RU74495U1 - MICROPROCESSOR CONTROL SYSTEM OF OIL-FILLED EQUIPMENT BY OIL CONDITION - Google Patents

Abstract

The utility model relates to the field of electric power.

The proposed system is designed for continuous remote monitoring of the performance of oil-filled equipment according to two of the most informative parameters - resistivity and oil temperature. This ensures the issuance of signals in the form of color information of the type "traffic light", and the possibility of transmitting them via digital, or radio - relay communication lines for emergency shutdown, or (and) to a centralized dispatch control system.

The system includes a conductometric sensor with a heat-sensitive microchip immersed in a controlled oil, structurally combined with a measuring and indicator unit containing circuits for powering the sensor circuits and converting the signals from the sensor to normalized voltages proportional to the current values of the measured parameters.

The system also includes a microprocessor-based circuit for automatically correcting the levels of emitted signals, taking into account the law of oil resistance change with temperature, which greatly simplifies its operation, does not require operator intervention and, in particular, allows the system to be used for proactive diagnostics of the state of autonomous oil-filled equipment in the absence of maintenance personnel (freestanding transformer).

The use of the considered system for diagnosing the condition of oil-filled equipment at substations in the region and in turbogenerators is highly efficient by reducing labor costs for scheduled equipment inspections and facilitating the work of operators.

The use of the system provides the possibility of centralized dispatch control of the state of the units, which significantly reduces the risk of emergencies and failure of expensive equipment.

Description

The claimed technical solution relates to the field of electric power and transport and is intended for continuous remote monitoring of the state of oil used as an electrical insulating fluid in high-power transformers, or as a lubricating and cooling fluid in turbines and other units. Mostly at facilities remote from service centers.

The quality of transformer and turbine oils directly affects the reliability and safety of oil-filled equipment.

As a rule, the degradation of oil during operation is monitored by a planned periodic monitoring, which does not provide the possibility of timely action in case of emergency in the period between inspections.

The most informative indicators of the state of the oil during operation are its resistivity and temperature. Most of the factors that negatively affect the properties of the oil - the appearance of mechanical impurities, chemical processes, and an increase in humidity lead to a decrease in its specific resistance. An increase in oil temperature beyond the permissible limit also clearly indicates violations in the operation of oil-filled equipment [1, 2].

A known system for operational monitoring of the operational characteristics of transformer oil [3], which is currently successfully used in Kazan electrical networks and allows you to perform express analysis of oil using a number of parameters using a computer. However, the system does not provide the ability to remotely control objects remote from the operator. In addition, with high accuracy characteristics of the system. requires the use of computers, which is not always acceptable, especially in small regional substations.

Also known is a remote system for continuous monitoring and signaling of the state of oil products [4]. The system provides reliable remote monitoring and signaling of the state of oil-filled equipment in terms of resistivity and oil temperature. The signals for both parameters are transmitted to the operator’s desk according to the traffic light principle. The normal state is a green signal, with a deviation from the norm - yellow, and in the event of a pre-emergency situation - red light and (or) sound signals with the possibility of automatic emergency shutdown of equipment. In addition, a digital indicator of the current value of the oil temperature is placed on the operator’s console. The system has been successfully operated at a number of substations, TPPs and state district power plants of JSC Tatenergo.

The described systems are intended mainly for installation at large energy facilities, where there are qualified maintenance personnel.

This is due to the fact that the resistivity of transformer and turbine oils depends not only on their contamination and waterlogging, but also on temperature [2]. Moreover, the temperature dependence is very high - the oil resistance sharply, according to a complex exponential law, decreases with its increase. As a result, for example, a good oil at high temperature will have such a low resistivity (not allowed at normal temperature) that a false emergency operation of the system can occur, despite the fact that the oil still has satisfactory performance.

Therefore, in each specific case, when a system signal appears about a threatening decrease in the oil resistivity, the operator must take into account the temperature indicator, enter the appropriate corrections, and only then decide on the possibility of further operation of the facility.

At the same time, a large number of powerful oil-filled transformers and turbine units are used in the energy sector, remote from control centers, the state of which is monitored only during scheduled periodic inspections. The practice of operating such facilities has shown the need to use a permanent proactive diagnostic system that would monitor and signal the occurrence of threatening situations associated with the deterioration of the characteristics of the oil. Obviously, in this case, automatic (without operator intervention) correction of the levels of the issued signals along the channel of resistivity should also be carried out taking into account changes in the ambient temperature.

In the absence of personnel (a freestanding transformer), the system should provide the ability to transmit corrected signals via a radio relay communication line, or in digital form to a central control room. In addition, during scheduled inspections of equipment, the system should have outputs for reading information about the actual state of the oil at the time of inspection by connecting a PC to it.

The proposed technical solution provides the above requirements for the diagnostic system. Given the likelihood of its operation in the absence of an operator, in the proposed system, the measuring and conversion unit and the operator panel are combined into a single measuring and indicator unit (IIB), which provides automatic temperature correction of the issued signals according to the specific resistance of the oil. Obviously, this eliminates the need for indicators of the current temperature and resistivity of the oil, which are used in existing systems [3, 4] and are intended for the operator to make appropriate corrections to the levels of issued signals.

