The recent advances in high-power semiconductor technology have made control of electric power in transmission lines more reliable and faster. Nowadays, FACTS devices are used in power systems in controlling and compensation of transmission lines. These devices are based on semiconductor and electronic technology that have advantages over traditional controlling devices. UPFC is one of the most recent kinds of FACTS that are made up from two PWM converters, which share a single dc link. UPFC is a controlling device in power systems that can control three important parameters, namely, impedance, voltage and phase angle, simultaneously. In addition, it is widely used in harmonic compensation in power systems. In this paper, based on instantaneous power theory, a control strategy has been developed to improve UPFC operation for simultaneous harmonic compensation and power flow control. The two main features of the proposed control model are improvement of dynamic stability and reduction of interaction between real and reactive powers. The simulation results clearly show satisfactory performance of the proposed model.

This paper presents the results of design, simulation and implementation of static V AR compensator (STATCOM). The power circuit of this STATCOM consists of a three-phase voltage source inverter with IGBT switches. The control circuit is based on using instantaneous reactive power theory (pq theory) and the programming language is C. The simulation and experimental results show acceptable operation of STATCOM in compensation for instantaneous reactive power and achieving unity power factor in utility side.

The most important part in the suitable performance of the active power filter is possible by precise harmonic extraction of load current. Current harmonic extraction is possible in both time and frequency domain. However, time domain methods have higher speed and low complexity. One of the most popular methods in this field is the instantaneous power theory method but, the main problem is when the grid voltage is not ideal. Therefore, this paper provides a method based on the instantaneous power theory that shows very good performance with the least complexity of implementation in all grid voltage states, whether asymmetry, distorted, or both at the same time. To examine the performance of the proposed method, the three -phase filtration is simulated in the MATLAB/Simulink environment under different grid voltage conditions and finally the experimental results are provided in the laboratory environment. The results verify the effectiveness of the proposed method where the THD% is decreased from 25% to 5%..

instantaneous unit hydrograph (IUH) is a hydrograph that has used for calculation of direct runoff hydrograph in watersheds and recent addition to formal methods, Shannon entropy theory consider for calculation of direct runoff hydrograph. If the system disorderly is measured in terms of entropy then the probability distribution of the events, provides in terms of entropy. In this theory, defined travel time as a random variable, the maximizing the entropy on based this parameter and also specifies constraints, the least-biased probability density function, determining parameters of the IUH and finally obtaining applicable IUH equation. In this study, six events of Lighvan watershed has been studied that located in Northwest Iran. After calculating travel time and determining parameters on based entropy, derivation applicable IUH equation and calculated direct runoff hydrograph. For estimated and more evaluated IUH and direct runoff hydrograph has used Gamma distribution that result showed good accuracy of the entropy theory. The results indicate acceptable performance of the entropy model shows the average correlation coefficient (0.828), mean error of peak (17.35%), entropy index (2.47 knot) and nash-sutcliff value (NS=0.742) in verification events.

In this paper, a novel risk-based, two-objective (technical and economical) optimal reactive power dispatch method in a wind-integrated power system is proposed which is more consistent with operational criteria.  The technical objective includes the minimization of the new voltage instability risk index. The economical objective includes cost minimization of reactive power generation and active power loss. The proposed voltage instability risk employs a hybrid possibilistic (Delphi-Fuzzy)-probabilistic approach that takes into consideration the operator’s experience, the wind speed and demand forecast uncertainties when quantifying the risk index. The decision variables are the reactive power resources of the system. To solve the problem, the Modified multi-objective particle swarm optimization algorithm with sine and cosine acceleration coefficients is utilized. The method is implemented on the Modified IEEE 30-bus system. The proposed method is compared with those in the previously published literature, and the results confirm that the proposed risk index is better at estimating the voltage instability risk of the system, especially in cases with severe impact and low probability. In addition, according to the simulation results compared to typical security-based planning, the proposed risk-based planning may increase the security and economy of the system due to better utilization of system resources.

power transmission lines are vital components of today's power systems. These power lines transmit the electricity produced in power plants in high volume and with very low losses to distant areas so that it can be reached to consumer through distribution networks. In fact, these lines are the intermediary between major energy producers and distribution networks. Accordingly, these transmission lines are of a great importance and must be protected appropriately with a suitable protection system. Distance relays are widely used to protect these lines due to their convenient coordination characteristics and simplicity. High impedance fault (HIF) can be a critical challenge for distance relays due to their low current amplitude and similarity to conventional events in power systems such as capacitive bank switching. For this reason, in this paper a new approach is presented based on the instantaneous frequency variations obtained from the current RMS in order to detect the high impedance fault. This method detects high impedance faults via calculating a Detection index (DI) and considering a threshold value. The proposed method has been tested using DIgSILENT and MATLAB software in an IEEE standard 39-bus network. The presented results evidently demonstrate that the proposed method is suitable for detecting HIF and Low impedance fault (LIF). In addition, this method has a proper performance during capacitor bank switching and can well distinguish between HIF and capacitive bank switching. Moreover, the presented method is resistant to noise and also is capable to detect the faulty phase.

