State Grid Zhejiang Electrical Power Company, State Grid Corporation of China and Hangzhou Electric Power | Date: 2015-10-14
The invention provides a method and a system for obtaining a flicker transmission coefficient of grid connection of photovoltaic power stations and defines subtransient reactance of a photovoltaic current transformer by considering that the frequency characteristic of impedance of the photovoltaic current transformer is similar to the subtransient reactance of a synchronous power generator and the subtransient reactance of an induction motor. Furthermore, the subtransient reactance of the photovoltaic current transformer can be obtained by utilizing parameters of the photovoltaic current transformer, so that the flicker transmission coefficient between any two nodes in a multi-port network diagram of a photovoltaic power station group, namely the flicker transmission coefficient of grid connection of the photovoltaic power stations, can be accurately obtained, and the difficult problem in the prior art can be further solved.
Zhejiang Truly Electrical Co., State Grid Corporation of China, State Grid Zhejiang Hangzhou Yuhang Power Supply Company, Hangzhou Electric Power and State Grid Zhejiang Electrical Power Company | Date: 2016-04-27
Provided are a method for identifying an overcurrent in an electric cable and a device for the same. The method includes: detecting whether a single-phase overcurrent occurs in three-phase current signals; determining an indicator feature vector sample of an overcurrent phase current signal in a case that it is detected that the single-phase overcurrent occurs in the three-phase current signals; calculating association coefficients between the indicator feature vector sample and predetermined indicator vector reference samples of indicators, where the indicator vector reference samples respectively correspond to reasons for the single-phase overcurrent; calculating association degrees between the indicator feature vector sample and the predetermined indicator vector reference samples based on a predetermined indicator weight vector and the association coefficients corresponding to the indicators; and finding a reason for the single-phase overcurrent, which corresponds to an indicator vector reference sample having a maximal association degree. Hence, an incipient failure of the electric cable is identified.
State Grid Corporation of China, State Grid Zhejiang Hangzhou Yuhang Power Supply Company, Hangzhou Electric Power and State Grid Zhejiang Electrical Power Company | Date: 2015-08-05
The invention provides a remote power-failure restarting method and a device. The remote power-failure restarting device comprises a signal processing chip, a relay driving chip and a relay, wherein the output end of the signal processing chip is connected with the input end of the relay driving chip; the output end of the relay driving chip is connected with a coil of the relay, and one end of the normally open contact of the relay is connected with a power supply, and the other end is connected with a power supply end required to be cut off for restarting the device. The signal processing chip receives a power-failure restarting command sent by the external world, and analyzes the power-failure restarting command to obtain a branch required to be cut off for restarting the device; the signal processing chip outputs a driving command to the relay driving chip, the relay driving chip controls the closure of the normally open contact of the relay after breaking according to the driving command, so that the power-failure restarting control to the device is realized, workers are not required to implement the power-failure restarting to the device in scene, the workload is reduced, and the time is saved.
Wang P.-C.,Hangzhou Electric Power
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010
Existing disconnector auxiliary contact and its introduction are not very reliable, which will influence that the bus differential protection would not protect the fault bus. Through the inductive analysis, it proposes two improved kinds of hardware and software solutions, and discusses their influences on widely used bus differential protection. Now combining with a case of auxiliary switch contact status error happened in a substation, this paper discusses the influences of disconnector auxiliary contact status error on bus differential protection and proposes the solutions against it.
Zhu T.,China Southern Power Grid Co. |
Wang C.,Hangzhou Electric Power
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2011
A complicated DC line fault of high voltage direct current (HVDC) is analyzed. During this DC line fault, the continuous lightning strikes resulted to action of several protections such as: DC line over-voltage protection, valve group differential protection, AC/DC conductor contact protection, bridge differential protection and 50 Hz protection, etc. In accordance with protection function principle of DC control concerned and fault records, a detailed analysis on the fault process is carried out. Furthermore, the improving suggestions such as: study on reason and influence of DC line over-voltage, attach importance to the coordination of thyristor valve and its control system with the DC protection, properly improve the logic of the open HSNBS, etc are put forward. © 2011 State Grid Electric Power Research Institute Press.
