In the actual power system, the additional excitation control of the generator is an important means to improve the stability of the power system and suppress low-frequency oscillation. The static var compensator (SVC) installed at the important pivot point or load node in the system is mainly used to absorb or continuously adjust the reactive power from the grid to maintain the voltage at the installation point constant 1-3 Providing rapid dynamic voltage support for such critical nodes is an important means to solve the problem of power system safety and stability. Based on the research results of generator additional excitation fuzzy variable structure control, the additional excitation of SVC and generator is carried out. Comprehensive control research. Combining the fuzzy control theory with the nonlinear variable structure control theory, an integrated controller of SVC and additional excitation fuzzy variable structure is designed, which can realize the two goals of generator power angle control and voltage control at SVC installation point. 2 fuzzy variable structure integrated controller design 2.1 system mathematical model taking n machine system as an example, the mathematical model of the system is as follows 111 generator no-load potential; k, k', is the i-th generator voltage regulator and additional Magnification of the excitation controller; Vf is the terminal voltage value of the i-th generator; Mfi is the additional excitation control input of the i-th machine. The active power Pei expression of the i-th generator is a practical first-order inertia model of SVC, as shown: the susceptance of the reactor; TC is the time constant; KC is the amplification factor; Combining equations (1) and (3), the equation of state for a multi-machine system with SVC can be obtained: time constant 1()); 1 is the input mechanical power is 0 lishMg and (4) is written as standard affine nonlinearity The form of the system is: reciprocal, the first line is derived on both sides of the above formula, and the (3) formula can be substituted into the above formula to obtain the control input Ue for the SVC. The specific fuzzy variables can be designed before the statement is declared. Slightly. 2.2 Design method of fuzzy variable structure integrated controller In order to make the designed controller consider both the generator power angle stability and the voltage control at the SVC installation point, it is necessary to decouple the generator additional excitation control and SVC control. The controller thus designed can obtain the corresponding control amount according to the change of the local state variables, which is convenient for the realization of the control strategy. As can be seen from equation (5), this is a control problem for a multiple input multiple output system. The input quantity is the input Uf of the additional excitation of the generator and the control input Ue of the SVC. The output function can be written as the following deformation structure controller. The method is as follows: First, the voltage change amount, its derivatives AVm and AVrn, are non-uniformly discretely transformed on the domain. The input quantities E and E of the controller are formed. The Avm and Avm are "subdivided" when they are small, and when they are large, they are "roughly divided" while eliminating the intermediate determination of the membership function (because This division method is itself a process of determining the membership relationship, thereby obtaining a discrete quantity as an input to the fuzzy variable structure controller. Then, the control law of the fuzzy variable structure controller with self-adjusting factor is designed to adapt to various situations of the actual system, so that the designed controller has strong self-adjustment. The control rule with self-adjusting factor in the whole domain can be expressed as the form of equation (2): because, when AVm is relatively large, it indicates that the system is far from the voltage level -Vm0=AVm(7) for the output function of the above formula You can design a specific fuzzy variable structure controller. In order to make the designed SVC controller realize the control by local signal, for the output function y2 balance state, the system needs to increase the control amount, so that the system reaches the steady state value of the voltage as soon as possible, so the weight of the voltage change amount at this time E is relatively large; when E is relatively small, it indicates that the system is close to the steady state of the voltage. In order to make the system voltage reach the steady state as soon as possible, the overshoot is minimized. Therefore, the weight E of the voltage change amount is relatively small, and the control amount is small. The weight E of the derivative of E in time is relatively large. The controller designed in this way can quickly restore the voltage at the SVC to a steady state, reducing the frequency and amplitude of the chattering. Finally, the obtained Ue is rounded to obtain the discrete control quantity Au (using the non-equidistant distance method. The fuzzy variable structure SVC controller also needs to comprehensively consider the limiting of the control quantity, and then the actual system can be controlled. The fuzzy variable structure SVC controller shown by the formula (12) has nothing to do with the operating point and network parameters of the system, and therefore has strong robustness to changes in system operating points and changes in network parameters. Here, the design of the generator additional excitation fuzzy variable structure controller adopts the design method of the text. Although there is the existence of SVC, the additional excitation fuzzy variable structure controller involved here is not substantially different. Only the additional excitation fuzzy variable structure controller is aimed at stabilizing the generator power angle, and the variable capacitive reactance of the SVC is cut off as an intermediate node when performing the solution. The method is as follows: First, the equation (5) is transformed into a linear system using a direct large-scale linearization theory. Then take a linear switching function Si for this linear system and derive its derivative, and obtain the derivative S. The input signal of the controller is the switching function and the derivative of the fuzzy quantities Si and Si. The control law is as follows: the final control amount will be obtained. After Ui is cleared, it can be controlled after limiting. The output of the controller designed according to this method is independent of the operating point and network parameters of the system. The additional control is only related to the switching function composed of the state quantity of the generator, so the change of the working point of the system and the network parameters The change is completely robust. 2.3 Control law selection Here we do not consider the coordinated control of each generator in the multi-machine system, but only according to the change function of each generator's switching function and other parameters. When the SVC is installed in an interconnected power system with the voltage at the installation point as the control object, the voltage and its variation can be measured in situ to achieve local signal control. When disturbance occurs in the system, the inertia of the measurement, control and triggering of the SVC controller is small, generally within 1 s, so the fast response characteristics can maximize the voltage of the SVC mounting point; at the same time, each station The additional excitation controller of the generator aims to stabilize the power angle of the generator, which can maximize the stability of the power system and at the same time make the generator terminal voltage have good dynamic characteristics. 3 The computer simulation system adopts the six-machine system of the Electric Power Research Institute. The structural parameters are shown in SVC installed on the 9th busbar. The conventional excitation and fuzzy variable structure control scheme are adopted on the additional excitation of the 2, 3, 4 and 5 units. The simulation conditions are as follows: a three-phase short-circuit fault occurs on the 10th busbar when the system is 0s, and returns to normal after 0.15s. The simulation results are as shown in the figure. curve. From and visible, the damping characteristics of the system under the fuzzy variable structure control and the voltage characteristics of the SVC are superior to the system response characteristics under conventional control. The voltage at the location of the SVC is maintained well; at the same time, the stability of the system is significantly improved by the action of the additional excitation fuzzy variable structure controller. 4 Conclusions In this paper, a fuzzy variable structure control method is used to design a comprehensive controller for SVC and generator additional excitation. The controller can simultaneously consider the two objectives of SVC installation point voltage control and generator power angle stability, and realizes the solution of SVC control and additional excitation control, so that the designed controller can implement the control strategy by using local signals. 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