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Sustainable Power Generation and Supply, 2009. SUPERGEN '09. International Conference on

Date 6-7 April 2009

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Displaying Results 1 - 25 of 521
  • [Copyright notice]

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    Freely Available from IEEE
  • Table of contents

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    Freely Available from IEEE
  • Switched-control based wide-area damping control of power systems

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (761 KB) |  | HTML iconHTML  

    Algorithms for wide area control of an excitation system are presented. The algorithms use a switched control method with speed feedback from a remote generator, and also account for communication delays. They can also reduce the negative effects of time delay. The wide area controller includes a lead-lag network. Simulation results show that the algorithms can improve the dynamic stability of an interconnected power system. View full abstract»

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  • Distribution network reconfiguration based on minimum cost of power supply

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB) |  | HTML iconHTML  

    Under the electricity market environment, when the power supply of distribution network is feed from several substations which power purchase prices are different, the optimal reconfiguration topology cannot depend upon the object of minimum network power losses. This paper proposes a reconfiguration algorithm which considering the minimal power supply cost or maximal benefit else. Associate a refined branch exchange algorithm which includes the differences of power purchase prices, substitute the actual network losses by approximate losses, and the use of complicated heuristic rules is avoided, network topology through the optimization can quickly confirmed. In this course, there is no need to calculate power flow, therefore the complexity of the problem can reduced evidently. The results of calculation example show the simplicity and utility of the proposed algorithm, and also have suggestive meaning for finding economical operation structure of the network. View full abstract»

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  • A new under-frequency load shedding scheme based on OBDD

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (361 KB) |  | HTML iconHTML  

    Under-frequency load shedding (UFLS) controls are means that usually are taken when generation deficiency occurs and frequencies of power systems are in extreme danger. A new UFLS scheme is designed to maintain the system frequency within an acceptable range for the possible generation deficiencies. The proposed scheme considers the spinning reserve and load models, estimates imbalance power through the rate of change of frequency after a disturbance and calculates the amount of load to be shed. The scheme adopts the way of searching, checking and optimizing. Simulation results are presented to illustrate the validity of the scheme. View full abstract»

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  • Estimation and forecasting of dynamic state estimation in power systems

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (277 KB) |  | HTML iconHTML  

    In this paper, a new method of real-time dynamic state estimation is proposed, in which the model parameters such as state transition matrix, model error and measurement error covariance matrices are all identified on-line. In this way, the degenerate estimated values caused by inaccurate state transition equations are removed, and the estimated precision is high. The method is employed in different scenarios while the estimation performance can be maintained effectively. This approach has been tested on IEEE 5-bus test system under various operating conditions, where normal operation, bad measurement, sudden load change / drastic generation variation are all investigated. The performance indices under different test cases are all evaluated. Test results support the feasibility of the proposed method for dynamic state estimation applications. View full abstract»

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  • Deterministic and probabilistic analysis of static voltage stability in power systems

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    The mechanism of static voltage stability was examined by a visual explanation, in that way, the static voltage stability criterion was obtained. It was indicated that the static voltage stability is determined by both characteristics in generation side and characteristics in load side. Then each kind of two-dimensional plane analysis can be unified in three-dimensional space. It is pointed that both critical voltage and voltage stability margin should be use for indexes. The impact of load model on static voltage stability is discussed by both deterministic and probabilistic analysis method. View full abstract»

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  • Optimal configuration of the active power filter in distribution network of single/multi harmonic sources

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (525 KB) |  | HTML iconHTML  

    Active power filter (APF) can resolve the harmonic pollution in the power network well, but the cost of APF is expensive, it need to be optimal configuration usually. The models of single and multi APF are established with making the average of total voltage harmonic distortion as the object function and the total harmonic distortion of different node as constraints in the paper. By applying improved particle swarm optimization (PSO) algorithm with convergence factor to configure APF in IEEE12 nodes system, the global optimal solution of optimal configuration of APF can be obtained. The computation results demonstrate that the improved PSO algorithm is superior to the basic PSO algorithm in the convergence speed, which solve the optimization configuration of active power filter effectively. View full abstract»

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  • A study on power system state estimation under extremely bad conditions

