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




The purpose of this paper is to introduce an advanced control of PV inverters when they are being employed as active filters. Simulations have shown that the suggested control works effectively. The findings during simulations prove that by implementing the suggested regulations framework, the overall harmonic distortion (THD) of both voltage and current is brought down to levels that are acceptable by industry standards.

State Feedback Control for Power Transfer Control of Electric Vehicle Dynamic Wireless Charging

In this paper, a state feedback controller combined with a feed-forward controller is proposed to control the power transfer of electric vehicle dynamic wireless charging. Based on the speed information and energy percentage requirement from the vehicle, the feed-forward controller calculates a desired trajectory for the charger dc link voltage. The state feedback controller regulates the dc link voltage to track the voltage trajectory generated by the forward controller.

Inter-cluster Power Control of Modular Multilevel Converters with Integrated Battery Energy Storage for EV Low Voltage Operation

This paper presents a method to operate each MMC cluster with independent powers during low ac voltage operation. The method reduces the use of circulating current in low voltage conditions. This facilitatates the state of charge balance of MMCs with integrated BESS in the clusters for such conditions. The method is proposed for EVs but other applications could eventually make use of it.

Evaluation of Drive Cycle Clustering Methods for Estimating the Drive Cycle Losses for the Design of Electrically Excited Synchronous Machines as EV Traction Drive

Evaluates different clustering methods for estimating the drive cycle losses of electric traction machines in a computionally efficient manner. Two motor types (electrically and permanent magnet excited synchronous machine, EESM and PMSM) are compared and it is highlighted for the first time in the literature that the EESM needs finer clustering in order to meet the same precision as the PMSM.

Design and Implementation of 3.5 kW Digital Controlled Battery Charge System

A 3.5 kW digital controlled battery charger is implemented with the ripple feed forward (RFF) technique to reduce the output voltage ripple. This battery charger is composed of front-stage of interleaved boost converter for PFC and full-bridge resonant converter for DC-DC conversion. The full load conversion efficiency of the full-bridge resonant converter is 94.3%, and the highest efficiency of system is 93.9%. Mostly, the output voltage ripple is reduced about 30 % by using the RFF.

Hybrid Sorting Strategy for Modular Multilevel Converters With Partially Integrated Second Life Battery Energy Storage Systems for fast EV charging

Electric vehicles charging stations requires huge amounts of power from the grid, what can be alleviated with battery energy storage systems. Two-Level converter is the preferred topology for commercial BESS, but this topology do not offer modularity for the energy storage stage. This work proposes a parallelized Modular Multilevel Converter with partially rated storage systems with an overall control scheme that governs independently the active power reference of each BESS-SMs. The proposed control allows the operation with any amount of Dummy-SMs, which are SMs with floating capacitors in their DC-link without battery energy storage unit. This feature allows the converter to keep operating under batteries faults or disconnection, facilitating the integration of 2nd life batteries to BESS-SMs with different degradation levels. The intra-power balance and the control of the capacitors voltage of Dummy-SMs, is achieved through an hybrid sorting of carriers made in the modulation stage, where LS-PMW is used. This hybrid control strategy, allows the converter to operate each of its SMs as BESS or Dummy, depending of the connection or disconnection of its BESS.

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