The research on the methodologies and implementation strategies in bulk power system restoration after a partial or complete collapse is of great significance. This paper provides the survey on the recent developments...
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ISBN:
(纸本)0863412467
The research on the methodologies and implementation strategies in bulk power system restoration after a partial or complete collapse is of great significance. This paper provides the survey on the recent developments of restoration methodologies and implementation strategies. And many new ways to form a power system restoration plan and how to deal with the sub-problems encountered during the restoration process are summarized and introduced. Also, the future work are presented, such as, how to consider the AC/DC hybrid system in the restoration process, how to utilize the distributed generation (DG) and how to use the wide-area measurement system (WAMS) for restoration.
In this paper, a novel real time data compression and reconstruction method is proposed to process a large amount of steady state and transient data of power system. Based on the biorthogonality filters group with the...
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In this paper, a novel real time data compression and reconstruction method is proposed to process a large amount of steady state and transient data of power system. Based on the biorthogonality filters group with the linear wavelet (WT) of lifting scheme and Huffman coding approach, the new algorithm is studied and developed. The field data are used to test the method. The results prove that the method is valid with less data processing time and as high as about 9 times of compression ratio. This method is suitable for the real-time compression of mass data recorded continuously by dynamicmonitoring devices of electric power system
A practical ride through scheme bases on super capacitor energy storage system for ASD (adjustable speed drive) equipment is presented in this paper. The topology of ASD discussed adopts AC-DC-AC structure and 12 puls...
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A practical ride through scheme bases on super capacitor energy storage system for ASD (adjustable speed drive) equipment is presented in this paper. The topology of ASD discussed adopts AC-DC-AC structure and 12 pulses diode rectifier as input interface. Super capacitor (SC) module connects to inverter DC bus to support DC voltage while power quality problems such as voltage sag or short-term outage take place in power source. A SC energy storage system based 15 kVA ASD prototype was developed. Digital simulation and physical experiments were carried out to verify the correctness and validity of proposed ASD ride through topology and control strategies
It is a trend to construct unattended substation in power system *** paper systematically analyses the superiority and limitation of MATLAB and Visual C++ and illustrates how to compile m-files to cpp-files by MATLAB ...
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ISBN:
(纸本)0863416381
It is a trend to construct unattended substation in power system *** paper systematically analyses the superiority and limitation of MATLAB and Visual C++ and illustrates how to compile m-files to cpp-files by MATLAB engines and integrate cpp-files code into existing C++ projects by Visual C++ to realize intelligent function on image recognition used for unattended *** intelligent function can effectively test illegal intrusion and fires through the detection and recognition of moving goals by three-image difference method and self-adapting threshold value segmentation algorithm and detect situations of disconnection link by use of image crop and image index processing and give warnings to alarm system. Because of lacking of brightness of image or nonlinear brightness and being influenced by kinds of noise,this paper determines to adopt contrast enhanced algorithm and high-frequency enhanced algorithm to repair grey-scale distribution and uses median filtering to remove noise of image. In the end,this paper brings forward the expectation about the image recognition of the unattended substation. When non-uniform of image illumination distribution, grey-scale of background changes largely and image segmentation has not the fittest threshold, so the paper uses self-adapting threshold segmentation algorithm to gain the image segmentation.
Induction-motors are the main component of the compositive load especially of the industry load and air- condition loads have been uppermost dynamic load in summer with the fast economy development, which are very imp...
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Induction-motors are the main component of the compositive load especially of the industry load and air- condition loads have been uppermost dynamic load in summer with the fast economy development, which are very important to analysis and control power system. So induction-motors and air-condition loads are studied seriously as dynamic loads in this paper. This paper studies the function mechanism and the influence of static and dynamic load characteristic on voltage stability by comparing the voltage stability simulation result of different loads based on a simple case of power system. The small disturbance analysis method is used and static load, induction-load and air-condition load are modelled in this paper. It is proved that power system get more and more voltage instability with induction-motor or air-condition load increasing, especially air-condition load.
A novel method for perturbed trajectory prediction of post-fault rotor angle is presented in this paper, which is based on phasor measurement unit (PMU) measurements and trigonometric function curve fitting technique....
