Review of trends and targets of complex systems for power system optimization

Optimization systems (OSs) allow operators of electrical power systems (PS) to optimally operate PSs and to also create optimal PS development plans. The inclusion of OSs in the PS is a big trend nowadays, and the demand for PS optimization tools and PS-OSs experts is growing. The aim of this review is to define the current dynamics and trends in PS optimization research and to present several papers that clearly and comprehensively describe PS OSs with characteristics corresponding to the identified current main trends in this research area. The current dynamics and trends of the research area were defined on the basis of the results of an analysis of the database of 255 PS-OS-presenting papers published from December 2015 to July 2019. Eleven main characteristics of the current PS OSs were identified. The results of the statistical analyses give four characteristics of PS OSs which are currently the most frequently presented in research papers: OSs for minimizing the price of electricity/OSs reducing PS operation costs, OSs for optimizing the operation of renewable energy sources, OSs for regulating the power consumption during the optimization process, and OSs for regulating the energy storage systems operation during the optimization process. Finally, individual identified characteristics of the current PS OSs are briefly described. In the analysis, all PS OSs presented in the observed time period were analyzed regardless of the part of the PS for which the operation was optimized by the PS OS, the voltage level of the optimized PS part, or the optimization goal of the PS OS.Web of Science135art. no. 107

Optimal allocation of FACTS devices in distribution networks using Imperialist Competitive Algorithm

Copyright © 2005-2015 Praise Worthy Prize. The publisher granted a permission to the author to archive this article in BURA.FACTS devices are used for controlling the voltage, stability, power flow and security of transmission lines. Imperialist Competitive is a recently developed optimization technique, used widely in power systems. This paper presents an approach to finding the optimal location and size of FACTS devices in a distribution network using the Imperialist Competitive technique. IEEE 30-bus system is used as a case study. The results show the advantages of the Imperialist Competitive technique over the conventional approaches. © 2013 Praise Worthy Prize S.r.l. - All rights reserved

Optimal control of distributed generators and capacitors by hybrid DPSO

In this paper, a comprehensive planning methodology is proposed that can minimize the line loss, maximize the reliability and improve the voltage profile in a distribution network. The injected active and reactive power of Distributed Generators (DG) and the installed capacitor sizes at different buses and for different load levels are optimally controlled. The tap setting of HV/MV transformer along with the line and transformer upgrading is also included in the objective function. A hybrid optimization method, called Hybrid Discrete Particle Swarm Optimization (HDPSO), is introduced to solve this nonlinear and discrete optimization problem. The proposed HDPSO approach is a developed version of DPSO in which the diversity of the optimizing variables is increased using the genetic algorithm operators to avoid trapping in local minima. The objective function is composed of the investment cost of DGs, capacitors, distribution lines and HV/MV transformer, the line loss, and the reliability. All of these elements are converted into genuine dollars. Given this, a single-objective optimization method is sufficient. The bus voltage and the line current as constraints are satisfied during the optimization procedure. The IEEE 18-bus test system is modified and employed to evaluate the proposed algorithm. The results illustrate the unavoidable need for optimal control on the DG active and reactive power and capacitors in distribution networks

Simultaneous RPD and SVC Placement in Power Systems for Voltage Stability Improvement Using a Fuzzy Weighted Seeker Optimization Algorithm

Voltage stability issues are growing challenges in many modern power systems. This paper proposes optimizing the size and location of Static VAR Compensator (SVC) devices using a Fuzzy Weighted Seeker Optimization Algorithm (FWSOA), as an effective solution to overcome such issues. Although the primary purpose of SVC is bus voltage regulation, it can also be useful for voltage stability enhancement and even real power losses reduction in the network. To this aim, a multi-objective function is presented which includes voltage profile improvement, Voltage Stability Margin (VSM) enhancement and minimization of active power losses. Voltage stability is very close to Reactive Power Dispatch (RPD) in the network. Therefore, in addition to voltage regulation with locating SVCs, considering all of the other control variables including excitation settings of generators, tap positions of tap changing transformers and reactive power output of fixed capacitors in the network, simultaneous RPD and SVC placement will be achieved. Simulation results on IEEE 14 and 57-bus test systems, applying Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Seeker Optimization Algorithm (SOA) and FWSOA verify the efficiency of FWSOA for the above claims

Current achievements and future directions of physical weed control in Europe

This paper reviews major results achieved with physical weed control methods and strategies especially adapted for horticultural and agricultural crops. Mechanical methods, such as weed harrowing and inter-row hoeing, have provided promising results in cereals, pulse and oil seed rape, particularly when they are part of a strategy that also involves cultural methods such as fertiliser placement or crop seed vigour. In row crops, intra-row weeds constitute a major challenge, and research has mainly aimed at replacing laborious hand weeding with mechanization. A number of investigations have focussed on optimising the use of thermal and mechanical methods against intra-row weeds. And new methods are now under investigation such as robotic weeding for row crops with abundant spacing between individual plants and band-steaming for row crops developing dense crop stands

Virtual Surgical Planning in Subscapular System Free Flap Reconstruction of Midface Defects.

OBJECTIVES: Reconstruction of the midface has many inherent challenges, including orbital support, skull base reconstruction, optimizing midface projection, separation of the nasal cavity and dental rehabilitation. Subscapular system free flaps (SF) have sufficient bone stock to support complex reconstruction and the option of separate soft tissue components. This study analyzes the effect of virtual surgical planning (VSP) in SF for midface on subsite reconstruction, bone segment contact and anatomic position. MATERIALS AND METHODS: Retrospective cohort of patients with midface defects that underwent SF reconstruction at a single tertiary care institution. RESULTS: Nine cases with VSP were compared to fourteen cases without VSP. VSP was associated with a higher number of successfully reconstructed subunits (5.9 vs 4.2, 95% CI of mean difference 0.31-3.04, p = 0.018), a higher number of successful bony contact between segments (2.2 vs 1.4, 95% CI of mean difference 0.0-1.6, p = 0.050), and a higher percent of segments in anatomic position (100% vs 71%, 95% CI of mean difference 2-55%, p = 0.035). When postoperative bone position after VSP reconstruction was compared to preoperative scans, the difference in anteroposterior, vertical and lateral projection compared to the preoperative \u27ideal\u27 bone position was82% of measurements. There were no flap losses. CONCLUSION: VSP may augment SF reconstruction of the midface by allowing for improved subunit reconstruction, bony segment contact and anatomically correct bone segment positioning. VSP can be a useful adjunct for complex midface reconstruction and the benefits should be weighed against cost

Modern Distribution Management System and Voltage VAR Control

This paper describes modern Distribution Management System (DMS) and Voltage/VAR Control (VVC) as one of its important components. Importance of DMS with respect to latest changes such as renewable energy sources, distribution generation, demand-respond is significant for the complete power system stability and control. In this paper VVC, as one of the most important applications in DMS, is explained and analyzed. VVC uses power system control equipment and calculates new optimal operational state. Typical VVC objective function is minimization of system power losses, violations of bus voltage limits, feeder capacity limits or combinations of these. Changes of controllable devices are presented through their injected current used in current iteration method for power flow. Test of Voltage/VAR control is performed on modified IEEE13 test network and results show that proper adjustments of OLTC transformers, capacitors and DG significantly reducepower losses while satisfying all operation constraints