Research On Key Technology Of A Novel Parallel Hybrid Active Power Filter

Abstract:Electrical energy plays an important role in the economic development and people's lives.But the power in the enterprise decreases every year in our country. With the rapid development of steel, non-ferrous metallurgy and petrochemicals, The total energy consumption is large.With the rapid development of power electrical technologies and widely used high power switch devices,non-linear loads in the grid are widely increased, which causes harmonic pollution and energy losses.Meanwhile,voltage fluctuation and voltage flicker caused by the impulsive load and reactive power variation have greatly disturbed the industrial production and people's lives.It also makes the electrical system have problems such as heavy reactive power compensation and harmonic suppression.The sustainable development of our country is facing great pressure.The theory and methods of the new hybrid active power filter in parallel are researched in the paper. The working mechanism, mathematical model,control strategy, compensation performance, new control methods and so on are researched in the paper. This paper proposes the structure of fault tolerant parallel active power filter. The basic researching method and technical proposal of fault tolerant APF are formed.The emphasis and achievement of the paper mainly manifests in the following aspects.(1)A novel parallel hybrid active power filter is proposed, which can suppress harmonics and compensate reactive power without over compensation according to the spot condition.The compensating principle of the compensation equipment is analyzed.The control strategy of the compensation equipment is researched and the active part is controlled as harmonic current source.The injection branch of the parallel hybrid active power filter is designed. The reason of the selecting injection branch is analyzed. The compensating performance of the compensation equipment is given under the changing of the grid.(2)The compound-recursive integral PI control method based on membership cloud theory is proposed for the parallel hybrid active power filter. The compound control includes feedforward control,feedback control and the DC-link voltage control. The5th passive filter filters the most serious harmonic components. The feedforward control suppresses the7th harmonic components. The remainder is filtered by the feedback control. The DC-link voltage is stabilized by controlling the public point harmonic voltage. The parallel and integral coefficients of the recursive integral PI control method are adjusted online by membership model. The parallel control is dominant when the current error is larger and make the error decreases quicklier. The integral control is dominant when the current error is in a small value.Then the stable non-error is obtained and the responding speed,robust and anti-disturb of the system are improved.(3)The fault-tolerant structure for the novel parallel hybrid active power filter is proposed.The fault-tolerant structure principle is analyzed. Several running models and corresponding principle are given under faults condition.The fault-diagnose method based on error voltage is researched, which detects faults by the error between the meter value and evaluating value of the inverter through the inverter voltage model.(4) A increasing PID control method based on two-dimension membership cloud model is proposed according to the fault-tolerant structure of the novel parallel hybrid active power filter. The parallel, integral,differential coefficients are adjusted online by two-dimension membership cloud model.The creation of different membership clouds and the rule-reasonor are improved.(5)A three-dimension membership cloud intelligent control method is proposed in order to improve the performance of the controller. The control method refers to the idea of PID control method but is different from PID control method.The three-dimension membership cloud intelligent control method has good control performance and don't depend on the mathematical model of the controlled object. It is designed according to operating experience or expert's knowledge.The proposed control method has simple control strategy without complicated reasoning and calculating, which can be in common use.The control process can realize the quantify input, quality reasoning, quantify output. According to the background of power quality control and the improvement of operating safety for the parallel hybrid active power filter, the parallel hybrid active power filter and corresponding technologies are proposed in the paper. It is beneficial to push on the practical application for the power electrical systems.There are59figures,10tables,100references.