Research On Optimal Micro-PMU Placement In Distribution Networks For Multi-Application Demand

Due to the intermittency and randomness of distributed generation(DG),the increasing penetration of renewable energy sources will bring great challenges to power distribution,power supply reliability and operation security,which promotes the improvements of distribution networks in operating,monitoring and controlling.Micro Phasor Measurement Unit(μPMU)with a micro-second resolution and milli-degree accuracy capability can obtain real-time and high-accurate magnitude and phase angle measurements of both voltage and current,thus creating favorable conditions for the safe operation of the distribution system.However,it is infeasible to install μPMUs at each node in the networks due to the high cost ofμPMU devices as well as construction and communication.Therefore,it is of great significance to study how to allocate μPMUs optimally to achieve a certain application goal,which is called optimal μPMU placement(OPP)problem.In this paper,the OPP problem in distribution networks is studied in depth considering network uncertainty,fault observability,state estimation accuracy,and load loss rate.The main research contents of this thesis are summarized as follows:(1)Study on optimal μPMU placement considering network uncertainty and fault observabilityThis paper proposes an optimal μPMU placement method considering network uncertainty and fault observability.Firstly,the uncertainty of distribution network is assessed based on probabilistic state estimation as well as information entropy theory.Then,fault observability is defined based on Monte Carlo simulation and a fault location method using μPMU data and interval algorithm.Finally,the optimal μPMU placement is selected using greedy algorithm based on the comprehensive indices of network uncertainty and fault observability obtained by installing μPMU on each candidate node respectively.Simulations on several practical feeders are carried out to evaluate the effectiveness of the proposed model and to summarize the principle of μPMU placement.(2)Study on optimal μPMU placement for improving state estimation accuracyThis paper investigates the problem of placing a limited number of μPMUs to improve the state estimation accuracy.Combined with pseudo-measurements and supervisory control and data acquisition(SCADA)measurements,an optimal μPMU placement model is proposed based on a two-step state estimation method.The E-optimal experimental criterion is utilized to measure the estimation accuracy.The nonlinear optimization problem is transformed into a mixed-integer semidefinite programming(MISDP)problem,whose optimal solution can be obtained by using the improved Benders decomposition method.Simulations on several systems are carried out to evaluate the effective performance of the proposed model.(3)Study on Optimal Placement of μPMU and DULR(Dual-Use Line Relay)considering fault reconfiguration and state estimation accuracyAn optimal μPMU and DULR placement method considering fault reconstruction and state estimation accuracy is proposed.Firstly,the DULR device with both measurement and relay protection functions is introduced.Then,aimed at minimizing the cost of μPMUs and DULRs,the placement model is established with state estimation accuracy constraint under normal state and the load loss constraints under multiple fault scenarios.Branch and bound method is utilized to solve it.Finally,whether to consider multiple fault scenarios and the sensitivity of DG and feeder terminal unit configurations are analyzed in the IEEE 33 and 123 node systems.