CN105242717A - Automatic switching device of cooling system of main transformer of transformer substation - Google Patents

Abstract

The invention provides an automatic switching device for a main transformer cooling system in a substation, which mainly includes a main transformer, an oil pump, several coolers, a PLC controller, a temperature controller, several thermal relays, several intermediate relays, and several AC contactors. Symmetric heat dissipation is adopted, several coolers are symmetrically arranged on both sides of the main transformer, and automatic switching control is adopted to realize the dynamic adjustment of the cooling system of the main transformer, which can effectively solve the problem of long-term over-temperature operation of the main transformer in the power system, and make the main transformer oil The temperature is maintained within the normal working range, which improves the efficiency and stability of the operation of the main transformer and its cooling system, and can prolong the service life of the main transformer and its cooling system.

Description

Automatic Switching Device of Main Transformer Cooling System in Substation

technical field

The invention belongs to the field of intelligent control of power distribution equipment, and in particular relates to an automatic switching device for a main transformer cooling system of a substation.

Background technique

With the sharp increase of power grid load and the country's great attention to power grid construction, the load capacity of power transformers has reached an unprecedented high level. During the summer load peak period, the phenomenon of heavy load, full load, and overload of the main transformer often occurs and occurs. The frequency is getting higher and higher and the time is getting longer and longer. The long-term overload of the main transformer not only seriously endangers the safe operation of the power grid, but may even cause accidents. Long-term heavy-load, full-load, overload, and over-temperature operation will also reduce the operating life of the transformer (the 6°C temperature rise rule of the main transformer), which is a serious threat to the country and enterprises. cause unnecessary economic losses.

When the substation is manned, the oil temperature and the cause of the failure can be roughly judged to manually switch on and off the fan and oil pump; when the substation is unattended, the fan and oil pump often run or stop for a long time.

The operation of unmanned substations relies on the support of modern means such as high automation and informatization. However, at present, large-scale unmanned substations in China only automatically switch and shut down all coolers according to the transformer oil temperature. This will first lead to energy consumption. Waste and excessive wear of fans, and secondly, it is impossible to realize the load change of the main transformer or the automatic adjustment of the cooling strategy when some coolers fail, and the power operation control center cannot obtain the fault status of the coolers and transformers in real time.

Contents of the invention

In order to make up for the deficiencies in the prior art, the present invention provides an automatic switching device for the main transformer cooling system of a substation, which adopts symmetrical heat dissipation, and several coolers are symmetrically arranged on both sides of the main transformer, and adopts automatic switching control to realize the main transformer The dynamic adjustment of the cooling system can maintain the oil temperature of the main transformer within the normal working range, improve the efficiency and stability of the cooling system of the main transformer, and prolong the service life of the main transformer.

Technical scheme of the present invention is realized in the following manner:

The automatic switching device of the main transformer cooling system in the substation mainly includes the main transformer, oil pump, several coolers, PLC controllers, temperature controllers, several thermal relays, several intermediate relays, and several AC contactors;

Among them, the oil pump is connected to the outside of the main transformer through the oil pipe, and the two ends of the oil pipe are connected to the oil tank of the main transformer to form a circulation circuit; the oil pipe outside the main transformer is arranged in a circuitous manner inside the cooler shell;

Several coolers are divided into two groups, and the coolers in each group are connected in parallel, and the two groups of coolers are symmetrically arranged on both sides of the main transformer; each cooler includes a fan and a fan motor, and the fan motor is connected through an AC contactor to the three-phase power supply; the fan is used to cool the oil pipe;

Each AC contactor is connected in series with a thermal relay, and the auxiliary contact of the thermal relay is in a normally closed state, and is connected in series with the outlet terminal of the coil of the AC contactor;

The normally open contacts of the intermediate relay are connected in series to the coil power line of the AC contactor;

The temperature controller includes a temperature sensor and a temperature switch, wherein the temperature sensor is used to detect the oil temperature in the oil tank of the main transformer, and the temperature switch is normally open and connected in parallel to the intermediate relay;

The temperature sensor is connected with the PLC controller through the A/D conversion circuit; the input ends of the temperature switch, the AC contactor and the power switch of the oil pump are all connected with the PLC controller through the driving circuit.

The AC contactor coil power supply is single-phase alternating current, and the single-phase alternating current supplies power to the AC contactor coil through the circuit breaker.

The two normally open nodes of the intermediate relay are respectively connected in series on the incoming and outgoing ends of the coil of the AC contactor.

The operating temperature of the temperature switch is 60°.

The PLC controller controls the start and stop of the fan motor through the AC contactor.

As a preference, the AC power terminal first passes through the three-phase circuit breaker to provide AC power for the intermediate relay, the fan motor, the AC contactor, the thermal relay, and the temperature controller.

