scholarly journals Two-Stage Linear Three-Phase State Estimation Formulation for Active Distribution Network

2018 ◽  
Author(s):  
Yuntao Ju
Keyword(s):  
Coordinate System ◽  
State Estimation ◽  
Reactive Power ◽  
Distribution Network ◽  
Polar Coordinate System ◽  
Rectangular Coordinate System ◽  
Linear Measurements ◽  
Two Stage ◽  
Linear State ◽  
Node Voltage

Linear state estimation (SE) formulation under a rectangular coordinate system has been proved to be applicable for real-time distribution network management. Micro phasor measurements’ model can be accommodated into this kind of SE easily. However, voltage magnitude, active power and reactive power measurements are transformed to linear measurements with large node voltage error. To cope with this issue, a linear state estimation under a polar coordinate system is adopted at the first stage to obtain accurate enough complex node voltage, and then nonlinear measurements are transformed to be linear with complex node voltage. At the second stage, linear SE under a rectangular coordinate system can be adopted to satisfy more strict network constraints. The proposed two-stage linear SE is validated on balanced 14, 33, 70,84, 119, 135 nodes network and IEEE 13, 34, 37,123 unbalanced test feeders.

scholarly journals Two-Stage Active and Reactive Power Coordinated Optimal Dispatch for Active Distribution Network Considering Load Flexibility

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5922
Author(s):  
Yu Zhang ◽  
Xiaohui Song ◽  
Yong Li ◽  
Zilong Zeng ◽  
Chenchen Yong ◽  
...  
Keyword(s):  
Real Time ◽  
Prediction Error ◽  
Reactive Power ◽  
Distribution Network ◽  
Constant Current ◽  
Economic Losses ◽  
Time Varying ◽  
Two Stage ◽  
Active Distribution Network ◽  
Active And Reactive Power

A high proportion of renewable energy connected to the power grid has caused power quality problems. Voltage-sensitive loads are extremely susceptible to voltage fluctuations, causing power system safety issues and economic losses. Considering the uncertainty factor and the time-varying characteristic, a linearized random ZIP model (constant impedance (Z), constant current (I), and constant power (P)) with time-varying characteristics was proposed. In order to improve the voltage quality of the voltage-sensitive loads in the day-here stage in an active distribution network (ADN), a linearized two-stage active and reactive power coordinated stochastic optimization model was established. The day-ahead active and reactive power coordination optimization was to smooth the large voltage fluctuation and develop a reserve plan to eliminate the unbalanced power caused by the prediction error in the day-here optimization. In the day-here real-time redispatch, the voltage was further improved by the continuous reactive power compensation device. Finally, the simulation results on the IEEE-33 bus system showed that the control strategy could better eliminate the unbalanced power caused by the prediction error and obviously improve the voltage of sensitive loads in the real-time stage on the premise of maintaining economic optimality.

scholarly journals Two-Stage Stochastic Programming Scheduling Model for Hybrid AC/DC Distribution Network Considering Converters and Energy Storage System

2019 ◽  
Vol 10 (1) ◽  
pp. 181
Author(s):  
Peng Kang ◽  
Wei Guo ◽  
Weigang Huang ◽  
Zejing Qiu ◽  
Meng Yu ◽  
...  
Keyword(s):  
Wind Power ◽  
Reactive Power ◽  
Distribution Network ◽  
Stochastic Scheduling ◽  
Second Order ◽  
Mixed Integer ◽  
Two Stage ◽  
Dc Distribution ◽  
Scheduling Model ◽  
Second Order Cone

The development of DC distribution network technology has provided a more efficient way for renewable energy accommodation and flexible power supply. A two-stage stochastic scheduling model for the hybrid AC/DC distribution network is proposed to study the active-reactive power coordinated optimal dispatch. In this framework, the wind power scenario set is utilized to deal with its uncertainty in real time, which is integrated into the decision-making process at the first stage. The charging/discharging power of ESSs and the transferred active/reactive power by VSCs can be adjusted when wind power uncertainty is observed at the second stage. Moreover, the proposed model is transformed into a mixed integer second-order cone programming optimization problem by linearization and second-order cone relaxation techniques to solve. Finally, case studies are implemented on the modified IEEE 33-node AC/DC distribution system and the simulation results demonstrate the effectiveness of the proposed stochastic scheduling model and solving method.

