Power supply system utilizing waste heat of transformer in transformer substation

Abstract

The utility model discloses a power supply system utilizing waste heat of a transformer in a transformer substation, which comprises a transformer shell, a semiconductor thermoelectric generator, a booster circuit and a transformer instrument, the other end of the semiconductor thermoelectric generator is connected with the input end of the booster circuit, and the output end of the booster circuit is connected with the transformer instrument; the semiconductor thermoelectric generator is configured to receive waste heat generated by the transformer shell and generate electromotive force through temperature difference, and the booster circuit is used for boosting voltage output by the semiconductor thermoelectric generator to constant target voltage needed by the transformer instrument, so that normal work of the transformer instrument is maintained. The power supply system is simple in structure, the waste heat of the transformer is used for supplying power to the transformer instrument, the waste heat is recycled and reasonably utilized, and the flexibility and reliability of the transformer instrument are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of equipment in a transformer substation, in particular to a power supply system using transformer waste heat in a transformer substation. BACKGROUND

[0002] As a widely used power transmission core device in the power system, the transformer inevitably generates loss in the process of power conversion, and usually releases heat to the atmosphere. At present, the waste heat generated by the operation of the transformer is mainly dissipated by the cooling device to ensure that the operating temperature of the transformer is maintained within a reasonable range. The waste heat energy of the transformer body is not effectively utilized. At present, there is no scheme for reasonably and effectively utilizing the waste heat of the transformer.

[0003] At present, the power supply scheme of the transformer instrument display device is as follows: a power box is arranged near the transformer, two 380V power sources are connected from the station power system, and after switching, they are connected to the transformer body control cabinet, and the switch power supply device is converted into the DC 24V power supply required by the transformer instrument.

[0004] The disadvantages of the current power supply scheme of the transformer instrument display device are as follows: the power box of the transformer substation mainly has 220V / 110V DC power and 380V AC power connected from the station power system. The transformer instrument adopts 24V DC power supply. The power box cannot directly supply power to the instrument, and a power conversion device needs to be configured. The entire power supply circuit has undergone multiple conversions. In addition, if the dual power supply switching device in the power box fails, there is a risk of all instruments losing power at the same time.

[0005] Therefore, there is an urgent need in the art to develop a power supply system using transformer waste heat in a transformer substation. The power supply system has a simple structure, uses waste heat of the transformer to supply power to the transformer instrument, recovers waste heat, reasonably utilizes waste heat, and improves the flexibility and reliability of the transformer instrument. CONTENT OF THE INVENTION

[0006] The purpose of the present application is to provide a power supply system using transformer waste heat in a transformer substation. The power supply system has a simple structure, uses waste heat of the transformer to supply power to the transformer instrument, recovers waste heat, reasonably utilizes waste heat, and improves the flexibility and reliability of the transformer instrument.

[0007] The present application provides a power supply system using transformer waste heat in a transformer substation, comprising:

[0008] The transformer shell, the semiconductor thermoelectric generator, the boost circuit and the transformer instrument, one end of the semiconductor thermoelectric generator is connected with the transformer shell through a heat-conducting material, the other end of the semiconductor thermoelectric generator is connected with the input end of the boost circuit, and the output end of the boost circuit is connected with the transformer instrument.

[0009] The semiconductor thermoelectric generator is configured to receive waste heat generated by the transformer housing and generate electromotive force using temperature difference, and the voltage boosting circuit is configured to boost voltage output by the semiconductor thermoelectric generator to a constant target voltage required by the transformer instrument, thereby maintaining normal operation of the transformer instrument.

[0010] In another preferred embodiment, the heat-conducting material comprises heat-conducting silicone grease.

[0011] In another preferred embodiment, the semiconductor thermoelectric generator comprises a plurality of N-type semiconductors and P-type semiconductors connected in series.

[0012] In another preferred embodiment, the semiconductor thermoelectric generator further comprises a current-conducting copper bar and the heat-conducting silicone grease.

[0013] In another preferred embodiment, the heat-conducting silicone grease is located between the transformer housing and the N-type semiconductors and P-type semiconductors.

[0014] In another preferred embodiment, the input end of the voltage boosting circuit comprises a positive end of the voltage boosting circuit and a negative end of the voltage boosting circuit, the positive end of the voltage boosting circuit is connected to the P-type semiconductor, and the negative end of the voltage boosting circuit is connected to the N-type semiconductor.

[0015] In another preferred embodiment, the voltage boosting circuit comprises an energy storage inductor, a switching tube, a diode, and a filter capacitor.

[0016] In another preferred embodiment, the voltage boosting circuit is a Boost converter, and the Boost converter comprises an energy storage inductor, a switching tube, a diode, and a filter capacitor.

[0017] In another preferred embodiment, the system further comprises a voltage feedback control loop configured to cause the semiconductor thermoelectric generator to provide a constant target voltage required by the transformer instrument, and the voltage feedback control loop comprises an input current detection unit, a micro-processing control circuit, and an output voltage detection unit.

[0018] In another preferred embodiment, the input current detection unit is configured to detect a current value output by the semiconductor thermoelectric generator, and the output voltage detection unit is configured to detect an output voltage at an output end of the voltage boosting circuit.

