Minimum Total Load Research Articles

Mobile energy storage systems with spatial–temporal flexibility for post-disaster recovery of power distribution systems: A bilevel optimization approach

In recent years, the damage to power distribution systems caused by the frequent occurrence of extreme disasters in the world cannot be ignored. In the face of the customer’s demand for high power supply reliability and high power quality, it is urgent to establish a resilient distribution network that can not only resist extreme disasters and quickly recover the power distribution system loads, but also ensure a high voltage quality of the distribution system during recovery process. Therefore, mobile energy storage systems with adequate spatial–temporal flexibility are added, and work in coordination with resources in an active distribution network and repair teams to establish a bilevel optimization model. The objective of the upper-level optimization model is minimum the total load curtailment of the distribution system after the disaster. And the objective of the lower-level optimization model is minimum the voltage offset of power supply buses during the recovery stage. A modified IEEE 33-bus distribution test system is used to verify this model. The simulation results show that the bilevel optimization strategy proposed in this research can effectively reduce the voltage offset during the recovery process of distribution systems, and ensure the minimum total load curtailment simultaneously.

A note: flowshop scheduling with linear deterioration and job-rejection

We study a scheduling problem on an $$m$$ -machine flowshop with linear deterioration of job processing times and job rejection. The objectives are minimum makespan and minimum total load, subject to an upper bound on the total permitted rejection cost. The problems are NP-hard (since the single machine makespan minimization version was shown to be hard), and we introduce pseudo-polynomial dynamic programming algorithms, thus proving that both problems are NP-hard in the ordinary sense.

Minimizing total load on parallel machines with linear deterioration

We study a scheduling problem with linear deterioration of job processing times. We consider parallel identical machines. The objective is minimum total load, i.e., minimum total processing times on all the machines. We propose a simple heuristic of a greedy type for this NP-hard problem. A lower bound based on the geometric mean of the job deterioration factors is also introduced. The greedy heuristic is shown to guarantee an optimal solution for small size problems, and our numerical tests indicate that in general it produces very close-to-optimal schedules.

Flowshop scheduling with learning effect and job rejection

We study scheduling problems on a proportionate flowshop. Three objective functions are considered: minimum makespan, minimum total completion time, and minimum total load. We consider a learning process; thus, the processing time of a job processed later in sequence is reduced. The scheduler has the option of job rejection; i.e., only a subset of the jobs are processed and the rejected jobs are penalized. An upper bound on the total permitted rejection cost is assumed. Since the single-machine versions of these problems were shown to be NP-hard, we focus on the introduction of pseudopolynomial dynamic programming algorithms, indicating that the problems are NP-hard in the ordinary sense. We provide an extensive numerical study verifying that the proposed solution algorithms are very efficient and instances containing up to 80 jobs are solved in no more than 5 ms.

Redesign ITS Central Library through Smart Building

Energy conservation is one of many technique applied to reduce the global warming effect. Sepuluh Nopember Institute of Technology (ITS) contributes to encourage energy conservation by ITS Eco Campus programs. It has so many activities, one of them is audit energy as one way to get energy efficiency in educational area. ITS central library is most accessable building both student and other academics community with total area more than 400 square matres and high occupation rate approximately 90% everyday. Energy audit techniques were carried out by an energy audit team to identify any energy conservation opportunities (ECOs). walk-through assessment and data analysis were conducted over all building zones. These levels of assessments proved that the building and its mechanical and electrical systems were improperly maintained and inefficiently operated. So that, ITS Central Library will be redesigned to be smart building by improving light intentensity level, humidity, and room temperature appropriate with ASHRAE90.1-2005. Thus exterior building like wall, glass, roof and floor will be redesigned to emphasize minimum total load. Replacement single glass to double glass reduce the load conduction and radiation through glass, approximately 2,7%.

A two-stage flow shop scheduling with a critical machine and batch availability

AbstractWe study a two-stage flowshop, where each job is processed on the first (critical) machine, and then continues to one of two second-stage (dedicated) machines. We assume identical (but machine-dependent) job processing times. Jobs are processed on the critical machine in batches, and a setup time is required when starting a new batch. The setting assumes batch-availability, i.e., jobs become available for the second stage only when their entire batch is completed on the critical machine. We consider three objective functions: minimum makespan, minimum total load, and minimum weighted flow-time. Polynomial time dynamic programming algorithms are introduced, which are numerically shown to be able to solve problems of medium size in reasonable time. A heuristic for makespan minimization is presented and shown numerically to be both accurate and efficient.

Multi-Machine Scheduling With Linear Deterioration

We study multi-machine makespan minimization of deteriorating jobs, i.e. jobs whose processing times are increasing functions of their starting times. We assume simple linear deterioration, and parallel identical machines. The problem is proven to be NP-hard even for two machines. A heuristic and lower bound are introduced and tested numerically. The heuristic is shown to be asymptotically optimal under very general conditions. We also study a non-conventional performance measure relevant to settings with deteriorating jobs, namely, minimum total load on all machines.

A new algorithm for service restoration in large-scale urban distribution systems

A method is suggested for (near) optimal restoration of large-scale urban distribution systems after heavy disturbances. The method is conceived to provide the minimum total load interruption cost by taking into account the current, voltage and system operating and structural constraints. An efficient restoration of load points is achieved by utilizing the MV busbars in HV/MV transformer stations which facilitate the load transfer among transformers and feeders while keeping low the number of switching operations. The optimal alternatives in supplying the nodes of the out-of-service area are searched for by generating the minimal paths to the boundary branches connecting this area with the sound area, which broadens the search domain.