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On-line monitoring and analysis of low frequency oscillation (LFO) are important for stability and security of a power system. This paper proposes a blind source separation (BSS) based method for LFO modal analysis of one-channel measured signal, which consists of a second-order blind identification (SOBI) algorithm and the Hilbert transform (HT) technique. This is the first time when a BSS technique...
This paper proposes a novel approach for short-term wind power forecast, where wind speed is predicted and used to forecast wind power through a power curve obtained from historical data. With the help of the empirical mode decomposition (EMD) method, wind speed is decomposed into mean trend and stochastic component. Subsequently, p-step forecast is conducted for the two components separately. The...
This paper presents a coil model of circuit breaker using MATLAB/Simulink and proposes a weighted morphological filter with dual structuring elements (SEs) to process the coil current of the circuit breaker. In order to make sure that the Simulink model of the trip and close coil is accurate enough, the genetic algorithm (GA) is applied to optimize its parameters, targeting the minimum difference...
Energy hubs play an important role in implementing the integrated energy system as an interconnection point between various energy components and networks. Energy networks also influence the management of the energy hubs. Therefore, the problem of optimal operation of the energy hubs and energy networks is modeled as a bi-level optimization problem in this paper. In the proposed bi-level model, the...
This paper proposes a Quasi-Monte Carlo (QMC) simulation based multi-objective economic dispatch, which aims to reduce the fuel cost and emission of the grid simultaneously. During the simulation, QMC models the stochastic behaviours of wind speed and distributed loads with low-discrepancy sequences. In comparison with conventional Monte Carlo (MC) simulation, the computational complexity of QMC is...
A model based on the Markov chain is proposed in this paper, which simulates steady-state variables of power systems to study the impact of the penetration of renewable energy generators (REGs). In this model, the power outputs of REGs are characterized by continuous time Markov chain (CTMC). In conjunction with the relationship between REGs' outputs and steady state variables, how these variables...
This paper presents a Group Search Optimizer with Multiple Producer (GSOMP) to solve the voltage control problem of the power systems penetrated with wind power. Although the utilization of wind turbines in power systems reduces the fuel cost and carbon emission efficiently, it also affects the reactive power flow, which might result in negative efffect on the power losses and voltage stability. In...
This paper proposes a wind power prediction method based on intrinsic time-scale decomposition (ITD) and least square support vector machine (LS-SVM) to improve the accuracy of wind power forecast. The proposed method employs ITD as a preprocessing method to decompose wind power data into a set of proper rotation components and a monotonous baseline signal. Afterwards, the backward difference of each...
Current transformers (CTs) may saturate during internal fault, external fault, over excitation, exciting inrush current and other phenomena, which would cause protection relay malfunction or even tripping. As a result, it is vital to mitigate the adverse effects of CT saturation. By analyzing the secondary current waveform, which has abrupt changes where saturation begins and ends, the paper proposes...
This paper presents a novel algorithm, named adaptive morphological lifting wavelet (AMLW). It is the first time to be applied for the detection of power quality disturbances (PQD). AMLW is a nonlinear wavelet transform which is based on morphological operation and the lifting scheme. The adaptability of AMLW lies in that the algorithm can select between two filters, the morphological gradient filter...
This paper proposes a new approach for detection and classification of power quality (PQ) disturbances in time domain. Most research in this field employs frequency domain analysis tools to analyse the features of PQ disturbances, such as Fourier transform and wavelet transform. However, the transient and steady-state characteristics of PQ disturbances are originally reflected on the waveforms of...
When a power system is contaminated by power quality problems, a short transition will appear before power system restoring to a new stability state. The short transitions of various power disturbances correspond to different principal component characteristics. According to these characteristics, in this paper, a scheme based on transient behaviors using morphological max-lifting scheme (MMLS) and...
The harmonic elements of stator current in induction motors will change under the condition of stator inter-turn short circuit. According to this characteristic, in this paper, a novel technique based on discrete wavelet transform (DWT) is proposed for the identification of induction motor stator inter-turn short circuit. The power systems computer aided design (PSCAD) is employed to simulate the...
This paper proposed an economic dispatch scheme based on stochastic frame. Compared with conventional dispatch, the stochastic dispatch fully considers the variation of distributed load variations in the grid between dispatch intervals. The objective function of the stochastic dispatch scheme aims to minimize the distribution of fuel cost rather than a single value. Due to the stochastic analysis,...
This paper presents a new algorithm which employs morphological filter and instantaneous reactive power theory for phasor measurement. A preprocessor is proposed to removes the decaying DC component from the input signal with a delay of two samples. The effects of sampling rate, time constant, frequency shift, harmonics and fault inception angle on the performance of the proposed algorithm have been...
This paper proposes a novel method for power quality (PQ) disturbance detection, based on morphology singular entropy (MSE). MSE consists of three techniques, i.e., mathematical morphology (MM), singular value decomposition (SVD) and entropy theory. The proposed method firstly utilizes MM to obtain the filtered outputs of the original signal at different levels. Then a matrix composed by the outputs...
This paper presents a novel algorithm for secondary current signal segmentation of saturated current transformer (CT) using three morphological gradient-based detectors. The saturation onset detector is used to monitor the occurrence of saturation and then trigger the positive/negative segmentation detector, which are designed to locate the starting point and the ending point of CT saturation. The...
Sympathetic interaction between transformers would lead to mal-operation of transformer differential protection. Based on the fact that the waveform of internal fault current has the sinusoidal features while the sympathetic inrush has not, a weighted mathematical morphological method is proposed for the identification of sympathetic inrush. In the simulation studies, the identification results have...
This paper presents an evolutionary algorithm, reference point based multi-objective group search optimizer using non-dominated sorting approach (r-NSGSO), for optimal power flow problem with multiple objectives. First, the six objectives of optimal power flow are reduced to two objectives which represent the secure and economic indices, respectively. The r-NSGSO integrates the non-dominated sorting...
This paper focuses on implementing a dimensional Q-learning (DQL) for solving reactive power optimization with discrete control variables. The proposed algorithm applies the traditional Q-learning to search the feasible region dimensionally, so that the memory amount of each agent can be largely reduced. Meanwhile, the safety margin of voltage amplitude and reactive power output of generators are...
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