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A novel method for perturbed trajectory prediction of post-fault rotor angle is presented in this paper, which is based on phasor measurement unit (PMU) measurements and trigonometric function curve fitting technique. A mathematical relationship of post-fault rotor angle and time is derived from a speed-governing system, which reveals that the perturbed trajectory of the post-fault rotor angle can be expressed by attenuation trigonometric functions. Using curve fitting technique and trigonometric function, a least square method to predict the perturbed trajectory is proposed. Numerical simulations are conducted in IEEE 9-bus system and the simplified north China grid to test the effectiveness of the proposed method. The proposed method can give more reasonable and more promising prediction results as compared with polynomial curve fitting technique.
Both static and dynamic electric load characteristics have considerable effect on short circuit ratio (SCR) or effective short circuit ratio (ESCR). This paper gives emphasis on the relationship between static/dynamic...
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Both static and dynamic electric load characteristics have considerable effect on short circuit ratio (SCR) or effective short circuit ratio (ESCR). This paper gives emphasis on the relationship between static/dynamic load characteristics and SCR (ESCR). Different power level with different power factor is considered for the impacts on SCR or ESCR of static load characteristics. Three-phase short-circuit current of induction motors is qualitative analyzed and simulation of the feeding current is carried out for the dynamic process of induction motor in the consideration of dynamic load characteristics. Case studies are carried out on WEPRI-36 system and Hunan power grid. Simulation results with power system analysis software package (PSASP) illustrates that load should be considered in calculating SCR.
Secondary voltage controlsystem is a significant segment of the hierarchical voltage control in power systems. Though voltage controller has both constant voltage regulators, such as generators and static reactive po...
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Secondary voltage controlsystem is a significant segment of the hierarchical voltage control in power systems. Though voltage controller has both constant voltage regulators, such as generators and static reactive power compensators, and discrete voltage regulators, such as OLTC and shunt capacitors/reactors, traditional secondary voltage control (SVC) only consider constant voltage regulators. A few of the papers consider discrete voltage regulators, but they are also treated as constant variable. In this paper, Considering the trait of continuous and discrete devices in secondary voltage control co-existing, a mixed secondary voltage control optimal model including continuous and discrete variables is established. The solution is gained by multi-agent particle swarm optimization algorithm. This method concerned with the advantages of multi-agent system and particle swarm optimization algorithm can get every setting value of regulator exactly and quickly. The proposed method is applied to the New England 39 nodes system. It is shown that by contrast to the traditional secondary voltage control, this method can achieve satisfactory controlling effort involved both constant and discrete controllers at the same time.
When relays trip a faulted line in power system, the flow on the faulted line will be transferred to the other lines. Those lines might be overloaded and then cascading tripped by the backup relays, which worsen the s...
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When relays trip a faulted line in power system, the flow on the faulted line will be transferred to the other lines. Those lines might be overloaded and then cascading tripped by the backup relays, which worsen the system state and even cause blackout. Generally, these kind of cascading trips are the origins of a lot of well-known blackouts. In this paper, by analyzing the defects of traditional backup protections, a new wide area backup protection scheme based on WAMS is presented to identify flow transferring. A new concept of flow transferring relativity factor (FTRF) is proposed to estimate the flow distribution after flow transferring occurs; and the method of calculating FTRF matrix online is also deduced. The simulation of 10-unit and 39-bus New England network shows that the proposed wide area backup protection scheme can identify flow transferring successfully and hence be superior to the traditional backup protection.
In substations, shielded cables are widely used to reduce transient electromagnetic interference to the relay and control equipments due to the switch operation. Both the transfer impedance and transfer admittance are...
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In substations, shielded cables are widely used to reduce transient electromagnetic interference to the relay and control equipments due to the switch operation. Both the transfer impedance and transfer admittance are quantities for expressing numerically the mechanism that allows the passage of electromagnetic energy across the cable shield. Theoretical models to compute both the quantities often rely on simplifying assumptions. This, together with the fact that the transfer impedance and admittance can vary considerably between cable samples of the same type, means that measurements become necessary. In this paper, based on the transmission line theory we present a simple method to measure the transfer impedance and admittance of shielded cable in magnitude as well as in phase over the frequency range (0.1 MHz-10 MHz) which covers the main interference frequencies in power system. To illustrate this method a coaxial cable with a braided shield has been measured and compared with the existing method. As an application, the proposed method is used to predict the induced voltage and current on the shielded cable due to the switch operation in substation
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