Furthermore, the PLC controller is FX2-80MT programmable controller, the temperature controller is BWY(WTYK)-803ATH, the three-phase circuit breaker is DZ158-25A, and the intermediate relay is JZ7.

The invention realizes the dynamic adjustment of the cooling system of the main transformer through the cooling system arranged symmetrically and adopts the automatic switching control, which can maintain the oil temperature of the main transformer within the normal working range, and improves the efficiency and stability of the cooling system of the main transformer. sex.

Description of drawings

Fig. 1 is a schematic diagram of the symmetrical heat dissipation structure of the main transformer of the present invention.

Fig. 2 is a schematic diagram of the main transformer oil circulation path of the present invention.

Fig. 3 is a schematic diagram of the circuit principle of the automatic switching system of the cooler in the present invention.

Fig. 4 is a schematic diagram of connection and wiring between the AC contactor and the thermal relay in Fig. 3 .

In the figure: ZJ is the intermediate relay, ZJ1 and ZJ2 are the normally open contacts of the intermediate relay, KM1-3 is the AC contactor, JRS1 is the thermal relay, JRS1Ⅰ-Ⅲ is the normally closed contact of the thermal relay, XQ is the AC contactor Coil, A1 and A2 are the terminals of the AC contactor, a1 and a2 are the terminals of the starting coil of the intermediate relay, L1, L2 and L3 are the terminals of the AC power supply.

detailed description

Referring to accompanying drawing 1, the specific scheme of the present invention is: in power system such as substation etc. outside the main transformer casing symmetrically arrange several groups of coolers. If the number of cooler groups is small, it is best to choose to set them on the main transformer shell on the side of the main transformer oil tank. The switching and stopping of each group of coolers is automatically controlled by the PLC controller and the temperature controller, which are not shown in Figure 1.

As shown in Figure 1, each group of coolers can be arranged in the same box or housing. Each set of coolers contains at least one fan, and of course there can be more than one. When applied to a large main transformer, the fan motor is powered by three-phase AC (380V).

Referring to Figure 2, the oil tank of the main transformer is connected to the oil pump outside the main transformer box through the oil pipe, and the other end of the oil pipe is connected to the oil tank of the main transformer to form a circulation circuit; the oil pipe outside the main transformer box is arranged in a circuitous manner inside the cooler shell, Facing the fan setup.

For ease of description, the case where the main transformer is provided with only two sets of coolers is taken as an example for the following introduction. In this example, each set of coolers contains 3 fans. Of course, there may be more than two fans in each group of coolers arranged symmetrically, and the number of fans in each group of coolers is not necessarily required to be the same.

As shown in accompanying drawing 3 and accompanying drawing 4, these two figures simply show the electrical schematic diagram of a group (ie, one side of the main transformer) cooler automatic switching system. Only the wiring principles of the main electrical components required to realize the most basic embodiment of the invention are shown in the figure.

In accompanying drawing 3, AC power terminals L1, L2, L3 provide AC power for intermediate relays, fan motors, AC contactors, thermal relays, temperature controllers and other components after passing through the three-phase circuit breaker DZ.

The fan motor of each fan is connected to a three-phase power supply (380V) through an AC contactor KM (1-3). Each AC contactor KM is connected in series with a thermal relay JRS1. The auxiliary contact (JRS1Ⅰ-Ⅲ) of the thermal relay JRS1 is in a normally closed state, and is connected in series with the outlet end of the coil XQ of the AC contactor KM; In Figure 3, the terminal A1 is called the incoming terminal. In this embodiment, the thermal relay JRS1 is provided mainly to effectively protect the motor from the power supply of the corresponding fan motor in the state of lack of phase operation and protect the fan motor from being burned out.

AC contactor KM and thermal relay JRS1 are powered by single-phase AC. The normally open contacts ZJ1 and ZJ2 of an intermediate relay ZJ are respectively connected in series to the incoming line end and the outgoing line end of the AC contactor coil XQ.

In the present invention, a temperature controller is also provided on the main transformer box, and the temperature controller includes a temperature sensor and a temperature switch K2, wherein the temperature sensor is used to detect the oil temperature in the oil tank of the main transformer, and the temperature switch K2 is normally open and connected in parallel in the middle On the relay ZJ. Specifically as shown in Figure 3, the three-phase circuit breaker DZ is connected to the one-phase power terminal L3 through the normally open contact of the temperature switch K2 of the temperature controller to the a1 terminal of the starting coil of the intermediate relay ZJ, and the intermediate relay The a2 terminal power supply of the starting coil of ZJ is introduced from the other phase power terminal L1 of the three-phase circuit breaker DZ.

