JPS6198199A - Defect detecting method of brushless exciter - Google Patents

Abstract

PURPOSE:To indirectly detect the defect of a brushless exciter by judging whether the amplitude of a brushless exciter exciting current falls within the prescribed range with respect to the operating state of a synchronous machine or not. CONSTITUTION:When a current of the maximum allowable exciting current value or higher flows for a time set by a timer 22 or longer, a brushless exciter defect detection signal 36 is generated through an OR gate 35. When a breaker open signal 26 is generated and a detection signal 25 of (n) times of a no-load rated exciting current is generated, a signal is applied through an AND gate 27 to a timer 28. When a reactive power relay phase advancing side operation signal 32 is generated and a rates exciting current value or higher detection signal 31 is generated, a signal is applied through an AND gate 33 to a timer 34.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a failure detection method for a brushless exciter that excites a synchronous machine.

[Prior art and its problems]

All figures are circuit diagrams when a synchronous generator is excited by a brushless exciter.
The rotary rectifier 5 converts the AC power generated in the rotating armature 6 by passing an exciting current through the fixed field winding 7 into DC power. The brushless exciter rotating part 8 is formed by this rotating armature i and the rotating current transformer 5, and the generator armature fl rotates together with this rotating part 8.
By passing DC power from the rotating rectifier 5 through the generator armature 13, alternating current power is generated in the fixed generator armature 2◇
In other words, the synchronous generator 1, which is composed of the generator armature 2 and the generator field winding 3, is excited by the brushless exciter 4 that does not require brushes, making maintenance and inspection easy. The AC power output from the generator 1 is supplied to the load via the circuit breaker 17, and at the same time, the excitation power is supplied to the fixed field winding of the brushless exciter 4 via the excitation transformer 10 and the thyristor rectifier 9. 7 is given. At this time, the output voltage of the synchronous generator 1 is detected by the potential transformer 13, and a gate signal is sent from the automatic voltage regulator 16 to the aforementioned thyristor rectifier 9 to maintain the synchronous generator output voltage constant.
1 is a current transformer for the exciter, and 12 is an exciter current detector. In addition, the voltage signal from the instrument transformer 13 and the current signal from the main circuit current transformer 14 are transferred to a reactive power relay 15.
The brushless exciter 4 of the synchronous generator shown in Figure 2 has no consumable parts such as brushes, and requires less maintenance and inspection. However, since the rectifier is rotating instead, the required excitation current is sent to the rotating generator field winding 3 due to a short circuit in the rectifier or a short circuit in the arm. In case the brushless exciter is no longer able to operate, a failure detection method such as extracting the voltage frequency signal between the neutral □ point of the brushless exciter's 40-turn armature winding and the ground and constantly monitoring its waveform. However, it has the disadvantage of being complicated and expensive. [Objective of the Invention] The present invention provides a failure detection method for a brushless exciter that enables a simple and inexpensive circuit to detect that the brushless exciter for exciting a synchronous machine is not in a state where it can supply a normal excitation current. [Summary of the Invention] The present invention monitors the operating state of a synchronous machine that receives excitation current from a brushless exciter and the excitation current of the brushless exciter, and This is an attempt to indirectly detect a failure of the brushless exciter by determining whether the magnitude of the current is within a predetermined range with respect to the operating state of the synchronous machine. Example] As shown in FIG. 2, when the brushless exciter 4 that excites the synchronous generator 1 is operating normally, the rotating generator'vL-field winding 3! ! The excitation current c is supplied from the brushless exciter rotation unit 8, but in this case, the automatic voltage regulator 1 is also supplied to the field winding 7 of the brushless exciter 4.
Since the exciter excitation current is supplied from the excitation transformer 10 to the thyristor rectifier 9 controlled by the thyristor rectifier 9 controlled by the thyristor rectifier 6, the inside of the rotating part 8 of the brushless exciter 8 may be damaged, for example, a failure of the rotary rectifier 5 or a failure of the rotating armature 6. When an abnormality such as a winding failure occurs, the excitation current supplied to the synchronous generator field winding 3 becomes insufficient or becomes zero, so the output voltage of the synchronous generator 1 decreases. The discharge dynamic voltage regulator 16 increases the excitation current flowing through the fixed field winding 7iC of the brushless exciter 4 in order to increase the current flowing through the synchronous generator field winding 3. The current transformer 11 and the exciter excitation current detector 12 detect, and this detected current is larger than the exciter excitation current predetermined according to the operating state of the synchronous generator 1, and this excessive current is detected. If this continues for a predetermined period of time, it is determined that the brushless exciter is abnormal and the protection device is activated. FIG. It is a circuit.

