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Precise current tracking is one of the important techniques to ensure the compensation performance of shunt active power filter (SAPF). Repetitive control is favored for its superior steady-state accuracy, but it has the problem of poor adaptability when frequency changes. This paper proposes a fractional-order internal model based frequency self-adaption control strategy. Fractional-order theory is introduced and Lagrange interpolation algorithm is implemented to achieve the superimposed fractional models. Parameter of the fractional delay link is designed and frequency characteristics of different methods are compared. Finally, this paper’s strategy is used on a SAPF prototype and experiments are carried out.

The UHVDC converter station is usually equipped with multiple sets of AC filters and capacitors, which can filter out harmonics at the AC side and make compensation for the reactive power consumed by converters. The impedance-frequency characteristic of the parallel sets of AC filters and capacitors is complex, which can easily lead to harmonic amplification in some frequency ranges. Therefore, it is urgent to make research about the overall filtering performance and partial harmonic amplification of AC filter sets at present. The admittance-frequency characteristics of the AC filter sets are used to analyze the overall filtering performance and partial harmonic amplification of AC filter sets. A practical case of an UHVDC converter station is presented to analyze the impacts of AC filters to power grid harmonics, and the results of the ETAP simulation model verify the effectiveness of the theoretical analysis.

To meet the requirement of large capacity for harmonic suppression and reactive power compensation, modular shunt active power filter (SAPF) system is attractive for its high-reliability and flexibility. However, a unique physical address is needed for each module in traditional SAPFs. If a module fails, the faulted module should be substituted by another one with the same physical address. Therefore it is hard to realise modularisation, and the cost of the system is high. In addition, in such a system, a single SAPF generally adopts the topology with LCL filter and are coupled because of grid impedance. Generally, this coupling is not taken into account when designing the control laws. In consequence, depending on the number of paralleled SAPFs and the grid impedance, the paralleled SAPFs do not behave as expected. In this study, a simplified N + 1 redundant SAPF system and its control strategy are presented. The SAPFs are modelled as a multivariable system. The analysis carried out enables to obtain an equivalent SAPF that describes the totality of paralleled SAPFs. The coupling effect is described and the control law design of paralleled SAPFs with LCL filters is clarified. The validity of the simplified N + 1 SAPF system and the efficiency of the control strategies are demonstrated by prototype experiments.

As one of the main effective equipment to deal with the grid harmonic problem, Active Power Filter (APF) becomes large-scale industrial application gradually. With the increasing requirements of high-capacity APFs in industries, multi-module parallel connected APF becomes an important developmental direction and research hotspot for its flexible capacity and high reliability. A redundant strategy which can make use of the undamaged bridge arm of the damaged modules is given in this paper, as shown in Fig.1. Compare with the method that removes the whole module when it is damaged, the flexibility of system can be improved by this redundant strategy. The feasibility and practicality of the proposed strategies are verified by prototype experiments.

En este trabajo, nos centraremos en las matrices poliméricas, las cuales pueden ser de tres tipos: Termoestables, Termoplásticas y Elastoméricas. De ellas, particularmente nos centraremos sólo en el uso de las matrices termoestables (diglicidiléter de bisfenol A (DGEBA)) y las matrices termoplásticas (polimetilmetacrilato (PMMA)). Ingeniería Industrial

Asparaginase of Escherichia coli, a tetramer of identical subunits, was tested as a vector to display linear peptides on the surface of each enzyme subunit. A recombinant gene encoding a chimeric protein composed of asparaginase, a tetanus toxin peptide (TTP) spacer (831–854 fragment), and the foreign cholesteryl ester transfer protein C-terminal fragment (CETPC) was expressed and targeted to the periplasm of E. coli. The purified chimeric enzyme exhibited approximately 83% activity of the native enzyme, allowing the rapid screening of recombinant clones. In contrast, an asparaginase–CETPC fusion protein without the TTP spacer produced only about 23% activity of the native enzyme. Rats immunized with bacterial cells containing the chimeric enzymes induced CETP-specific immunoresponse. In contrast, rats inoculated with the cells expressing asparaginase only did not generate specific anti-CETP antibodies. Our study showed that asparaginase of E. coli was an effective carrier for displaying foreign peptides or epitopes. Moreover, the use of the TTP spacer appeared to play a critical role in maintaining the catalytic activity of the chimeric enzymes by redirecting the foreign CETPC peptide to the surface of the enzyme. The chimeric enzyme constructs fusing asparaginase with foreign peptides via a TTP spacer could be utilized as a rapid pepscan technique for antigen epitope mapping. The fusion protein of asparaginase–TTP–CETPC could also be useful for the development of a vaccine against atherosclerosis.