Electromechanical damping system is essential to ensure acceptable performance. However, when an error occurs in the transmission system, power transmission lines and buses voltage fluctuated severe, To eliminate the fluctuations in the power system stabilizer (PSS) is used to optimize the overall system performance, the problem of PSS parameters to an onlinear optimization problem with the objective function of the proposed conversion and optimization algorithms using Cuckoo (COA) and the cuckoo search algorithm (CS) optimization problem is solved. Stabilizers are adjusted so that the active power oscillations in the transmission system are considerably reduced. PSS parameters in network design and simulation of four standard generators under different working conditions are evaluated and analyzed. By comparing the results of the two algorithms in the network, COA efficiency and excellence in sustainable building several power generator system to the CS algorithm is proved.

In this paper, a novel structure based on Bridgeless AC/DC Converters for BLDC Motor is proposed. For now, to drive this kind of dc motors, step down and step up converters and converters with capability of increase and decrease in output voltage with bridgeless diode structures are presented. In this paper by using a novel structure, this possibility is provided to have a converter that can work in desired and separate states such as buck, boost or buck boost operations. In this paper focus will be upon buck-boost operation to access appropriate usage of both decrease and increase at output voltage advantages. Also this converter would not need to a diode bridge at primary of circuit. At output of this converter only a dc-link capacitor exists, that it will decrease the need of electrolytic capacitors that result to decreased circuit volume and cost. Removing of input diode bridge and input dc-link capacitor has caused to a better quality of input current waveforms. As well as, power factor for input power supply of this converter will work near to unit amounts.

Downlink channel estimation of Massive MIMO is an important challenge is 5G wireless communication.  A classic method for this purpose is training-based method which leads to decreasing in transmitted information rate. To cope with this problem, recently, a blind channel estimation method has been presented in which by assuming that the value of large scale fading coefficient is known, the channel gain is estimated in multiuser Massive MIMO system. In this paper, we propose a new method that simultaneously estimates both channel gain and large scale fading coefficient by applying two different power control gain in the coherence interval. The proposed method is applicable for ZF and MR precoding. The proposed method has higher transmitted information rate (does not need to transmit the large scale fading coefficient) and lower MSE in high SNR values with respect to reference method.

Conventional Off-Line (50-60Hz) light emitting diode (LED) drivers usually need an electrolytic capacitor to reduce power imbalance between ac input and dc output, and to decrease the low-frequency component of the output ripple. However, electrolytic capacitor is the key component which limits the lifespan of LED driver. If a driver uses a pulsating output current, the electrolytic capacitor can be omitted. This paper proposes a high power factor LED driver with high frequency pulsating driving current, in which electrolytic capacitor has omitted from the topology. The driver has two outputs that allow the number of driving LEDs to increase, an LED string will be connected to each output and a single switch is used in series with each LED string, thus the number of switches is equal to the number of outputs. Output and Storage capacitor voltages are sensed and used to implement the control method to regulate the output current. Low cost and high efficiency can be obtained due to the power structure and the proposed control method. Simulations, calculations and experimental results are provided for the proposed circuit.

A novel current source multilevel inverter is introduced in this paper which is an appropriate alternative to be employed for low/medium power applications. the proposed converter is formed basic modules which paralleling these modules increse output current levels and improve quality of injected current to load or grid. in order to validate advantages of proposed converter versus the several multilevel current source inverters, a full comparison is provided. the simulation results shows the good performance of the proposed converter in off grid and grid-connected applications. Also experimental results for single-phase load confirm the practicablity of the proposed converter.