| 摘要 |
PROBLEM TO BE SOLVED: To execute the detection of active single operation of an inverter without fail. SOLUTION: In an inverter 2, which is interconnected with the system S where a power factor controller 26 generates an inverter gate reference signal from the difference between an active current command value Ip * and an output current Idi and the voltage Vout at interconnection point and the current is controlled by sine wave PWM control, a reactive current command value Q* which changes in triangular form is generated 32, and a voltage Vout signal is delay by 90 deg. 31, and a reactive current command value IQ* which changes in triangular form is made by multiplying it by the command value Q*, and it is added to a command value Ip * 24. On the other hand, reactive power QDET is detected from the voltage Vout and the current Iout 12, and |QDET-Q*| is compared with the reference value 35, and when it is over the reference value, this outputs an inverter stop signal. At power failure of the system, a breaker 52R2 is turned off and the system interconnection is cut off, so the reactive power control ceases to work, and QDET becomes a fixed value dependent upon load, so |QDET-Q*| changes into triangular wave form, and it gets over the reference value. |
