In the electrical power system, the coordination of directional overcurrent protection relays (DOPR) plays a preeminent role in protecting the electrical power system with the help of primary and back up protection to keep the system vigorous and to avoid unnecessary interruption. The coordination between these relays should be pursued at optimal value to minimize the total operating time of all main relays. The coordination of directional overcurrent relay is a highly constrained optimization problem. The DOPR problem has been solved by using a hybridized version of particle swarm optimization (HPSO). The hybridization is achieved by introducing simulated annealing (SA) in original PSO to avoid being trapped in local optima and successfully searching for a global optimum solution. The HPSO has been successfully applied to five case studies. Furthermore, the obtained results outperform the other traditional and state of the art techniques in terms of minimizing the total operating of DOPR and convergence characteristics, and require less computational time to achieve the global optimum solution.

The hybridization of PSO for the Optimal Coordination of Directional Overcurrent Protection Relays (DOPR) of the IEEE bus system proposes a new method for coordinating directional overcurrent protection relays in power systems. The method combines the hybrid particle swarm optimization (HPSO) algorithm and a heuristic PSO algorithm to find the minimum total operating time of the directional overcurrent protection relays with speed and accuracy. The proposed method is tested on the IEEE 4-bus, 6-bus, and 8-bus systems, and the results are compared with those obtained using traditional coordination methods. The collected findings suggest that the proposed method may produce better coordination and faster operation of DOPRs than the previous methods, with an increase of up to 74.9% above the traditional technique. The hybridization of the PSO algorithm and heuristic PSO algorithm offers a promising approach to optimize power system protection.

The use of a directional overcurrent protection relay (DOPR) to protect an electrical power system is a crucial instrument for keeping the system dynamic and avoiding undue interruption. The coordination of a DOPR’s primary and backup relays is modelled as a highly constrained optimization problem. The goal is to determine an ideal value that will reduce the overall working time of all primary relays. The coordination is accomplished by the use of particle swarm optimization hybridization (HPSO). Comprehensive simulation experiments are carried out to evaluate the efficacy of the proposed HPSO by employing the time multiplier setting (TMS) and plug setting (PS) as an optimization variable and constant, respectively. The HPSO has been examined satisfactorily utilizing certain IEEE benchmark test systems (9-bus and 14-bus). The outcomes are contrasted with earlier heuristics and evolutionary approaches. Based on the acquired findings, it is clear that the obtained results exceed the other conventional and state of the art procedures in terms of total DOPR operation and the computing time necessary to achieve the global optimal solution.

This paper presents a novel two arbiter groups based stochastic time-to-digital converter (STDC) to achieve a better linearity and larger measurement range compared to a traditional STDC. Traditional STDCs with one arbiter group have a bad linearity and narrow measurement range, for the nonlinear time-to-digital transfer function that described by a Gaussian cumulative distribution function (CDF). To improve the linearity, a basic two arbiter groups based STDC is proposed firstly. Through properly shifting the time offset distributions of the two arbiter groups away from each other by applying a global time offset reference to them, a virtual uniform distribution could be formed between the two shifted time offset mean values. To achieve a large measurement range, a dual-input dual-output periodic signal generator (DIDO-PSG) and a global time offset setting circuit (GTOSC) are further designed for the proposed STDC to obtain two pairs of time offset distributions with twice measurements for one input time interval. Through properly setting the mean values of the four time-offset distributions based on GTOSC, an overall transfer function with a large linear part that contributes to a good linearity could be achieved. Finally, a test chip prototype fabricated in a 0.18-μm CMOS technology demonstrates 550-fs time resolution and 0.105-ns measurement range with –1.81 LSB INL at 50MS/s, which is much better than traditional STDCs.

Nested oversampling successive approximation (Nested-OSA) technique is proposed in this paper. This technique provides enhancement in the effective accuracy of the readout circuit for microelectromechanical systems (MEMS) capacitive accelerometer. The readout circuit with Nested-OSA technique contains a main switchedcapacitor amplifier which achieves capacitance-to-voltage conversion and an auxiliary switched-capacitor amplifier which suppresses the “holding error” appears in OSA process. The approach reduces the DC gain error and DC offset of amplifier to 4-order infinitesimal and 2-order infinitesimal. The charge injection and dynamic settling process of the Nested-OSA readout circuit are explained in detail. Theoretical analysis and simulations show that the suppression of gain error and offset of readout circuit using the Nested-OSA technique can be achieved while consume relatively low power.

采用射频磁控溅射法在玻璃衬底上制备出锑掺杂的氧化锡（SnO22:Sb）薄膜.制 备薄膜是具有纯氧化锡四方金红石结构的多晶膜薄，晶粒生长的择优取向为［110］.室温下光致发光测量结果表明，在392nm附近存在强的紫外-紫光发射.研究了不同氧分压对薄膜结构及发光性质的影响，并对SnO22:Sb的光致发光机制进行了探索性研究.