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



A Novel Non-Mirrored Buck-Boost Flying Capacitor Multilevel DC-DC Converter Topology

Enabling future electrification of air and ground transportation requires flexible, compact, and highly efficient power converters. Four-switch non-inverting buck-boost dc-dc converters allow for wide and overlapping input and output voltage ranges, enabling integration of fuel cells and batteries whose voltages vary with state of charge and operating conditions. In this work, we propose a novel non-mirrored buck-boost (N-MBB) Flying Capacitor Multilevel (FCML) dcdc converter. The proposed topology integrates the conventionally separated buck and boost bridge-legs, which is enabled by novel monolithic bidirectional GaN transistors. Compared to the conventional mirrored buck-boost FMCL converter, the proposed topology shows a higher inductor volume but advantageously a lower component count, better utilization of the installed chip area and flying capacitors, and lower conduction losses. The final paper will contain a detailed description of the operation modes, a comparative evaluation regarding component stresses, and discuss topology variations with adjusted trade-offs and even dc-ac conversion functionality.

A Modular MMC Based DC-DC Converter with DC Fault Blocking Capability

This paper introduces an MMC based DC-DC converter that can be used to interconnect DC networks of different or similar voltage levels and manage a bidirectional power flow. It provides a DC fault blocking capability at both DC sides and is easily scalable to higher voltage and power ratings due to its modular design. The functional principle of the converter is analyzed and detailed design criteria are provided. The performed analysis is validated by hardware in the loop simulations.


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.


Excited near its resonant frequency, a thin transverse-type rectangular Piezoelectric Transformer with common ground electrodes (PTCGE) converse an electric voltage in driving part, providing mechanical vibrations and converted back to an electrical signal in the output part. They are dedicated to the systems of electronic or electromechanical that require voltage source boosted or bucked with good galvanic isolation for DC/AC or DC/DC converter commercialized in monolithic fabrication. Otherwise, problems are occurred in modeling, design and characterization of these devices. Approaches conducted on the transverse-type PTs are recently neglected the distance between the primary and secondary electrodes called « gap ». The finite element Approach (FEA) not allows appear the mathematical expressions in the structure and keeps high storage memory. In this paper, the Polynomial Approach is reported to this device for analyzing the free vibration modes and the electrical behaviors especially the gap dependence on the voltage gain letting the bottom surface completely covered with ground electrodes taking into account the gap. Then, a good agreement is found in our results through a comparison of those obtained with the FEA ones.

An Inter-Phase Balancing Strategy based on Model Predictive Control for Discontinuously Operated Cascaded H-Bridge StatComs

The conventional implementation of discontinuous modulation (DM) in cascaded H-bridge static compensators negatively affects the inter-phase capacitor voltage balancing, particularly during grid unbalanced conditions. This paper integrates the DM implementation and the inter-phase capacitor voltage balancing using a finite control set model predictive control approach. This advanced predictive DM implementation outperforms the conventional DM while preventing the capacitor voltages from diverging during unbalanced grid conditions. The effectiveness of the proposed strategy is verified with simulation results considering different unbalanced grid cases.