Information on the normal condition of the oil (green signal), as well as warning (yellow) and emergency (red) signals according to controlled parameters (automatically adjusted by temperature) are sent directly to the system output for transmission via a radio relay communication line and are duplicated by color indicators made on the front panel of the IIB. In addition, the system provides for the possibility of transmitting information about the state of oil through digital communication channels, as well as the direct connection of a computer (such as a laptop-book) for measuring real (unadjusted) values of oil parameters during scheduled field visits of oil-filled equipment.

The indicated capabilities are achieved due to the fact that a conductometric sensor with a heat-sensitive microcircuit [5] is placed in a controlled oil. Signals from the sensor are fed to the inputs of the ISS located directly on the top of the sensor. Such an arrangement shortens the communication line between the sensor and the IIB, which reduces errors from interference and leaks when measuring high (over GOhm) resistances.

In the ISS, the signals on both channels are normalized, converted to digital form and fed to the inputs of the microcontroller. According to a given program, the microcontroller processor automatically (taking into account the oil temperature) adjusts the levels of output signals along the resistance channel. LED indicators are connected to the outputs of the microcontroller (the readings of which are duplicated by “dry” contacts for transmitting signals via a radio relay communication line), and it is also possible to remotely transmit digital information and directly connect the system to a computer.

The essence of the proposed technical solution is illustrated in the figure, which shows an embodiment of the utility model.

The system sensor includes a flat multi-plate capacitor C, whose dielectric is a controlled medium, and a heat-sensitive microcircuit with a t / u conversion function. The signals from the sensor on both channels are processed in the measuring and conversion unit as follows:

The signal through the temperature channel is formed due to the supply of a stabilized current of about 1 mA from the ISB to a thermosensitive sensor microcircuit that generates an output voltage equal to U _T = 10t _k mV, where t _k is the current oil temperature. This voltage with the help of a normalizing amplifier 1 with the function U / Uн is amplified and converted to a voltage normalized in the operating range (-5- + 5V). The received analog measuring signal with the help of the ADC of the temperature channel 3 is converted into a digital signal and fed to the input of the microcontroller 5. According to a given program, the signals of the traffic light type are generated in the microcontroller, which are transmitted to the electronic key 6, which controls the corresponding LEDs of the temperature channel, and the remote control key 7 signal transmission.

The signal along the resistance channel is formed by applying a measuring voltage to the capacitor plates C. The resultant

through the equivalent resistance R, the current is transformed by the converter (2) into the normalized voltage Un. Through the ADC (4), the resistance signal digitally enters the microcontroller (5), where (depending on the signal according to the oil temperature) it is automatically corrected taking into account the law of oil resistance change with temperature. Next, the corrected signal along the resistance channel is processed in the microcontroller similarly to the signal along the temperature channel and, using the keys 8, 9, is output to the system.

The signal levels on both channels are programmed depending on the type of equipment being monitored and the type of oil.

The IIB also provides an output connector to which digital signals are supplied via temperature and resistance channels that correspond to the current (not adjusted) values of the monitored parameters, which allows express measurements of oil characteristics using a computer (laptop) during routine on-site inspections of oil-filled equipment, as well as transmit information through digital communication channels.

Literature

1. Lipshtein R.A., Shakhnovich M.I. Transformer oil. M. "Energoatomizdat", 1983. 295 p.

2. Adamchevsky I. Electrical conductivity of liquid dielectrics. L. "Energy", 1972. 293 p.

3. Kolushev D.N., Petrukhin L.V., Rotbert I.L., Sivelkin V.V., Sidorov E.P. The system of operational control of operational characteristics of transformer oil. Certificate No. 6066 for utility model. Bull. "Industrial Designs" No. 2, 02.16.98.

4. Gavrilov E.B., Ionova I.V., Kolushev D.N., Lysko V.V., Minina V.G., Rotbert I.L., Sidorov E.P., Shirokov A.V. Remote system for continuous monitoring and signaling of the state of petroleum products. Certificate No. 29790 for utility model. Bull. "Industrial Designs" No. 15.27.05.2003.

5. Rothbert I.L., Kolushev D.N. Sensor for monitoring the performance of petroleum products. Industrial design patent No. 46987 of March 16, 2000, Bull. "Industrial Designs" No. 3.2000

Claims (1)

A microprocessor control system for oil-filled equipment according to the state of oil, which contains a conductivity sensor with a thermosensitive element, a measuring and converting unit (IPB) and an operator panel (ON), including schemes for issuing color signals about the state of the oil (as a traffic light) and transmitting these signals via a radio relay line communication, characterized in that the IPB and software are schematically and structurally combined into a single measuring and indicator unit (IIB), placed directly on the object, while excluding from the IIB an indicator of the current temperature value is introduced and an additional microprocessor-based temperature correction scheme is introduced, which provides automatic resetting of the levels of the issued signals through the resistivity channel, taking into account the law of oil resistance change with temperature, while the corrected color signals are transferred to the front panel of the IIB, and also transmitted to the centralized control and dispatch control system.