The location and sizing of distribution substations integrated with urban spatial information is a optimization problem which primary characteristics are the existence of many suboptimal cost peaks and the solution sp...
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Real time test is a necessary step for the control device of equipment before it is installed in power system. In this paper, a closed-loop test platform which is based on Real Time Digital Simulator (RTDS) is establi...
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ISBN:
(纸本)9787506292214
Real time test is a necessary step for the control device of equipment before it is installed in power system. In this paper, a closed-loop test platform which is based on Real Time Digital Simulator (RTDS) is established to test the performance of FACTS device controller. In this paper, Static Var Compensator (SVC) which is installed in a power plant is used for damping Sub Synchronous Oscillation (SSO) excited by fixed series compensator installed in the transmission line which is to improve the power transfer capability. The control approach, operation mode and the install location of SVC are studied in this paper and the real controller performance has been verified by the proposed test platform. Beside, this platform can also used for the test of performance of other FACTS devices controller.
An improved differential evolution (IDE) algorithm was presented for power system load economic dispatch (ED), a classical nonconvex, nonlinear, combinational optimization problem. Despite for its simplicity and high-...
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An improved differential evolution (IDE) algorithm was presented for power system load economic dispatch (ED), a classical nonconvex, nonlinear, combinational optimization problem. Despite for its simplicity and high-efficiency, differential evolution (DE) algorithm is prone to local optimal solution sometimes. Based on analysis of DE searching mechanism, IDE algorithm adopts adaptive control parameters according to swarms' distribution condition and the overlapping individuals undertake chaotic searching to improve its robust and global optima searching capability. The proposed IDE algorithm was tested on two systems consisting of 3, 40 and 69 thermal units whose incremental fuel cost function took into account the valve-point effects. The results indicate that IDE algorithm outperforms DE, GA, and PSO algorithms in solving load dispatch problems.
Distinguishing the transferring fault is one of difficulties for transformer differential protection. According to CT (current transformer) saturation characteristic, a new algorithm of distinguishing the transferring...
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Distinguishing the transferring fault is one of difficulties for transformer differential protection. According to CT (current transformer) saturation characteristic, a new algorithm of distinguishing the transferring fault is put forward. As the primary current of CT crosses zero, a small linear transmission part of CT would appear, no matter how CT saturated. Based on this characteristic, the waveform of the differential current would expose discontinuous parts when an external fault occurred;in contrast, this phenomenon would not appear for an internal fault. The morphological gradient is adopted to deal with the waveform between two adjacent extremal points of the differential current. By dividing the gradient waveform into three parts and calculating each part's area, the discontinuous in the differential current could be detected according to the relative size of three above areas. By judging whether the discontinuous parts are existed in the differential current, the transferring faults could be easily distinguished. Simulation results show that this algorithm can distinguish the internal fault, external fault and the fault transferred from the external to the internal under the condition of CT saturation.
Aim at the stability problem of multi-infeed direct current (MIDC) systems, voltage source converter based HVDC (VSC-HVDC) was applied to MIDC systems for improving the voltage characteristic of common AC bus in MIDC ...
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Aim at the stability problem of multi-infeed direct current (MIDC) systems, voltage source converter based HVDC (VSC-HVDC) was applied to MIDC systems for improving the voltage characteristic of common AC bus in MIDC systems. A physical model of a dual-infeed HVDC and VSC-HVDC system was set up, and its mathematical model was developed. The rectangular coordinate form of VSC's power transmission equations was deduced through coordinate conversion. Based on the inverse system method for multivariable nonlinear control, the nonlinear controllers of VSC-HVDC system were designed. Simulation results performed on PSCAD/EMTDC show that the designed nonlinear controllers of VSC-HVDC can improve effectively the dynamic character of VSC-HVDC system, stabilize effectively the voltage of dual-infeed HVDC and VSC-HVDC system when AC side is disturbed, reduce the probability of commutation failure in the inverter of HVDC systems, and increase the operation reliability of HVDC systems.
The characteristics of voltage modal transformation based on fault component in fault location and protection location are discussed in detail with regard to the changes of the system parameters and fault types. A new...
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The characteristics of voltage modal transformation based on fault component in fault location and protection location are discussed in detail with regard to the changes of the system parameters and fault types. A new phase-selector based on voltage modal fault component is proposed. It uses voltage fault component and works fast after a fault occurs. A fault selection scheme is also proposed to solve problems of sensitivity as faults located on remote end of transmission lines. The simulation results of ATP and MATLAB show the feasibility of the scheme.
As a measurement tool, wide area measurement system (WAMS) has the measurement error and bad data unavoidably. If the raw data is applied direcdy, the unpredictable consequence will be resulted in. Aiming at this prob...
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As a measurement tool, wide area measurement system (WAMS) has the measurement error and bad data unavoidably. If the raw data is applied direcdy, the unpredictable consequence will be resulted in. Aiming at this problem, a novel dynamic state estimator for generator state variables is proposed. The mathematical model and the flowchart of the algorithm are described. Bad data detection and elimination approach is given as well. The simulation results show that the proposed method can provide the estimated trajectories of the generators in real-time, which eliminates the impact of measurement error and bad data and gives the backbone for WAMS based dynamic applications and real-time control.
The prediction analysis in nonlinear systems will be discussed carefully in this paper. We are mainly using CM (1,1) model to forecast data sequences, and the usual forecast precision is approximate to 90%. In this p...
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The prediction analysis in nonlinear systems will be discussed carefully in this paper. We are mainly using CM (1,1) model to forecast data sequences, and the usual forecast precision is approximate to 90%. In this place we have found a generating rule that may realize chaotic synchronization at least in short and medium term, and we can analysis and forecast in this way. We hope to offer an effective prediction method to study certain properties of DNA base sequences, 20 amino acids symbolic sequences of protein structure, and the time series that can be symbolic in finance market et al.
This paper introduced a real-time digital modeling approach for Electrical Arc Furnace (EAF) based on recorded field data. The model equaled the arc furnace to a current source controlled by the field data, and via ad...
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This paper introduced a real-time digital modeling approach for Electrical Arc Furnace (EAF) based on recorded field data. The model equaled the arc furnace to a current source controlled by the field data, and via adopting a phase locked technique, the synchronization between simulation and field data was performed, which made a long time real-time simulation possible. Besides, the model was used for evaluating the performance of SVC system which contributes to compensate Var and mitigate the harmonic and flicker caused by EAF. The simulation was implemented on the Real Time Digital Simulators (RTDS) and the results of simulation illustrate that the proposed EAF model and evaluation system can be used for testing a physical control system of SVC system and evaluating the control strategy.
The electric propulsive shipping power grid is a typical independent power supply system, and the anti-jamming ability to non-linear load is quit weak because of the limitation of generation capacity. So the influence...
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The electric propulsive shipping power grid is a typical independent power supply system, and the anti-jamming ability to non-linear load is quit weak because of the limitation of generation capacity. So the influence of the harmonics becomes more serious. Meanwhile, the variation range of the voltage and frequency is often large, which can cause the tuning point deviation of the passive filter easily. A novel method to suppress the harmonics of this kind grid by adopting the phase-shifting strategy is put forward in this paper. The phase current can be divided into two branches through phase-shifting windings, and specific phase-shifting angle can be achieved by choosing proper winding turns and connection way. The configuration of the phase-shifting windings is analyzed in detail and the optimal selection of the phase-shifting angle is also done. The accuracy and the effectiveness are verified by the EMTDC/PSCAD based simulation results.
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