scholarly journals Placement of measurements for electrical distribution network state estimation

2018 ◽  
Vol 39 ◽  
pp. 03001
Author(s):  
Irina Golub ◽  
Yana Kuzkina
Keyword(s):  
State Estimation ◽  
Distribution Network ◽  
Estimation Procedure ◽  
State Variables ◽  
Smart Meters ◽  
Minimum Number ◽  
Network Operation ◽  
Measurement Units ◽  
Linear State ◽  
Electrical Distribution Network

The paper is concerned with the problem of placement of the minimum number of smart meters to ensure either the observability of all state variables in distribution network or the observability of voltage magnitudes. Voltage control is important in the distribution network with distributed generation sources which adoption can lead to unpredictable overvoltage exceeding admissible values. The algorithm for smart meters including measurements of voltage magnitudes and active and reactive current injections is similar to the algorithm of choosing the minimum number of phasor measurement units to ensure topological observability. Optimal control of the active distribution network operation requires monitoring to be based on a classical linear state estimation procedure. The results of the research demonstrate the effectiveness of the proposed approaches and are illustrated by example of a test distribution network.

scholarly journals Using smart meters for checking the topology and power flow calculation of a secondary distribution network

2019 ◽  
Vol 139 ◽  
pp. 01059
Author(s):  
Irina Golub ◽  
Evgeny Boloev ◽  
Yana Kuzkina
Keyword(s):  
Power Flow ◽  
Reactive Power ◽  
Distribution Network ◽  
Smart Meters ◽  
Power Flow Calculation ◽  
Flow Calculation ◽  
Three Phase ◽  
Secondary Distribution ◽  
Linear State ◽  
Selection Of

The paper analyzes options of using smart meters for power flow calculation and for assessing the state of a real three-phase four-wire secondary distribution network based on measurements of average values of active and reactive power and of voltages. The work is based on the authors’ research on allocation of measurements to ensure secondary distribution network observability and on selection of the most efficient method for linear and non-linear state estimation. The paper illustrates solution of a problem on identification composition of load nodes in the phases and reveals challenges related to voltage account in the neutral wire and in its grounding.

scholarly journals Multi objective reactive power and voltage optimization of distribution network based on adaptive genetic annealing algorithm

2020 ◽  
Vol 185 ◽  
pp. 01042
Author(s):  
Yong Yang ◽  
Lei Chen ◽  
Weiyan Zheng ◽  
Xinquan Wei ◽  
Guangxian Lv ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Optimization Model ◽  
Reactive Power ◽  
Power Optimization ◽  
Distribution Network ◽  
Reactive Power Optimization ◽  
Capacitor Switching ◽  
Annealing Algorithm ◽  
Line Loss ◽  
Node Voltage

In this paper, a multi-objective reactive power optimization model of distribution network is established, which takes the minimum of line loss, reactive compensation capacitor switching loss and node voltage deviation as objective, considering the constraints of node voltage, reactive power of wind turbine, capacitor switching times. The improved adaptive genetic annealing algorithm is used to solve the model. IEEE33 system is taken as an example to verify the effectiveness of the reactive power optimization model. When the shunt capacitor and wind turbine are in the optimal reactive power compensation, the line loss of the distribution network can be minimized.

Using a Polar Coordinate System in the Classroom

1990 ◽  
Vol 37 (8) ◽  
pp. 42-45
Author(s):  
William M. Carroll
Keyword(s):  
Elementary School ◽  
Coordinate System ◽  
School Level ◽  
Polar Coordinate System ◽  
School Students ◽  
Rectangular Coordinate System ◽  
Polar Coordinate ◽  
Supplementary Material ◽  
Cartesian Coordinate ◽  
Additional Exposure

Most elementary school students have experiences with a rectangular graphing system that helps to prepare them for ideas in algebra and analytic geometry. Mathematics books at the elementary school level contain a section on graphing, though it is often one of the later chapters, where it may be treated as supplementary material. In science and in social studies, students may find various data graphed or may have a project in which they have to graph daily temperatures, rainfall, or test scores. Biorhythms, record sales charts, or, for the more ambitious, the daily stock market give additional exposure. Designing graphics on the computer monitor often requires some placement by a rectangular coordinate system. By the time students meet the Cartesian coordinate system with its x- and y-axes and use it to graph equations, the idea and techniques should be somewhat familiar.

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