Available transfer capability (ATC) determines the largest transfer that can be implemented in a certain direction across the power grid without violating security constraints. The uncertainties including load level, ...
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ISBN:
(纸本)0863412467
Available transfer capability (ATC) determines the largest transfer that can be implemented in a certain direction across the power grid without violating security constraints. The uncertainties including load level, aging and maintenance of elements and weather conditions, which have great influence on powersystem operation should be taking into account when calculating ATC. Considering time-varying nature and uncertainty of system parameters, the time-dependent model is adopted to describe the effects of weather conditions, aging and maintenance on element fault rates. Time-varying restoration time and load are modeled using random variables. The sequential simulation technique is applied to sample the system states, then based on linear programming and DC power flow ATC calculation is proposed. The algorithm based on MATLAB 6.5 is developed. IEEE 14-bus test system is used to verify the presented approach.
This paper presents an approach to the detection of harmonics and reactive currents in single-phase circuit according to the orthogonal characteristic of sine function. The method is simple and practical, which cannot...
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The power line tower lightning surge impedance is computed using an electromagnetic field approach. After comparing the results computed by our method and those tested with both a vertical conductor and reduced scale ...
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ISBN:
(纸本)3952299049
The power line tower lightning surge impedance is computed using an electromagnetic field approach. After comparing the results computed by our method and those tested with both a vertical conductor and reduced scale 4-poles model of tower, the method we used is proved to be right and more practical as the soil and the grounding system of the tower can be considered in the method. Using this method, the lightning surge impedance of the full scale UHV tower with grounding system is analyzed and the results show that the lightning surge impedance of a tower on the perfect ground has a little difference with those of an actual tower considering both its grounding system and soil resistivity, and when the soil resistivity is changed, the surge impedance changes slightly. Furthermore, a circuit model of the tower is obtained by Vector Fitting method based on the results we computed. Using the circuit model, the lightning surge performance of a power transmission line can be analyzed more accurately by EMTP or other methods.
In this paper, a novel method for perturbed trajectory prediction of post-fault rotor angle is presented based on PMU (phasor measurement unit) measurements and trigonometric function curve fitting technique. A mathem...
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ISBN:
(纸本)9780780391932
In this paper, a novel method for perturbed trajectory prediction of post-fault rotor angle is presented based on PMU (phasor measurement unit) measurements and trigonometric function curve fitting technique. A mathematical model about the relationship of post-fault rotor angle and time is derived from a speed-governing system model, which reveals that the perturbed trajectory of the post-fault rotor angle can be expressed by trigonometric functions. By curve fitting technique, a least square method to predict the perturbed trajectory using trigonometric function is proposed. Numerical simulations are conducted on IIEEE 9-bus system to test the effectiveness of this method. The proposed method can give more reasonable and more promising prediction results as compared with polynomial curve fitting technique.
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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ISBN:
(纸本)9780780391932
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 15kVA 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.
An equivalent continuous-time state-space model for VSC-HVDC in the synchronous dq reference frame has been established in the paper. Based on the model, relevant control strategies have been developed for the cases o...
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The black start restoration of a powersystem after a complete blackout is a very important issue to safety of the powersystem. The reasonable network reconfiguration strategy is necessary for establishing the main n...
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A novel technique for treating electrically thin dispersive layers with the finite-difference time-domain (FDTD) method based on Z transforms is introduced. The proposed model is based on the subcell technique, where ...
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ISBN:
(纸本)3952299049
A novel technique for treating electrically thin dispersive layers with the finite-difference time-domain (FDTD) method based on Z transforms is introduced. The proposed model is based on the subcell technique, where the constitutive relations are locally averaged in the FDTD grid. The most significant feature of the proposed model is its ability to model rather complicated dispersive layers having multiple pole pairs. The model is validated with several numerical examples making comparison with the exact results.
Direct torque control (DTC) has achieved utilization on two-level inverters and three-level diode-clamped inverters, and it has high performance of speed control. But DTC hasn't been utilized to cascaded multileve...
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With the electrical load increasing rapidly, the fault probability of power equipment is also rising greatly. This paper put forwards a new method of monitoring transformer-running state based on acoustic wave analysi...
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ISBN:
(纸本)0863416381
With the electrical load increasing rapidly, the fault probability of power equipment is also rising greatly. This paper put forwards a new method of monitoring transformer-running state based on acoustic wave analysis. Firstly, the acoustic wave signal of the transformer running is collected by the system on chip (SOC) microcomputer. Then the signal is stored by a high-capacity secure memory (SD) card. The sound intensity and spectrum of acoustic wave is different when the power transformer running between normal and abnormal condition. Finally, the fuzzy algorithm is utilized to analyze the state of transformer. It is proved that the monitoringsystem based on acoustic wave analyzing can find the transformer's incipient fault on-line, and the transformer running safety and reliability can be assurance effectively.
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