Liu Z.,Guangdong Electric Power Design Institute |
Xia W.,Guangdong Electric Power Design Institute |
Liu M.,South China University of Technology
Dianwang Jishu/Power System Technology | Year: 2013
In allusion to power imbalance during switching microgrid from grid-connected operation mode to non-plan island operation mode, under the premise of not changing the operation and control mode of distributed generations (DG) the complex energy storage device composed of super capacitor and battery is taken as the main power supply during the island operation of microgrid. A switching control strategy is drafted for the transition of operation mode of microgrid from grid-connected mode to non-plan island mode to ensure normal power supply for important load and normal operation of DGs before and after the transition; when the operation mode of microgrid is switched from island mode to grid-connected mode, the pre-synchronizing control is applied to the complex energy storage device to effectively lessen the impact and oscillation during the switching process. The effectiveness of the proposed control method and storage is verified by PSCAD/ EMTDC based simulation results of the switching process between the two operation modes of microgrid.
Wang S.,Guangdong Electric Power Design Institute
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2011
According to the characteristics of micro-grid and distributed generation, the design, operation, optimization and control of micro-grid are discussed. With an engineering example, its design principle is pointed out: reliability, flexibility and power balance. Its configuration and operational modes are analyzed. The parallel mode, island mode and dual mode are described and their design characteristics are presented. Suggestions are made for the control system and optimized operation of micro-grid and distributed generation, and the overall concept of MEMS(Micro-grid Energy Management System) is proposed. Some issues, such as anti-island protection and short-circuit current, are explained. The solution of anti-island protection applying active and passive detections is submitted.
Xie C.,Guangdong Electric Power Design Institute
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2014
In a nuclear power plant, between the generator terminal and the step-up transformer, generator circuit breakers are installed, and generator circuit breaker failure protection is also installed. This paper analyzes the protections and the value settings of the nuclear power plant generator, and points out the problems in the generator circuit breaker failure protection design. First, in the protection of some jump starter generator circuit breakers, de-excitation, and the main valve closing, as the current criteria are not satisfied, the starter generator circuit breaker failure protection cannot be directly activated. Secondly, during the turbo-generator program tripping process, the generator circuit breakers break down and cannot trip, neither can the generator circuit breaker failure protection be activated. Based on the harm caused by these problems, this paper proposes some improvements on the nuclear power plant generator breaker failure protection design, further improving the generator circuit breaker failure protection design in the nuclear power plant. © 2014 State Grid Electric Power Research Institute Press.
Wang C.-C.,Guangdong Electric Power Design Institute
Dianwang Jishu/Power System Technology | Year: 2010
In ±500 kV DC power transmission project from right bank hydropower station in Xiluodu to Guangdong province, following technologies, such as the transmission line structure of double DC circuit on the same tower, common starting point and ending point for both DC lines, common converter station and sharing equipments in UHVAC yard, are adopted. The hierarchical structure of DC control system for this project, the configuration and jurisdiction of control functions, the coordinative control between two DC transmission circuits and the configuration of backup reactive power control function are discussed, and three kinds of feasible hierarchical structural schemes are proposed and related technical comparison among these schemes are performed. According to comparison results the scheme, a DC control system, which consists of an independent DC controlling hierarchy for double circuit lines, i.e., the control in station hierarchy, a bi-pole control hierarchy and pole control and converter control hierarchy, is recommended as optimal scheme.
Peng M.-X.,Guangdong Electric Power Design Institute
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011
Based on the limit equilibrium theory, the backfill is treated as a perfectly elastic-plastic material which follows the Mohr-Coulomb yield criterion, and is assumed to be an isotropic, homogeneous and incompressible (or non-expansive) perfectly continuous medium. The stress singularity and its stress boundary condition are introduced, and a statically determinate and solvable mathematical model for the limit equilibrium boundary value problem is established without considering the stress-strain relationship. Then the slip-line field and stress field in plastic zone of the backfill are solved by use of the slip-line method, furthermore, the passive earth pressure on retaining walls and the reaction on slip surfaces are derived. Geometric and mechanical similarity principle is presented by means of dimensionless analysis. The results show that the slip-line solution to the passive earth pressure is generally less than or equal to the Coulomb's solution, and the classical Rankine's earth pressure or the classical Coulomb's earth pressure satisfying non-singularity condition is in accordance with the slip-line solution, and the Hencky's first theorem and second theorem are not generally applicable.
