JPS61102129A - Parallel operation method of inverter device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a parallel operation method for inverter devices, and particularly to a parallel operation method using individual control.

Conventional technology An inverter device configured with a forward converter, an inverter, and even a battery is used as an uninterruptible power supply, for example, to supply power to a load by parallel operation, but it is necessary to control the output frequency and output % pressure of each power supply. In some cases, an individual control method is used in which load notification is performed individually. For this individual control, each device detects the effective and reactive components of the output power, and the effective component gives the output frequency control a drooping characteristic, while the reactive component provides output 1.
); Add drooping characteristics to 5-pressure control. As a result, the load sharing of each device is determined by the effective component being determined by the frequency drooping characteristic and the reactive component being determined by the voltage drooping characteristic.

Problems to be Solved by the Invention In the conventional parallel operation system, when there is an abnormality in the frequency droop characteristic due to a failure or other cause, or during a transient response, the effective power flows from the side of the device whose frequency has decreased (from the other device. As a result, the DC voltage of the device into which the active ingredient has flowed increases, potentially causing the device to stop operating due to overvoltage, and depending on how the failure occurs, there is also a possibility that the system will go down.

A possible solution to this problem is to monitor the DC voltage and increase the output frequency as the DC voltage rises to prevent the effective power from flowing into the system, but this increases the detection delay due to detection based on the rise in DC voltage. It is not enough to prevent the flow from flowing in. Furthermore, in an uninterruptible power supply using a floating charging method, since the DC voltage fluctuation of the battery is large (30% to 40%), it is impossible to prevent the effective power from flowing in by detecting the DC voltage.

Means and Function for Solving the Problems The present invention provides drooping characteristics to the output frequency control and output voltage control for the effective and reactive components of the output power by the control circuit, respectively, and also provides drooping characteristics for the output power control circuit depending on the polarity of the detected amount of the effective component. Detects the flow of effective power from other inverter devices, increases the output frequency of the inverter device according to the detected amount, and makes the rate of increase greater than the rate of decrease in the output frequency when the inverter device outputs effective power. When the detected effective amount has a polarity opposite to that in normal conditions, the control gain is increased compared to the normal control gain to quickly increase the frequency control output, thereby suppressing the inflow of effective power. .

Embodiment FIG. 1 is a block diagram showing an embodiment of the present invention. The inverter family f1.2 is, as shown representatively in device 1,
The main circuit includes a forward converter 3, a smoothing capacitor 4, an inverter 5, and a filter 6, and supplies power to a load 7 in parallel connection. Furthermore, the control circuits of the inverter devices 1 and 2 are as follows:
Voltage control section 8, frequency control section 9, and gate logic section 10
and an effective/reactive component detection section 11, and individually controls the output voltage and output frequency of the inverter 5 within the device itself.

The effective/reactive component detection unit 11 detects the active component P and the reactive component Q of the output power from the detection signals of the detectors 12.13 of the output voltage V and the output current (2) of the inverter device 1 itself. The voltage control unit 8 obtains a voltage control signal Vc in which feedback control is performed by matching the output voltage setting value Vs and the output voltage detection value V, with drooping characteristics due to the reactive component Q. Frequency control section 9
obtains a frequency control signal fc in which the output (reference) frequency setting value f8 has a drooping characteristic due to the effective component P. The gate logic unit 10 provides each switch element of the inverter 5 with a gate output having a phase and a pulse width according to the voltage control signal Vc and the frequency control signal fc.

Here, the frequency control unit 9 detects the inflow of effective power from other inverter devices based on the polarity of the effective component P,
The control circuit is configured to rapidly increase the frequency control signal fc in accordance with this detected amount, and by increasing the output frequency when the effective power flows in and controlling the effective power to a greater extent, the share of the actual power can be reduced. Return to normal. This also suppresses the inverter DC voltage rise due to the inflow of effective power, thereby preventing equipment operation stoppage due to overvoltage. In addition, since inflow detection is not affected by DC voltage fluctuations, it can also be applied to devices with large DC voltage fluctuations, such as floating charging type uninterruptible power supplies.

