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In this article, a 2.5m five-stage inductive power transfer (IPT) system based on domino cylindrical solenoid coupler (CSC) compensated, respectively, in layers is proposed. The system is considered to be used as 220 kV post insulators application, transferring power for sensors and measuring instruments of smart grids. The distributed series compensation method is applied to double-layer CSC. Compared with the two types of parallel schemes, this method can significantly reduce the current of the main circuit. Compared with the concentrated series compensation method, this method can effectively reduce the resistance caused by the stray capacitance. The interaction between the post insulator and the magnetic coupling structure is analyzed. The circuit model of the system with constant voltage output characteristics is analyzed. A prototype with a maximum efficiency of 66.7% is built. When the power is transferred to a larger value of 77.8W, the efficiency can still reach 62%. Comparing with previous works, the wireless distance is extended while the efficiency is improved. [ABSTRACT FROM AUTHOR]

With the emergence of the multicore architecture and the increase of chip operating frequency, power optimization has become a key step of circuit logic synthesis. Aiming at the XNOR/OR circuits, with the goal of minimizing power, construct the optimal polarity fixed-polarity Reed–Muller (FPRM) circuits power optimization scheme. However, the power optimization for FPRM circuits is a multipeak combinatorial optimization problem, we first propose a metaheuristic optimization algorithm (MOA), which includes the global exploration optimizer, local deep exploitation optimizer, and initial population and uses the proposed differential evolution optimization, fierce wolf siege algorithm-based tabu search, and improved skew tent map to make the population evolve. Based on the proposed Huffman tree construction algorithm and MOA, we propose an efficient power optimization approach (EPOA) to find the minimum power FPRM circuit. Experimental results on the benchmark circuits confirm the effectiveness of EPOA. [ABSTRACT FROM AUTHOR]

In this article, a shielding scheme based on ferrite magnetic antennas (SS-FMA) is proposed. The scheme can effectively provide a path for the magnetic field lines of three-dimensional couplers to be concentrated and conducted. The SS-FMA is considered to be applied for long range inductive power transfer (IPT) systems of post insulators to powering smart grid sensors and improve the efficiency under the influence of metal components. The negative influence of the aluminum flanges on the magnetic field distribution is analyzed. The suppression effects of the shielding scheme on the abovementioned influence have been analyzed. Parameters of the SS-FMA are optimized. The equivalent circuit model is established, and the abovementioned process is explained from the perspective of the circuit model. A prototype of a post insulator that includes IPT system and SS-FMA has been built. When the coils of the IPT system are attached to the flanges, the efficiency can still reach 47.8% under the influence of SS-FMA, which is an increase of 13.7% compared with no shielding scheme. When the coils are slightly away from the flanges, efficiency of the system including SS-FMA can be quickly improved to 54.3%. [ABSTRACT FROM AUTHOR]

Due to environmental concerns, renewable energy sources (RESs) gradually replace conventional power generations. Over the past decade, wind and solar electricity generation have increased from 55 to 275 million MW·h and from 2 to 96 million MW·h, respectively, in the U.S. Recently, FERC order 2222 allows distributed energy resources, including distributed renewable generation and energy storage, to participate in the electricity wholesale market through aggregations. Limited rotating inertia of renewable generation resources results in reduced system inertia, which will increase the rate of change of frequency due to sudden mismatches of generation and demand. During the high visibility national social event, the brightness of LED TV display put simultaneous demand change in power systems. With the development of slim, tightly packaged, and yearly update features of smart TV, the penetration of different LED displays climbed rapidly from 9% to 60% in the U.S. during 2012–2019. In this article, the impact of societal events on frequency stability caused by large viewership on LED TVs are discussed. Increasing RESs penetration and FERC order 2222 are considered in this study. The power demand data of a 55-inch LED TV are collected and analyzed to address the problem. This article discusses the frequency stability issue caused by LED TVs in a low inertia power system. It can help system operators to develop frequency control practices accordingly. [ABSTRACT FROM AUTHOR]

Frequency scanning is a powerful and versatile approach for subsynchronous resonance (SSR) screening in power grids. Among different numerical and analytical frequency scanning techniques, the harmonic injection method is well suited for the scan of black-box models with active elements, such as in wind farms and solar plants. The results can be used for SSR risk assessment, in which accuracy performs a decisive role. The ideal situation for this method, which leads to the most accurate results, is to perform one simulation per single-frequency injection. However, for SSR studies with a wide range of frequencies and simulations with very small time steps (scale of μs), this comes at the expense of increased simulation time. This article proposes a technique to improve the accuracy of the harmonic injection method through the optimization of the crest factor while injecting all frequencies at one shot, therefore also reducing simulation time. The proposed technique was tested on a wind farm connected to a radial test case and on a portion of a Texas synthetic grid with multiple active elements, including two wind farms and a VSC-based STATCOM. The frequency scan results were benchmarked with both time-domain transient simulations and the ideal multiple single-frequency injection case and compared with other techniques. The results show that the proposed method is superior in accuracy when compared to the other techniques and is 11.71 times faster when compared to multiple single-frequency injections. [ABSTRACT FROM AUTHOR]

As one of the most promising renewable energy resources, a large amount of wind energy has been implemented all around the world since 1990s. Increasing the size of the wind turbines and the harsh operating environment lead to the higher failure rates on the wind turbines compared with the other renewable resources. As a result, not only unplanned maintenance and repairments increases but also the downtime of the wind turbine increases the operational cost significantly. In addition, the long-distance transmission lines are required to transfer the wind generation power to the load centers due to the remote operation location of the wind farms. To improve the power transfer capability, the series-compensated lines are adopted in many cases. However, subsynchronous control interactions (SSCI) could happen between the series-compensated transmission lines and the wind turbines. This may damage the wind turbine components severely and cause stability issues in the power grids. Currently, various condition monitoring systems have been developed and applied for the wind turbines. Different SSCI detection mechanisms are also proposed in many studies. This article proposes a field-programmable gate array CPU-based holistic monitoring system which not only provides both condition and SSCI monitoring functions simultaneously in real time but also records the necessary data for the postevent analysis. [ABSTRACT FROM AUTHOR]

The demand side management (DSM) has been conceived to improve the efficiency and flexibility of the power grids. Currently, different types of DSM programs, such as demand response, the efficiency of power delivery, heating, ventilation, and air conditioning (HVAC) improvements and distributed energy storage, have been developed and implemented by different utility companies. Since DSM is not a one-size-fit-all program, detailed consumers’ consumption data are required to both develop and improve effective DSM programs for different consumers. The rapid expansion of the advanced metering infrastructure in recent years has produced an enormous amount of data which can be utilized by utility companies for the DSM applications. Based upon the consumption characteristics of different types of consumers, various DSM programs can be developed and applied accordingly. This article analyzes and studies the practical smart meter data of commercial consumers from New York City considering the potential of commercial consumers’ participation for DSM applications, and it provides a better understanding of the power consumption pattern of commercial consumers in the urban area. Both utility companies and commercial consumers could benefit from this article to develop and participate in DSM programs, respectively. [ABSTRACT FROM AUTHOR]