The Means And Application Of Structure Preserving Power System Coordination Control Including FACTS

With the development of power electronic technology,the power system appears to be more and more nonlinear.However,the stability of power system will guarantee the safe operation of it.How to keep the power system stable relates to both the loss of national economy and the level of people's living.In fact,the power system is suffered from many kinds of disturbances which are always random every time.The fluctuation of loads is a large threaten to the stability of power system.The main method to solve this problem is control which can bring the system to the original statement or the new balanced statement when it is suffered from disturbance.Whether the control method is proper directly relates to the scope and speed of the system approaching its original or new balanced statement.There are two main factors to how to design a reasonable control method: one is the correct establish of the power system's math model which can reflect the actual situation,the other is the effective control method whose precision can meet the requirement.There are lots of nonlinear elements in every part of power system.Most of these elements are the users' electric equipment that is the loads.The study of the model of generator,transformer and transmission line is tend to be mature.But the loads are always modeled as constant impedance.This model can only be applying to such a situation where the variation of voltage and power is not very high.If there is a fault in the power system,the nonlinear property of loads must be considered.At present,the most widely used control methods are PID,PSS and LOEC,etc.Their basic principle is the classical approximate linearization.Whereas,such control methods based on the classical approximate linearization can't meet the requirement of the precision in some situation.The state feedback exact linearization controlling based the theory of differential algebra and differential geometry can cover the shortage.Its principle is coordinate transformation which will map a nonlinear system to a linear system.This method is not an approximate method thus the bias is very low.This paper will integrate the above two aspects to study a single-machine infinite power system with several nodes.Taking the fast development of FACTS into consideration,this paper will use the STATCOM as a reactive compensator which will guarantee the stability of power system and improve the node's voltage stability.