Yoshiya Ogihara

Novel active filter system composed of inverter bypass circuit for suppression of harmonic resonance at the Yamanashi Maglev test line

The authors have developed and proposed a novel active filter system composed of an inverter bypass circuit for the suppression of harmonic resonance conditions caused between the inductance behind the load bus and the capacitance of VAr equipment, especially at lower harmonic frequencies. They have installed this new harmonic compensation system in combination with TCR-type SVC and shunt LC filters at the Yamanashi Maglev test line. Here, they describe the outline of the reactive power and harmonic compensation systems, and harmonic resonance test results which show satisfactory performance of the active filter.

Switchgear component commonality design based on trade-off analysis among inventory level, delivery lead-time and product performance

The shortening of product delivery lead-times can usually be achieved by keeping high-level components in inventory, however in small-volume production systems, maintaining such inventories is often a costly as well as a risky business strategy. If the risk of maintaining unsold inventory can be decreased, even small-volume manufacturers may be able to justify holding more significant quantities of versatile inventory. This paper discusses a component commonality effect to breakthrough the trade-off relationship between inventory levels and delivery lead-times for such small-volume production systems. By using the same component in different products, inventory maintenance costs can be dramatically reduced, but component commonality design problems are inherently complex, since excessive module commonality may lead to lower product performances, and there are trade-off relationships between product performance and cost reductions obtained through component commonality. In this paper, such a design problem is formulated as a multiobjective component commonality design optimisation problem considering inventory level, delivery lead-time and product performance, and the optimal solutions are obtained as a Pareto optimal solution set. Detailed procedures concerning the proposed design method, including inventory simulation, are discussed and developed for a switchgear design problem. Finally, an example switchgear design problem is solved to illustrate that optimal use of component commonalities across different modules can significantly reduce inventory costs, while also shortening product delivery lead-times.

Novel active filter system composed of inverter bypass circuit for suppression of harmonic resonance

We have developed a novel harmonic compensation system consisting of shunt LC filters on the load side, a step-down transformer on the receiving end, and a small-capacity active filter with one end connected to the secondary winding of the transformer and the other to the load bus. The active filter which constitutes the bypass circuit for the main service transformer is current-controlled to give adequate damping of the harmonic resonance caused by the inductance behind the load bus, especially at lower harmonic frequencies. We have installed this new compensation system in combination with a TCR-type SVC and shunt LC filters at the Yamanashi Maglev Test Line. We present an outline of the reactive power and harmonic current compensation systems, and harmonic resonance test results which show satisfactory performance of the active filter.

Switchgear Component Commonality Design Method Considering Delivery Lead-Time and Inventory Level

Product families are groups of related products that take advantage of part commonalities at various levels to streamline delivery of maximal product variety with minimal cost impact and as short as possible lead-times. This paper proposes a new integrated product design method for build-to-order production system based products, using the product family concept, which considers product performance, delivery lead-time and inventory cost. The development and discussion of this method uses a switchgear design problem as a concrete and practical design case. A build-to-order production system has been applied to switchgear manufacturing due to its small-scale production and a variety of customer requirements. However, if the risk of maintaining unsold inventory can be decreased, manufacturers can justify holding an amount of versatile inventory. In this paper, inventory production system is applied to the switchgear production problem to shorten the delivery lead-time. The switchgear design and production problem is formulated using three objective functions, which are subassembly procurement lead-time, inventory cost and area occupied by various switchgear configurations. Moreover, to assist inventory cost evaluations, a simulation procedure for the inventory system is proposed. The proposed method is used to obtain a Pareto optimal solution set of the three objective functions. Finally, an example switchgear design problem is solved to illustrate that optimal use of component commonalities across different modules can significantly reduce inventory costs, while also shortening product delivery lead-times.Copyright