Advanced Materials Research Vols. 960-961

Abstract: A measurement system used for step response of impulse voltage dividers has been designed. This software can be used for various kinds of step response waveforms and can calculate them accurately. The calculation methods used in this system are in full compliance with the requirements in DL/T992-2006 and IEC60060-2. When the software used for the step response of impulse divider,the calculation results meet the requirements of stepwave response parameters with good accuracy. This software is simple to calculate and it can greatly enhance the efficiency of the step response parameter extraction calculations.

Abstract: The simulation of glow discharge in N₂ in a needle-plane configuration with PIC/MCC method is presented. In the discharge channel the electric field driven by space charges is solved by PIC method, and various collisions between particles are described with MCC method. The electric field intensity, the electric potential and the net charge distribution in the discharge area are obtained. The numerical results are consistent with the corresponding features of glow discharge. This work can provide references to further study of glow discharge.

Abstract: The actual engineering control systems are nonlinear [1-2] and uncertainty [3-4] at the same time, so the robustness and fault diagnosis of systems are more meaningful [5-6]. Sometimes the system is with switching characteristics, which makes the study of switched systems more meaningful. As one of the nonlinear systems, switched systems exist in the practical systems widely, and the phenomenon of delay exists in industrial control nature, or in the life of people widely [7-8]. So the fault diagnosis research [11-12] of nonlinear switched systems with time-delay [9-10] has attracted the attention of many scholars. Motivated with the above issues, the general form of a class of switched systems with time-delay is described in detail, which also mentioned lemma 1 (Schur complement lemma) and lemma 2, the two lemmas will be applied to the proof process of the conclusion. The core part is observer design for time-delay systems fault, which puts forward the uniformly bounded stable condition of fault estimation error system expressed as the linear matrix inequality, and Lyapunov stability is applied to the strict proof. At last, the simulation of MATLAB in a numerical example proved the validity of the conclusion.

Abstract: Aiming at the problem that the current measurements provided by phasor measurement unit (PMU) is difficult to introduce to traditional state estimation, a new method to solve the compatibility problems of PMU and supervisory control and data acquisition (SCADA) is presented in this paper. By the rotated-pseudo-measurement (RPM) method, current measurements are transformed into the pseudo measurements and decoupled in polar coordinates, so that they could taken into nonlinear state estimation. Then the RPM method is simulated compared with the current transformation (CT) method. According to the result, it is showed that the RPM method has many advantages compared with the CT, such as independence of other measurements, small error in propagation and more significant in improving estimation accuracy. Moreover, the RPM method has the compatibility with traditional nonlinear state estimation and the fast calculating speed, which have good prospects of practice.

Abstract: A new algorithm based on K shortest paths is presented for quick search of the transmission section, and then the timely electricity network topology is transferred into a directed graph. Using this new algorithm, k shortest paths would be directly searched for; the transmission section influenced greatly by the power flow shift is then obtained quickly. To avoid leaving part of the search because criteria are too small tributary drain election when using a single path to ensure the integrity of the transmission section. Finally CEPRI36 nodes system simulation is analyzed, and the effectiveness of the algorithm is demonstrated.

Abstract: Aiming at the characteristic of nonlinear and natural unsteadiness in rotary inverted pendulum system. This kind of system uses the DSP TMS320F28335 of TI as the control and testing core of this system, adopts DC motor JGB37-3530 and motor drive L298, high precision potentiometer WDY35D4 as sample controller. Angle-to-resistance-to-voltage conversion is achieved by potentiometer, sensors export analog voltage to the first-order filter for filtering noise and transmit signal to the interior of TMS320F28335 and take ADC sample, then use digital filter algorithms to filter the signal again. Finally using double-loop PID control scheme to control motor precisely. Both DSP algorithm and program are implemented by Model-Based Design in Matlab, according to the process of model-simulation-code generation, this rotary inverted pendulum realizes the function of pendulum inverted and rotated. Experiments show this system has a stable and rapid transient process, possesses good stability and resisting disturbance.

Abstract: The control core of this design is MCU AT89C51,with the sensor MPX4115,it can complete the detection of weighting signal.Use the ADC0832 chip to achieve signal conversion, the input use a square 4*4 keyboard,the output display use the LCD LM4229.Use C Language Programing to achieve the modular design of software,use proteus simulation system to achieve the measure of weight of nine kinds of goods,The weighing range from 0.546Kg to 4.980Kg;Its resolution is 0.001Kg;This system has the function of calculating total price,storing single price,alarming when the goods overweights. Key words: AT89C51MCU;A/D exchange;Sensor

Abstract: Smart grid must be evaluated correctly so that its development stage is determined and weak links, restrict factors in development are found. Based on it, the path from the stage to the next stage is planned for power enterprises. In view of the poor accuracy of conventional assessment methods, caused by subjective factors and uncertainty, the fuzzy comprehensive assessment method is applied to assess smart grid. Firstly, a smart grid assessment system is founded based of IBM’s smart grid maturity model, and then method and procedure of fuzzy comprehensive assessment method are introduced. The study on an example shows that this approach is effective and feasible.

Abstract: This paper presents a control strategy of solid oxide fuel cell (SOFC) generation system integrated into microgrid. To enhance the dynamic response of SOFC, storage battery is paralleled via a DC bus, and the hysteretic control of bi-directional DC-DC converter is adopted. The common DC-AC inverter adopts an improved droop control. The active synchronization control is applied to ensure the smooth mode transition of microgrid. The simulation results show the dynamic performance of SOFC generation system in different operation modes.

Abstract: Modeling of the wind and PV hybrid microgrid is carried out by PSCAD/EMTDC. The model includes direct-drive wind power generator, Single-stage photovoltaic power generation system and storage battery. Simulate and analyze the operating characteristics of the microgrid running in grid-connected and islanding mode, which take into account the actual wind speed and light intensity. The simulation results show that the battery is able to regulate the voltage of the point of common coupling and smooth the power fluctuation of wind generator and PV generation system in the grid-connected mode. The microgrid can isolate itself from the grid in a rapid and seamless fashion when the battery adopting P/V and Q/f control strategy based on the droop characteristics.