Control of WPT Transmitter Coils for Power Distribution to Two Receiver Coils without Feedback

This paper proposes the algorithm to control the current ratio of the transmitting (Tx) coils for proper power distribution to the two receiving (Rx) coils in wireless power transfer (WPT) system. The proposed algorithm assumes that each Rx coil appears at different times to consider the situation where multiple users request power transmission as practically as possible. That is, suppose the second Rx coil enters the charging space later than the first Rx coil. When each coil enters the charging space, only the Tx coil is used to obtain the value required for calculation. Using the obtained result, the optimized Tx coil current is calculated by the proposed algorithm and proper power distribution to both Rx coils is achieved. Three Tx coils and two Rx coils are constructed using the ANSYS MAXWELL simulation tool. As a result of applying the proposed algorithm, it was confirmed that a similar level of power was transmitted between 40∼60%, respectively. The sum of the power transmitted to the two Rx coils also appeared as more than 75%.

Wind Farm Power Optimization and Fault Ride-Through under Inter-Turn Short-Circuit Fault

Inter-Turn Short Circuit (ITSC) fault in stator winding is a common fault in Doubly-Fed Induction Generator (DFIG)-based Wind Turbines (WTs). Improper measures in the ITSC fault affect the safety of the faulty WT and the power output of the Wind Farm (WF). This paper combines derating WTs and the power optimization of the WF to diminish the fault effect. At the turbine level, switching the derating strategy and the ITSC Fault Ride-Through (FRT) strategy is adopted to ensure that WTs safely operate under fault. At the farm level, the Particle Swarm Optimization (PSO)-based active power dispatch strategy is used to address proper power references in all of the WTs. The simulation results demonstrate the effectiveness of the proposed method. Switching the derating strategy can increase the power limit of the faulty WT, and the ITSC FRT strategy can ensure that the WT operates without excessive faulty current. The PSO-based power optimization can improve the power of the WF to compensate for the power loss caused by the faulty WT. With the proposed method, the competitiveness and the operational capacity of offshore WFs can be upgraded.

A Study on the Power Reserve of Distributed Generators Based on Power Sensitivity Analysis in a Large-Scale Power System

Converter-based generators (CBGs) that use renewable energy sources (RESs) are replacing traditional aging coal and nuclear power generators. Increasing the penetration of CBGs into the entire power generation process reduces both the inertia constant of the power system and the total amount of power reserves. Additionally, RESs are very intermittent and it is difficult to predict changes in them. These problems, due to CBGs using RESs, pose new challenges to net–load balancing. As a solution, this paper proposes a virtual multi-slack (VMS) droop control that secures the stability and efficiency of system operation by controlling the output of CBGs distributed in various regions. The VMS droop control makes it possible to increase the inertia constant of the power system and to respond quickly and appropriately to load changes through the proposed VMS droop control based on power sensitivity. It is also proposed that the process selects proper power reserves of CBGs for stable VMS droop control. To verify the effectiveness of the proposed VMS droop control and the proper power reserve selection method for CBGs, several case studies were performed using a real Korean power system.

Conformable chebyshev differential Equation of first kind

In this paper, the Chebyshev-I conformable differential equation is considered. A proper power series is examined; there are two solutions, the even solution and the odd solution. The Rodrigues’ type formula is also allocated for the conformable Chebyshev-I polynomials.

Challenges and Solutions on Interference Management in D2D System of Cellular Network

A single bidirectional link is used to allow communication between two devices in the device-todevice (D2D) communication system. D2D technology has to implement with the current cellular system. As both users D2D and cellular use the same licensed spectrum for transmission the chances of interferences increases. It is challenging for researchers to find out the proper mechanism to decrease interference and maximize performances. In this paper, we try to survey the challenges and their solutions to enable D2D communication in the cellular network with low interference. Here we describe the peer discover, mode selection process and interference management with power control and resource allocation. Finally, we can say that with proper power control, spectrum slicing and resource allocation we can mitigate co-tier and cross-tier interferences.

An Islanded Microgrid Droop Control using Henry Gas Solubility Optimization

Coordination of various distributed generation (DG) units is required to meet the growing demand for electricity. Several control strategies have been developed to operate parallel-connected inverters for microgrid load sharing. Among these techniques, due to the lack of essential communication links between parallel-connected inverters to coordinate the DG units within a microgrid, the droop control method has been generally accepted in the scientific community. This paper discusses the microgrid droop controller during islanding using the Henry Gas Solubility Optimization (HGSO). The most important goals of droop control in the islanded mode of operation are the frequency and voltage control of microgrid and proper power sharing between distributed generations. The droop controller has been designed using HGSO to optimally choose PI gains and droop control coefficients in order to obtain a better microgrid output response during islanding. Simulation results indicate that the droop controller using HGSO improves the efficiency of micro-grid power by ensuring that variance in microgrid frequency and voltage regulation and effective power sharing occurs whenever micro-grid island mode or when variation in load occurs.

Nature’s Indifference

This chapter argues that in Spinoza’s philosophy, popular movements do not necessarily testify to an underlying popular power driving political life; nor is efficacious political power necessarily popular. First, it argues that a collectivity’s own proper power, its power sui juris, is not some underlying disposition waiting to be expressed, but rather is manifested in the actual effects it durably produces. Correspondingly, it is a mistake to take social movements challenging oligarchy as exemplars of the power of the people, unless and until they durably consolidate an egalitarian social order. Second, it argues that within Spinoza’s metaphysics, nonideal regimes may well endure, either due to the support of an external power, or from their own power, but where that power is internally structured in an oligarchic or repressive manner. In sum, Spinoza accepts Chapter 6’s first two Hobbesian problems, and acknowledges the all-too-common divergence between ethics and efficacy in politics.