Repair based Constraint Handling Techniques for Microgrid Sizing and Energy Management Optimisation


Microgrid sizing and energy management system (EMS) optimisation problems have conflicting objectives while subjected to complex constraints. These problems are usually solved by using meta-heuristic algorithms, which are originally developed to solve unconstrained problems. Therefore, appropriate constraint handling technique (CHT) must be employed to solve constrained problems. It appears that use of CHTs in these problems is rare. This study proposes using two types of repair-based penalty approaches to solve a microgrid sizing and EMS problem. Cuckoo search algorithm is employed to solve the multi-objective optimisation problem, which minimises the levilised cost of electricity (LCOE) and dump load, while maximising the reliability of power supply. A case study based on the Westray Island standalone microgrid in Scotland is conducted to compare the effectiveness of the repair approaches, in terms of the objective function values and convergence speed.

Keywords: Constraint handling, Energy management system, Microgrid, Renewables, Repair methods, Sizing

Impact of Wave Energy Integration on Sizing and Energy Management of a Microgrid: Case study


This paper investigates the impact of integrating a wave energy converter (WEC) on sizing the battery and energy management of a microgrid utilising wind, solar and diesel generator at the generation side. A sequential co-optimisation model for sizing and energy management is proposed to minimise the levilised cost of electricity (LCOE) and dump load, while maximising the reliability of power supply. Cuckoo search algorithm is employed to solve the multi-objective optimisation problem. Moreover, a repair-based penalty approach is integrated for effective constraint handling. The Westray Island standalone microgrid in Scotland is considered as a case study. Annual hourly weather data of Westray Island and the demand profile are used to simulate the system in MATLAB environment. The numerical results show that the battery capacity is reduced when WEC is integrated in the microgrid. However, with the WEC integration, the LECO slightly increases with increased reliability of the power supply.

Keywords: Constraint handling, Energy management system, Microgrid, Sizing, Wave energy



Development of Short-Term Wind Power Forecasting Methods

This paper presents new approaches for short-term wind power forecasts developed by the authors. Day-ahead and hours-ahead wind power forecasts were derived from the wind speed forecast data generated by High Resolution Deterministic Prediction System (HRDPS) Model at the Environment and Climate Change Canada (ECCC). Following a statistical analysis to verify the accuracy of the ECCC wind speed forecasts themselves, a power curve transfer model was developed to offer day-ahead wind power forecasts by converting the ECCC wind speed forecasts to wind power forecasts. An hours-ahead wind speed forecasting method was developed using a fusion approach to predict wind power for look-ahead times ranging from 30 minutes to six and a half hours with 5-min time steps to meet forecast delivery requirements of utilities and system operators. Using operational data over three years from seven wind farms in different locations in Canada, the forecasting methodologies were validated for their good performance on the basis of statistical metrics and error distribution analyses.

Study of a DC Micro-Gird Configuration to Produce Hydrogen (DCMG-H2)

The configuration of a cutting-edge DC Micro-Grid system to produce Hydrogen (DCMG-H2) from Renewable Energy Sources (RESs) is described.

This analysis clearly highlights the unnecessary power conversions in an ACMG in practice when the system can be converted to a DCMG.
Next, based on eliminating these AC-DC converter components from ACMG, an efficient fully DCMG system is introduced that contains DC loads, such as electrolysers, and Photovoltaic (PV) and Battery Energy Storage (BES) systems.

The proposed investigations can significantly address the new technical demand for implementing DCMG-H2 using the low-cost energy from PVs and can enable up-scaling of hydrogen production.

Analysis of A Fully Electric Tractor Performance Through Field Trials in Rwanda

Off-road agricultural vehicles contribute significantly to greenhouse gas (GHG) emissions including tractors which has not been considered in the past. While tractor operation poses threats to environment generally through toxic gas emissions, tractors are key components in mechanizing agriculture practices which satisfies food demand with an increased efficiency. This paper will shade more light on performance and viability of a fully electric tractor evaluated through several field trials


This article discusses the occurrence of high frequency interactions between power electronics converters in dc microgrids. Such interactions occur around the switching frequencies of the converters and are dependent on the filters connected between the converters and the dc network. The resulting resonances, under certain conditions, may coincide with some of the converters switching frequencies. In such a situation there is an expressive amplification of voltage or current, polluting the voltage along the feeder, resulting in large circulation of current at high frequency. This is an issue that can affect loads and converters connected to the microgrid and that is difficult to identify, since it occurs in frequencies beyond the frequency range usually identifies by the power quality analyzers. Simulation and experimental results are shown, based on typical converter values used in low voltage dc microgrids.

Reactive Power Control and Power loss Reduction by using FACTs Devices in Rwanda Network

In this paper The effects of reactive power have been discussed, the total losses reduced from 5% to 0.5% and reactive power were controlled in this work with different
techniques by using capacitor banks and
static VAR compensators, Thyristor controlled reactor (TCR),SSSC, STATCOM and Unified power flow controller (UPF) were simulated by using MATLAB/SIMULINK software.


The interactions of the low-pass filters, or output filters, present in multiple power electronics converters (PEC) connected to an electric grid create conditions to the circulation of high-frequency current among the passive elements of the filters. It is verified by simulation and field measurements that such current can achieve significant values if the converters are connected in the same feeder or next to the other. Power quality analyzers (PQA) may not record the high-frequency component, which is related to the switching frequency. At some cases, however, PQA records incorrect harmonics measurements as a side effect due to the electrical variables contain high frequency spectral components and the sampling rate designed for the PQA. The conclusion is that existing PQAs may be not prepared to correctly identify and quantify the high-frequency components that are most probably present in the modern electric networks, and in microgrids, with many PEC-based distribution energy resources.