Research On The Modeling Of Harmonic Pollution Users And Its Hazard Assessment

With the wide application of power electronic facilities and nonlinear equipment, the harmonics pollution of the power system is increasingly serious and the security of power network equipment is in danger. To ensure the power quality, power quality network monitoring devices are established to detect the data at the key node and PCC. Based on the data, the grid company can pick the interference source and ask the user install abatement equipment according to the polluter pays principle. Harmonic voltage at nodes and harmonic current on lines is the main indicators of power quality. But harmonic voltage can only reflect the total effect of all interference sources, it couldn’t use to estimate the hazard of the individual user. When it comes to multiple interference sources, harmonic current detected on service line couldn’t evaluate individual sources of pollution imperfectly. Hence, by establishing user model of the harmonic pollution and identifying the online data, accurate evaluation for user pollution is one of the most important problems of the harmonics grid management at present.The model of customer harmonic pollution is one of the load models, which represents the harmonic pollution level to the power grid when the customer worked. Using the model can figure out the harmonic voltage and injected harmonic current when the customers connected to the power grid, so as to correctly evaluate the users’ harmonic pollution. Combined with the customer harmonic model, we can analysis the injected pollution of the users based on the power quality data at monitoring point and guide the governance solution design and equipment selection. Typical equipment or users’harmonic pollution model also help to carry out exact users access prediction and assessment, providing technical support for choosing access point and customer design.The paper analysis the operational mechanism of typical harmonic pollution customers, then explain decoupling model and coupling model and other methods of parameter identification. In accordance with the need of engineering practice, this paper put forward a statistical modeling and parameter identification method based on harmonic amplitude measurement data, and then uses the pollution model to evaluate the users’ harmonic injection impact. If ignoring the coupling between different harmonics, the method can build decoupling model in frequency domain according to the harmonic circuit of different harmonic orders and uses partial least squares regression to identify the model parameters according to monitoring data. In addition, correlation coefficient is used to represent the coupling effect between different harmonic orders to build the coupling model of pollution customers. In practical engineering application, most harmonic monitoring data only contain the amplitude of harmonic voltage and current, but no the phase data, therefore the two models can’t totally applied The paper put forward a modeling method using harmonic amplitude which can accurately identify the model parameters. This method has a high value of engineering application Actual project running load are rarely in a steady state, the condition data are generally fluctuate within a certain range, the use of a certain time or a certain time period of the monitoring data identified model parameters are not able to get the full characterization pollution Characteristics of users. The paper proposed the concept of statistical models based on the randomness and volatility of the actual load, the parameters of the model are represented by a probability interval, the model can veritably represent the characterization of the running pollution load.Harmonic pollution model not only can be used for user harmonic hazard assessment, but can also be the basis of forecast evaluation of similar load for reasonable assessment the harm of access users to be injected into the grid to achieve the purpose of prevention.Because of the user to define different harmonic injection hazards, yet there is not a standard hazard evaluation. According to the different evaluation indicators, the paper analyzes the current harmonics comprehensive hazard assessment method, Compared and analysised the application of harmonic voltage, harmonic current, harmonic power, non-linearity and harmonic probability density in hazard assessment for the typical user’s typical operating conditions.Then,the simulation verify the correctness of the assessment methods of harmonic voltage, harmonic current and harmonic power.The paper describes several modeling methods of harmonic Pollution Users, when the reactive power compensation capacity of the user side is known, we can accurately identify the model parameters, and through simulation examples demonstrate the feasibility and accuracy of these methods. But when the reactive power compensation capacity of the user side is unknown, these methods are no longer applicabled, still need further study.