Applied Mechanics and Materials Vols. 291-294

Abstract: The steam temperature control is important to Ultra-supercritical (USC) unit for safe and efficient operation under load tracking. In this paper, a model predictive control (MPC) method is introduced for reheated steam temperature control of USC unit. Two inputs (i.e. damper, spray attemperator) are employed to control two outputs (i.e. primary reheater outlet temperature and finish reheater outlet temperature). Step response models of the reheater temperature are achieved using the two inputs by two outputs model. In simulation, the reheated steam temperature can be controlled around the setpoint closely in load tracking. The simulation results show the effectiveness of the proposed methods.

Abstract: The paper studied the frequency characteristics of UHVDC transmission line and UHVDC transmission line boundary and their attenuation to high frequency components of fault-generated transient signal. The paper points out that existing approaches which utilize protectors to distinguish local side’s internal or external fault can’t protect the whole line. UHVDC transmission line and UHVDC transmission line boundary’s attenuation to high frequency fault-generated transient signal is overall considered, and a single-ended transient based voltage protection method which distinguishes the opposite side’s internal and external fault is proposed. The Yunnan-Guangdong UHVDC model of actual parameters was built up by PSCAD, and simulation experiment was conducted.

Abstract: Low voltage ride-through (LVRT) capability has become more important to the doubly-fed induction generator (DFIG) as the penetration of wind power increases. This paper analyses the LVRT influence on the neighboring wind farm, mainly considering the crowbar action during a fault. On the basis, a new protection scheme for the DFIG is proposed to prevent the negative influence, primarily based on a rotor series resistor and a reactive power compensation device. And the adaptive control strategy is presented. Through the simulation, characteristics of DFIG in the neighboring wind farm with and without the protection scheme are compared. The results show that the cascading crowbar action can be avoided by the protection scheme and it is advantageous for grid voltage restoration.

Abstract: Proposed one kind of improvement artificial immunization algorithm calculates the electrical power system generation expansion planning, this algorithm maintained the basic immunity algorithm comprehensive search ability, also the concept which is apart from through the introduction vector causes the immunity algorithm theoretically to guarantee the understanding the multiplicity. Through the simulation experiment computed result indicated this algorithm is feasible. And so on compares with the heredity algorithm, this algorithm overall situation search ability strong, the convergence rate is quick.

Abstract: It brings all kinds of negative and positive impact on distribution network with the distributed generation connection. Feeder voltage of the distribution network will be affected. Distributed generation can play a good supporting role to the feeder voltage, which also can make feeder voltage exceed the maximum safe voltage. The details have an important relationship with the capacity, size and location of distributed generation. The voltage supporting model and voltage calculation method of distributed generation connected with distributed network is given in the paper. The IEEE 34 Node model was chosen to be discussed how different factors can influence the feeder voltage. This paper analyzes distributed generation’s influence to the distribution system voltage level.

Abstract: The extraction and analysis of fault information is key to making the transmission line protection configuration scheme. This paper analyzes the mechanism of DC line faults, like lightning, mental and non-mental grounding fault, short to AC line. By referring to actual parameters of Yunnan-Guangdong ±800kV UHVDC transmission system, simulation model is established by PSCAD/EMTDC. According to simulation tests of dc transmission line faults: lightning, grounding fault, high resistance grounding fault and short to DC line, the transient responses of UHVDC line faults are summed up.

Abstract: Transformer winding deformation is a main type of transformer fault. The Frequency Response Analysis is a effective method to detect transformer winding deformation. Based on the traditional Frequency Response Method, the current source method is a new way to detect winding deformation. This method adopts the current source as sweep frequency source and uses the current frequency response curve to judge winding deformation. The simulation shows that the current source method is feasible. For some special transformers, this method can realize transformer winding on-line monitoring and diagnosis.

Abstract: To deal with the power system static voltage security issues, this paper provides a power system low voltage risk assessment model. We constructed a low voltage consequence severity model by combining the utility function and node importance, and set up a low voltage evaluation index based on risk theory. The validity and reasonability of the model are proved by the IEEE14 bus system.

Abstract: The operating departments of power system use different information systems for work convenience. The differences in appliances, data sources, structures and maintenance personnel lead to the independence between data sources as well as heavy workload of data exchange and maintenance. The simulation of different problems needs various tools while the establishment of grid model requires hard work. This paper, on the basis of function requirement analysis, made project design of integrative simulation platform, and developed a data graphical integrated modeling platform featuring the functions of steady state, electromechanical transient and electromagnetic transient with the ability of multi-source data fusion by using the programming language C#. The platform can integrate data of PSDB, PSD-BPA and PMIS, automatically form PSASP and PSD-BPA power flow calculation data, electromechanical transient simulation data and generate “.psc” files for PSCAD\EMTDC electromagnetic transient simulation analysis according to the selected sectors and components on the graphical interfaces.

Abstract: This paper concentrates on modeling and simulation of the automatic transmission assembly using Matlab/Simulink. The entire simulink model includes four major models. They are the torque convertor and its lockup clutch model, the automatic transmission gearbox model, the equivalent spring model and the logical model respectively. After building the model, a comparison between this Simulink model and Carsim software is provided and the result curves matches very well, which proves that the Simulink model is accurate.