JPH0470861B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a power system equipped with private power generation equipment, which determines the presence or absence of a power outage based on the presence or absence of current in a connecting section between an external power system and the private power generation equipment, thereby confirming a power outage. It relates to a device that performs control.

[Conventional technology]

FIG. 3 shows a single line diagram of an electric power system including a power failure confirmation/disconnection device as shown in, for example, Japanese Patent Laid-Open No. 56-19185. In the figure, reference numeral 1 denotes an external power system (external power source), which is connected to a system having a private power generation facility 7 via a connector and a disconnector 2 . 3 is an instrument current transformer installed in the communication bus A of the external power system 1, 4 is a current detector, and 5 is a power outage confirmation disconnection device. A generator G of a private power generation facility 7 is connected to a load bus B via a shield and a disconnector 6, and its output voltage is detected by a transformer 8 and given to a voltage setting device 9. 10 is an automatic voltage regulator, which includes a voltage detector 11 and a reference voltage setter 1.
2. A comparator 13 is provided, and the output of the comparator 13 creates a voltage control signal and sends it to the field power supply device 14. Reference numeral 15 denotes load equipment, which is composed of a plurality of loads M. 16 is a power factor improvement capacitor,
Load bus B via each capacitor and disconnector 16A
It is connected to the.

Next, the operation of this device will be explained.

The power failure confirmation and disconnection device 5 monitors the current of the communication bus A detected by the current detector 4, and when the current value reaches zero level, the power factor of the generator G in the power generation equipment 7 is high. If the power factor is close to leading, the control signal (excitation increase command) to increase the generator field is delayed. If it is the phase, a control signal (excitation reduction command) for reducing the generator field is given to the voltage setting device 9. This allows external power supply 1
If there is no power outage, the output of the generator G will increase or decrease, so if there is no change in the load equipment 15, the communication bus A will no longer have a current flow but a current will flow. When the external power supply 1 is out of power, the communication bus A remains without current, so if the no-current period continues for a certain period of time, the power outage confirmation/disconnection device 5 determines that there is a power outage and contacts the disconnector. A trip command of 2 is given to disconnect the external power supply 1 and the generator G.

[Problem that the invention seeks to solve]

However, with this conventional device, when the load capacity of the load equipment and the power generation output of the private power generation equipment fluctuate slightly in an approximate state, the current flowing through the connecting bus A will fluctuate around the zero level. While the fluctuating state continues, the alternating excitation increase/decrease control by the power outage confirmation/disconnection device 5 continues, resulting in a problem that an unfavorable disturbance state for the generator continues and unstable operation of the generator continues.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a generator safety device that can perform power outage disconnection control without causing unstable operation of the generator.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a determination unit that detects the presence or absence of repetition of a generator output increase/decrease control operation by a power outage confirmation and resolution unit within a predetermined period of time and outputs an output when the operation is repeated a predetermined number of times, and an output of the determination unit. and a phase-advanced power adjustment unit that generates a command to partially disconnect the power factor improving capacitor group for the load in the power generation equipment in response to the power generation equipment.

[Effect]

In this invention, when the load capacity of the load equipment and the power generation output of the in-house power generation equipment fluctuate slightly in an approximate state, and the current flowing through the connecting bus starts to fluctuate around the zero level, the power factor improvement of the load equipment is performed. A part of the provided capacitor group is disconnected, and the leading phase current supplied by the capacitor group decreases, and the current passing through the connecting switch 2 increases according to the amount of decrease in this leading phase current. , the repeated increase/decrease operation of the generator output is stopped.

[Embodiments of the invention]

FIG. 1 shows an embodiment of this invention.
This device differs from the conventional device shown in FIG. 3 in that it includes a determination/reactive power adjustment section 17. This determination/reactive power adjustment section 17 constitutes a generator safety device 18 together with a power outage confirmation/disconnection device (referred to as a power outage confirmation/disconnection section in this embodiment) 5.

