JP2744107B2 - Monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial application field) The present invention relates to a DC transmission system or a DC current detector of a DC interconnection facility such as a frequency converter or the like, in which a signal of a DC voltage detector is normal. The present invention relates to a monitoring device that monitors whether or not the above is true.

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

The DC sides of converters 1A and 1B are DC reactors 2A and 2B, respectively.
Connected by the DC transmission line 3 via the
The AC sides of A and 1B are connected to respective AC systems 6A and 6B via converter transformers 4A and 4B and circuit breakers 5A and 5B.

The conventional converters 1A and 1B are provided with constant margin angle control circuits 12A and 12B, constant voltage control circuits 11A and 11B, and constant current control circuits 13A and 13B, and the constant margin angle control circuits 12A and 12B have their margin angles. Setting device 1
The converters 1A and 1B operate so that the margin angles follow the margin angle reference values output from the 8A and 18B.

A voltage reference value which is an output of the DC voltage setting devices 14A and 14B,
DC voltage detection values input to summing circuits 17A and 17B via voltage / voltage conversion circuits 16A and 16B for detecting DC voltage with DC voltage detectors 15A and 15B and converting them to values that can be easily handled by control circuits Is obtained by the summing circuits 17A and 17B, and the value of the difference is input to the constant voltage control circuits 11A and 11B so that the DC voltage of the DC transmission line 3 is controlled to follow the voltage reference value. Will be done. Also, the current reference values, which are the outputs of the transmission control circuits 26A and 26B, and the DC current are detected by the DC current detectors 21A and 21B, and the current / voltage conversion circuits 22A and 22B
The DC current detection value converted into a value that can be easily handled as a control circuit is input to the summing circuits 23A and 23B. By inputting the value of the difference to the constant current control circuits 13A and 13B,
The DC current flowing through the DC transmission line 3 is controlled so as to follow the current reference value.

The switches 24A and 24B are closed only in the converter that operates the converter in the reverse converter, and the current margins output from the current margin setting units 25A and 25B are input to the summing circuits 23A and 23B. The function of the current margin and the constant margin angle control circuits 12A and 12B, the constant voltage control circuits 11A and 11B, and the output of the constant current control circuits 13A and 13B have the most advanced control angle of the converter as the output. If the switch 24B is now closed and the switch 24A is open, the control lead angle priority circuit 28A will be The output of the constant current control circuit 13A is output, and the control advance angle priority circuit 28B
The constant margin angle control circuit 12B and the constant voltage control circuit 11B
Of these outputs, the output that advances as the control angle, generally the output of the constant voltage control circuit 11B, is output. Outputs of the respective control lead angle priority circuits 28A and 28B are input to phase control circuits 29A and 29B, where they are converted into pulse signals that determine the ignition timing of the converter, and a pulse amplification circuit is provided.
It is configured to be supplied as a gate pulse signal to each converter via 30A and 30B.

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 the DC voltage or the DC current.

When the detected amount of DC current becomes abnormal in the increasing direction, the output of the constant current control circuit becomes the leading direction, and the DC current decreases. If an abnormality occurs in the decreasing direction, the output of the constant current circuit will be in a lagging direction, resulting in a DC overcurrent.

When the detected amount of DC voltage becomes abnormal in the decreasing direction, the DC voltage is increased by the constant voltage control circuit.

In either case, there is a risk that the system will go down.
In addition, it may damage the modulator or adversely affect the system.

SUMMARY OF THE INVENTION An object of the present invention is to solve the disadvantages of the conventional example. When an abnormality occurs in the detection of DC current and the detection of DC voltage, the abnormality is detected and the system is adversely affected. It is an object of the present invention to provide a monitoring device for preventing damage to the system and adversely affecting the system.

[Configuration of the invention]

(Means for Solving the Problems) Means for achieving the object of the present invention are as follows.

To compare the active power amount corresponding to each detected DC current calculated from the DC current detection amount and the DC voltage detection amount with the output value of the active power detector in the DC interconnection equipment Thus, detection abnormalities of DC current and DC voltage are detected.

(Operation) How the means for solving the above problem operates will be described. Compare the detected values of DC current, and if the values are equal, compare the calculated active power value with the detected active power value,
If the values are not equal, it is determined that the DC voltage detector is abnormal. When the detected values of the DC current are not equal, the DC current value in which the detection of the DC current is abnormal is determined from the comparison between the calculated active power value and the detected active power value.

(Embodiment) FIG. 1 is a diagram illustrating the configuration of an embodiment according to the present invention. In FIG. 1, devices performing the same functions as in FIG. 2 are denoted by the same reference numerals. Monitoring equipment for DC interconnection equipment 100A, 1
00B is an active power calculator 80A, 80B, a detection abnormality determiner 81A,
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 1A will be described here.

