Research On Suppressing Negative Effects Of Internal Mixer Based On Semi-tensor Product Stability Analysis

Due to the negative effects caused by an internal mixer of a rubber factory, this paper proposed a method to eliminate the harmonic and the reactive power impulse on the power grid. Since there is only 0.5 minutes in an internal mixer’s working cycle that it does work, the instantaneous harmonics and reactive power impulse may cause serious oscillation on the grid, exceeding the national standard GB/T-14549-93. Hence, to address this issue, TSF( Thyrisor Switched Filter) and APF( Active Power Filter) is utilized in this paper. According to the their features of low costs and effective elimination on harmonics, TAPF, a technology based on the coordinating control of TSF and APF in parallel, is proposed in this paper to eliminate the harmonics and the reactive power impulse. The proposed technique also can be utilized to address the power quality issues caused by heavy loads with enormous reactive impact and serious harmonics similar to the internal mixer. The main research contents include:Firstly, due to the complexity of the established module including the power grid, the TAPF and the internal mixer, Semi tensor product is applied to solving the uneven matrix equations describing the transient stability of the bus voltage. Based on the above, the parameters of the TAPF system can be designed. Thus, the transient instability of the grid voltage caused by the internal mixer can be eliminated. Additionally, to predict the TAPF working effects, the analyzation of transient grid voltage stability margin on different switching combinations is proposed, effectively increasing the stability of TAPF.Secondly, to ensure the coordinating operation of filtering channels and the inverter and to eliminate the harmonic oscillation when the TSF and the APF are used to filter the same order harmonics, the harmonic detecting strategy for specific order ones is proposed to achieve the decoupling control of TSF and APF. According to the actual working condition, a TAPF control strategy is proposed, ensuring the system stability and increasing the control effect.Next, to increase the responding and computing rates of the whole system, sliding window iteration DFT and mean low-pass filter based on instantaneous reactive power theory are utilized in this paper. And then, a module established in Simulink is used to validate the whole scheme. The simulating results show that the proposed TAPF can satisfy the rapidity demand.Finally, an experimental platform based on DSP2812 is established, validating the proposed technology. Experiments that TSF and APF works respectively, that APF and TSF are used to filter the same order harmonic, that APF and TSF are used coordinately have been done. The experimental results shows that the proposed control strategy can eliminate the self harmonic and reactive power disturb, reduce the APF capacity and increase the system responding rate. The whole scheme can eliminate the negative effect caused by the harmonic and the reactive power impulse, satisfying the national standard GB/T-14549-93.