Analysis And Control Of Transient Power Angle Stability Of Offshore Platform Generator

With the development of China’s economy and the vigorous development of Marine resources,the number of offshore platforms and the degree of interconnection within platforms continue to increasing.Due to the frequent changes of environment,climate,load and other factors,the probability of large disturbance to the power system of offshore platform will increase significantly.However,due to the limited system capacity and scale,the antidisturbance performance of offshore platform power system is relatively poor.In this case,it is very important to study the transient stability analysis and control method suitable for offshore power platform.Therefore,the main work of this paper is to measure the power angle,predicting the trajectory of the disturbance of the transient power angle,judging the stability of the transient power angle and improving the stability of the transient power angle by using stored energy.Firstly,a real-time power angle measurement of synchronous generator is proposed,which is based on the Second-order Generalized Integrator with Frequency-locked Loop(SOGI-FLL).The SOGI-FLL algorithm is used to replace the Discrete Fourier Transformation algorithm(DFT)to improve the measurement accuracy of the measured signal in the dynamic process,and it is used to extract the positive sequence components of the measured signal.Meanwhile,the power angle error existing in the transient process is compensated by using the generator swing equation.Secondly,a self-memory Grey Verhulst model considering error compensation is constructed.The model is based on the self-memory Grey Verhulst theory,and the error caused by long time prediction is corrected.Based on this model,the disturbance trajectory of transient power angle can be predicted in real time.The simulation results demonstrate the accuracy and effectiveness of the proposed prediction model.Thirdly,the transient angle stability analysis method based on the geometric criterion of phase trajectory is studied.The geometric characteristic criterion of phase trajectory derived from the single-machine infinite-bus system is extended to the multi-machine system by the method of critical machine identification and multi-machine system equivalent.Parabolic fitting method is used to judge the variation trend of the first derivative,so as to judge the transient power angle stability of the system.The simulation results show that this method can make accurate judgment.Finally,from the perspective of the access capacity and location of energy storage,the influence of energy storage on the transient stability of the system is analyzed in detail.The simulation results show that the addition of energy storage device has a favorable effect on the transient power angle stability of the system.The increase of power emitted by the energy storage device is also beneficial to the stability of the system.In addition,the specific capacity of the energy storage device should be selected according to the economic and applicability indexes of the actual power system construction.