FIG. 2 shows a specific configuration of the control circuit in FIG. 1,
The broken line blocks are shown in correspondence with the respective parts in FIG. The active/reactive component detection section 11 calculates the effective component P and the reactive component Q by the active power calculation section 11A and the reactive power calculation section 11B, respectively. The frequency control unit 9 obtains a reference frequency setting signal fs to the setter 9A, obtains the deviation between this set value fs and the effective portion P, and uses the deviation between the set value fs and the effective portion P as a control signal for the voltage controlled oscillator 9B, and uses the output frequency of the oscillator 9B as the control signal. Output as fo. Here, in normal times, the difference between the effective component P and the set value fe is obtained, but when the effective power flows in from another inverter system, the polarity of the effective component P becomes reverse polarity, and the diode element 9
It is added to the set value f8 through the bypass path by C. Therefore, under normal conditions, the effective component P has the opposite polarity to the set value fs and is matched, and when the effective power flows in, the effective component P reverses its polarity and is added to the set value with the same polarity as θ. , the input/output of the frequency control section 9 is as shown in FIG. In Fig. 3, the horizontal axis shows the effective component P, the vertical axis shows the frequency control signal fc, and when the effective component P has positive polarity (normally), it has a drooping characteristic due to the effective component P. When the component P has negative polarity (when the effective power flows in), the diode 9C is conductive, and the control signal fc increases with a high gain (increase rate). Therefore, at the time of inflow, inva~
The output frequency of the inverter suddenly increases, changing the effective power from inflow to outflow, and normalizes the power sharing of the inverter device.

The voltage control unit 8 obtains a voltage control voltage by the voltage control amplifier 8A from the set voltage 8, the detected voltage V, and the reactive component Q, and converts this voltage into a frequency signal f at a constant level of the triangular wave generation circuit 8B.
A pulse-width modulated voltage control signal Vc is obtained by the comparator 8C by comparing it with a triangular wave signal of frequency 1 phase that matches c. From these frequency control signal fc and voltage control signal VC, the inverter gate logic section 10 generates gate pulses U, V, W, X, and Y for each phase switch element.

Get 2.

Effects of the Invention According to the present invention, the inflow of effective power is detected from the polarity of the active component detection section, and this detection rapidly increases the output frequency of the inverter to prevent the inflow of effective power. It is possible to detect a shared abnormality at high speed by detecting the effective component, and to reliably prevent a phase splitting abnormality and prevent a system down due to the occurrence of a DC overvoltage, regardless of the magnitude of the DC voltage fluctuation. In addition, since each inverter is controlled individually, the number of parallel operations is not limited and can be easily achieved by partially modifying the control circuit of each inverter. Reduce.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a concrete diagram of the control circuit in FIG. 1, and FIG. 3 is an input/output diagram of the frequency control section 9 in FIG. It is a characteristic diagram. 1.2... Inverter device, 5... Inverter, 7
Load, 8 Voltage control section, 9 Frequency control section, 10 Gate logic section, 11 -- Effective portion/
Reactive component detection section, 9A...Reference frequency setter, 9B
...■Pressure controlled oscillator, 9C...diode. Figure 1 ・2 1.2-11 Yeshiba-y: 1tx 5-111 Yeshiba-7 Fuuu 4. Hei 8-11 Electric No. 1 Sada-Lii No. a p part g ----l'IJJ'plj&pq10-111 Gate Rosin 2 parts

Claims (1)

[Claims] Multiple inverter devices are connected in parallel to supply power to the load, and each inverter device uses an individual control circuit to control the inverter output frequency with a drooping characteristic using the effective portion of the output power, and to control the output voltage with a drooping characteristic using the reactive portion of the output power. A parallel operation device that detects the flow of effective power from another inverter device based on the polarity of the detected amount of effective power, increases the output frequency of the inverter device in accordance with this detected amount, and adjusts the rate of increase. 1. A method for parallel operation of inverter devices, characterized in that the inflow of effective power is suppressed by controlling the rate of decrease in output frequency to be greater than the rate of decrease in the output frequency when the effective power is output from the inverter device.