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (257 KB) |  | HTML iconHTML  

    During the operation of modern power system, the unanticipated occurrence of large disturbances, communication errors, exceptions in SCADA system and lacking of maintenances etc will affect the normal operation of state estimation, which plays a significant role in keeping the security of power system. Therefore, to seek a state estimation algorithm that can keep fairly good momentum and can obtain a relative accurate result under these extreme conditions is meaningful both in theory and in practice. On the basis of analyzing the extremely bad conditions and the unfavorable impactions they brought during the system operations, this paper proposes a state estimation method which consists of heuristic double topology modeling method and WLS state estimation on the combination system. In the method, the accuracy of the structure model and the measurements, which are the determining factor of the state estimation result, can be ensured by the heuristic double modeling method, therefore, the state estimation in this paper can still obtain a relative accurate result even in extremely bad conditions. The testing scenario proves the validity and availability of the method in this paper. View full abstract»

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  • Coordinated design of probabilistic PSS and FACTS controllers to damp oscillations

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (363 KB) |  | HTML iconHTML  

    This paper presents an application of probabilistic theory to coordinated design of power system stabilizers (PSSs) and FACTS controllers, taking static VAr system (SVC) as an example. The aim is to enhance the damping of multi electromechanical modes in a multimachine system over a large and pre-specified set of operating conditions. In this work, conventional eigenvalue analysis is extended to the probabilistic environment in which the statistical nature of eigenvalues corresponding to different operating conditions is described by their expectations and variances. Probabilistic sensitivity indices (PSIs) are used for robust damping controller site selection and initial parameter setting. A probabilistic eigenvalue-based objective function for coordinated synthesis of PSS and SVC controller parameters are then proposed. The effectiveness of the proposed controllers is demonstrated on an 8-machine system. View full abstract»

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  • Effect of the coupling between hydraulic turbine set and power grid on power grid dynamic stability

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (315 KB) |  | HTML iconHTML  

    With the proportion of hydroelectric power station in power grid and the single-turbine capacity larger and larger, the effect of hydraulic turbine set on power system dynamic stability will be more significant. The power oscillation phenomenon, which affects the safe and stable operation of power system, occurred many times in China. For example, on October 29th, 2005, low frequency oscillation occurred in Central China Power Grid. The most of researches on the hydraulic turbine system and power system were carried out independently in the past. First, according to the physical characteristics of the draft tube hydraulic system, the hydraulic turbine set model considering the draft tube hydraulic pressure dynamic was established in this paper. Secondly, based on the single machine infinite bus system, the effect of draft tube hydraulic pressure pulsation on the power grid dynamic security and stability was studied and the coupling between the hydraulic turbine set and power grid was investigated. Thirdly, taking Zhelin Hydropower Plant in Jiangxi Power Grid as an example, the influence of the draft tube hydraulic pressure pulsation to power grid stability was illustrated in this paper. The loads of unit 5, 6 at Zhelin hydropower station have a wide range of vortex operating conditions, about 20~100 MW. In this case, the vortex frequency will enhance as the loads of vortex operation conditions increase. View full abstract»

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  • Application of the battery energy storage in wave energy conversion system

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (186 KB) |  | HTML iconHTML  

    The output power of the Wave Energy Conversion (WEC) system, such as AWS, varies, which may not satisfy the requirements of the grid code for the integration of wave generation into power grids. To deal with this issue, in this paper the Battery Energy Storage (BES) is applied to smooth the output power of the WEC. The BES is integrated to the converters of the WEC, and the controllers for the battery energy storage systems and the back-to-back converters of WEC are designed, respectively. The power quality of the wave farm (WF) using BES is tested, and the effectiveness of the controllers proposed is demonstrated under the system disturbances. View full abstract»

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  • Design of adaptive optimal reclosure based on digital substation network

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (367 KB) |  | HTML iconHTML  

    This paper presents a new scheme for power line autoreclosure technology, the integrated adaptive optimal reclosure. The background of the development is firstly outlined and the basic principles of these new techniques are described. These include the adaptive reclosure and the optimal reclosure techniques. The new scheme proposed is based on the latest development in digital substation, in which the proposed new techniques are implemented into a specially designed integrated reclosure device, which is responsible for the protection of a number of line sections associated with the substation. Studies show that these new developments offer potential for significantly improving the performance of the power system protection and control. View full abstract»

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  • An improved transformer percentage restraint method based on transmission line information

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (254 KB) |  | HTML iconHTML  

    Transformer is one of the most important elements in power system, but the correct operation percentage of protection relay is far less than that for line protection. Current differential protection has been the main protection technique for transformer unit. This protection technique, however, suffers a low sensitivity or reliability due to the problems such as CT saturation and transformer magnetizing inrush. Based on digital substation system, studies have found that the fault generated electric quantities can not only be used by the relay to achieve the line protection but also used for developing transformer protection techniques. The protection system can effectively block transformer protection when inrush occurs. The results from simulation test show that the new method is with simple principle and good reliability. View full abstract»