The invention uses a programmable logic controller PLC to realize automatic switching and stopping of each cooler group. Among them, the output of the temperature sensor is connected to the PLC controller through the A/D conversion circuit; the input ends of the temperature switch K2, the AC contactor KM, and the power switch of the oil pump are all connected to the PLC controller through the driving circuit.

According to the requirements of the standard oil temperature of the main transformer, set the operating temperature of the temperature switch K2 (normally open) to 60°. When the temperature signal detected by the temperature sensor in real time reaches 60°, the PLC issues an instruction to close the normally open contact of the temperature switch K2, thereby starting the intermediate relay ZJ. After the normally open contacts ZJ1 and ZJ2 of the intermediate relay are closed, the AC contactor KM Three-phase AC power will be applied, which will start the fan motor. This group of coolers completes automatic switching.

More specifically, in the above embodiment, the PLC controller is FX2-80MT programmable controller, the temperature controller is BWY(WTYK)-803ATH, the three-phase circuit breaker is DZ158-25A, and the intermediate relay is JZ7.

In actual use, for example, for seasonal peaks, regular daily peaks, and increased load on the main transformer, on the basis of the above-mentioned embodiments of the present invention, those skilled in the art can program the PLC controller as required , select all the fans in each group of coolers to work or a specific number of fans to work, which can effectively solve the problems of long-term heavy load, full load, overload, and over-temperature operation of the main transformer. It can also be set that the specific fans in each group of coolers are switched on and off within a specific time, so that some fans work and the other fans are used as backup, which can avoid long-term full-load operation of the fan motor and effectively reduce the fan motor. The failure rate can also prolong the service life of the fan motor.

The invention has simple structure and flexible control, and can effectively solve the problems of long-term over-temperature operation of the main transformer of the power system and automatic and intelligent switching of the cooling system. The cost is low, the cooling effect and the protection effect on the main transformer are outstanding, and the service life of the main transformer can be prolonged, so the economic effect is also remarkable.

The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be assumed that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, several equivalent substitutions or obvious modifications are made without departing from the concept of the present invention, and the performance or use is the same, all should be regarded as belonging to the present invention by the submitted claims The scope of patent protection determined by the book.

Claims (7)

1. main transformer of transformer substation cooling system automatic switching device, mainly comprises main-transformer, oil pump, some refrigeratorys, PLC, temperature controller, some electrothermal relays, some auxiliary reclays, some A.C. contactors;

It is characterized in that,

Oil pump is connected to main-transformer outside through oil pipe, and oil pipe two ends connect main fransformer oil box-shaped and become flow cycle; The oil pipe of main-transformer outside is roundabout is arranged at cooler casing inside deviously;

Some refrigeratorys are divided into two groups, and the refrigeratory often in group is all connected in parallel, and these two groups of refrigeratorys are symmetricly set on main-transformer both sides; Each refrigeratory includes fan and fan electromotor, and fan electromotor is connected to three-phase supply through an A.C. contactor; Fan is used for oil cooling service pipe;

Each A.C. contactor is all connected an electrothermal relay, and the auxiliary contact of electrothermal relay are normally off, and are connected on the leading-out terminal of described ac contactor coil;

The normally opened contact of auxiliary reclay is connected in series on ac contactor coil power lead;

Temperature controller comprises temperature sensor and temperature switch, and wherein temperature sensor is for detecting the oil temperature in main-transformer fuel tank, and temperature switch is normally open and is connected in parallel on auxiliary reclay;

Temperature sensor is connected with PLC through A/D change-over circuit; The input end of temperature switch, A.C. contactor, oil pump power switch is all connected with PLC through driving circuit.

2. main transformer of transformer substation cooling system automatic switching device according to claim 1, is characterized in that: ac contactor coil power supply is single-phase alternating current, and this single-phase alternating current is that ac contactor coil is powered through isolating switch.

3. main transformer of transformer substation cooling system automatic switching device according to claim 1, is characterized in that: often open node and be connected on respectively on ac contactor coil end of incoming cables and leading-out terminal for two of auxiliary reclay.

4. main transformer of transformer substation cooling system automatic switching device according to claim 1, is characterized in that: the operating temperature of temperature switch is 60 °.

5. main transformer of transformer substation cooling system automatic switching device according to claim 1, is characterized in that: PLC controls startup and the stopping of fan electromotor by A.C. contactor.

6. main transformer of transformer substation cooling system automatic switching device according to claim 1, is characterized in that: ac power supply terminal first after three-phase breaker for auxiliary reclay, fan electromotor, A.C. contactor, electrothermal relay, temperature controller provide alternating current.

7. the main transformer of transformer substation cooling system automatic switching device according to any one of claim 1-6, it is characterized in that: PLC selects FX2-80MT Programmable Logic Controller, temperature controller adopts BWY (WTYK)-803ATH, three-phase breaker model is DZ158-25A, and auxiliary reclay adopts JZ7 type.