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Analyses of transformer electromagnetic vibration noise are presented in this study. A finite element model is established which combines transient electromagnetic field analysis, mechanical field analysis and acoustic analysis to calculate the sound pressure level of the radiated noise around the transformer. Transient electromagnetic field analysis is performed to get the Lorentz, reluctance magnetic...
When predicting the noise level of substation, the model of transformers and reactors as noise sources is very important. A new acoustic mode of the transformers and reactors is built in ultra-high voltage substation. Each of the transformers and reactors is equivalent to several point sources based on equivalent source method. And in the process of the equivalent, the measurement and calculation...
This paper proposes the MLR (multiple linear regression) algorithm for parameter estimation of power system post-fault configuration based on the PMU real-time measurement and generator dynamic equations. Using real-time data collected by wide-area measurement system, the algorithm can take complicated cascading fault events into consideration without any information about the specific parameter and...
Subsynchronous oscillation may cause the unstable torsional vibration of turbine-generator shaft system, and even damage the generator shaft, endangering the safe operation of power system. Based on the simulation, this paper uses Static Var Compensator to damp subsynchronous oscillation by utilizing extra voltage control and modal separation control. The subsynchronous oscillation effect of Static...
Based on modeling of photovoltaic cell and array according to project requirement and modeling of converter according to grid-connected control tragedy, the model of photovoltaic generation system is established. By principle of constant power-loss, the equivalent method of large photovoltaic station is proposed in order to being applied in large power system simulation. Thereafter, making use of...
For the sake of the existing traditional out-of-step detection criterions' defects caused by the lack of oscillation central location and direction of migration which cannot characterize the dynamic process of the oscillation center, on the basis of the wide-area measurement information of the migration of out-of-step oscillation center in the equivalent two-generators system, the paper proposes the...
Taking source-side maintenance as an example, the possibility of wide area control of smart substation was studied in this paper. Source-side maintenance IED which meets the IEC61850 standard was proposed. On the basis of analyzing the IED's logical model and information flow, the corresponding data IED object model is designed. The transmission principles of sampling data based on the publish subscribe...
As the requirement for the power quality is increasing nowadays, the distributed source energy has been widely used. The association of different Distributed Generation System (DGS) could cause as many problems as it may solve. Micro-grid associates the distributed generation and the loads as a subsystem. The generation and loads could separate from the distribution system to isolate the micro grid's...
Based on the N330-17.75-540/540 steam turbine unit, the thermodynamic methods were firstly used to test the influence of the economics in different loads with different input pressures (fixed-pressure operation and sliding-pressure operation). And then the variation of the slightly increasing output was explored, which was caused by the exhaust pressure changes of the steam turbine. The best operation...
The damping characteristic of a single-machine infinite bus system is analyzed, and the relation graph of damping torque to transmission power is plot. The influence of changing tie-line power flow on the low-frequency oscillation modes of Central China Power Grid is researched, by way of changing power flow in one section and others remaining the same. The proposed method can be used for the actual...
Based on the space vector pulse width modulation (SVPWM) principle, the detailed SVPWM algorithm is derived in this paper and some improvements have been made taking over modulation and sector transition into consideration. Then the improved algorithm is simulated under MATLAB/SIMULINK. Multiple modulating methods-continuous and discontinuous are achieved in the simulation by changing some particular...
The radio interference is one of the important electromagnetic environment parameters for UHV DC transmission line. This paper validates the radio interference calculating formula of DC transmission line recommended by CISPR though measured data from three 500 kV DC transmission lines that have been built in China. The radio interference from plusmn800 kV Yun Guang UHVDC transmission line with different...
This paper analyses the main characteristics of transient electromagnetic environment in power system with wavelet theory. Combining with the accomplished actual project, the transient data of secondary system of a certain power plant is mentioned to be analyzed and processed as a concrete application of the wavelet theory. Good results are obtained in both the separation of the signal and noise by...
Load prediction is necessary in VQC, because if the variation tendency of voltage and reactive power can be forecasted, the system can analyze and control in advance. There are many algorithms for load prediction. This paper presents an improved control method based on very-short-term forecast. The voltage and reactive power data queues are acquired from electric line with high speed, then the values...
This paper consists of the discussions about intelligent high stabilized UPS power supply system in power frequency which is constituted of contravariantor, DSP, control for accumulator's charge and recharge and automatic protection circuits. Particular explanation about principles and structure of hardware and software are also included. This system can guarantee uninterruptible power supply in any...
Manual operation in power substation's VQC is out of date, and the nine-area control method has been widely adopted, but there are problems and deficiency for this method. This paper improves the nine-area control method, and presents a novel comprehensive VQC control technology. With the help of high-performance MCU, it implements adaptive prediction of electrical parameters, and then fuzzy logic...
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