Enhancement of flexibility in multi-energy microgrids considering voltage and congestion improvement: Robust thermal comfort against reserve calls

In recent years, multi-energy microgrid (MEM) has gained increasing interest, which could use clean and efficient electro-thermal resources, multi-energy storages (MESs) and demand response potential to improve the flexibility of MEM. However, maximizing the flexibility potential of MEM and alongside managing the electrical parameters (EPs) is a challenging modeling problem. In this paper, a probabilistic nonlinear model is presented to maximize the flexibility with all the power grid constraints taking into account EPs constraints using power flow. To this end, voltage profile and congestion improvement, robust thermal comfort provision during reserve call and MESs utilization are the key properties of the proposed model. The outcome of suggested model ensures sustainability in the MEM performance, which is an essential feature in modern smart cities. The presented model is applied to a distribution network in the UK and results illustrate how equipment scheduling and demand response leads to observe the EPs limitation and maximizes MEM flexibility. The achieved results show a decrease in MEM revenue (decrease of 34% and 24% without and with reserve commitment, respectively) and in contrast, a significant increase in flexibility compared to non-compliance with EPs constraints

Modeling of solid waste collection and transportation in metropolitan areas using WAGS model: implication of CO2 emission and external costs

Annually more than 80% of the overall budget of the uran solid waste management system in Iran is allotted to collection and transportation of the solid wastes. The main objective of the current study is to evaluate the external costs associated with solid waste collection, transfer, and transportation in Tehran for the period of 2018 to 2032 based on the current situation. Waste guidance system as well as Energy and Environment software were applied to anticipate the external costs. Results of the present study indicated that more than 535 million US dollars would be required during the next 15 years in the solid waste collection, transfer, and transportation sector to supply necessary machinery, manpower, fuel, maintenance and other relevant expenses. The principal fraction of the required budget (i.e. 48.99%) should be allocated to provide collection and transportation equipment costs. Manpower, fuel, maintenance, and miscellaneous expenses require 30.34, 7.37, 12.78 and 0.5 percent, respectively of the overall expenses in the solid waste collection, transfer, and transportation sector. In the context of global warming impact, more than 970 million tons of carbon dioxide will be anticipated to be emitted by solid waste collection, transfer, and transportation sector in Tehran during the studied period imposing 23.1 million US dollars to compensate its external effects

Tuzlu Sularda Elektiriksel İletkenlik Ölçümünden Klor Tahmini

Sulamada yüksek konsantrasyonlarda bitki üzerinde toksik etki oluşturan tuzluluk değerlendirmesi, elektriksel iletkenlik ve klor iyon ölçümlerini içermektedir. Elektriksel iletkenlik ölçümü klor belirlenmesinden daha kolay olduğu için bu çalışmanın amacı, İran’ın batısındaki yer altı sularında klor iyon konsantrasyonu ile elektriksel iletkenlik arasındaki deneysel ilişkiyi belirlemektir. Su örneklerinin büyük miktarı 1063 laboratuvar ve 2252 tarla örneği İran’ın batısındaki 66000 km2’lik alandan toplanmıştır. Elektiriksel iletkenlik bir iletkenlik hücresiyle, Cl- iyonu konsantrasyonu da AgNO3çözeltisi ile titrimetrik olarak belirlenmiştir. Elde edilen veriler bitkinin tuza toleransına göre EC değerleri dikkate alınarak gruplandırılmıştır. Bunlara linear, polinominal ve power regresyon modelleri uygulanmıştır. Uygulamada 3315 örneğe ait değerlerin hepsi kullanılmıştır. Uygulanan her 3 regresyon modelinde EC değeri ile Cı değerleri arasında oldukça önemli düzeyde %99 ilişki bulunmuştur. Aynı zamanda farklı grupların verileri için diğer modeller geliştirilmiştir. Sonuç olarak EC değeri 3 dsm-1 den küçük olanlar dışında EC ile su örneklerindeki Cl- konsantrasyonu arasında iyi bir uyumluluk ve korelasyon olduğu kanısına varılmıştı

