JPH0250725U

JPH0250725U -

Info

Publication number: JPH0250725U
Application number: JP12925388U
Authority: JP
Priority date: 1988-09-30
Filing date: 1988-09-30
Publication date: 1990-04-10

Description

[Brief explanation of drawings]

第１図はこの考案の一実施例の構成を示すブロ
ツク図、第２図は従来の無効電力補償装置の一例
の構成を示すブロツク図である。１……電力系統、２……負荷、３……遅相回路
、３Ａ……リアクトル、３Ｂ，３Ｃ……サイリス
タ、４……進相コンデンサ、５……直列共振回路
、７……無効電流検出回路、８……点弧角演算回
路、９……インバータ回路、１０……ヒステリシ
スコンパレータ、１４……高調波除去回路、２０
，２１……基本波除去回路。 FIG. 1 is a block diagram showing the structure of an embodiment of this invention, and FIG. 2 is a block diagram showing the structure of an example of a conventional reactive power compensator. 1... Power system, 2... Load, 3... Slow phase circuit, 3A... Reactor, 3B, 3C... Thyristor, 4... Phase advance capacitor, 5... Series resonant circuit, 7... Reactive current detection Circuit, 8... Firing angle calculation circuit, 9... Inverter circuit, 10... Hysteresis comparator, 14... Harmonic removal circuit, 20
, 21...Fundamental wave removal circuit.

Claims

[Scope of utility model registration request]

A phase delay circuit consisting of a series circuit of a reactor and a thyristor is connected in parallel to a load supplied with power from the power system, and a phase advance capacitor is connected in parallel to this phase delay circuit, and the resonant frequency matches the power system fundamental frequency. A series resonant circuit inserted between the neutral point side terminal of the phase advance capacitor and the power grid neutral point,
The reactive current component in the load current is removed by multiplying the fundamental current component extracted by a harmonic removal circuit from the load current flowing from the power system to the load by a voltage obtained by shifting the phase of the grid voltage by 90 degrees based on the fundamental wave. a reactive current detection circuit to detect, and a point of the thyristor through which a compensating reactive current that cancels a reactive current component in the load current detected by the reactive current detection circuit flows as a composite current of the phase delay circuit and the phase advance capacitor. a firing angle calculation circuit that calculates an arc angle and conducts the thyristor at the calculated firing angle; and an inverter circuit that injects a compensation harmonic current into the power system from a connection point between the phase advance capacitor and the series resonant circuit. Then, a second basic wave is calculated from the harmonic current component extracted from the load current by the first fundamental wave removal circuit and the current flowing through the slow phase circuit and the phase advance capacitor, with the positive and negative minute values set as upper and lower thresholds, respectively. The harmonic current component in the load current and the harmonic current component in the load current are compared by comparing the sum with the harmonic current component extracted by the wave removal circuit with the upper threshold value and the lower threshold value, and controlling the inverter circuit based on the comparison result. A reactive power compensator comprising a phase circuit and a hysteresis comparator that keeps the sum of harmonic current components in the current flowing through the phase advance capacitor within a predetermined positive and negative minute value range.