Key Engineering Materials Vols. 439-440

Abstract: The mode-switching control method of thyristor controlled series capacitor (TCSC) is of great importance to power system stability. It is very difficult, if not impossible, to realize mode-switching only by changing firing angles. Considering the impedance characteristics of TCSC, a set of mode-switching control methods is proposed. Simulation and experimental results show that the proposed switching method can make the switching process faster and possess better dynamic performance.

Abstract: The paper analysis on the fourth party logistics (4PL) enterprise competitiveness based on the connotation of simple; according to the characteristics of the fourth party logistics, the first put forward the fourth party logistics enterprise competitiveness evaluation index system, then apply the method of entropy index system, and last using the neural network to competitive analysis and quantitative evaluation of fourth party logistics enterprises, and get appraisal conclusion.

Abstract: It needs a scientific and complete index system for a comprehensive evaluation on the safety of foods in some region or some country. And the use of advanced evaluation technologies is also an important work of food safety evaluation. The paper eliminated the redundant data in index membership for object classification by defining distinguishable weight and extracted valid values to compute object membership. The improved algorithm of membership degree transformation includes three calculation steps which can be summarized as “effective, comparison and composition”, which is denoted as M (1,2,3). The paper applied the new algorithm in fuzzy evaluation on the safety of foods. Evaluation results show the validity of the improved model and the model can achieve the dynamic evaluation of the safety of foods in some region or some country.

Abstract: Distributed software systems often intertwine the handling of application functionalities with distribution related issues including location transparent access to services, workload allocation among different hosts, adaptation to changing conditions of the network. In the paper, a computational reflection based distributed query model is proposed. The model uses computational reflection to divide the distributed query system into two levels: the meta level and the base level. Meta objects that existed in the meta level are responsible for control and description of the base level, hence the state change of the base level could be captured by the meta level and be controlled according to the meta level’s reaction. The advantages of the model are that adapt different changes such as data resources in the network, network conditions, query plan, and provide the capability of fault tolerance.

Abstract: Based on grey system, a new kind of new information non-equidistant optimum grey model GM(1,1) to line-drawing data processing in computer aided design was proposed in which the response function is based on new information x(tn) . The objective function is built to make the fitting mean relative error least and the program was compiled with bacterial foraging algorithm (BFA) combined with particle swarm optimization (PSO) algorithm to optimize the background value and modify the initial value x(tn) of response function. The method of precision inspection was introduced. The programming was authorized with MATLAB7.6 language. Two examples were given, their results were compared with the results based other Grey models, respectively. The method can be used for model establishing on equal interval, as well as on non-interval. Moreover, GM(1,1) model’s fitting precision and prediction is advanced and the scope of application is enlarged. The model is simple and practical, and has a generalizing value in the field of CAD.

Abstract: Based on the exponential trait of grey model and the definition of integral, the reconstruction method of GM(1,1) model’s background value function of non-equal distance sequence was put forward and a kind of non-equidistant optimum grey model GM(1,1) to line-drawing data processing in computer aided design was proposed. The new model chooses the modified first component of X(0) obtained by optimizing as the starting conditions of the grey differential model and the parameter of the background value function also obtained by optimizing with chaos immune particle swarm optimization algorithm (CIPSO) to make the fitting mean relative error least. The method of precision inspection was introduced. Then, the programming was authorized with MATLAB7.6 language. An example was given, the results were compared with the results based other Grey models, respectively. The method can be used for model establishing on equal interval, as well as on non-interval. Moreover, GM(1,1) model’s fitting precision and prediction is advanced and the scope of application is enlarged. The model is simple and practical, and has a generalizing value in the field of CAD.

Abstract: The inter-cluster separation (ICS) algorithm adds the separation item into the objective function to minimize the fuzzy Euclidean distance and maximize the inter-cluster separation. However, ICS is sensitive to noisy data, so an improved inter-cluster separation (IICS) algorithm is proposed to deal with this problem. It is claimed that IICS is an incorporation of ICS and improved possibilistic c-means (IPCM) clustering. IICS can produce both possibilities and memberships simultaneously, and it overcomes the noise sensitivity problem of ICS and the coincident clusters problem of possibilistic c-means (PCM) clustering. Further, IICS does not depend on the parameters that exist in IPCM. The experimental results show that IICS compares favorably with ICS.

Abstract: Fuzzy learning vector quantization (FLVQ) benefits from using the membership values coming from fuzzy c-means (FCM) as learning rates and it overcomes several problems of learning vector quantization (LVQ). However, FLVQ is sensitive to noises because it is a FCM-based algorithm (FCM is sensitive to noises). Here, a new fuzzy learning vector quantization model, called noise fuzzy learning vector quantization (NFLVQ), is proposed to handle the noises sensitivity problem of FLVQ. NFLVQ integrates LVQ and generalized noise clustering (GNC), uses the membership values from GNC as learning rates and clusters data containing noisy data better than FLVQ. Experimental results show the better performances of NFLVQ.

Abstract: DSTATCOM used the direct current control method to suppress the voltage flickering which is caused by the undulatory property load, its reactive current tracking performance plays a decisive role for the inhibitory effect of the device.Considered the parameter installation difficulty and electrical network parameter dynamic change characteristic for conventional PI control when designs the controller, fuzzy logic was proposed that used to make the online adjustment for PI controller's parameter, which makes DSTATCOM has strong auto-adapted and robustness character. When the electrical network parameter changed, DSTATCOM still can suppress the voltage flickering very well. The digital simulation result has confirmed the control policy accuracy and validity.

Abstract: In view of low-pressure area for dynamic reactive power compensation device application present situation, a more advanced static reactive power compensation techniques was proposed that is STATCOM (Static Synchronous Compensator-STATCOM) which based on the modern power electronic technology, and it applied to the low-voltage dynamic reactive power compensation area, developed a new and more advanced low-voltage dynamic reactive power compensation device. In this paper, STATCOM compensation system simulation model was established in MATLAB6.5, futher to study its real-time compensation. Theory analyze and simulation results indicate that compare with static capacitor compensation，dynamic compensation achieved zero phase angle between power source current and voltage on rating frequency，demand for power supply rating power is reduced and power transmission performance is ensured.