Huang C.,Hangzhou Electric Power
Advances in Science and Technology of Water Resources | Year: 2016
As the current standard NB/T 35023-2014 "sluice design specification" involves stilling basin with rectangular cross section, excluding stilling basin with trapezoid section, energy dissipation calculation for stilling basin with trapezoidal cross section were studied on the basis of the classical hydraulics theory and numerical analysis. The analytical formula of shrinking depth and the equation of conjugate depth after hydraulic jump of stilling basin with trapezoidal cross section were derived. Using theory of high-order equation, simple iterative formulas for conjugate depth after hydraulic jump of stilling basin with prismatic trapezoidal cross section and diffused trapezoidal cross section were given, respectively. Finally, the calculation formulas for depth and length of the stilling basin with trapezoidal cross section were obtained according to the energy dissipation equation. Calculation results of a practical project validate the proposed formula has high accuracy. © 2016, Editorial Board of Advances in Science and Technology of Water Resources, Hohai University. All right reserved.
Tu Q.,Zhejiang University |
Xu Z.,Zhejiang University |
Zhang J.,Hangzhou Electric Power
IECON Proceedings (Industrial Electronics Conference) | Year: 2010
A circulating current suppressing controller (CCSC) is presented to eliminate the inner balancing currents in modular multilevel converter (MMC). Based on the double-fundamental-frequency, negative-sequence rotational frame, the three phase alternative circulating currents are decomposed to two DC components, and are limited to a low level by a pair of proportional integral controllers. This control strategy does not affect the MMC outer dynamics in the ac side. Simulation results based on PSCAD/EMTDC demonstrated the circulating current suppressing effect of the proposed CCSC and proved that the distortion of the arm current is mitigated significantly. © 2010 IEEE.
Hangzhou Electric Power, State Grid Corporation of China, HANGZHOU DA YOU Science and Technology DEVELOPMENT CO. | Date: 2012-06-20
A battery locking device for a new energy vehicle including: a battery compartment fit for a battery, the battery compartment being provided with a battery inlet; and a battery clamping device provided on the battery compartment and controlled by a linkage mechanism. Since the battery clamping device is controlled by the linkage mechanism, during the mounting or removing of the battery, the battery can be integrally clamped or released by merely operating an operating end of the linkage mechanism. Compared with the prior art in which the battery is fixed through bolts, the battery can be integrally clamped or released by the battery locking device through a single operation, which greatly simplifies the disassembling or assembling process of the battery and reduces the time required for replacing the battery. A new energy vehicle provided with the above battery locking device has the same advantages.
HANGZHOU DA YOU Science, Technology DEVELOPMENT CO. and Hangzhou Electric Power | Date: 2011-09-19
A method for controlling battery replacement based on distance data and a system thereof are provided. The method includes: reading current distance data of an electric vehicle, wherein the current distance data indicates the total distance that the electric vehicle has traveled; receiving related recharge information for the electric vehicle submitted by a user, wherein the related recharge information includes a distance account, and the distance account indicates that the user currently adopts a billing policy in which the user is credited with a fixed amount of distance in a fixed period of time; and determining whether to perform an operation of replacing a battery of the electric vehicle according to the distance data and the billing policy. By using the present invention, distance data of an electric vehicle and distance account information can be obtained, and by using the distance data and the distance account information battery replacement can be controlled conveniently, which ensures continuous electricity provided for the green operation of the electric vehicle.
Hangzhou Electric Power, Hangzhou Da You Science and Technology Development Co. | Date: 2013-02-06
A movable charging connector includes a movable socket device and a plug device. The movable socket device is provided on a base plate (1), and includes a socket module and at least one guiding cylinder (4) which are fixedly provided on a movable mounting plate (3). A tension spring (18) is provided between the movable mounting plate (3) and the base plate (1). When the plug device and the movable socket device are connected with each other, the movable mounting plate (3) and the tension spring (18) is cooperated with each other, such that the moveable socket device can be moved in any direction. Since the tension spring (18) and the movable mounting plate (3) are provided and the guiding cylinder (4) can be fitted with the guiding post (2) on the plug device, the self-adapting connecting between the movable socket device and the plug device is ensured to achieve the movable function of the charging connector. Therefore green environmental protection energy is supplied for the operation of the electric vehicle.