JPH03284116A - Supervisory apparatus - Google Patents

Abstract

PURPOSE:To detect an abnormality in a detector and avoid the harmful influence of the detection abnormality upon a system by a method wherein active electric energy values which are obtained from detected DC current values and a detected DC voltage value by a processor and correspond to the respective detected DC current values are compared with the output of an active power detector. CONSTITUTION:Active electric energy values PdA and PdC are obtained from a DC voltage detected by a DC voltage detector 15A and DC current values IdA and IdC detected by DC current detector 21A and 21C by an active power processor 80A. A detection abnormality judging apparatus 81A judges that there is a DC voltage detection abnormality if an active energy value P which is detected by an active power detector 7A is not equal to the active electric energy values PdA and PdC when the DC current values IdA and IdC are equal to each other and outputs a DC voltage detection abnormality signal to a constant voltage control circuit 11A. If PdA P and PdC=P or PdA=P and PdC P when the DC current values IdA and IdC are not equal to each other, it is judged that there is an abnormality in the DC current detector 21A or the DC current detector 21C respectively and the selection signal of the abnormal detector is outputted to a DC current value selector 82A.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention provides a method for detecting signals from a DC current detector and a DC voltage detector of a DC power transmission system or DC interconnection equipment such as a frequency converter. This invention relates to a monitoring device that monitors whether or not.

(Prior Art) FIG. 2 shows a schematic block diagram of a conventional control method for a converter in a DC power transmission system.

The DC sides of the converters IA and IB are connected by a DC transmission line 3 via DC reactors 2A and 2B, respectively, and the AC side of each converter IA and IB is connected to a converter transformer 4A.
.

4B, and are connected to the respective AC systems 6A and 6B via circuit breakers 5A and 5B.

Conventional converters IA and IB have constant margin angle control circuits 12A and 1.
2B, constant voltage control circuit 11A, IIB, constant current control circuits 13A, 13B, constant margin angle control circuit 1
2A and 12B operate so that the margin angles of the converters IA and IB follow the margin angle reference value which is the output of the margin angle setters 18A and 18B.

Voltage/voltage conversion circuits 16A, 16B detect the voltage reference value output from the DC voltage setters 14A, 14B and the DC voltage with DC voltage detectors 15A, 15B, and convert them into values that can be easily handled by the control circuit. The summing circuits 17A, 17B determine the difference between the DC voltage detection value inputted to the summing circuits 17A, 17B via the summing circuits 17A, 17B, and the value of the difference is inputted to the constant voltage control circuits 11A, 11B.
The DC voltage of the DC power transmission line 3 is controlled to follow the voltage reference value. In addition, the transmission control circuit 26A
, 26B, and the detected DC current value which is detected by the DC current detectors 21A and 21B and converted into a value that is easy to handle as a control circuit by the current/voltage conversion circuits 22A and 22B. Summing circuit 23A
, 23B. By inputting the value of the difference to the constant current control circuits 13A and 13B, the DC power transmission line 3
The direct current flowing through the current is controlled so as to follow the current reference value.

The switches 24A and 24B are turned off only for the converter that operates the converter as a reverse converter, and the current margin setter 25A,
The current margin which is the output of 25B is the summing circuit 2.
It is input to 3A and 23B. This current margin function, the constant margin angle control circuits 12A, 12B, the constant voltage control circuits 11A, IIB, and the constant current control circuit 13
A.

Due to the function of the control advance angle priority circuits 28A and 28B which output only the output of the converter 13B whose control angle is most advanced, it is assumed that the switch 2411 is closed and the switch 24A is closed. If it is open, the output of the constant current control circuit 13A is output to the control advance angle priority circuit 28A, and the output of the low margin angle control circuit 12B and the constant voltage are output to the control advance angle priority circuit 28B. Control circuit] Among the outputs of -1B, the output that is leading as a control angle, generally the output of the constant voltage control circuit 11B, is output. Each of the control advance angle priority circuits 2
The outputs of 8A and 28B are outputted by phase control circuits 29A and 28B.
29B, where it is converted into a pulse signal that determines the firing timing of the converter, and is sent to the pulse amplification circuits 3OA and 3.
The signal is configured to be applied as a gate pulse signal to each converter via 0B.

Configuring the control circuit as described above is a known technique.

(Problems to be Solved by the Invention) The conventional example shown in FIG. 2 has the following problems when an abnormality occurs in the detection of DC voltage or DC current.

When the detected amount of DC current becomes abnormal in the direction of increase, the output of the constant current control circuit becomes in the direction of increase, and the DC current decreases. When an abnormality occurs in the decreasing direction, the output of the constant current circuit becomes delayed, resulting in a DC overcurrent.

When the detected amount of DC voltage becomes abnormal in a decreasing direction, the constant voltage control circuit causes the DC voltage to increase.

In either case, there is a risk that the system will go down. It may also damage the converter and adversely affect the grid.

An object of the present invention is to solve the problems of the conventional example. When an abnormality occurs in the detection of DC current and DC voltage, the purpose of the present invention is to detect the detection abnormality and prevent it from adversely affecting the system or converting the converter. The purpose of the present invention is to provide a monitoring device that prevents damage to the system and adverse effects on the system.

[Structure of the invention]

(Means for solving problems) Means for achieving the above object of the present invention are as follows.

With DC interconnection equipment, some DC current detection amount.

An abnormality in the detection of DC current and DC voltage is detected by comparing the active power amount corresponding to each detected DC current calculated from the detected DC voltage amount with the value of the output of the active power detector.