Zitterbewegung in External Magnetic Field: Classic versus Quantum Approach

We investigate variations of the Zitterbewegung frequency of electron due to an external static and uniform magnetic field employing the expectation value quantum approach, and compare our results with the classical model of spinning particles. We demonstrate that these two so far compatible approaches are not in agreement in the presence of an external uniform static magnetic field, in which the classical approach breaks the usual symmetry of free particles and antiparticles states, i.e. it leads to CP violation. Hence, regarding the Zitterbewegung frequency of electron, the classical approach in the presence of an external magnetic field is unlikely to correctly describe the spin of electron, while the quantum approach does, as expected. We also show that the results obtained via the expectation value are in close agreement with the quantum approach of the Heisenberg picture derived in the literature. However, the method we use is capable of being compared with the classical approach regarding the spin aspects. The classical interpretation of spin produced by the altered Zitterbewegung frequency, in the presence of an external magnetic field, are discussed.Comment: 16 pages, no figure

Investigationon power quality problems of electrical substations feeding CNG stations in Iran

Power quality characteristics of Electrical substations feeding CNG stations as nonlinear and time variant loads which cause high amount current and power variations and low power factor for their feeding power systems are investigated. The power quality characteristics of the substation are verified through experimental measurements with the help of power quality measurement instruments. In addition, the application of an efficient static var compensator in the structure of TCR-FC has been proposed for voltage fluctuation reduction, reactive power compensation and power factor improvement. Through the simulations done with Matlab-Simulink the efficiency of the proposed SVC is verified

A flexible approach for overcurrent relay characteristics simulation

Accurate models of overcurrent (OC) with inverse time relay characteristics play an important role for the coordination of power system protection schemes. This paper proposes a new method for modelling OC relays curves. The model is based on fuzzy logic and artificial neural network. The feedforward multilayer perceptron neural network is used to calculate the operating times of OC relays for various time dial settings (TDS) or time multiplier settings (TMS). The new model is more accurate than traditional models. The model has been validated by comparing the results obtained from the new method with linear and nonlinear analytical models

Evaluation of Moving Average Window Technique as Low-pass Filter in Microprocessor-Based Protecting Relays

Over the last decades, with the increase in the use of harmonic source devices, the filtering process has received more attention than ever before. Digital relays operate according to accurate thresholds and precise setting values. In signal flow graphs of relays, the low-pass filter plays a crucial role in pre-filtering and purifying waveforms performance estimating techniques to estimate the expected impedances, currents, voltage etc. The main process is conducted in the CPU through methods such as Man and Morrison, Fourier, Walsh-based techniques, least-square methods etc. To purify waveforms polluted with low-order harmonics, it is necessary to design and embed cutting frequency in a narrow band which would be costly. In this article, a technique is presented which is able to eliminate specified harmonics, noise and DC offset, attenuate whole harmonic order and hand low-pass filtered signals to CPU. The proposed method is evaluated by eight case studies and compared with first and second order low-pass filter

CW_min Estimation and Collision Identification in Wi-Fi Systems

Wi-Fi networks are susceptible to aggressive behavior caused by selfish or malicious devices that reduce their minimum contention window size (CWmin) to below the standard CWmin. In this paper, we propose a scheme called Minimum Contention Window Estimation (CWE) to detect aggressive stations with low CWmin’s, where the AP estimates the CWmin value of all stations transmitting uplink by monitoring their backoff values over a period of time and keeping track of the idle time each station spends during backoff. To correctly estimate each backoff value, we present a cross-correlation based technique that uses the frequency offset between the AP and each station to identify stations involved in uplink collisions. The AP constructs empirical distributions for the monitored backoff values and compares them with a set of nominal PMF’s, created via Markov analysis of the DCF protocol to estimate CWmin of various stations. After detecting the aggressive stations, the AP can choose to stop serving those stations. Simulation results show that the accuracy of our collision detection technique is 96%, 94%, and 88% when there are 3, 6, and 9 stations in the WLAN, respectively. For the former WLAN settings, the estimation accuracy of CWE scheme is 100%, 98.81%, and 96.3%, respectively