The control flow of this generator safety device 18 shown in FIG. 2 will be explained.

A detection signal from a current detector 4 that detects the current flowing through the communication bus A is led to a power failure confirmation/resolution section 5.
This power outage confirmation/interpretation unit 5 determines whether the current value No. 1 of the current input from the current detector 4 is at the zero level or the present level, as described with reference to FIG. If so, depending on the power factor of the generator G, an excitation increase command or an excitation decrease command is sent to the voltage setting device 9 through the timer. At the same time, the first stage flip-flop 51 is set. The set output of flipflop 51 is supplied to AND element 52. According to the excitation increase command or excitation decrease command, the output of the generator G increases or decreases after a predetermined time, so after a predetermined time _T0 , the current value No. 2 taken in from the current detector 4 becomes a valid level,
The second flip-flop 53 is set and at the same time the timer starts running. The set output of flip-flop 53 is supplied to AND element 54. If the capacity of the load equipment 15 is constant, it will remain in this state for a certain period of time, so the timer times up and the flip-flop 51 is reset before the flip-flop 55 is set. However, if the load capacity and the output of the generator G fluctuate in an approximate state, the To
When the current value No. 3 taken in later becomes zero, the flip-flop 55 is set, and the set output energizes the reactive power adjustment section 56 and capacitor 16.
A command to disconnect one capacitor of the group (capacitor trip command) is sent to a specific capacitor 16A.
If all the current values (No. 1 and No. 2 in this example) taken within the predetermined time Too (>To) are at zero level, the timer times up and the communication is interrupted. Generates a device trip command.

In this way, in this embodiment, when the current flowing through the connecting bus A slightly fluctuates around the zero level, when the alternating control of increasing and decreasing the generator output is repeated a predetermined number of times within a predetermined time, the load equipment Since a part of the capacitor group provided for power factor improvement is disconnected, the phase-advanced current supplied by the capacitor group is reduced. As a result, the current passing through the communication bus A2 increases in accordance with the amount of decrease in the phase-advanced current, so the repetition of the alternating increase/decrease control is stopped.
The operation of generator G becomes stable.

In addition, although the current detector is used in the above embodiment, a power detector or a power direction detector may be used instead. In addition, the reactive power adjustment section 56
Instead of simply generating a signal for partially disconnecting the capacitors, it may be configured to generate a signal for selectively disconnecting the capacitors of the 16 group of capacitors.

〔Effect of the invention〕

As explained above, in this invention, when the load capacity and the generator output slightly fluctuate in an approximate state, and the power failure confirmation and disconnection unit is about to start repeated control to increase and decrease the generator output, the power factor of the amount that breaks out of the above approximate state is obtained. Since the capacitor is disconnected, power outage confirmation and disconnection control can be performed without causing unstable operation of the generator.

[Brief explanation of the drawing]

FIG. 1 is a power system diagram using an embodiment of the present invention, FIG. 2 is a control flow diagram showing the operation of the above embodiment, and FIG. 3 is a power system diagram using a conventional power failure confirmation control device. In the figure, 1... External power system, 2... Connector/disconnector, 4... Current detector, 5... Outage confirmation/disconnection section, 7... In-house power generation installation, 16... Power factor improvement capacitor , 17... Judgment/reactive power adjustment section, A
...Communication Department, G... Generator. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Detect the current in the connecting line connecting the generator of the private power generation equipment and the external power source, and if the current value is zero, increase or decrease the output of the generator to maintain the current value at zero for a predetermined period of time. A power failure confirmation/disconnection unit that opens a contact, disconnector, or circuit installed in the communication line when detected, and a judgment that detects whether or not the increase/decrease control operation is repeated within a predetermined time and outputs an output when the increase/decrease control operation is repeated a predetermined number of times. A generator safety device comprising: a reactive power adjusting section that receives the output of the determining section and generates a partial disconnection command to a group of power factor improving capacitors of a load equipment in the power generation equipment.