Study On The Technology Of Synchronous Phasor Measurement And Its Application In State Estimation

The synchronous phasor measurement technology is one of the most important technologies in modern electric power industry.GPS-based synchronized phasor measurement unit(PMU) can measure the power angle or phase angle of bus voltage directly.As the PMU measurements have high precision,synchronous sampling and short updating,the technology of synchronous phasor measurement plays a major role in dynamic monitoring,security stability analysis and control and state estimation(SE) in power system.SE is the signify partition of energy management system(EMS).The other high level application software of EMS are influenced by the performance of the SE.The paper studies the problem of application of PMU measurements in the SE and the data quality assessment of synchronous phasor measurement technology.This paper describes the current situation and the development trend of GPS-based synchronous phasor measurement technology at home and abroad,then investigates the theory and developing trend of power system SE.This paper expatiates the mathematical description of measurement system,electric power grid and measurement equation in power system SE.The three basic methods in SE are also expatiated in this paper.This paper investigates the influence of using PMU in SE and analyzes several kinds of application models of PMU measurements in SE,then compares the simulation results of four non-linear representative models which are using PMU measurements.This paper proposes the equality constraints two-step estimation model(ECTSE) which adapted to static SE and gets the tracking results of SE for the nodes which are in the nonlinear area through using the equivalent impedance method on the condition of one load continuum change.The effectiveness of the proposed model is illustrated with numeric simulation using IEEE 14 and 57-bus system.The measurement results of PMU are different when there are noises,direct current,aperiodic or harmomic component and frequency leak.If these measurement data are used in power system dynamic control area,the system may make an inaccurate decision or take a false control action to cause serious results.In order to use PMU measurements more reliably,this paper proposes a new method-differential of absolute value to compute the quality parameter of PMU measurements thereby evaluating the reliability of phasor data in order to identify bad data.The validity of this new method is illustrated with numeric simulation.