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Application of automatic differentiation technique to the transient simulation of distributed generation system

Dianli Xitong Zidonghua/Automation of Electric power systems 2010年第23期34卷 71-75+101页

作者： Wang, Chengshan Huang, Bibin Li, Peng Gao, Fei Ding, Fei Ding, Chengdi Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin 300072 China

In view of the diversity of the distributed generation control system and the influence on the simulation efficiency due to adoption of the user-defined model based on the basic elements of control systems, a control system compositional modeling method is proposed that consists in combining the basic elements into a number of functions. The corresponding compositional function values and derivatives can be accurately and highly efficiently found using the automatic differentiation technique, effectively increasing the computational efficiency of the simulation program while maintaining the code maintainability and scalability. This method is validated with an example. © State Grid Electric power Research Institute Press.

关键词： Distributed power generation

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Discussion on setting calculation of loss-of-excitation protection for large turbogenerator

Discussion on setting calculation of loss-of-excitation prot...

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2010 International Conference on Electrical Machines and systems, ICEMS2010

作者： Yao, Siwang Wang, Weijian Luo, Ling Gui, Lin Qiu, Arui State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China

Loss of excitation (LOE) is a common fault found in the generators. The most widely applied method for detecting a generator loss of excitation is the use of impedance relays to sense the variation of impedance as viewed from the generator terminals [1]. However, compared with China's approachs, in the setting of impedance circle, the IEEE's allow the circle to extend along the negative X axis, meanwhile, in the latest edition of the "IEEE Guide for AC Generator Protection", the circle is further extended, reaching to -1.25X_d.We think this is adverse, to prove our point, the paper ,basing on the IEEE 9 bus model and using computer digital simulation, have studied various loss-of-excitation conditions and some system disturbances that may lead to the relay false tripping. simulation results indicate that the IEEE's method not only can't accelerate the operation effectively, but also will increase the chances of maloperation.

关键词： Impedance Generators Relays Analytical models power system stability Reactive power

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Study on transferred lightning overvoltage in microgrid

Study on transferred lightning overvoltage in microgrid

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Asia-Pacific International Symposium on Electromagnetic Compatibility

作者： Hongqiao Yu Shuiming Chen Pengcheng Yang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University

ISBN: (纸本)9781424456215

If the microgrid is stroke by lightning, the lightning overvoltage which transferred though distribution transformer has great influence on the safety of the microgrid. The models of microgrid and high-frequency transformers are established based on the electromagnetic transient calculation program PSCAD/EMTDC. The transferred overvoltage with different lightning strike position in microgrid is researched in this paper. The effect of surge arresters on restricting overvoltage is also analyzed. The simulation results show that surge arresters must be installed at both sides of transformer due to the high overvoltage when the transformer has no load. If the transformer is connected with cables, the overvoltage will be reduced. The longer the cable is, the lower the overvoltage is. The types of loads have a little influence on the overvoltage.

关键词： Lightning Voltage control power transformer insulation Frequency Capacitance Laboratories power system simulation power system modeling power generation Electromagnetic modeling

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Study on lightning protection of cables and transformer in Microgrid

Study on lightning protection of cables and transformer in M...

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China International Conference on Electricity Distribution, CICED

作者： Hong-qiao Yu Shui-ming Chen Yang Peng-cheng State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457700668

The cable and transformer are important distribution equipment in Microgrid. Due to the low insulation level, the insulation of them is easily damaged by lightning. The models of high-frequency transformer and the calculation model of induced lightning with transmission line based on electromagnetic transient calculation software PSCAD / EMTDC are designed in this paper. The lightning protection of cables and transformer in Microgrid, the transferred overvoltage of transformer and the effect of the length of cables and the load types to overvoltage level are researched. The conclusion shows that the induced overvoltage and transferred overvoltage could be reduced efficiently after installing surge arrester at the cables and transformer, but the direct lightning overvoltage is not reduced in the safety range; The longer the cables, the lower the overvoltage is; The inductively load can reduce the overvoltage level slightly while the capacitive and resistance loads has no influence.

关键词： power cables Load modeling Arresters Cable insulation EMTDC Lead PSCAD

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Notice of Retraction: The Optimal Bidding Based On The Prospect Theory

Notice of Retraction: The Optimal Bidding Based On The Prosp...

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IEEE PES Asia-Pacific power and Energy Engineering Conference (APPEEC)

作者： Ji-keng Lin Xudong Wang Key laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin China

This article has been retracted by the publisher.

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A study on steady characters of inverter interfaced distributed generation in three phase symmetrical system

A study on steady characters of inverter interfaced distribu...

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International Conference on power system Technology (powerCON)

作者： Qiang Jin Yong-Li Li Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin China

Recently inverters are all-pervading used as the connective instrument of distributed generations and distributed power system. When inverter interfaced distributed generations are connected to the distribution system, it may bring some new problems on load flow and fault characteristic and protection. The analysis on steady characters of PQ control mode and VF control mode inverter interfaced distributed generation is done when the system is three phase symmetrical. Generally speaking there are limits on power and current in control system for the security of distributed generations and power electronic devices in inverter, so the analysis is more complex. The mathematical analysis on three phase symmetrical system is done and restriction equations are described whether three phase symmetrical fault occurs or not. For the solution of the equation groups expresses the steady state of the system, so the solution of the equation groups is one and only. Then the restriction equation groups are solved. The solution in different areas shows the reason of steady non-linear character of inverter interfaced distributed generations and the simulation shows the conclusion correct. The steady characteristic curves of PQ control mode and VF control mode inverter interfaced distributed generation about voltage and current and power are got from the function of voltage and current and power at the same time. PQ control mode and VF control mode inverter interfaced distributed generation behave similarly but not identically when three phase symmetrical fault occurs in three phase symmetrical system. The disadvantageous influence on protection is analysed by the way.

