Process and devices for detecting and localizing damages in electrical installations

p0001The present invention relates to a method for the detection and localization of defects in electrical systems according to the preamble of claim 1 and an apparatus according to the preamble of claim 7 for implementing the method.

p0002From a technical article by H. Nieschwietz and W. Stein in the "Elektrotechnische Zeitschrift etz-a" band 97 (1976), No. 11, pp 657-663, from which the present earth's Dung, a gatttungsgemäßes method is known. It is applied in accordance with this article as a means of quality control of high-voltage transformers. In the paper are described as alternative Verfarhen electrical partial discharge measurements and acoustic measurements.

p0003Furthermore, in published during the priority period to the present patent DE-A-35 26 149.8 and the post-published EP-A-0228613 and EP-A-0239678, to which express reference is gennommen, methods and apparatus for partial discharge known measurement or high-frequency decoupling and ultrasound monitoring. To avoid repetition, therefore these measurements refer to these two applications for details.

p0004Object of the present invention is to provide methods of the measuring arrangements known to date or to provide an arrangement and a method for operating global monitoring systems ELECTRICAL, esp. Generators and power units, which early detection of damage and especially a diagnosis to enable and localization of damage. Further, to allow any one of claims 1-6 by specifying particularly suitable and without major alterations einerichtbarer measuring points de retrofitting of power plant units with the arrangement for carrying out the process.

p0005the measures in accordance with the second part of claim 1. To solve this problem are proposed.

p0006Unlike the methods known in the prior art, the evaluation of these measurement signals is carried out not only by comparison with calibration signals, but it should be simulated in a computer as Hock frequency network the entire electrical system, which also the simulation of damage and the persecution allows the costs associated with this damage signals throughout the network. In modern computer systems, it is possible in a conventional manner to simulate networks and to simulate the input signals at any points in such networks and to follow the signal paths and occurring changes in the signals. By Vergliech of measurement signals with simulated signals so a very precise diagnosis of the type of damage and the damage site can accomplish, the quality of diagnosis naturally increases with the number of samples collected.

p0007Suitable measuring points are specified in claim 2 and further advantageous embodiments of the inventions are included in the claims 3 to 6, as they are erläuteret detail with reference to the drawing.

p0008Devices for carrying out the method are described in claims 7 and 8 and also illustrated by the drawings.

p0009Exemplary basis of a power plant unit, a possible embodiment of the invention is shown in the drawing. Show it<ul><li>FIG. 1 is a schematic, per se known circuit diagram of a power plant unit with measuring points for decoupling high-frequency signals and sound signals,</li><li>FIG. 2 is a schematic longitudinal section through a turbogenerator with excitation system,</li><li>FIGS. 3 and 4 are schematic flow charts for the processing and evaluation of the measurement signals.</li></ul>

p0010In Fig. 1, the schematic diagram of a power plant unit, are known from the prior art to be details that are important for the invention is not of importance, not called on. Significant parts of the generator GE, the generator protection GS, the two machine transformers MT a, MT b, the two own consumption transformers EBT a, b EBT and network protection capacitors NSK. According to known per se or in the arrangements contained according to published patent applications mentioned above, the specified items of the power plant unit with acoustic sensors, particularly for ultrasonic signals equipped. The machine transformers MT a and MT b each have three sound pickups US 1a or US 1b, while the Registered demand transformers EBT a, or EBT b with two example each sound pickups US 7a or US 7b equipped. Furthermore, the generator GE has in its front and in the rear water collection ring (as shown in FIG. 2 is easier to see), for example, three sound pickups US 2, US 4, US 5 on. All these sound sensor together form a branch of the proposed operation monitoring system, which detect and partially localize damage due to acoustic signals allows.

