Time filter

Source Type

Niu Y.,Shandong University | Zhang F.,Shandong University | Zhang H.,State Grid Corporation of China | Liang J.,Shandong University | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2016

By taking the hybrid energy storage system (ESS) composed of the value regulated lead acid (VRLA) battery and the vanadium redox battery (VRB) as an example, in view of the intrinsic characteristics of conventional unit frequency regulation, a charge and discharge strategy and optimal capacity planning of hybrid ESS participating in the automatic generation control (AGC) by assisting conventional units is studied. Firstly, according to the characteristics of conventional unit frequency regulation, an optimal control strategy taking into acount the suppression of reverse frequency regulation, dead zone oscillation, ESS over discharge, and forced state of charge (SOC) homing is proposed. Secondly, considering the cost of ESS configuration and the frequency regulation income of power generating units, a capacity planning model is developed. Finally, based on the particle swarm optimization (PSO) algorithm, the simulating calculation of the actual operation data of a power station is conducted. The results show that the frequency regulation performance and the running cost of the method are both better than those of the conventional unit frequency regulation. © 2016 Automation of Electric Power Systems Press.

Zhang Y.,Shandong University | Liang J.,Shandong University | Wang P.,Dezhou Power Supply Company
China International Conference on Electricity Distribution, CICED | Year: 2016

On the account of more and more inevitable scene of angled space crossed transmission line in real project, classical distribution parameter model is no longer applicable, and coupling effect between two lines needs to be reconsidered. This paper popularizes mutual impedance from limited conductor to angled space crossed lines, and analyses the characteristic of mutual impedance coefficient along the line. Based on the segmented nominal-π line model, in which mutual impedance of each section is obtained by Neuman's Integral, the location equation is derived by utilizing the feature that the voltages calculated from two sides are equal at the fault point. Simulations in PSCAD compare the differences of fault-location results between in the condition of considering and ignoring coupling effect of space crossed transmission lines. The calculation results demonstrate that the proposed algorithm has higher accuracy, and is not affected by fault types. © 2016 IEEE.

Zhang Y.-P.,Lanzhou Jiaotong University | Du B.-X.,Dezhou Power Supply Company | Tian M.-X.,Lanzhou Jiaotong University
Gaodianya Jishu/High Voltage Engineering | Year: 2011

In the ultra-high voltage (UHV) transmission systems, controllable shunt reactor (CSR) with high-speed response can improve the transmission power and power quality by means of restricting the over-voltage and changing the power fleetly and smoothly. In order to research the compensation degree of CSR and its relation with characteristics of UHV line, on the basis of equations of uniform transmission line and ∏-type equivalent circuit of UHV line with distributed parameters considered accurately, the formula for calculating compensation degree of controllable shunt reactor which is applicable to various loads of receiving system is achieved by power flow calculation. The relationships of compensation degree, transmission power, voltage and length of the line are analyzed. For example, when transmission power of UHV transmission line is fixed and the load of receiving-end is inductive, the lower the power factor is, the lower the compensation degree is. But the situation is contrary when load of receiving-end is capacitive. The results provide a theoretical foundation for designing the control system of UHV controllable shunt reactor.

Li C.-B.,Shandong University of Technology | Li C.-B.,Ningde Power Supply Company | Tan B.-X.,Shandong University of Technology | Gao P.,Shandong University of Technology | And 4 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

On the basis of D-type traveling wave theory, a fault location method for T-connection lines is presented which doesn't need judge fault branch and the calculation is simple. Wave progress in T-connection lines is studied, and based on D-type traveling wave theory, two double-terminal results are calculated by using the time that the first traveling wave head generated during the fault reaches the ends of the three-terminal power lines. Various situations are simulated and analyzed by ATP simulation software and MATLAB software. The simulation results show that this method takes advantage of the initial traveling waves within a short time to achieve fault location fast and accurately.

Jiang Y.Z.,Shandong Electric Power Research Institute | Liang Z.G.,Shandong University | Li C.,Shandong University | Du B.X.,Dezhou Power Supply Company
Advanced Materials Research | Year: 2014

This paper discusses effect of phase sequence layout on electric field under overhead lines. Charge simulation method is used. Examples of two circuit overhead lines and four circuit overhead lines show that phase arrangment of lowest height conductors has major influence and phase arrangment of middle height conductors has lesser influence on electric field under overhead lines. Interlacing placed lowest height conductors with different phase and phase arrangement of middle height conductors different from that of lowest height conductors help to reduce electric field.

