Multi-objective modelling of day ahead scheduling of MMG-based distribution networks accompanied by DEA considering economics,emissions and power quality

ABSTRACT

This paper presents the state of the art relating to multi-objective modelling for day ahead scheduling of multi micro grid-based distribution networks, using optimal power flow (OPF) accompanied by data envelopment analysis (DEA). In this paper eco-reliability cost function, power quality enhancement and emission reduction are treated as the objective functions and the uncertainties of renewable distributed generations (DGs), load demand and market price are incorporated into the problem. This method is able to find the optimum operation of DGs in grid-connected or isolated MGs, power transaction between each MG and upstream networks/other MGs and hourly reconfiguration instants. For this purpose, firstly OPF is applied to the problem, then the obtained optimal solutions are prioritised by DEA and ranking is done, based on the efficiencies of the optimal solutions. Finally, the provided results validate the practicability of the proposed method and accuracy of the outcomes.     

A novel symmetric/asymmetric multilevel current source inverter topology with lower number of components and lowest power rating of switches

A novel multilevel current source inverter (MCSI) configuration is introduced in this paper. The ability of handling with asymmetrical DC sources is one of the substantial advantages of the proposed inverter. In asymmetric mode, by appropriate selection of DC sources magnitude, a considerable increase can be obtained in the number of output levels without any manipulation on inverters’ hardware. In MCSIs, the number of required circuit devices is very important because the overall costs, circuit size, reliability and control complexity are dependent on them directly. The proposed inverter can generate all desired current levels using a lower number of elements. Besides, it is known that reduction of number of switches from conventional inverters imposes an undesired increase in total semiconductor device power (SDP). But, the total SDP of the proposed inverter is kept equal to conventional inverter. To validate the superiority of the proposed inverter, a full comparison is provided. Also, the computer simulation and experimental results are presented.     

Optimal planning of distributed generation from the DisCo and the DGO viewpoints considering the uncertainties in future demand and electricity price

Since electricity demand is increasing continuously, it is necessary to invest in expansion of distribution network capacity. From the asset management point of view, it is necessary to encourage the private sector to invest in distribution network. To do this, distribution network managers must provide important opportunities for private sector to profit from their investments. One of the options for private sector is to invest on distributed generations (DGs). In this regard, distribution company (DisCo) must sign power purchase agreement (PPA) with DG owners (DGOs). So, optimal siting, sizing and PPA rates from economic point of view are important challenges which are considered as the main contribution of this paper. The proposed methodology of this paper applies load and price uncertainties into the planning problem. The proposed scheme involves using non-dominated sorting genetic algorithms II (NSGA II), since it attains non-dominated solutions in which DisCo and the DGO can put their personal preferences into practice. To evaluate the effectiveness of the suggested method, the computer simulations are done on a 33-bus distribution network and the results are discussed.     

Selective harmonic elimination method for wide range of modulation indexes in multilevel inverters using ICA

Selective harmonic elimination（SHE） in multilevel inverters is an intricate optimization problem that involves a set of nonlinear transcendental equations which have multiple local minima. A new advanced objective function with proper weighting is proposed and also its efficiency is compared with the objective function which is more similar to the proposed one. To enhance the ability of the SHE in eliminating high number of selected harmonics, at each level of the output voltage, one slot is created. The SHE problem is solved by imperialist competitive algorithm（ICA）. The conventional SHE methods cannot eliminate the selected harmonics and satisfy the fundamental component in some ranges of modulation indexes. So, to surmount the SHE defect, a DC-DC converter is applied. Theoretical results are substantiated by simulations and experimental results for a 9-level multilevel inverter. The obtained results illustrate that the proposed method successfully minimizes a large number of identified harmonics which consequences very low total harmonic distortion of output voltage.     

A Location Privacy-Preserving Method for Spectrum Sharing in Database-Driven Cognitive Radio Networks

The great attention to cognitive radio networks (CRNs) in recent years, as a revolutionary communication paradigm that aims to solve the problem of spectrum scarcity, prompts serious investigation on security issues of these networks. One important security concern in CRNs is the preservation of users location privacy, which is under the shadow of threat, especially in database-driven CRNs. To this end, in this paper, we propose a Location Privacy Preserving Database-Driven Spectrum-Sharing \((\hbox {L-PDS}^2)\) protocol for sharing the spectrum between PUs and SUs in a database-driven CRN, while protecting location privacy of both primary and secondary users, simultaneously. We also present two specific algorithms as implementations of \(\hbox {L-PDS}^2\) protocol. Our analytical results for the privacy protection capability of \(\hbox {L-PDS}^2\) protocol prove that it provides location privacy preservation with very high probability for users of both networks. Moreover, the simulation results show that the proposed algorithms are efficient in terms of run time.     