p0011The invention proposes zuzätzlich equipping a power plant unit with at least 3, but preferably much more measuring points for decoupling radio frequency (RF). Such measuring points may consist in particular in the following facilities:<ul><li>a) HF 1a, 1b HF: Capacitive divider of high-voltage bushings of Mashinen-Transformmatoren MT a, b MT;</li><li>b) HF 2a, 2b HF: high frequency Winder stands in connection with coupling quadrupoles as Ünterteiler to the existing network protection capacitors NSK;</li><li>c) HF 3: Capacitive RF 3.1 or inductive HF 3.2 coupling within the generator, strand, on the switch lines by ground coverings or additional coupling capacitances;</li><li>d) RF 4: high-frequency current transformer on neutral derivative RF 4.1 or RF capacitive divider 4.2 in the neutral point to earth;</li><li>e) HF 5: high-frequency current transformer via a separate ground wire of the stator core;</li><li>f) HF 6: Capacitive coupling on generator shaft and exciter bearings possibly with additional antennas and power;</li><li>g) HF 7a, 7b HF: Capacitive coupling using the cable-Erdbelages or resistive dividers with Hock frequency characteristic on subsistence-level voltage;</li><li>h) HF 8: Capacitive or galvanic (ohmic) connection in the generator protection GS.</li></ul>

p0012FIG. 2 shows a longitudinal axial section of a turbogenerator with GE exciter mechanism by which the spatial arrangement of the measuring points shown in the diagram in Fig. 1 is illustrated. In itself known parts of the turbogenerator, the Dür the present invention is not important, it will not be discussed in detail. Recognizable is the array of acoustic sensors in the front and rear water collector rings of the generator GE, where only one is schematically indicated by each 3 sensors in each water collection ring. In front Slurry collector this is the pickup US 3.2, the back water collecting ring the pickup US 3.1. Also indicated in this figure more of the points in FIG. 1 measuring the high-frequency decoupling with her schematically angeduteten construction. As shown, a high-frequency decoupling through capacitive or inductive HF 3.1 HF 3.2 coupling within the generator continuously as possible to the circuit lines, through ground coverings or additional coupling capacitances. the coupling to the switching lines allows a particularly favorable measuring point. Further, a coupling-out by high-frequency current transformer on neutral derivative HF 4.1 or a capacitive divider in the star point to earth HF 4.2 is indicated. Another particularly favorable measuring point HF 5 is obtained by a Hock-frequency current transformer via a separate ground wire of the stator core. Further, another measuring point HF 6 is indicated in accordance with the earlier post-published DE-A-35 43 927.0, which allows a capacitive coupling via shaft generator and exciter bearings.

p0013The evaluation of the obtained Betriebsmeßsignale 3 and 4 is illustrated with reference to flow charts in Figs. Diagrammatically. It is assumed that m measuring points for high frequency signals and n measurement points for noise signals on the electrical system are present. Both radio frequency (RF) signals, as well as sound signals (US) will be first checked whether the signals from the interference-free operation of the plant stem. Such signals are for monitoring of no importance and will not be processed further. Abnormal signals but are passed on, stored and can initially a comparison between the RF and US signals are used for a first Plausibiltatsuntersuchung processed for further analysis. In the further processing of the RF signals can first be determined by comparing the measured signals from different phases the faulty phase. Further, a determination of the affected plant component is usually possible through use of the sound signals. After this rough locating a detailed analysis can be carried out by means of a simulated fault in a network model of the power plant unit concerned or component. This detailed analysis then provides a diagnosis with details of the fault and the fault location. Even at this stage, a comparison with the results from the sound signals diagnoses is again possible, if necessary still existing discrepancies can also be displayed, printed or saved.

p0014Fig. Figure 4 shows further details of the evaluation. First, it is indicated that it may be in the RF and US signals each to a greater number of locations and measurements. The measuring points for high-frequency signals are partially designed even for three phases R, S, T. About limit monitor a preselection of the detected signals is made, said signals exceed the predetermined limits, are stored and analyzed. Again an analysis system for detection of pulses, that is, which are not indicative of pulses to a a disorder, but the usual operation of the system. Recognized transients are - as already explained - compared with simulated signals and printed or displayed the result. In addition, a study by transient and digl. possible with a printout of the resultant images. The sound signals a tracking via pure Over time analysis in a conventional manner is possible.

p0015The present invention is particularly suitable for early detection of faults in the electrical installations and u by partial discharges or breaking sparks. Like. Noticeable.