(Operation) How the means for solving the above problem functions will be explained. The detected values of DC current are compared, and if the values are equal, the active power calculation value and the detected active power are compared, and if the values are not equal, it is determined that the DC voltage detector is abnormal. If the detected DC current values are not equal, the DC current value at which the DC current detection is abnormal is determined by comparing the active power calculation value and the active power detection value.

(Embodiment) FIG. 1 is a diagram illustrating the configuration of an embodiment according to the present invention. In FIG. 1, devices that perform the same functions as in FIG. 2 are provided with the same reference numerals. DC interconnection equipment monitoring device 100A
, 100B is an active power calculator 80A.

80B, detection abnormality determiners 81A and 81B, and DC current value selectors 82A and 82B.

Since the operation of the monitoring device in the control circuit is the same for both converters, only the operation of the monitoring device for converter IA will be described here.

Voltage/voltage conversion circuit 1.6A for converting the value detected by the DC voltage detector 15A to a value that can be easily handled by the control circuit.
DC voltage vd of value via DC current detector 2]A,
21C, current/voltage conversion circuit 22A.

The active power calculator 80A calculates the active power amount PdA+PdC from the DC current values 1 dA and ldC converted into values that can be easily handled by the control circuit at 22G.

The detection abnormality determiner 81A compares the values of IdA and Idc, and if the values of IdA and Idc are equal, compares the active power amount P detected by the active power detector 7A with the value of PdA+Pdc, and determines that they are not equal. If so, it is determined that the DC voltage detection is abnormal, and the DC voltage detection abnormal signal is sent to the constant voltage control circuit 1.
Output to 1A.

If the values of IdA and Idc are not equal, compare the values of active power P, PdA, and Pdc, respectively, and find that PdA≠
P, Pd (H: In case of p, DC voltage detector 21A
1) dA=P, Pd, -7! :
In the case of P, it is determined that the DC voltage detector 21G is abnormal,
The abnormality detector selection signal is output to the DC current value selector 82A.

The DC current value selector 82A selects the DC current value detected by the normal DC current detector and outputs it to the summing circuit 23A.

When comparing the amount of active power, a range is given to the determination value as appropriate in consideration of the loss of the converter. Furthermore, considering the comparison of the amount of active power in a transient state, in order to match the detection delay of the active power detector, a time limit is appropriately set on the DC power value and the DC voltage value used for calculating the active power.

As explained above, according to the present invention, when an abnormality occurs in DC current detection, the abnormal DC current detector is determined and the output value of the normal detector is excluded, which has a negative effect on the system. not give.

If an abnormality occurs in the detection of DC voltage, it is determined whether the detection is abnormal, and if the control system is multiplexed, processing such as pre-holding is performed in the constant voltage control circuit, and the faulty series is disassembled to replace the healthy series. By controlling the system, there will be no negative impact on the system.

In addition, when the control system is single, the constant voltage control circuit performs processing such as pre-holding and performs a soft stop, which prevents damage to the converter and adverse effects on the AC system. .

〔Effect of the invention〕

As explained above, according to the present invention, when an abnormality occurs in the detection of DC current and DC voltage in DC interconnection equipment, the detection abnormality can be determined, so that it does not adversely affect the system. This can prevent damage to the converter and adverse effects on the system.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention applied to DC interconnection equipment, and FIG. 2 is a block diagram of a conventional device. IA, I8... Converter, 2A, 2B... DC reactor, 3. DC transmission line, 4A, 4B, converter transformer, 5A, 5B... Breaker, 6A, 6
B...AC system, 11A, IIB...constant voltage control circuit, 12A, 12B...constant voltage control circuit, 13A, 13B...constant current control circuit, 14A, 14B
DC voltage setting device, 15A, 15B/DC voltage detector, +6A, 16B Voltage/voltage conversion circuit, 17A, 17
B, 23A, 23B...Summing circuit, 18A, 18
B... Margin angle setting device, 19... Transmission circuit, 21
A, 21B, 21C, 210... DC current detector, 2
2A, 22B, 22G, 220...Current/voltage conversion circuit, 24A, 24B...Switch, 25A, 25B・Current margin setter, 26A, 26B
...Transmission control circuit, 27...Current reference value output circuit, 28A, 28B...Control advance angle priority circuit, 29A, 29
B... Phase control circuit, 30A, 30B... Pulse amplification circuit, 7A,
7B...Active power detector, 80A, 80B...Active power calculator, 81A, 81B/Detection abnormality determiner, 82A, 82B...DC current value selector, 100A, 1
00B...Monitoring device, 8A, 8B...AC current detector, 9A, 9B...
Voltage detection transformer.

Claims (1)

[Claims] In a monitoring device for monitoring the DC current and DC voltage of a converter in which one converter operates as a forward converter and the other converter operates as an inverse converter, a monitoring device is provided for detecting the DC current of the converter. two sets of DC current detectors,
a current comparing means for comparing the outputs of the DC current detector to determine whether they match or do not match; a DC voltage detector for detecting the DC voltage of the converter; and an output signal of the DC voltage detector and the DC current of the two sets. two sets of active power calculation means for calculating active power from the output signal of the detector; an active power detector for detecting the actual active power of the converter; and an output signal of the two sets of active power calculation means. a calculation power comparison means for comparing and determining whether they match; and two sets of active power comparison means for comparing the output signal of the active power detector and the output signals of the two sets of active power calculation means and determining whether they each match or do not match. If the current comparison means detects a match and the calculated power comparison means detects a mismatch, an abnormality is detected in the DC voltage detector, and if the current comparison means detects a mismatch and the two sets of active power comparison means 1. A monitoring device characterized in that when a mismatch is detected, it is determined that one of the two sets of DC current detectors has become abnormal.