Advanced Materials Research Vols. 354-355

Abstract: Optimizing the operation of thermal power plant auxiliaries can effectively reduce the power consumption rate and improve production efficiency. This paper establishes the optimal operation model for variable-speed pumps and fans, which are the main auxiliaries in thermal power plant. The model is based on the operating characteristics of pumps and fans and considers parallel and series operation. The object is to minimize the power of auxiliaries; the constraints contain the requirements of system flow or head, speed limits, flow limits, power limits and pipeline performance. Because of the complexity of the model, the pumps and fans operating performance curves are transferred to piece-wise linear curves at first, then a new 0-1 variable is introduces to characterize the choice of a different Q-P curve at a different speed. The model has been converted to mixed integer linear programming problem and uses commercial modeling tools to solve. The case is to verify the effectiveness of this method.

Abstract: Nonlinear loads are widely spread in automobile industry along with the development of power electronic technology, which causes proliferation of power quality problems, such as harmonics, voltage fluctuation, etc. The problems result in detrimental effects to the power distribution systems, increasing power loss in the network and affecting the safety operation of electrical appliances. This paper analyzed the power quality problems and proposed an enhancement scheme implemented in an automobile factory. The scheme has already got an application in one of the transformer substations. It’s revealed that the proposed scheme can improve significantly the power factor of the 400V bus in car body workshop, and the harmonics injection to the utility grid can be within the limit of related standard．

Abstract: Neutral point grounding which is related to voltage level, network structure, insulation, communication and relay protection is very important problem to power system. Nowadays, the choice of neutral point grounding mode mainly relies on operation experiences or theoretical analysis which could not give a direct view of the dynamics of electric power system during disturbances. Therefore, this paper has established the simulation model of electric power system neutral point grounding with PSCAD/EMTDC to show the dynamics of neutral point grounding when disturbed by single-phase grounding in transmission lines, and the application of each neutral point grounding mode has been analyzed according to simulation results. The dynamic model of neutral point grounding in this paper is meaningful to the analysis of high-order, non-linear transients of power system as well.

Abstract: The capacity of thermal power plants takes up 75 per cent of whole power generation capacity in China, and so a reserve of generation capacity margin that may adapt to the variations in power network load is of paramount importance. This paper proposes a concept: installed capacity margin, and basic mathematic modeling and example is analyzed. It would be supply theoretical help for real little thermal power plants shutdown schedules based on building detailed mathematical models after investigation of region-specific load structure characteristics and installed generator compositions.

Abstract: In this paper, the generalized Finsler lemma and augmented Lyapunov functional are introduced to establish some improved delay-dependent stability criteria of neutral stochastic delayed neural networks. The stability criteria in the new results improve and generalize existing ones. Two examples are included to show the effectiveness of the results.

Abstract: A current direct control is proposed in the paper. The topology structure of a hybrid filtering equipment is presented. The traditional current detecting and controlling method for the structure is discussed. The relationship between the grid current and harmonic suppressing current is educed, which proves that the step of harmonic detection be left out in theory. A current direct control based on the grid current error is proposed, which is simple. It is not necessary to detect harmonic and reactive current. So influence factors on the real time and precision of the filter are reduced. The simulating model of the hybrid filtering equipment is constructed and the new current direct control is applied in the model. The simulating results show that the good performance of harmonic suppression and reactive compensation is obtained with the current direct control.

Abstract: A new soil model named as 3d combined-layer soil model is firstly proposed. According to the concept of image, the Green function of this soil structure is derived using complex image method. Based on it, the surface potential distribution (SPD) of different soil structure configuration is calculated, moreover, the influence of soil parameters on SPD is analyzed. It can be seen from the results that the variations of the soil parameters such as soil thickness and resistivity can bring different influence to the SPD of the soil, and it is related not only to the distances, but also the angle for the grounding electrode. Therefore, the 3DSM may be more accurate for the calculation of SPD.

Abstract: In the condition of distributed generation, the DG’s islanding is an important operation, which can improve the reliability of distribution systems in the process of service restoration. In order to form an optimal islanding scheme when a fault occurs in distribution systems, this paper proposes the model and algorithm for islanding considering DG systems. This model is based on CSP, and solved by the back-tracking algorithm. At last, a simulation example verifies the efficiency and superiority of the proposed algorithm.

Abstract: Data-Intensive applications in power systems often perform complex computations which always involve large amount of datasets. In a distributed environment, an application may needs several datasets located in different data centers which faces two challenges including the high cost of data movements between data centers and data dependencies within the same data centers. In this paper, a data placement strategy among and within data centers in a cloud environment is proposed. Datasets are placed in different centers by a clustering scheme based on the data dependencies. And within the center, data is partitioned and replicated using consistent hashing. Simulations show that the algorithm can effectively reduce the cost of data movements and perform a evenly data distribution.

Abstract: This paper analyzes the simulation function about switching operation simulation in the training simulation system of intelligent substation, and proposes a kind of training methods about switching operation, it promote running on duty personnel training, and effectively utilizes the substation simulation training system. At the same time puts forward intelligent reasoning machine system.