Collisional loads on electrical equipment will cause electrical voltage fluctuation. The equipment used to prevent electrical voltage fluctuation has the problem of unsatisfactory use effect. Therefore, an adaptive voltage controller based on fuzzy control is designed. The mathematical model of fuzzy control and the virtual control path of capacitance and inductance in electrical equipment are established. The working frequency and electric voltage of the control path are set as the input term of the model, the working frequency factor is set as the output term, and the multi-directional conducting crystal valve is used to connect and control the transmission. Electrical voltage of circuit and switching circuit is compensated to improve the fluctuation of electric voltage. The high precision acquisition circuit of AD760x controller data acquisition card is further introduced, and the estimation process of electrical voltage control delay under fuzzy control is designed to improve the control effect.
The experimental results show that the designed controller has good control effect and strong robustness. With the gradual increase of collisional load of electrical equipment, serious fluctuations of electrical voltage begin to occur, resulting in unstable operation of electrical equipment, leakage and circuit breaking phenomena often occur. The origin of collisional load is the large number of access of non-linear electrical equipment in the power grid. In order to reduce the impact of collisional load on electrical voltage, adaptive voltage controller based on switching virtual circuit, PID control, excitation regulation, adaptive neural network is gradually generated.
The purpose is to compensate for electrical useless power and carry out voltage. Compensation and fluctuation suppression [1]. The dynamic regulation effect of these controllers is generally not good and the design is difficult.
Therefore, based on the principle of electric voltage control, an adaptive controller of electric voltage based on fuzzy control is designed. Non-fuzzy control can not describe too many complex variables in a short time. Reducing the processing steps will affect the control accuracy, which is counterproductive. However, fuzzy control has absolute advantages in complex non-linear variable control. It mainly describes a process of fuzzy reasoning, can accommodate more information, and the content of information has a strong correlation with real life [2]. Formula: is a dynamic variable; represents the maximum value; represents the objective control function; represents the limitation condition; is the limitation of equality; is the limitation of inequality. In the adaptive control of electrical voltage, the limitations of the fuzzy control mathematical model include generator torque, working frequency and local current. Formula (2) shows that if there are many collisional loads in the circuit, the working frequency factor will be lower. The structure of the fuzzy control is shown in Fig. 1. In order to reduce the impact load and improve the working frequency factor, the electrical voltage adaptive controller based on the fuzzy control takes the working frequency and electric voltage in the control path of electrical equipment as the input items of the fuzzy control mathematical model, while the working frequency factor is the output items of the model. The input items are assigned to the set, and the two sets of parameters are fuzzified simultaneously. The operation model obtains the switching condition of the multi-directional conducting crystal valve. The data collected above are fuzzily reasoned and defuzzified according to the fuzzy rules.
Electric voltage adaptive controller based on fuzzy control will simultaneously carry out adaptive control and fuzzy control of electric voltage, which requires high dynamic characteristics of dynamic variables. To improve the dynamic characteristics, we can start from two aspects: first, to obtain accurate electrical voltage parameters and multi-directional conductive crystal valve switch, which is also an important prerequisite for modifying the fuzzy rules and improving the accuracy of fuzzy reasoning [4]; second, to reduce the control delay and improve the self-discipline of fuzzy control. According to the function of the module, the hardware structure of the adaptive voltage controller based on fuzzy control can be divided into four modules: mining module, processing module, fuzzy control module and AC module. Among the four modules, the mining module can obtain the multi-directional conductive crystal valve switch. The information acquisition work of this module is real-time acquisition. The data acquisition card used is AD760x. AD760x can synchronize multi-channel sampling. The working process and data between different acquisition channels do not interfere with each other. The sampling accuracy is high and the calculation precision is precise. It has 32 bits, 12 bits in the acquisition channel, an average acquisition rate of 200 Kb/s, and its own pulse width modulation signal output function [5], which provides great convenience for the fuzzy control module. Figure 2 is a high-precision acquisition circuit diagram of AD760x. As shown in Figure 2, AD760x is powered by 5V power supply, the chip pin is controlled by programmable logic, and the input terminal is differential input, which supports digital selective output. The digital selective output port and the digital selector are connected by two capacitors. The capacitance value is one high and one low, so the signal can be output iteratively. When collecting voltage data above 15 V, AD760x will divide the voltage three times, and convert the voltage into voltage below 9 V for collecting, which enhances its acquisition accuracy. The design of electric adaptive controller based on fuzzy control needs to focus on the control delay, because the voltage fluctuation of electrical equipment is not simple, and the response of field equipment, information mining, data processing and other processes will produce delay [6]. Fig. 3 is the process of estimating the delay of electrical voltage control by fuzzy control. Overall, it is a dynamic estimating process. The limitations and the delay estimates are input into the estimating controller for dynamic estimating. Electrical voltage controlled parameters generally fluctuate non-linearly and unevenly. The reason for dynamic linearization of these dynamic variables is to stabilize the waveform of parameter variation, filter the noise waveform and get the smooth curve [7]. The function position of linearization is the instant operating point of electrical voltage. The instant operating point is related to the period of fuzzy control, which means that the instant operating point is not fixed. The fuzzification of controlled parameters refers to extracting balance parameters from the electrical voltage output to adjust the linearized output and improve the estimation accuracy of the model for the electrical voltage control delay. In this paper, thermostatic element a simulation experiment is carried out on the data of Beijing power grid with recent electrical voltage fluctuation faults, from which 2,000 electrical voltage parameters are extracted. The control period and delay estimation period are both 6 s. The simulation experiment circuit is shown in Figure 4.
The simulation experiment circuit uses 220 V AC power supply with a frequency of 100 Hz. Load R2 and R3 are fixed loads, R4 is variable load, R2-R4 can represent non-linear electrical equipment, R5 is resistance value of electrical equipment. In the experiment, by turning on fixed resistance R2 or increasing resistance R4, shunting and voltage dividing of electrical equipment can be carried out to increase impact load. Because the resistance value of electrical equipment is not changeable, the adaptive voltage controller based on fuzzy control directly acts the control signal on the variable load R4, reduces the impact load by adjusting the resistance value of R4, and realizes the adaptive voltage control. Fig. 5 shows the relationship between control displacement and control time of an adaptive voltage controller based on fuzzy control.
Fig.
5 shows that, when the fixed resistance R2 is not connected, the adaptive ability of the electric voltage gradually improves after changing the resistance value of the variable resistance R4, and the fluctuation of the control displacement is not obvious, which accords with the actual situation of the electric voltage, and the control effect is good. After switching on the fixed resistance R2, the control displacement only produces some small fluctuations, which is very robust. The control displacement rises first and then keeps stable, which accords with the actual situation. In this paper, a self-adaptive controller of electric voltage is designed by using the mathematical model of fuzzy control. Starting with how to improve the working frequency factor, the control structure, acquisition circuit and control delay estimation process of the controller are designed, so that the control effect of the controller can be further improved. The experimental results show that the controller has good control effect and strong robustness, and the control results accord with the real fluctuation of electrical voltage.