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This paper investigates the sparse recovery models for bad data detection and state estimation in power networks. Two sparse models, the sparse L1-relaxation model (L1-R) and the multi-stage convex relaxation model (Capped-L1), are compared with the weighted least absolute value (WLAV) in the aspects of the bad data processing capacity and the computational efficiency. Numerical tests are conducted...
Fluctuating outputs of distributed generations, time-varying load demands and estimation errors of loads bring substantial uncertainty risks to the active distribution network restoration, which becomes a challenge to the traditional deterministic algorithms. In this paper, a robust restoration approach is proposed to solve this issue, considering both DG outputs and load demands uncertainties. Firstly,...
This paper proposes a robust three-phase state-estimation method that is applicable to both balanced transmission networks and unbalanced distribution networks with nonlinear measurements. We extend the recently introduced bilinear formulation of state estimation problems to a robust three-phase model. The original nonlinear state estimation is solved by resorting to two auxiliary linear model and...
A coordinated economic dispatch method for multi-area power systems is proposed. The proposed algorithm is based on the partition of the system states into internal and boundary state variables. For fixed boundary states, the local operator computes the critical region containing the point of boundary states and the coefficients of its optimal cost function then communicates them to the coordinator...
Based on alternating direction method of multipliers (ADMM), this paper presents a fully distributed algorithm, which can flexibly handle dynamic economic dispatch (DED) problem for both interconnected and isolated microgrids. In this scheme, each microgrid only solves its local problem with very few interchange of information among its neighboring microgrids. Numerical tests show that all microgrids...
There are mainly two kinds of state estimation measurements' model in recent research. One model considers that direct measurements and indirect measurements are uncorrelated, the other model considers that indirect measurements have strong correlation with the direct measurements where they are derived, and the correlation can be described as covariance elements in weight matrix. In fact, without...
Microgrids are always connected to utility grid and the grid connection code must be satisfied. Therefore, it's necessary to control the exchanged active power between microgrids and utility grid on point of common coupling (PCC) by regulating distributed resources (DERs). In this paper, this control problem is formulated firstly. Then a distributed method is proposed to solve this problem with minimum...
In active distribution networks (ADNs), the output of Photovoltaics (PVs) and loads cannot be accurately estimated because of insufficient measurements and highly frequent fluctuation of PVs. Therefore, it is necessary to implement the voltage control considering the uncertainties of PVs and loads. In this paper, a robust voltage control (R-VC) considering these uncertainties is proposed for ADNs...
Although much of today's power system remains steady, the integrations of wind power make a portion of the system become fluctuant. To monitor these fluctuations, we need to utilize phasor measurements and shorten the time interval for state estimation. On the other hand, however, this means huge increase in computation burden. As a tradeoff between accuracy and computation efficiency, a multi-time...
Ultra-short-term forecasting results of the loads of distribution transformers are one of the main sources of the pseudo measurements in state estimation programs for distribution networks, and the forecasting accuracy seriously affects the state estimation results. This paper describes a robust exponentially weighted load forecast model to improve the forecasting accuracy. Firstly, a load change...
The problem of coordinated multi-area economic dispatch is considered. A method based on multi-parametric quadratic programming is proposed in which local economic dispatch in each area is solved with interchange flows as parameters, and the overall cost is minimized by a coordinator. It is shown that the proposed method converges to the global optimum solution within a finite number of iterations.
The reliability of power system dynamic simulation and transient stability assessment depends on the accuracy of parameters. Parameter identification is a crucial way of obtaining accurate parameters. However, the assessment of identifiability should be carried out a proiri. This paper demonstrates a new approach to evaluate the identifiability of power system transient model parameters, which considers...
In this paper, a novel probabilistic load flow (PLF) method that combines Nataf transformation with Zhao's point estimate method (PEM) is proposed. The new method can deal with correlated non-normal input random variables (RVs) in PLF evaluation with improved accuracy and less computation time than existing methods. The proposed method is applied to a modified IEEE 118-bus test system with wind farms...
In this paper, a supplemental control for enhancing primary frequency response of DFIG-based wind farm is proposed. First, the related properties of DFIG-based wind power generation system, along with the existing inertia and frequency control are introduced. Then, the expected primary frequency response from DFIG-based wind farms during contingencies is explored. In order to meet the requirements...
Outage load caused by N−1 contingencies can be restored automatically or manually in distribution network. Therefore, the restored load can be considered as an index to represent the distribution network security level. In this paper, a security evaluation method is proposed, in which a MIQCP (Mixed Integer Quadratic Constrained Programming) based restoration model is used. Meanwhile, methods are...
This paper proposes a real-time hybrid transient simulation platform combining the real-time digital simulator (RTDS) and a transient stability analysis (TSA) program to simulate large scale AC/DC hybrid systems. To improve the accuracy of simulation results, a frequency dependent network equivalent (FDNE) is implemented in this simulation platform. And a latest GTFPGA card is used to realize the...
Parallel variable density spiral imaging is an efficient fast imaging technique that combines spiral-based fast k-space acquisition and sensitivity encoding reconstruction of parallel imaging. However, due to its ill-conditioned system matrix, sensitivity encoding reconstruction can suffer from severe noise amplification or residual aliasing artifacts. To solve the problem, a regularized reconstruction...
In China, large-scale wind power is integrated to the power grid in a concentrating way by connecting a group of wind farms together. Each wind farm is consisted of hundreds of wind turbines and covers a large geographical area. However, such a system is vulnerable to occasional faults which can easily develop into cascading failures of adjacent wind farms, making the wind farms lose most of their...
According to the situation that the number of real-time measurements and sensors in distribution system is limited, a new method is discussed for the topology identification of distribution system. The concept of optional matching loop power is raised in this paper. Based on optional matching loop power, several possible topologies are found, then run state estimator in every possible topology respectively...
To accommodate the integration of wind power, spinning reserve constraints should be involved in real-time generation dispatch. Based on the Lagrangian relaxation framework, a two-stage algorithm is used to solve the dynamic economic dispatch problem with reserve requirements considering wind power generation. An improved dynamic programming method is proposed to solve subproblems involving reserve...
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