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  • Study on the transmission performance index of the complex power grid

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB) |  | HTML iconHTML  

    Power grid is the bridge between power plants and loads. It has direct influence to the security, reliability and economic efficiency of power system operation. With the power grid continuous expanding, it becomes more and more difficult to understand and analyze this influence clearly. According to mentioned above, this paper proposes a new index named power grid transmission performance index (PI). With this index, several traditional power grid transfer problems can be explained, such as transfer capability assessment, coordination among power plants, power grid and loads, as well as the capacity margin assessment of power grid. Numerical analysis shows that the proposed method is a convenient way to analyze complex power grid and lays foundation for the further study of complex power grid. View full abstract»

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  • Effect of external ground on lightning performance of 69 kV and 24 kV circuits in MEA's distribution system

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (398 KB) |  | HTML iconHTML  

    Back flashover generated from a lightning stroke hit on an overhead ground wire or a pole is one of the major causes of sustained interruption in Metropolitan Electricity Authority (MEA)'s distribution system. One effective way to reduce the effects of lightning overvoltage from back flashover is an attachment of external ground wire connected between the overhead ground wires and a ground rod. This paper analyzes the effects of lightning performance of 69 kV and 24 kV circuits installed on the same pole by ATP-EMTP. The lightning performance is evaluated in terms of top pole voltage, critical current and back flashover rate. The study results show that external ground wires can contribute toward improving these three performance indices and therefore offers a promising solution to improve reliability of the double-circuit subtransmission and distribution lines in MEA. View full abstract»

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  • The characteristics of electromagnetic current transformers with DC bias

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (238 KB) |  | HTML iconHTML  

    Both geomagnetically induced currents (GIC) and high voltage direct current (HVDC) projects using the earth as its path can cause direct current flowing in the ground. Direct current flux will be produced and has detrimental effects on power systems. Few references can be found about the effects of dc bias on the current transformer that is very important to both metering and protective aims. In this paper, the characteristics of electromagnetic CTs are discussed. At first, the primary current is determined, and a decaying dc offset is found which will affect the CT's dynamic performance. Then the CT's steady state and transient state characteristics with dc bias are researched. It shows that the turns ratio, direct current and some other parameters have effects on the CT's time-to-saturation which is important to protective engineers. EMTP simulation results confirm the validity of the results. View full abstract»

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  • A protection scheme of transmission line based on nature frequency

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB) |  | HTML iconHTML  

    This paper proposes a protection scheme for transmission lines based on nature frequency of fault-generated travelling wave. The fault component of current signals are first computed and decoupled into their modal components, and then the mode spectrums are computed by FFT to extra the fundamental frequency of nature frequencies, through comparing the fundamental frequency at both ends of lines to identify internal and external faults. The scheme operates rapidly, reliably and is immune to CT saturation, operation mode and transient resistance; it can endure the influences of various fault inception angles, fault location, The performance of scheme is investigated for various faults on a typical Electro-Magnetic Transient Program/Alternative Transients Program (EMTP/ATP) simulated transmission feeder. View full abstract»

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  • Study on harmonic resonance of traction line in electrified high-speed traction system

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (382 KB) |  | HTML iconHTML  

    Modern pulse width-modulated (PWM) converter-fed locomotives generate current harmonics which propagate along traction line. The traction line is distributed at high frequencies, so the injected harmonics may cause resonances. This paper presents a way for analyzing resonance in electrified high-speed traction system, by calculating the harmonic current along the traction line. According to harmonic voltage generation process and distributed characteristics of traction line, the formulas representing the harmonic spectra of PWM converter input voltage and harmonic impedance of traction system are presented. Frequency spectrum characteristics of traction voltage and current are simulated and analyzed while the locomotive runs along the traction line. Results indicate that properties of both harmonic current and voltage vary, the former has greater variation; series resonances occur at some frequency and the position depends on locomotive position along the line; harmonic current contents are small, the mains are 3-9th harmonics and series resonances ones. View full abstract»

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  • Preliminary studies on construction of urban energy organic networks system

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (813 KB) |  | HTML iconHTML  

    Distributed energy system (DES) has become the main development tendency of future power generation system. DES refers to a power generating system, cogeneration system and poly generation power system without bulk power transmission to remote areas, which can be in accordance with the energy requirements of user and which makes use of a series of system that can satisfy environmental protection and that is suitable for being in or close to the load center. If joint with the large electrical networks reasonability, it will improve the efficiency, quality and security of power supply greatly; reduce the environmental pollution and the pressure of the rising energy requirements to the power networks. This paper combines with the integrated solar building, the security need of urban energy, putting forward the construction of urban energy organic networks, which is designed to expand the means of networks energy, optimize integration energy system, guide urban development with the minimum ecological and resource cost, and to get the maximum benefit in a wide range of areas. View full abstract»

