Pichai Jintakosonwit

Control and performance of a fully-digital-controlled shunt active filter for installation on a power distribution system

This paper presents a fully-digital-controlled shunt active filter for harmonic termination of a power distribution system. The main purpose of the active filter based on voltage detection is not to compensate for current harmonics but to damp out harmonic propagation caused by line inductors and shunt capacitors for power factor correction. However, time and phase delays inherent in digital controllers might lead to unsatisfactory harmonic-damping performance although digital controllers are preferable to analog controllers. This paper deals with the design and implementation of a digital controller for a shunt active filter based on voltage detection. Experimental results obtained from a laboratory system developed in this paper verify the viability and effectiveness of the fully-digital-controlled active filter.

Implementation and performance of automatic gain adjustment in a shunt-active filter for harmonic damping throughout a power distribution system

This paper discusses automatic gain adjustment in a fully-digital-controlled shunt active filter. This is the first step in cooperative control of the multiple active filters based on voltage detection for harmonic damping throughout power distribution systems. In general, the active filter should be equipped with an optimal control gain corresponding to the characteristic impedance of a distribution line. However, it is difficult to know circuit parameters of a real distribution line having various shunt capacitors and loads. Therefore, a main purpose of the gain adjustment is to make the active filter damp out harmonic propagation without considering the circuit parameters. In addition, the gain adjustment can reduce the compensating currents and losses in the active filter, and moreover it can avoid over-damping performance. Experiment results obtained from a 200-V, 20-kW laboratory system verify the effectiveness of the active filter equipped with automatic gain adjustment.

Implementation and performance of cooperative control of shunt active filters for harmonic damping throughout a power distribution system

This paper proposes the cooperative control of multiple active filters based on voltage detection for harmonic damping throughout a power distribution system. The arrangement of a real distribution system would be changed according to system operation, and/or fault conditions. In addition, shunt capacitors and loads are individually connected to, or disconnected from, the distribution system. Independent control might make multiple active filters produce unbalanced compensating currents. This paper presents hardware and software implementations of cooperative control for two active filters. Experimental results verify the effectiveness of the cooperative control with the help of a communication system.

Implementation and Performance of an Anti-Resonance Hybrid Delta-Connected Capacitor Bank for Power Factor Correction

This paper presents a new three-phase anti-resonance hybrid delta-connected capacitor bank for power factor correction in low-voltage industrial power systems. In general, shunt capacitors connected in series with reactors should be designed carefully before installation in order to avoid series and/or parallel harmonic resonance between the capacitors and system inductances. However, the system parameters vary dynamically according to the power system configurations and loads. Consequently, harmonic resonance might occur after the capacitors have been installed. The main objective of the proposed hybrid capacitor bank is to compensate for reactive power without any harmonic resonance. The hybrid capacitor bank is a combination of delta-connected capacitors connecting in series with three small-rating single-phase inverters without any matching transformer. The inverter is used to improve the characteristics of the capacitors. This paper deals with the implementation and control of the hybrid capacitor bank. Experimental results verify the viability and the effectiveness of the proposed anti-resonance hybrid delta-connected capacitor bank for reactive power compensation.

Performance of automatic gain adjustment in shunt active filters for harmonic damping throughout power distribution systems

This paper discusses automatic gain adjustment in fully-digital-controlled shunt active filters. This is the first step in cooperative control of the active filters based on voltage detection for harmonic damping throughout power distribution systems. In general, an optimal control gain is equal to the characteristic impedance of a distribution line. However, it is difficult to know circuit parameters of a real distribution line, that is, feeder connections, shunt capacitors and loads. Therefore, the main purpose of the gain adjustment is to make each active filter damp out harmonic propagation without considering the circuit parameters. Moreover, the gain adjustment can reduce the compensating currents and losses in each active filter. The two active filters with constant or automatic-adjustable gains are experimentally compared. Experiment results verify the effectiveness of the active filter with automatic gain adjustment.