B. Chen

Analysis and realization of a fast repetitive controller in active power filter system

The repetitive control and resonant control are widely used in grid-connected voltage-source converters recently, such as uninterruptible power supplies (UPS), photovoltaic inverter (PV) and active power filter (APF). This paper introduces a new repetitive control strategy in APF system, whose repetitive period is only one half of the traditional and could eliminate all odd harmonics as a bank of resonant controllers. Compared to traditional repetitive control, proposed control strategy has faster tracking speed and smaller steady-state error; Compared to traditional PR control, it could be simply implemented in digital processor. Theory analysis with simulations and experiments demonstrate the validity and superiority of proposed fast repetitive control strategy.

Analysis and realization of a novel repetitive controller in active power filter system

The repetitive control has been widely used in grid connected voltage source converters, such as uninterruptible power supplies (UPS), photovoltaic inverter (PV) and active power filter (APF). This paper introduces a new repetitive control strategy in the APF system; the proposed control strategy has a forgetting factor (FF), which could improve control system robustness. Control system stability and convergence analysis points out that control system characteristics depend on characteristic expression, which is essential for controller design. Appropriate design of this characteristic expression could make control system have good stability and fast convergence rate. Combination of industrial application, this paper presents a controller analysis and design methods, at last, simulations and experiment results demonstrate the validity of proposed repetitive control strategy.

High-reliability and harmonic-sharing dual parallel topology for active power filter

This paper chooses the proportional resonant controller for the controlling of Active Power Filter, and proposed a new control topology for dual parallel APF application. The APF_I near the load side employs the proportional resonant controller to compensate the 5th, 11th, 17th and 23rd harmonics; The APF_II near the system side also employs the proportional resonant controller to compensate the 7th, 13th, 19th and 25th harmonics. Both APF_I and APF_II choose the system side harmonic current for feedback control, and also have fast dynamic response due to the proportional resonant controllers. Compared with traditional dual parallel APF, this topology let two parallel APFs have different compensation characteristic, which could compensate selected harmonics and realize harmonic sharing. When one of them is out of working, the other APF could still compensate almost half of all harmonics. Proposed parallel system has advantage for system expansion, cost saving and power-rate improving. The circuit currents for different harmonics are also discussed. This paper analysis the system characteristic and design the system configuration and control parameters. The simulation on MATLAB/simulink also demonstrates the validity and superiority of proposed system configuration and control strategy.

Realization and improvement of repetitive control in rotating frame for active power filter system

The repetitive control, which is based on a delay of fundamental period, is widely used in grid-connected voltage-source converters, such as uninterruptible power supply (UPS), photovoltaic (PV) inverter and active power filter (APF). This paper presents four repetitive controllers in rotating frame for APF system, whose repetitive period is T, T/2, T/3, and T/6 respectively. Compared with traditional repetitive control, these repetitive controllers have fast dynamic response and also have similar structure, which could also be easily implemented in digital processor for APF system. Regeneration spectrum and sensitivity function based analysis methods provide a way for parameters design and performance comparison between each controller. Simulation and experiment results demonstrate the validity and superiority of each controller.

A novel compact structure of the three-phase virtual air gap controllable reactor

Virtual air gap controlled reactor (VGR) is an electrical device based on the working principle of the saturation in the iron cores. The magnetic permeability of the iron cores in the VGR can be changed smoothly by regulating the direct current in the exciting windings. The higher the magnetic permeability of the iron cores, the greater the inductance of the VGR is, and vice versa. Since the advantage of the inductance of the VGR can be adjusted smoothly, it results in wide applications in the power system, such as arc suppression coil, soft motor starter, reactive power compensator. However, the size of traditional VGR is large, so that it also needs large place for installation. In this work, the compact structure of the three-phase VGR based on the six limbs technology is proposed. The structure can greatly reduce the size of the VGR. The MAGNET software is used here to prove the effectiveness of this approach.

Electromagnetic hybrid compensation method of three-phase unbalance for high-speed railway traction supply system

For power quality in V/V traction system of the high-speed railway, a kind of electromagnetic hybrid compensation system (EHCS) is proposed. The EHCS is constituted by small-capacity railway static power conditioner (RPC) and high-capacity magnetic static var compensation (MSVC). By utilizing the transient power transfer capability of RPC reasonably, EHSC overcomes the problem of high installation capacity in the traditional SVC compensation system. Because RPC is completely autonomous and disconnected from MSVC, the reliability of EHCS is improved. Under the premise of meeting corresponding standard requirement of power quality, the mathematical model for hybrid compensation method is proposed and further optimized to make the compensating capacity of MSVC smaller. The simulation and experimental results verify that hybrid optimized compensation method can limit the negative-sequence current and power factor within the desired bounds efficiently.

Feedback decoupling and distortion correction based reactive compensation control for single-phase inverter

This paper analyzes the characteristic of singlephase converter system and establishes the active power and reactive power model in d-q axis, which is the same with the there-phase system in d-q axis and could employ decoupling feedback control for reactive compensation and active power control. For realizing d-q transformation in single-phase system, a new orthogonal decomposition method with sliding window filter (SWF) is presented. While, for the sake of SWF, the coupling between active power and reactive power could not be eliminated completely, which leads to poor dynamic process in control system and significant distortion in compensation current. For overcoming these shortages, this paper presents a distortion correction based control strategy, which not only could improve the control system dynamic characteristics, but also eliminate compensation currents distortion. At last, simulations with different control strategies demonstrate the validity and superiority of proposed control strategy.

Noise reduction of saturable magnetically controlled reactor using magnetic-mechanical analyses

The saturable magnetically controlled reactor (MCR) applying dc control currents has been widely used in the voltage regulation and reactive power compensation in the electric power system [1].

Characteristics investigation of bridge-type saturated core fault current limiter

Due to the increasing demands for electric energy and installation of distributed generation, the rising fault current poses a great threat to those existing power system components.

Optimal design of superconducting controlled reactor based on immune algorithm and ANSYS

Superconducting controlled reactor (SCR), as a novel dynamic reactive compensation facility, has many advantages such as free harmonic, fast response, low losses and high voltage withstand [1]. However, due to SCR special structure and magnetic circuit, capacity gears of SCR designed by traditional methods are not accurate enough.