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  • PMU placement based on power system characteristics

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    We present a novel method for placing PMU in power systems based on power system intrinsic characteristics. In the method power system was first analyzed for find out the major or critical interchanges and major load areas, major control systems, critical equipments and power plants in the power system. The overall PMU facilities should provide comprehensive information of line flows, bus conditions, and control actions for power system dispatcher. Then based on coherent characteristics of rotor angles as well as bus voltages, placement of PMU is optimized. All potentially critical-modes, critical bus-clusters and generators are identified by transient stability evaluation and small signal stability analysis, and then PMU are assigned to those critical buses or power plants. The effectiveness of the proposed approach is verified with a real large-scale power system. PMU placement scheme is being implemented in Northwest China power grid. The proposed approach can also be used to different sized power systems. As the power systems become more populated by PMU, the proposed novel method is a useful and convenient tool for systematic installation of PMU around the network, which may assist system planners in deciding on the location of new PMU installments for better dynamic monitoring and control. View full abstract»

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  • A practical solution method of dynamic reactive power optimization in AVC

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (235 KB) |  | HTML iconHTML  

    Under the environment of AVC (Automatic Voltage Control), this paper proposes a new idea about solving the power system dynamic reactive power optimization problem to coordinate with and adaptation of AVC, with the analysis of effect and mechanism of reactive power source and load. And based on the idea, it gives a practical solution method of reactive power optimization between the dynamic and static. According to the property of reactive power sources and the key features of reactive power load circle variation, it makes full use of continuous reactive power regulation resources, to realize the effective optimal combination of discrete reactive power resources ahead of the day time, which will be the foundation of further research. View full abstract»

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  • A new state estimation method with bad data rejection properties

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (349 KB) |  | HTML iconHTML  

    A new power system state estimation method with bad data rejection properties is proposed. The method uses a new objective function which a window-likelihood function is used to evaluate each measurement's influence and rejection of failed measurements or measurements whose absolute value of measure error is beyond error limits is a consequences of the objective function form. Power flow equation and zero injection of link bus are considered as constraints in order to improve correctness of state estimation. Mathematical model of the optimization problem is built based on both the new objective function and constraints, and modern inner point algorithm is used to solve the problem. The reason of good performance of bad data rejection of the method is analyzed. The proposed method does not need to perform additional observability analyze, bad data detection, or subjective weighting factors setting, thus substantial reduction in maintenance efforts can be achieved. Numerical simulations are cared out using 4 bus test system, 30, 118 bus test models and a practical utility system. Test results of test system verify that the proposed method has good performance of bad data rejection and archives high good measurement rate in practical system. View full abstract»

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  • Reliability evaluation for main electrical scheme of simultaneous AC-DC power transmission

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB) |  | HTML iconHTML  

    H. Rahman and B. H. Khan have given a new model for simultaneous AC-DC power transmission through a transmission line. This paper model formation to evaluate the reliability of main electrical scheme. Use advanced four state component model, redefined abnormal state and maintainable state, combined maintenance state based on condition of component and schedule maintenance state to maintenance state on the basis of taking account of the condition-based maintenance and then confirmed the conversion relationship and the parameter to each state. The main electrical scheme is simplified on the basis of function and gets more simple net. For DC station, it simplified with the method of combining components and dividing subzone. Apply advanced four state component model to make certain reliability parameters of each part and get reliability parameters of main electric scheme through Markov model. View full abstract»

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  • Research on the Automatic Electricity Use Restricting Load-shedding

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (225 KB) |  | HTML iconHTML  

    The Electricity Use Restricting Load-shedding (EURLS) is a method to deal with the frequency decline caused by the power shortage or the accident of the power system. At present, the EURLS is implemented manually. This paper proposes an Automatic Electricity Use Restricting Load-shedding (AEURLS) to solve the problems of the manual EURLS. The AEURLS uses the design methods of the UFLS for reference. This paper first analyses the differences between the AEURLS and the UFLS, and then proposes the design principles of the AEURLS. Finally, this paper proposes three schemes for the Northeast Power Network. The simulation results prove that the AEURLS could solve the problems of the manual EURLS and it could be a theoretical reference for the practical use. View full abstract»

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