Peng M.,Guangdong Electric Power Design Institute
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012
Although the conventional Mononobe-Okabe method is widely used in practice, it is only applicable for calculating total limit earth pressure of non-cohesive soil, and not for solving earth pressure distribution. Based on the limit equilibrium theory in this paper, the backfill is treated as a perfectly elastoplastic material which follows the Mohr-Coulomb yield criterion, and a family of slip-lines in the plastic zone is assumed as straight lines, i.e. the plane slip surfaces. The influence factors including inclination of wall, slope angle of backfill, cohesion and internal friction angle of soil, adhesion and external friction angle between wall and soil, surface uniform surcharge, plastic critical depth, horizontal and vertical seismic coefficients are considered. And a more reasonable plastic slip wedge analysis model is established to solve the seismic active earth pressure on retaining wall, the reaction force on slip surface and their distributions by using limit equilibrium method. Furthermore, the geometric and mechanical similarity principle is first presented by means of dimensional analysis. The results show that the total seismic active earth pressure increases with the increasing algebraic value of the horizontal seismic coefficient; but it does not always decrease with the increase of the algebraic value of the vertical seismic coefficient; and it may decrease first and then increase when the horizontal seismic coefficient is rather large.
Peng M.-X.,Guangdong Electric Power Design Institute
Yantu Lixue/Rock and Soil Mechanics | Year: 2010
The problem of critical depth for plastic zone behind the retaining wall has not yet been solved well. The conventional calculation formula is only applicable for some special cases. This paper is based on the limit equilibrium theory, in which the backfill is treated as a perfectly elastoplastic material following the Mohr-Coulomb yield criterion; and it is assumed that a family of slip lines in the plastic zone are straight lines, i.e. the plane slip surfaces. The elastic overburden is put forward to replace the conventional tension crack; and a more reasonable slip wedge analysis model is established. The analytical solutions of the plastic critical pressure and critical depth and the possible maximum depth in plastic zone for active earth pressure on retaining wall in general case are deduced using limit equilibrium method. The calculation results show that the analytical solution of the plastic critical depth is identical with the result by iterative calculation in existing literatures and the conventional calculation formula is a special case of this analytical solution.
Guangdong Electric Power Design Institute | Date: 2011-06-01
A method of physicochemical treatment of wastewater of orimulsion oil comprises the following steps: wastewater of orimulsion oil is entered the bottom of an extractive equipment (4) intermittently and is raised spirally in it; is mixed with extracting solvent adequately that is pre-placed in it and the mixture is separated naturally; orimulsion oil is kept in the extracting solvent forming an extraction phase (6) above a water phase (7) which is discharged from the bottom of extractive equipment (4).
Guangdong Electric Power Design Institute | Date: 2013-12-12
A method for optimizing the configuration of a distributed CCHP system is disclosed. The method includes: creating a digital model database containing digital models of various energy use, conversion forms in the distributed CCHP system; creating a feasible configuration solution database according to load demands, constraints and combined screening strategy, wherein the total number of the configuration solutions in the configuration solution database is set as N; performing an all-year hourly operational strategy optimization on each configuration solution in the configuration solution database, based on an annual load demand curve, until the annual operating costs, annual one-time energy consumption and annual pollutant emission of the i^(th )configuration solution are calculated, wherein iN; selecting a configuration solution with characteristics selected from the group consisting of the least annual operating costs, the least annual one-time energy consumption, the least amount of annual pollutant emission, and any combination thereof, as the optimal configuration solution.
Guangdong Electric Power Design Institute | Date: 2010-07-20
A DCS control module for a transformer in nuclear power engineering, comprises: an input command processing logic unit (1), a malfunction processing logic unit (2), a state processing logic unit (3), an output command generating logic unit (4) and a 6.6 kV switchgear of the transformer. The present invention utilizes the distribution control system (DCS) integral with the power units to realize the control of 6.6 kV transformer switch, the sharing of the operator station with the power unit control system, and the overall monitoring, and the operation reliability of the power units is improved.