This paper presents a three-phase variable inductor for reactive power control in an electric power system. The variable inductor is constructed with three orthogonal-cores, and is controlled by a simple dc-dc converter. In order to reduce the harmonic currents of the variable inductor, we made a partial gap in the orthogonal-core. The trial three-phase 100 kVA variable inductor demonstrates that the variable inductor can be put to practical use in a 6.6 kV ac distribution system.

Development of 3-phase 100 kVA orthogonal-core type variable inductor with sinusoidal output

One method for calculating flux-MMF relationship of an orthogonal core is described. The calculation is based on a three-dimensional magnetic circuit model of the orthogonal core. The model is derived by dividing the orthogonal core, inclusive of the surrounding region, into elements comprising a three-dimensional magnetic circuit. Using this model, the flux-MMF relationship of the orthogonal core with arbitrary dimensions can be calculated from the B-H characteristic of the core material. The calculation method presented is useful for optimum design of devices using an orthogonal core. >

One Method For Calculating Flux-MMF Relations Hip Of Orthogonal-core

This paper describes a fundamental consideration on high speed control of the orthogonal-core type variable-inductor. The variable-inductor is applicable to a VAR compensation in the electric power system. The transient characteristics of the variable-inductor under the condition of DC control are discussed based on simulation and experiment. For high speed operation, we present an instantaneous control of the primary current. A simple control circuit using a DC-DC converter is demonstrated in this paper.

High speed variable-inductor controlled with DC-DC converter

By using an orthogonal-core-type variable inductor and capacitor, we will realize a simple, reliable, and high-quality voltage regulator. However, the nonlinear magnetization characteristic of the orthogonal core causes harmonics in the output current. Last year, in order to reduce the harmonic current of the variable inductor, we proposed an orthogonal core with wedge gaps. A trial three-phase 100 kVA variable inductor demonstrates that the variable inductor can be put to practical use in a 6.6-kV ac distribution system. For wide Appl.ication, it is necessary to establish a design method for the orthogonal core. This paper presents a method of calculating the characteristics an orthogonal core with wedge gaps.

Calculation of the Characteristics of an Orthogonal-Core-Type Variable Inductor with a Wedge Gap.

This paper presents analysis and design control scheme including the nonlinear effects of the output-filter inductor and active switches of the inverter systems Since the filter inductance will drop dramatically when the inverter system is operated at heavy loads, system dynamic performance will vary over a wide range Q-parameter is selected as an input variable of the control scheme to improve the system performance The dc link of the inverter system is a constant value, but the variation of the modulation will also affect the linear control of the system The reference command of an inverter system is a sinusoidal wave In the paper, a nonlinear controller is used to compensate the nonlinear results of the sine-modulated inverter during each cycle Inverter systems with the proposed control scheme can compensate the influence due to variations of filter inductance and nonlinear effect of the active switches no matter it operated at the light loads or the heavy loads Thus, a robust inverter system can be achieved

Development of a fuzzy-Q control for achieving robust inverter systems

Discusses transient operation of the orthogonal-core-type DC-AC converter for a grid-connection-type photovoltaic (PV) power system. In particular, they consider the transient operation when the converter is connected to and disconnected from the utility grid on the basis of simulation and experiment. Furthermore, they examine the converter behavior when a line-to-line fault occurs in the utility grid. It is shown that the DC-AC converter has excellent tolerance for various faults which occur in a PV power system. >

Transient operation of orthoginal-core type DC-AC converter for photovoltaic power system

This paper describes the use of an orthogonal core to in a VAR compensator to stabilize line voltage in an electrical power system. An orthogonal core is a kind of variable inductor that uses the nonlinear B-H characteristics of an iron core. The inductance of the secondary winding decreases with the dc control current of the primary winding. Utilizing this feature, we developed a three-phase VAR compensator with a capacity of ±5 kVA, constructed from three-phase connected orthogonal cores and capacitor banks. Here, we discuss the fundamental operation of the VAR compensator, and demonstrate the static and dynamic operations of the trial VAR compensator. Experimental results show that the VAR compensator is useful for line voltage stabilization. A possible for first response of the compensator is also described.

M. Maeda

Papers

High speed variable-inductor controlled with DC-DC converter

Transient operation of orthoginal-core type DC-AC converter for photovoltaic power system

Application of an Orthogonal Core to a VAR Compensator.