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



Nonlinear Oscillation Behaviors Analysis of DFIG- WT-dominated System with Transient Control Switches

Abstract—Same as synchronize generator dominated system, transient oscillation also occurs in doubly fed induction generator-based wind turbine (DFIG-WT) dominated system. However, since DFIG-WTs employ normal/transient vector controls, they have strong nonlinear and discontinuous features. These features lead the oscillation responses of DFIG-WT-dominated system to be significantly changed, especially after large disturbance. The oscillation characteristics would be time-varying and could not be predicted according to pre-fault states as usual. This paper analyzes the transient oscillation characteristics of DFIG-WT- dominated system and discusses the effects of transient control switches. Firstly, the regulation process of transient controllers under fault are analyzed. Then, a series of transient model of DFIG-WT in different fault stages are established. Next, the transient oscillation characteristic of DFIG-WT-dominated system is analyzed. Finally, as a key factor that impact the post-fault initial states, the influence rules of transient control parameters are discussed.


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.

Multiphysics Simulation of a PCB-Embedded-Package enclosing a GaN System on Chip – GaN HEMT Half Bridge with Integrated Gate Drivers

An innovative power module configuration ”PCB-Embedded-Package enclosing a GaN System on Chip – GaN HEMT Half Bridge with Integrated Gate Drivers” is being developed for the first time for a high-power power electronics application. To assess the innovative power module’s reliability and feasibility, it is initially being developed and analyzed in a multiphysics simulation environment and the findings are presented. The power module is ultimately optimized to have a reliable and feasible virtual model before hardware prototyping.

Design and Implementation of 1 MHz DC-DC LLC Resonant Converter with GaN Enhancement Mode HEMT

In this paper, a 1 MHz LLC half bridge resonant converter with GaN Enhancement mode HEMT (GaN E-HEMT) is implemented. The power density of the power converter is improved with higher switching frequency and achieve higher efficiency with soft switching technique. The operating principle of half bridge LLC resonant converter is discussed and the characteristics and gate driver circuit requirements of the wide bandgap devices are studied. Finally, the digital signal processor, TMS320F28035, is used to realize the laboratory prototype with the input voltage 400 V, the output voltage 12 V, and rated output power 240W. The synchronous rectifier is used on the secondary side to reduce conduction loss to improve efficiency. The experimental results show that efficiency can be as high as 94.1% at 50% load and 92.1% at full load.


Elevated temperature and thermal cycling are one of the biggest limiting factors in the service lifetime of power modules in power electronic systems. Thus, accurate and high-bandwidth junction temperature measurement of power semiconductors is essential for condition monitoring as well as for remaining useful life estimation procedures. The extraction of temperature sensitive electrical parameters (TSEP) has been identified as a promising approach for junction temperature sensing. However, TSEPs are usually affected not only by temperature but also by other effects, such as load current and aging effects. In addition, the overall temperature sensitivity of the TSEP is influenced by several individual sensitivities of separate device parameters. A strong understanding of these impacts is crucial for highly accurate temperature determination. However, sensitivity analysis of TSEPs to these influences is rarely performed in the literature. Therefore, this paper introduces a sensitivity analysis method of turn-on process TSEPs derived from fitting a simulation model to measurement results through a genetic algorithm. To verify the method, the sensitivity of SiC power MOSFET turn-on TSEPs to threshold voltage, internal gate resistance and transconduction gain are extracted and evaluated.

3D Printed Heat Sinks in GaN-based power converters

A proposal to use additive manufacturing is presented in this paper to overcome such issues. A comparison of materials, shapes, and conventional vs. 3D printed heat sinks is presented in this paper.

Converter optimization with empirical and fitted formulation

We propose a curve fitting based power electronics converter design method. Compared with traditional database based converter, this method is easier to be implemented. With this method, we successfully design the power stage of a 1.5kW boost converter.