Abrez Mondal

Design and Operation of Smart Loads to Prevent Stalling in a Microgrid

This paper investigates the benefits of smart loads in an iXndustrial microgrid. Such smart loads offer the microgrid greater flexibility to regulate frequency for large fluctuating load scenarios, commonly encountered in industrial plants. A case study of stone-crushing facility is analyzed when it is fed by natural gas engine driven generator sets (also known as “gensets”). The problem of genset stalling is addressed in this work, and a solution of deploying smart loads is presented. Furthermore, smart load algorithms are proposed to restore the services at an industrial site in a timely manner.

Evaluation and sizing of energy storage systems for microgrids

This paper evaluates the energy storage systems (ESS) in the microgrids. The ESS unit is regarded as an added energy resource in microgrid system to support the power balance when regular distributed energy resources (DERs) are incapable of matching the load demand. Sizing and specifications of ESS are investigated in this paper using several test case scenarios. An overall evaluation of the energy storage functionality is carried out for the microgrid by looking at different storage options for diverse operating scenarios.

Modeling, analysis and evaluation of smart load functionality in the CERTS Microgrid

The objective of this work is primarily aimed at investigating the behavior of the CERTS Microgrid test bed with the integration of smart loads. The smart loads are primarily employed to relieve the system frequency as soon as it begins to deteriorate. The installed smart load assembly is modeled in this paper and its performance with the different distributed energy resources (DERs) in the existing CERTS Microgrid test bed is analyzed. This paper also evaluates the benefits of using these smart loads as a means to prevent the DERs from stalling in the islanded mode of operation.

Analytical methods for characterizing frequency dynamics in islanded microgrids with gensets and energy storage

Microgrids with increased penetration of renewables experience serious challenges due to large frequency excursions under power system disturbances. An energy storage system can provide frequency regulation, but the effectiveness depends on whether it is configured for the grid-forming or grid-following mode of operation. For this purpose, two critical parameters are studied for frequency regulation in distribution systems; first, the initial rate-of-change-of-frequency (ROCOF), and second, the minimum value of frequency, also known as frequency nadir, following a load change. The aim of this paper is to identify analytical methods for accurately calculating the frequency parameters like ROCOF and frequency nadir. Reduced-order models are developed to determine the frequency deviation against power system disturbances. The results are verified against simulation models validated by testing at the Consortium for Electric Reliability Technology Solutions Microgrid test bed.

Operation and impact of energy storage system in an industrial microgrid

This paper analyzes the performance of a stone crushing facility powered by an islanded microgrid comprising two natural gas engine driven generator sets (also known as gensets). The goal is to achieve the microgrid performance in accordance with the ISO 8528-5 Standard. For improving the system frequency response, different approaches are evaluated including applying underfrequency load shedding and increasing generator inertia. However, it is shown that integration of energy storage system with fast frequency controls offers the best solution for satisfying the ISO 8528-5 Standard. Results from modeling and simulation using MATLAB/Simulink are presented to show the impact on microgrid performance.

Cascading collapse of a large-scale mixed source microgrid caused by fast-acting inverter-based distributed energy resources

Power electronics-based distributed energy resources (DERs) are being increasingly deployed for achieving high energy efficiency, power quality, and flexibility of power system operation and controls. They facilitate access to various kinds of energy sources including renewables, fuel cells, microturbines, variable speed engine-generator sets, etc. However, recent tests carried out at the Consortium of Electric Reliability Technology Solutions (CERTS) Microgrid have indicated that their deployment in the mixed source microgrid can cause a cascading collapse during extreme events. Simulation models of two types of DERs are developed in PSCAD/EMTDC software and validated with the experimental test results. The validated models are used to study a cascading collapse problem in a large-scale mixed source microgrid on the benchmark IEEE 33-bus test system. This paper evaluates three alternative techniques to prevent the cascading collapse in the large-scale microgrid caused by fast-acting power electronics-based DERs.

Improved frequency regulation in an islanded mixed source microgrid through coordinated operation of DERs and smart loads

The advent of microgrids paved the way for energy decentralization and self-sufficiency among consumers. Reciprocating engine driven synchronous generators (also known as gensets) are one of the most commonly found distributed energy resources (DERs) installed in a microgrid. A key concern in microgrid operation is the frequency regulation, especially when it is islanded from the main grid. In recent years, the inverter-based DERs have witnessed huge growth. When fast responding inverter-based DERs are working in parallel with the slow acting gensets within the islanded mixed source microgrid, many challenges exist in coordinating their operation. In particular, an inverter-based DER is susceptible to collapse due to its large transient loading, and this can bring down the entire system. This paper investigates load sharing and proposes new techniques for improved frequency regulation in an islanded mixed source microgrid. For dealing with extreme scenarios, a smart load shedding scheme is integrated into the coordinated operation of DERs.

Analytical Methods for Characterizing Frequency Dynamics in Islanded Microgrids With Gensets and Energy Storage

Microgrids with increased penetration of renewables experience serious challenges due to large frequency excursions under power system disturbances. An energy storage system can provide frequency regulation, but the effectiveness depends on whether it is configured for the grid-forming or grid-following mode of operation. For this purpose, two critical parameters are studied for frequency regulation in distribution systems; first, the initial rate-of-change-of-frequency (ROCOF), and second, the minimum value of frequency, also known as frequency nadir, following a load change. The aim of this paper is to identify analytical methods for accurately calculating the frequency parameters like ROCOF and frequency nadir. Reduced-order models are developed to determine the frequency deviation against power system disturbances. The results are verified against simulation models validated by testing at the Consortium for Electric Reliability Technology Solutions Microgrid test bed.

Analysis and prevention of prime-mover stalling in a mixed source microgrid

Natural gas powered inverter-based distributed energy resources (DERs) are becoming increasingly popular. In such DERs, the output frequency is decoupled from the prime-mover speed. This is advantageous in terms of improved efficiency and reduced emissions for the internal combustion engine. However, under large load conditions the prime-mover can stall leading to a voltage collapse. This paper presents an analysis of prime-mover stalling in inverter-based DERs. Detailed studies are conducted on a mixed source microgrid comprising both inverter- and synchronous generator-based DERs. A modified active power-frequency droop control technique is proposed for the inverter-based DER to prevent its prime-mover from stalling in the mixed source microgrid.

A dSPACE-based control of a hybrid renewable energy system with wind and photovoltaic power

In recent years, non-conventional sources of energy such as wind and solar have gained increased attention as viable means of power generation. This paper discusses a hybrid scheme consisting of a permanent magnet synchronous generator (PMSG)-based wind energy system and photovoltaic panels which are integrated with a battery to store extra energy when available and to meet additional power requirement during shortage. The PV panel supplies the battery through a SEPIC converter for maximum power point tracking (MPPT). The PMSG supplies the battery through a boost converter which regulates the output. The outputs of the wind and photovoltaic systems share a common DC link through which the total power from the hybrid system is fed to a three-phase load using an inverter implementing space-vector pulse-width modulation (SV-PWM). The controller modeled in MATLAB/Simulink software is simple and is implemented through real-time simulation using dSPACE board.