关键词： Equations Mathematical model

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Total Supply Capability and Ideal Total Supply Capability for distribution system: Definition, model and algorithm

Total Supply Capability and Ideal Total Supply Capability fo...

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China International Conference on Electricity Distribution, CICED

作者： Jun Xiao Wei Zhai Wenzhuo Gu Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University TJU China

ISBN: (纸本)9781457700668

This paper proposes the definition, model and algorithm of two quantitative indices named the Total Supply Capability (TSC) and Ideal Total Supply Capability (ITSC) for distribution planning. The TSC of a distribution system is comparable to Total Transfer Capability (TTC) in transmission systems, which is defined as the maximum load it can serve under the N-1 guideline for distribution systems, taking into account the capacities of the substation transformers, network link topology, link capacity, and other constraints. The ITSC of a distribution system is the calculated TSC which considers capacities of tie lines are large enough. Mathematical models for TSC and ITSC are set up and procedures to calculate TSC and ITSC are presented. Based on TSC and ITSC calculation, a concept named Potential Supply Capability(PSC) is proposed, which depicts the “potential” or “hidden” TSC of the distribution system. Finally, TSC and ITSC calculation have been performed in a test system with promising results. The case study has shown that TSC and ITSC algorithms are efficient approaches to analyze and evaluate the existing distribution system.

关键词： Load modeling Silicon Conductors Mathematical model

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Cascaded battery energy storage system based on dual active bridges and a common DC bus

Cascaded battery energy storage system based on dual active ...

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International power Engineering Conference (IPEC)

作者： Yiding Jin Qiang Song Wenhua Liu Weixin Sun State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China

Along with the increasing system capacity, large-scaled energy storage systems are supposed to be connected into 10kV or higher networks. Urban network has strict criterions on power quality of the power electronic devices connected. Moreover, the occupancy and noise of industrial frequency transformers also become restraints to the promotion of urban network energy storage. For that reason, this paper proposes a battery energy storage system based on cascaded dc-ac converter, dual active bridges, and a common dc bus. High frequency transformers are used to replace the industrial frequency transformer for insulation, and battery groups are connected to the common dc bus with respective dc-dc interfaces. This multilevel converter system is easy to modularize, easy to extend, and allows different kinds of batteries to work together. The main circuit and proper control system are designed, with the soft-switching condition and current control issues of the dual active bridge analyzed in detail. The simulation results from EMTDC model verify the operation principles and corresponding control strategies.

关键词： Batteries Voltage control Converters Switches Bridge circuits

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Intelligent control Technology of Tripping and Reclosing for Double-circuit Transmission Line on the Same Tower

Intelligent Control Technology of Tripping and Reclosing for...

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IEEE PES Asia-Pacific power and Energy Engineering Conference (APPEEC)

作者： B. T. Li Y. L. Li Key laboratory of power system simulation and control of ministry of education Tianjin University TJU Tianjin China

Intelligent control technology of tripping and reclosing is present for double-circuit transmission line on the same tower aiming at solving the problems existing in reclosure commonly used nowadays. Way of only tripping faulty conductor(s), which can enhance the power transmission on condition of fault, is applied for each fault type. Identification of transient and permanent fault based on fault point voltage is carried out after tripping. If permanent fault occurs, the whole fault circuit(s) is(are) opened and reclosure(s) is(are) locked; if transient fault occurs, reclosing scheme in phase order is started. Breaker of the remote terminal operates first when reclosing each phase; each reclosing time delay is set at the optical reclosing time in order to damp out the oscillation and stabilize the system; reclosing angle is set at the ideal angle for decreasing transient aperiodic component of the second short circuit current.

关键词： Intelligent control Transmission lines Poles and towers Circuit faults power system transients power transmission lines power transmission Fault diagnosis Voltage Delay effects

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An Economic Evaluation Method on power Distribution system Considering N-1 Guidelines

An Economic Evaluation Method on Power Distribution System C...

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IEEE PES Asia-Pacific power and Energy Engineering Conference (APPEEC)

作者： Fengzhang Luo Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University TJU Tianjin China

An economic analysis method is proposed for distribution system planning considering the N-1 guidelines, in which the fundamental properties of power supply capability and the economic benefit are combined. The economic efficiency and the potential power supply benefit of a distribution system are thus evaluated. A complete system of economic evaluation indices is presented, including the static profitability indices and the dynamic investment benefit indices. Applications show that this method and index system can take into account both the basic characteristics of distribution system and the special features of power energy that differ from general merchandise. So they can not only evaluate the economic benefits for project investment combining with the traditional approaches of engineering economics, but can also assess the economic benefits of system-owned assets for power supplying effectively, as well as for the economy evaluation of the distribution system in operation or the planning schemes. This method can even be applied to assess the economic benefits of transmission system.

关键词： power system economics power generation economics power distribution Guidelines power supplies power system planning Investments Profitability Merchandise power engineering and energy

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