After taking the element of adjacent matrix as the function of the state of edges in the network structure, the representation of the element in corresponding adjoint matrix has been given an in-depth analysis. With t...
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ISBN:
(纸本)9781457710001
After taking the element of adjacent matrix as the function of the state of edges in the network structure, the representation of the element in corresponding adjoint matrix has been given an in-depth analysis. With the use of simplifying method on each element in adjoint matrix, the complete connected matrix could be formed equally with the each element as the set of connected routes. Based on the above analysis and processing, the new connected routes finding algorithm is established, which is a systematic method and suitable for all kinds of network connections. Finally, the successful application to substation configuration has validated the efficiency of the novel algorithm in powersystem topology analysis, in which the connected routes can be formed in off-line way and be used for topology analysis in on-line way. Therefore, the aim to reduce topology analysis time could be achieved.
The transient mathematical models of two VSC-HVDC systems which are supplying active and passive networks respectively are developed in d-q synchronous reference frames. All the controllers were designed and realized ...
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The transient mathematical models of two VSC-HVDC systems which are supplying active and passive networks respectively are developed in d-q synchronous reference frames. All the controllers were designed and realized current decoupled controls by applying PI (Proportional-Integral) regulators. A 2-Level VSC-HVDC supplying active network with fixed DC voltage control in rectifier side and fixed active powercontrol in inverter side was modeled, then a 3-Level VSC-HVDC supplying passive network with fixed DC voltage control in rectifier side and fixed AC voltage control in inverter side was modeled thereafter, then their operational characteristics were tested and compared by simulations in PSCAD/EMTDC, which verified the effectiveness and stability of the designed controllers and validated great potentiality in future VSC-HVDC projects.
A three-terminal DC transmission system based on modular multilevel converter (MMC) is developed to solve the problem of power supply for distributed islands or *** system,with flexible features,may generate high qual...
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A three-terminal DC transmission system based on modular multilevel converter (MMC) is developed to solve the problem of power supply for distributed islands or *** system,with flexible features,may generate high quality output voltage and reduce construction costs and power losses in the converter ***,the three-terminal DC system based on MMC faces more complex situations in operation and its control *** this paper,the mathematic model of three-terminal DC system based on MMC is *** according to the structure of MMC,a method of carrier phase-shift SPWM is *** the system-level control,the decoupling controller for threeterminal DC system based on MMC is designed.A multi-point DC voltage control strategy based on DC voltage error method,which doesn't need communication between converter stations,is proposed to improve the system *** simulation with PSCAD/EMTDC,the feasibility and effectiveness of the proposed model and control strategies are verified.
Due to the energy crisis and global warming problems, most of the countries place more and more emphasis on the development of distributed generation (DG) using renewable energy. In China the installed capacity of dis...
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Due to the energy crisis and global warming problems, most of the countries place more and more emphasis on the development of distributed generation (DG) using renewable energy. In China the installed capacity of distributed generators is rising, from isolated micro-grid system to grid connected system. With the increasing penetration of distributed generation, especially for the converter interfaced DG, their impacts on the protection of distribution system cannot be neglected. In this paper, the models of two types of DG, i.e. converter based DFIG and inverter interfaced DG, are reviewed. Moreover, the fault analysis of the two types of DG is investigated systematically and the impacts on protections are analyzed as well.
Service restoration is a problem with multiple objectives and constraints, when the distribution systems with DGs (distributed generators) come up large area blackout. In this article the model of multiple objective s...
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Service restoration is a problem with multiple objectives and constraints, when the distribution systems with DGs (distributed generators) come up large area blackout. In this article the model of multiple objective service restoration about distribution systems with DGs has been built, considering users’ priority, the action times of hand switches or tele-switches and network losses after service restoring. Multi-agent GA can be used to search the Pareto optimal solution set for the multiple objectives service restoration problem. Agent's competitive and selflearning actions reflect the principal of survival of the fittest and diversity. It can reduce complex rate and improve efficiency using challenge match method to form Pareto solution to store populations. At last the calculation example manifests the quickness and precision of the multiple objective service restoration for blackout based multi-agent GA, and it is better suit for the distribution system than single objective method.
A multi-input and multi-output linear model of multi-machine powersystem was established based on perturbation analysis, and the complex torque coefficient of target generator was deduced in detail. From a mathematic...
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A multi-input and multi-output linear model of multi-machine powersystem was established based on perturbation analysis, and the complex torque coefficient of target generator was deduced in detail. From a mathematical perspective, the meaning of complex torque coefficient was explained. Meanwhile, the reasonability about non-target generators being equivalent to different models was discussed when investigating subsynchornous oscillation phenomenon in a multi-generator system. The results showed that the complex torque coefficient method was suitable for multi-generator system and the procedure of simplifying non-target generator as single rigid body or voltage sources with fixed frequency was inappropriate. Then a case study of IEEE second benchmark verified the conclusions above.
The pulse width modulation technique and dynamic operating mode characteristics of direct drive permanent magnet synchronous generator (PMSG) are researched firstly. A novel sliding mode variable structure directed po...
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The pulse width modulation technique and dynamic operating mode characteristics of direct drive permanent magnet synchronous generator (PMSG) are researched firstly. A novel sliding mode variable structure directed powercontrol algorithm applied to PMSG is proposed, and then design the controller using tip speed radio and flux-weakening control scheme. It can not only provide a constant switching frequency without involving any synchronous speed coordinate transformation and generator side phase information, but also can reduce the capacitance of generator-side converter. Simulation and experimental results show that the proposed theoretical analysis method and control strategy is effective under the platform PSCAD/EMTDC.
Frequency stability refers to the ability of a powersystem to maintain steady frequency following a severe system upset resulting in a significant imbalance between generation and load. The rate of frequency change (...
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Frequency stability refers to the ability of a powersystem to maintain steady frequency following a severe system upset resulting in a significant imbalance between generation and load. The rate of frequency change (df/dt) is an instantaneous indicator of power deficiency and can incipient recognition of power imbalance. The new method presented in this paper assumes the application of the WAMS as a base for their successful implementation. The adaptive scheme aims to extract the relevant powersystem parameters from on-line measurements. Therefore, the scheme can adapt its sensitivity to the current operating conditions, eliminating the need for many assumptions that have to make when tuning the conventional local scheme. In the predictive step, this model is used to estimate a frequency trajectory following a disturbance. The proposed scheme uses the local frequency rate information to adapt the load shedding behavior to the size and location of the experienced disturbance. Based on this prediction it can be determined whether emergency UFLS control actions are necessary.
This paper proposes a high-powercontrollable current quality disturbance generator, which is composed of multiplex cascade H bridge modules, and simulates current quality problems, such as positive and negative curre...
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This paper proposes a high-powercontrollable current quality disturbance generator, which is composed of multiplex cascade H bridge modules, and simulates current quality problems, such as positive and negative current distrubance, current fluctuation, harmonic current and so on. The device adopts a topology with decoupling fundamental and harmonic current. A power module parallel-connected on the fundamental connection reactance outputs harmonic current, while cascade fundamental power modules generate fundamental and low order harmonic current, which realizes decoupling control of fundamental and harmonic current. This paper proposes the control strategies of all types of current disturbances, and the Ether Cat-based controller. Finally, a 10 k V/1MVA controllable current quality disturbance generator has been created. The experiment result proves that the proposed main circuit topology, control strategy and Ether Cat-based controller are feasible and efficient. The emergence of this device creates a fundamental platform for measurement, analysis, evaluation and control of current quality in grid.
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