| 摘要 |
PURPOSE:To prevent the overload on a transformer and to prevent detachment from a power system by providing an overload prevention limitter limiting output reactive power. CONSTITUTION:The setting unit 16 of the overload prevention limitter 21 sets the limitation value of leading reactive power to -1.0pu and the like A subtracter 9-3 calculates a difference -0.1pu with the set point -1.0pu of the setter 16 and adds it to a negative value passage circuit 18 when a reactive power detection circuit 15 detects reactive power -1.1pu based on respective detection values of a transformer for meter 5-2 and a current transformer for meter 6-2. Since an operation value is negative, it passes through the negative value passage circuit 18 and it is added to a primary delay circuit 20-1. In such a case, the effect of a limitter is large when the gain K of the primary delay circuit 20-1 is large and the output of an invalid power compensation device is immediately limited to less than -1.0pu. Delay reactive power is similarly limited. Thus, the overload of the transformer is prevented, detachement from the power system can be prevented and the power system can be stabilized much more with constitution provided with the overload prevetion limitter limitting output reactive power to less than the set point which is set in the upper limit part of a range where the transformer is not overloaded. |
