); Simon Koopmann (RWTH Aachen University, Germany)

This paper presents a method for the linearization of the non-linear power flow equations, which can be used in mixed integer linear optimizations. The power flow equations are linearized around an operating point using the Taylor approximation. The linearization implies an approximation error, which can be iteratively reduced by modifying the operating point. In addition to existing approaches, controllable assets like voltage regulated transformers or phase shifters are integrated into the linearized grid constraints. The model is exemplarily applied to an operation planning model of distributed energy resources considering grid restrictions. The results show that this approach reduces the approximation error significantly and that it is robust for different real distribution grids as well as for different generation and load scenarios.