Zhang F.,Shandong University | Dong X.,Shandong University | Liang J.,Shandong University | Han X.,Shandong University | And 2 more authors.
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2013

A hybrid algorithm is proposed to calculate the minimum load margin under the constraint of static voltage stability. A fast and efficient method is proposed to identify the limit induced bifurcation for the continuation power flow method, which considers the impact of reactive compensation device switching on load margin, applies the power factor of load increment to constrain the direction of load growth, and takes the generator reactive constraint into account to improve the adaptive step control strategy. A variable weight coefficient and variable learning factor strategy is adopted for the particle swarm optimization method, which applies a precocity criterion to carry out the particle variance with a certain probability and combines with the simulated annealing process to prevent local optimization. Case test verifies the effectiveness of the proposed algorithm.

Zhao Q.,Yanshan University | Zhang J.,Dezhou Power Supply Company
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2013

A passive lossless snubber based on magnetic coupling is proposed, which restrains the reverse recovery current and reduces the overlapping area of voltage and current during the turning-on period of switch. Therefore, the efficiency of PFC(Power Factor Correction) is enhanced and the EMI(ElectroMagnetic Interference) reduced. The energy is absorbed and transferred through the resonance of snubber inductor and capacitor. The coupled winding makes the energy of snubber inductor easy to be reset and no additional voltage stress is introduced by the snubber to the switch. The operating principle of snubber and the parameters design of key passive components are presented in detail. The experimental waveforms and efficiency comparison tests of 500 W prototype show the high efficiency of the proposed snubber.

Wang K.-X.,Shandong University of Technology | Wang K.-X.,Linyi Power Supply Company | Zhu C.,Dezhou Power Supply Company | Sun J.-J.,Shandong Electrical Power Engineering Consulting Institute Co. | Chen P.,Shandong University of Technology
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

For transmission lines, the paper analyzes the wave propagation process and the wave's refraction and reflection phenomena after the failure. On this basis, the paper proposes fault location method combining two traveling waves' theories. First, single-ended location principle is used to give preliminary fault location. And then the accurate results are given by single-ended principles combining with initial wave arrival time difference at both ends. The advantage of this method is that the results are obtained by single-ended location principle, eliminating the line length's error and the influence on location accuracy from circuit accurate time synchronization on both sides in double-ended principle location method so as to improve the accuracy and reliability of location. ATP simulations show that the combined traveling wave fault location scheme of transmission lines is feasible and fault location accuracy is improved obviously.

Gao H.-L.,Shandong University | Liu Y.-Q.,Shandong University | Su J.-J.,Dezhou Power Supply Company | Cui D.-M.,Dezhou Power Supply Company | And 2 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

To solve the problems related to configuration and principle of backup protection in conventional substations, this paper proposes a new scheme of substation-area differential backup protection (SDBP) oriented to intelligent substations. The new scheme takes the whole substation and all connected transmission lines as the object to be protected. Through defining four types of differential zone, the SDBP can accurately locate the faulted component according to whether the differential zone lies in restraining state or operating state. The tripping strategy of SDBP is determined by action signals from both main protection and circuit breakers. This paper describes in detail the scheme's operating principle, fault location process, and coordinating method with main protection. The intelligent substations adopting proposed scheme will be configured by bay oriented main protections and only one set of SDBP, which simplifies the configuration and setting of backup protection. The validity of SDBP scheme has been verified by PSCAD simulation model under the condition of normal state and fault state with different types and locations.

Liu X.,Harbin Institute of Technology | Wang X.,Dezhou Power Supply Company | Huang N.,Harbin Institute of Technology | Xu D.,Harbin Institute of Technology
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2012

According to the traits of power quality data in symmetry, parity and periodicity, a data compression algorithm based on pattern similarity and LZW compressed encoding is introduced, which normalizes the distance of pattern similarity to identify the distortion for the lossy compression of undistorted data and the lossless compression of distorted data, and adopts reasonably the LZW compressed encoding to increase the compression ratio. Models are established in MATLAB7.10 environment for six kinds of typical power quality disturbance signal, simulative experiments are designed to check the distortion detection capability of normalized distance, and the comparison of compression effect between the proposed algorithm and the one-dimension discrete wavelet transform show its performance and feasibility.

Loading Dezhou Power Supply Company collaborators
Loading Dezhou Power Supply Company collaborators