A two-stage optimization and control for CCHP microgrid energy management

A microgrid energy management system (MEMS) optimally schedules the operation of dispatchable distributed energy resources to minimize the operation costs of microgrids (MGs) via an economic dispatch (ED). Actual ED implementation in the MEMS relies on an optimization software package called an optimization solver. This paper presents a comparative study of optimization solvers to investigate their suitability for ED implementation in the MEMS. Four optimization solvers, including commercial as well as open-source-based ones, were compared in terms of their computational capability and optimization results for ED. Two-stage scheduling was applied for the ED strategy, whereby a mixed-integer programming problem was solved to yield the optimal operation schedule of battery-based energy storage systems. In the first stage, the optimal schedule is identified one day before the operating day; in the second stage, the optimal schedule is updated every 5 min during actual operation to compensate for operational uncertainties. A modularized programming strategy was also introduced to allow for a comparison between the optimization solvers and efficient writing of codes. Comparative simulation case studies were conducted on three test-bed MGs to evaluate the optimization results and computation times of the compared optimization solvers.

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Modelling, optimization and control of continuous two-stage Cephalosporin C production

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/1195/1/012037 ◽

2021 ◽

Vol 1195 (1) ◽

pp. 012037

Author(s):

J F Y Chin ◽

J Nandong

Keyword(s):

Fermentation Broth ◽

Operating Conditions ◽

Cephalosporin C ◽

Two Stage ◽

Power Requirement ◽

Trade Off ◽

Optimization And Control ◽

Cephalosporin C Production ◽

And Control ◽

Derivatives Of

Abstract Cephalosporin is one of the most consumed antibiotics for its effectiveness against a wide variety of infections. Most cephalosporin products are the semi-derivatives of Cephalosporin C (CPC), a metabolite of the fungus Acremonium chrysogenum. Since naturally the desired metabolite is not produced in a large amount by the fungus, an innovative operational strategy is required to increase its yield for the production of the antibiotic to be economically feasible. One way to increase the cephalosporin productivity is by increasing the concentration of thin hyphae cell in the bioreactor, but this will lead to a higher blower power requirement for providing adequate availability of oxygen in the fermentation broth. Lack of oxygen will retard the growth rate and reduce the productivity. Conversely, excessive aeration of the fermentation broth will lead to high shear stress that can kill the cells. The present work investigates through dynamic simulation the effectiveness of a continuous two-stage aerobic fermentation for the CPC production. The operating conditions are optimized to determine an optimal trade-off between the cephalosporin productivity and blower power. An increase of the dissolved oxygen in the first bioreactor from 10 % to 20 % can increase CPC productivity by 75.5 % from 24.42 mg/L.hr to 42.86 mg/L.hr.

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