80 research outputs found
Robust Matrix Completion State Estimation in Distribution Systems
Due to the insufficient measurements in the distribution system state
estimation (DSSE), full observability and redundant measurements are difficult
to achieve without using the pseudo measurements. The matrix completion state
estimation (MCSE) combines the matrix completion and power system model to
estimate voltage by exploring the low-rank characteristics of the matrix. This
paper proposes a robust matrix completion state estimation (RMCSE) to estimate
the voltage in a distribution system under a low-observability condition.
Tradition state estimation weighted least squares (WLS) method requires full
observability to calculate the states and needs redundant measurements to
proceed a bad data detection. The proposed method improves the robustness of
the MCSE to bad data by minimizing the rank of the matrix and measurements
residual with different weights. It can estimate the system state in a
low-observability system and has robust estimates without the bad data
detection process in the face of multiple bad data. The method is numerically
evaluated on the IEEE 33-node radial distribution system. The estimation
performance and robustness of RMCSE are compared with the WLS with the largest
normalized residual bad data identification (WLS-LNR), and the MCSE
Load Forecasting Based Distribution System Network Reconfiguration-A Distributed Data-Driven Approach
In this paper, a short-term load forecasting approach based network
reconfiguration is proposed in a parallel manner. Specifically, a support
vector regression (SVR) based short-term load forecasting approach is designed
to provide an accurate load prediction and benefit the network reconfiguration.
Because of the nonconvexity of the three-phase balanced optimal power flow, a
second-order cone program (SOCP) based approach is used to relax the optimal
power flow problem. Then, the alternating direction method of multipliers
(ADMM) is used to compute the optimal power flow in distributed manner.
Considering the limited number of the switches and the increasing computation
capability, the proposed network reconfiguration is solved in a parallel way.
The numerical results demonstrate the feasible and effectiveness of the
proposed approach.Comment: 5 pages, preprint for Asilomar Conference on Signals, Systems, and
Computers 201
Chance-Constrained Day-Ahead Hourly Scheduling in Distribution System Operation
This paper aims to propose a two-step approach for day-ahead hourly
scheduling in a distribution system operation, which contains two operation
costs, the operation cost at substation level and feeder level. In the first
step, the objective is to minimize the electric power purchase from the
day-ahead market with the stochastic optimization. The historical data of
day-ahead hourly electric power consumption is used to provide the forecast
results with the forecasting error, which is presented by a chance constraint
and formulated into a deterministic form by Gaussian mixture model (GMM). In
the second step, the objective is to minimize the system loss. Considering the
nonconvexity of the three-phase balanced AC optimal power flow problem in
distribution systems, the second-order cone program (SOCP) is used to relax the
problem. Then, a distributed optimization approach is built based on the
alternating direction method of multiplier (ADMM). The results shows that the
validity and effectiveness method.Comment: 5 pages, preprint for Asilomar Conference on Signals, Systems, and
Computers 201
State Estimation in Low-Observable Distribution Systems Using Matrix Completion
The need for distribution system state estimation is on the rise because of the increased penetration of distributed energy resources and flexible load. To manage the distribution systems in real time, operators need to firstly overcome the challenge of low observability in distribution systems. Also, because of the amount of data present from smart meters, distributed generation measurements, switches, etc., the ideal distribution state estimation methods need to be able to process heterogeneous data. In this paper, an algorithm is developed for voltage phasor estimation in low-observability distribution systems. The algorithm is based on the matrix completion approach from signal processing. The traditional matrix completion formulation is augmented with power-flow constraints to improve results while requiring less data. This method can also use all types of measurements (voltage magnitude, voltage angle, real power, reactive power) to complete the state matrix
Comprehensive Analysis Method of Acquiring Wall Heat Fluxes in Rotating Detonation Combustors
Accurate perception of the combustor thermal environment is crucial for
thermal protection design of a rotating detonation combustor (RDC). In this
study, a comprehensive analysis method is established to calculate the
non-uniform heat flux distribution of the RDC by utilizing the measured
temperature distribution of the combustor outer wall obtained by the high-speed
infrared thermal imager. Firstly, in order to determine the inverse heat flux
solving method, a physical model based on the geometric characteristics of the
RDC is constructed and its thermal conductive process is simulated, given by
different heat flux boundary conditions. Then the wall heat fluxes are
inversely calculated by the Levenberg-Marquardt (L-M) method based on the above
numerical data. Results show that the L-M method can obtain more accurate heat
flux distribution even in the zones with large heat flux gradients, considering
the axial heat conduction within the combustor outer wall caused by the
non-uniform heat flux. Finally, the wall heat flux distribution is analyzed
coupling the L-M method together with the experimental measurements in kerosene
two-phase RDC. The analyses show that the highest temperature of combustor
outer surface and the highest wall heat flux occurs within the region of 20mm
from the combustor head, which corresponds to nearly 14% of the combustor
length. With the increase of axial distance, the heat flux is rapidly reduced,
and then the heat flux distribution is more uniform at the downstream region of
the combustor. The heat flux peak and thermal heat rate are positively
correlated with the combustor equivalence ratio in the range between 0.44 and
0.64.Comment: 26 pages, 21 figure
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