Optimal planning of distributed generation with application of multi-objective algorithm including economic,environmental and technical issues with considering uncertainties

This paper proposes a stochastic multi-objective model for integration of distributed generations (DGs) in distribution networks. The proposed model determines the optimal location and size of DGs by optimising different objective functions dependently and simultaneously subject to the operating constraints. If proper sizes of DGs are located in suitable sites and are also managed properly they can improve integrity, reliability and efficiency of the system. Regarding the widespread impact of uncertainties, some strategies must be devised in order to incorporate them well into power system modelling and hence achieve the best possible strategy to be adopted which its characteristics keep closer to reality. The most important uncertainties in network planning are load forecasting and market price errors. The proposed scheme is solved using non-dominated sorting genetic algorithms II, allowing the distribution company (DisCo) to exercise his/her personal preferences. To validate the effectiveness of the proposed scheme, simulations are carried out on a 33-bus distribution network and finally the attained results are discussed.     

Detecting relay attacks on RFID communication systems using quantum bits

RFID systems became widespread in variety of applications because of their simplicity in manufacturing and usability. In the province of critical infrastructure protection, RFID systems are usually employed to identify and track people, objects and vehicles that enter restricted areas. The most important vulnerability which is prevalent among all protocols employed in RFID systems is against relay attacks. Until now, to protect RFID systems against this kind of attack, the only approach is the utilization of distance-bounding protocols which are not applicable over low-cost devices such as RFID passive tags. This work presents a novel technique using emerging quantum technologies to detect relay attacks on RFID systems. Recently, it is demonstrated that quantum key distribution (QKD) can be implemented in a client–server scheme where client only requires an on-chip polarization rotator that may be integrated into a handheld device. Now we present our technique for a tag–reader scenario which needs similar resources as the mentioned QKD scheme. We argue that our technique requires less resources and provides lower probability of false alarm for the system, compared with distance-bounding protocols, and may pave the way to enhance the security of current RFID systems.

     

Time domain single-phase reclosure scheme for transmission lines based on dual-Gaussian mixture models

The basic principle of new adaptive reclosures are to first identify whether a fault is transient or permanent and consequently to determine the reclosing moment. In this paper a novel method to enhance self-adaptive single phase autoreclosure of transmission lines is presented. Using Gaussian Mixture Models (GMM) the redundancy of setting the threshold is omitted. The proposed algorithm could prevent closing command in permanent faults and adapt dead time in temporary events. The method is derived by processing line terminal voltage around the period of dead time. The proposed scheme uses two sampled windows from the inception of the fault and two groups of GMM. Simulations performed in EMTP/ATP environment advocate the validity of the proposed algorithm convergence speed as well as fast and accurate protection scheme for reclosing relaying. The design of GMM is easy and the relative factors of the structure elements can be regulated due to the desirable effects. Since the discrimination method is done with stochastic characteristics of signals in time domain without application of any deterministic index, more reliable and accurate classification is achieved.     

Resilience-oriented distribution network optimal planning to improve the continuity of power supply

ABSTRACT

A widely dispersed asset, electric grid has enormous impacts on people’s lives. Recently occurred various high-impact low-probability (HILP) threats have raised the concerns about the classical reliability-oriented view. Therefore, withstanding unexpected and less frequent severe situations still remain a significant challenge. As a critical infrastructure (CI), power systems are more and more expected to be resilient to HILPs. So, utilities put their endeavours to harden enough their networks against HILPs. In this regard, there is a great need to a methodology able to optimise the hardening programme investments. This scheme could potentially save a large amount of money, as well as increase the resilience of the programme. So, this paper is organised to provide a comprehensive study on optimal resilient planning of distribution networks aiming to find an optimal solution for simultaneous optimal feeder routing problem and substation allocation, finding types of installed conductors and cost-effective hardening of the lines considering the deliberate attacks on urban CIs, costs and operational parameters in normal and resilient modes of distribution networks. Voltage limitation and thermal limit of feeders are modelled using fuzzy set theory. To validate the effectiveness of the proposed scheme, simulations are carried out on a relatively large-scale distribution network.     

Improved configuration for symmetric and asymmetric multilevel inverters with reduced number of circuit devices

In this paper, a topology developed for multilevel voltage source inverters is proposed. The suggested modular configuration consists of several series-connected units, which can be applied as symmetric and asymmetric inverters. In the asymmetric mode, different solutions are suggested to generate an increased number of output voltage levels. In multilevel inverters, the number of required circuit elements determines the total cost, circuit size, installation area, complexity of control scheme and reliability of the inverters. The comparison study among the proposed inverter by considering all the presented algorithms for it, cascaded H-bridge (CHB) inverter and recently proposed converters, confirms that the proposed inverter uses a reduced number of circuit elements. In order to show the practicability of the proposed converter, a prototype of the proposed structure is implemented and tested. The simulation and experimental results are in good agreement with each other, indicating the effectiveness of the proposed inverter.