Detected by the DC voltage detector 15A, and the DC voltage V _d of the value through a voltage / voltage conversion circuits 16A to convert easily handled value by the control circuit, a DC current detector 21A, is detected at 21C, current The active power calculator 80A obtains the active power amounts P _dA and P _dC from the DC current values I _dA and I _dC which have been converted into values which can be easily handled as control circuits by the / voltage conversion circuits 22A and 22C.

In the detection abnormality determiner 81A, the values of I _dA and I _dC are compared, and I _dA
When the values of _PdA and _PdC are equal, the active power amount P detected by the active power detector 7A is compared with the values of _PdA and _PdC , respectively. It outputs a voltage detection abnormal signal to the constant voltage control circuit 11A.

If the values of I _dA and I _dC are not equal, the active power amount P
The values of P _dA and P _dC are compared, and if P _dA ≠ P, P _dC = P, it is determined that the DC voltage detector 21A is abnormal, and P _dA = P, P _dC
In the case of ≠ P, it is determined that the DC current detector 21C is abnormal,
The selection signal of the abnormality detector is output to 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.

In comparing the active power amounts, the judgment value is appropriately given a range in consideration of the loss of the converter. Also, considering the comparison of the active power amount in the transient state, the DC power value and the DC voltage value used in the calculation of the active power are appropriately timed in order to match the detection delay of the active power detector.

As described above, according to the present invention, when an abnormality occurs in the detection of DC current, the abnormal DC current detector is determined, and the output value of the normal detector is selected, so that the system is adversely affected. Do not give.

If an abnormality occurs in the detection of DC voltage, the detection abnormality is determined.If the control system is multiplexed, the constant voltage control circuit performs pre-holding processing, etc. By performing the control, the system is not adversely affected.

Further, when the control system is single, since the constant voltage control circuit performs a process such as pre-holding and performs a soft stop, it is possible to prevent the converter from being damaged and the AC system from being adversely affected. .

〔The invention's effect〕

As described above, according to the present invention, when an abnormality occurs in the detection of DC current and the detection of DC voltage in DC interconnection equipment, the detection abnormality can be determined, so that the system is adversely affected or conversion is not performed. This can prevent damage to the vessel and adverse effects on the system.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment in which the present invention is applied to a DC interconnection facility, and FIG. 2 is a block diagram of a conventional apparatus. 1A, 1B …… Converter, 2A, 2B …… DC reactor, 3 …… DC transmission line, 4A, 4B …… Transformer transformer, 5A, 5B …… Circuit breaker, 6A, 6B …… AC system, 11A , 11B …… Constant voltage control circuit, 12A, 12B …… Constant margin angle control circuit, 13A, 13B …… Constant current control circuit, 14A, 14B …… DC voltage setting device, 15A, 15B …… DC voltage detector, 16A, 16B… voltage / voltage conversion circuit, 17A, 17B, 23A, 23B… summing circuit, 18A, 18B… margin angle setting device, 19… transmission circuit, 21A, 21B, 21C, 21D… DC current Detector, 22A, 22B, 22C, 22D: Current / voltage conversion circuit, 24A, 24B: Switch, 25A, 25B: Current margin setting device, 26A, 26B: Transmission control circuit, 27: Current reference value Output circuit, 28A, 28B… Control lead angle priority circuit, 29A, 29B …… Phase control circuit, 30A, 30B …… Pulse amplifier circuit, 7A, 7B …… Active power detector, 80A, 80B …… Active power calculation Detector, 81A, 81B …… Detection abnormality detector, 82A, 82B… ... DC current value selector, 100A, 100B ... monitoring device, 8A, 8B ... AC current detector, 9A, 9B ... ... voltage detection transformer.

Claims (1)

(57) [Claims] 1. A monitoring device for monitoring a DC current and a DC voltage of a converter in which one converter operates as a forward converter and the other converter operates as an inverse converter, wherein the DC current of the converter is monitored. Two sets of DC current detectors provided for detection, current comparison means for comparing outputs of the DC current detectors to determine coincidence / non-coincidence, and a DC voltage detector for detecting a DC voltage of the converter; Two sets of active power calculation means for calculating active power from the output signal of the DC voltage detector and the output signals of the two sets of DC current detectors; and active power for detecting active power on the AC side of the converter. A detector, 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 to determine whether or not they match each other. Match detection And when the two sets of active power comparing means detect a mismatch, the DC voltage detector is abnormal, and when the current detecting means detects a mismatch and one of the two sets of active power comparing means detects a mismatch, A monitoring device for determining whether one of two sets of DC current detectors has become abnormal.