In FIG. 1, the detection signal 21 indicates a detection signal 21 for detecting an excitation current exceeding the allowable maximum excitation current value. When the raising excitation current, which is generally a value of 0 for the exciter's rated excitation current and is equal to or higher than this allowable maximum excitation current value, continues to flow for the time set by the timer 22, it passes through the OR gate 35. Brushless exciter failure detection signal 36 is issued - Circuit breaker 1
A circuit breaker open signal 26 is issued indicating that circuit breaker 7 is open;
In addition, the brushless exciter 4 is emitting a detection signal 25 that is n times or more the no-load rated excitation current (here, n is a value larger than 1, and is generally about n+1.5). Even though the generator 1 is under no load, the brushless exciter is requesting an excitation current higher than the no-load rated excitation current. 28, and when the set time of the timer 28 is exceeded, a brushless exciter failure detection signal 36 is issued via an OR gate 35.

The synchronous generator 1 is normally connected to a bus bar via a circuit breaker 17, and operates in parallel with another AC power source (not shown). When the excitation current of the synchronous generator l running in parallel is changed, a reactive cross current flows between this synchronous generator l and other AC power supplies connected to the bus, so the power factor of the synchronous generator 10 changes. do.

Therefore, the generator voltage detected by the instrument transformer 13 and the generator current detected by the main circuit current transformer 14 are input to the reactive power relay 15. When the excitation of the synchronous generator 1 is strengthened, the power factor becomes lagging, so the lagging side of the reactive power relay 15 operates,
Conversely, when the excitation is weakened, the 150 leading phase side of this reactive power relay operates. Therefore, the reactive power relay phase advance side operation signal 32 is issued (that is, it means that the excitation current of the synchronous generator 1 is insufficient), and in spite of this, the brushless exciter 4 does not issue the rated excitation current value or more detection signal 31. If so, these two signals are given to the timer 34 via the AND gate 33, and if these two signals continue for more than the set time of the timer 34, the brushless exciter failure detection signal 36 is issued via the OR gate 35. [Effects of the Invention] According to the present invention, when power for exciting a synchronous machine is supplied from the rotating section of the brushless exciter, either the rotating armature or the rotating rectifier that constitutes this rotating section To prevent the excitation power of a synchronous machine from becoming insufficient or zero due to a failure, the operating state of this synchronous machine and the excitation current of the brushless exciter required for this operating state are determined in advance, and the actual If the flowing excitation current of the brushless exciter exceeds this predetermined value and continues for a certain period of time, it is determined that the brushless exciter has failed.

This fault detection method is easily accomplished (using simple logic circuits) and is simpler than the traditional method of monitoring the waveform between the neutral point of a rotating armature and ground. It is reliable, can be implemented at low cost, and can be expected to have great effects.

[Brief explanation of the drawing]

FIG. 1 is a logic circuit diagram showing an embodiment of the present invention.
The figure is a circuit diagram when a synchronous generator is excited by a brushless exciter. 1... Synchronous generator, 2... Generator armature (fixed), 3... Generator field winding (rotating),
4... Brushless exciter, 5... Rotating rectifier, 6... Rotating armature, 7... Fixed field winding, 8...・・Brushless exciter rotating part,
9... Thyristor rectifier, 10... Transformer for excitation, 11... Current transformer for exciter, 12.
... Exciter excitation current detector, 13 ... Instrument transformer, 14 ... Main value or higher detection signal, 22
, 28 , 34... Timer, 25...
・Detection signal of n times or more of the no-load rated excitation current, 26...
...breaker open signal, 27. :j3...AND
Gate, 3 toe...Detection signal of rated excitation current value or higher, 3
2... Reactive power relay phase advance side operation signal, 35.
...OR gate, 36...Brushless exciter failure detection signal. 25 7 enemy dialect i j Jojiko name 4L way year old, t 糺σ)jl
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Claims (1)

[Claims] 1) An exciting current is passed through the fixed field winding of an AC exciter, and the DC power obtained by the rotating armature and rotating rectifier of the exciter is rotated together with the rotating part of the exciter. In a brushless exciter configured to supply a field winding to a synchronous machine field winding, a failure occurs if the excitation current of the AC exciter exceeds a predetermined value when the synchronous machine is in a predetermined operating state. A failure detection method for a brushless exciter characterized by determining that. 2) In the failure detection method according to claim 1, if the excitation current of the AC exciter continues at a value equal to or higher than the allowable maximum excitation current for a certain period of time while the synchronous machine is operating, a failure is determined. A failure detection method for a brushless exciter, characterized by: 3) In the failure detection method according to claim 1, when the synchronous machine is operating with no load, the excitation current of the AC exciter is higher than the current obtained by multiplying the no-load rated excitation current by a predetermined multiplier. A failure detection method for a brushless exciter, characterized in that a failure is determined if a large value continues for a certain period of time. 4) In the failure detection method according to claim 1, when the synchronous machine operates as a generator, the excitation current of the AC exciter is A failure detection method for a brushless exciter, characterized in that a failure is determined if a value greater than the rated excitation current continues for a certain period of time.