UPQC (Unified power Quality Conditioner) is an advanced custom power device, which can be used in the case that the load is non-linear and the system supply voltage is distorted simultaneously. It consists of a series and shunt Voltage Source Converter (VSC) whit a common DC link. The shunt VSC is mainly intended for conditioning the current flowing from a load into the network and series VSC is mainly used to protect sensitive loads against power quality problems caused by disturbances in supply system.  In this paper, a new control strategy for the UPQC is proposed. This control strategy is based on two different methods; the instantaneous power Balance Method and Synchronous Reference Frame Method. These two methods have been used earlier independently. Each of them has merits and demerits. To overcome their drawbacks, the instantaneous power balance methods have been applied to the shunt VSC and synchronous reference frame method has been applied to the series VSC of UPQC. The simulation results of UPQC in a typical distribution system, carried out by PSCAD/EMTDC, verify the performance improvement of UPQC. It is shown that using this combination of control strategy, the power quality problems in distribution systems can be solved easily.

Harmful impacts of oil whirl fault in sleeve bearing can be avoided by early detection of the fault. In this paper, after describing the oil whirl fault, an analytic approach is applied to determine frequency of the harmonics produced by the fault in instantaneous power waveform of induction motor. Then, using appropriate air gap function, winding function approach is used for simulating squirrel cage induction motor with bearing oil whirl fault. The instantaneous power spectrum, plotted using simulation results, approves creation of the proposed harmonics. These harmonics are also evident in instantaneous power of an induction motor that operates on oil pipe line, where vibration analysis shows presence of oil whirl fault in its bearing. Finally, the most appropriate harmonic as the oil whirl fault index is selected using simulation by considering their relative amplitudes as well as their sensitivity to the fault type, fault degree, motor load level and three-phase unbalance of the stator voltages.

Single phase grid-tied inverters are remarkably increasing in low-power applications such as residential and industrial power supplies. In the single phase system, the inherent ripple power at twice the line frequency results in undesirable low-frequency ripple in the dc-link voltage and output ac current. This issue can be eased through the installation of bulky electrolytic capacitors in the dc link. However, such passive filtering approach may inevitably lead to limited system lifetime and reliability. To overcome these problems, auxiliary power decoupling methods are used to reduce the size of the electrolytic capacitor and replace it with film capacitor. In this paper, By introducing a shunt switching compensator (SSC) and exploiting instantaneous power theory (pq theory), the size of the required capacitance remarkably decreased. The proposed controlling system, based on the Modified pq theory and single-phase modeling, was similar to a three-phase unbalanced system regarding the structure. The system simulation was according to the 3Kw photovoltaic system used at the Birjand University. The simulation results verify the proposed power decoupling technique. At the end, a cost comparison between the proposed structure and prevalent structure is also done.

One of the factors that can be the link between our intentions and actions and their external consequences is human agency, which indicates the conscious design and intentional execution of actions by the individual in order to influence future events.Objective and Method: This research with a developmental approach of psychometric method and method 1, examines the psychometric indices of the Human Factor Characteristics Scale using the classical theory of test score measurement and the graduated question-answer theory. The purpose of this study, which included high school students in Tehran, was selected by cluster sampling of 500 people as a sample size and statistical analysis was performed on 481 data. To collect the data, the ion Human Agent Characteristics Scale (2011) was used and the research questions were evaluated using IRTPRO and SPSS software.Results:The assumption of local independence based on Pearson x2 index was established by applying Simjima's calibrated question-answer theory and the assumption of being one-dimensional based on the analysis of multidimensional question-answer theory. Diagnosis parameters with question-answer approach and classical approach Test score Both item 25 approach had the lowest and item 2 had the highest diagnosis parameter. The answer thresholds for all the questions were so far apart that no option was covered by the other option, and the options were independently selected by individuals at intervals of theta. The total scale was calculated with Cronbach's alpha of 0.945, intentionality of 0.894, foresight of 0.780, self-reactivity of 0.871 and rethinking of 0.762. Also, the role of each item in internal consistency was investigated by the loop method, which all questions had a favorable role in internal consistency of this scale. The value of the validity coefficient obtained from the question-answer theory was obtained by marginal method for intentionality 0.92, forethought 0.85, self-reaction 0.91, rethinking 0.83..