[0019] In another preferred embodiment, the micro-processing control circuit comprises a PID controller configured to adjust the time of switching tube opening and closing according to a set voltage value PID controller.

[0020] In another preferred example, when the switch tube is turned on, the semiconductor thermoelectric generator charges the energy storage inductor, the diode is in the off state at this time, preventing the filter capacitor from discharging; when the switch tube is turned off, the energy storage inductor discharges the filter capacitor and the transformer instrument, the inductor current begins to slowly decrease, and the output voltage U o = U i + U L , where U L is the voltage of the energy storage inductor.

[0021] For the inductor, when the switch tube is turned on, U on = U i , when the switch tube is turned off, U off = U o -U i , by the volt-second balance principle, U i *T D = (U o -U i )*(T S -T D ), (Ts refers to the total time of the switch tube 32 turning on and off, T D refers to the time of the 32 tube turning on), D = T D / T S . Simplifying to Uo = U i / (1-D), the semiconductor thermoelectric generator output voltage Ui = ∑α ab *(T1-T2).

[0022] In another preferred example, the output voltage of the boost circuit output end is U o = ∑α ab *(T1-T2) / (1-D), where α ab is the Seeback coefficient of N-type semiconductor and P-type semiconductor, with units of V / K;

[0023] T1 is the temperature at the transformer housing, and T2 is the temperature at the environment, with units of K;

[0024] D is the modulation duty cycle output by the microprocessor control circuit, ranging from 0 to 1.

[0025] In another preferred example, the power generated by the semiconductor thermoelectric generator matches the power required by the transformer instrument, and the power generated by the semiconductor thermoelectric generator is about 20W, and the power required by the transformer instrument is in the range of several to tens of watts.

[0026] It should be understood that, in the scope of the present application, the above technical features of the present application and the technical features specifically described in the following (such as the examples) can be combined with each other to form new or preferred technical solutions. Due to the limited space, they will not be listed one by one here. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. It should be understood that the drawings in the following description are only some of the embodiments of the present application, and those of ordinary skill in the art can also obtain other embodiments from these drawings without creative labor.

[0028] Figure 1 is a schematic diagram of a power supply system using transformer waste heat in a substation according to the present application;

[0029] Figure 2 is a structural schematic diagram of a boost circuit according to an embodiment of the present application;

[0030] Figure 3 is a structural schematic diagram of a semiconductor thermoelectric generator according to the present application.

[0031] In each drawing, the following marks are used

[0032] 1 - transformer housing

[0033] 2 - semiconductor thermoelectric generator

[0034] 21 - N-type semiconductor

[0035] 22 - P-type semiconductor

[0036] 23 - current-carrying copper bar

[0037] 24 - heat-conducting silicone grease

[0038] 3 - boost circuit

[0039] 31 - energy storage inductor

[0040] 32 - switch tube

[0041] 33 - diode

[0042] 34 - filter capacitor

[0043] 4 - transformer instrument

[0044] 5 - input current detection unit

[0045] 6 - microprocessor control circuit

[0046] 7 - output voltage detection unit DETAILED DESCRIPTION

[0047] The inventors have developed, through extensive and in-depth research, a power supply system using transformer waste heat in a transformer substation. The system effectively recovers the waste heat of a transformer based on the Seebeck effect of semiconductor materials, uses the waste heat of the transformer for thermoelectric power generation, and converts the fluctuating voltage output by the thermoelectric power generator into a stable voltage required by an instrument through a BOOST converter, thereby constructing a reliable distributed power supply form. Through matching with the energy demand and energy characteristics of transformer distributed instruments (loads), the inventors have proposed a new transformer instrument power supply method, which improves the reliability of instrument power supply while fine-tuning energy use, is conducive to the safety, stability, and reliability requirements of equipment, and promotes the green and energy-saving development of the industry.

[0048] In the following description, many technical details are presented in order to better enable the reader to understand the present application. However, it will be apparent to those skilled in the art that the claimed technical solutions can be implemented even without these technical details and based on various changes and modifications of the following embodiments.

[0049] Terminology

[0050] As used herein, transformer instrument refers to "transformer oil level meter, transformer oil surface temperature meter, transformer winding temperature meter, etc."

[0051] Thermoelectric power generation: converting heat energy into electrical energy using the temperature difference between high and low temperature heat sources;

[0052] Low-grade waste heat: waste heat with low concentration and small energy generated by a heat source with a temperature lower than 800℃, such as sensible heat, in industrial production and other activities;

[0053] It should be noted that the relative terms such as first and second and the like in the application file of the present patent are only used to distinguish one entity or operation from another, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including one" does not exclude the presence of another identical element in the process, method, article or device including the element. In the application file of the present patent, if it is mentioned that a certain action is performed according to a certain element, it means that the action is performed at least according to the element, including two cases: the action is performed only according to the element, and the action is performed according to the element and other elements. The expressions of multiple, multiple times, multiple varieties, etc. include 2, 2 times, 2 varieties and more than 2, more than 2 times, more than 2 varieties.

[0054] In the present application, all directional indications (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, motion condition, etc. between components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the directional indications will also change accordingly.

[0055] The present application has at least one of the following advantages

[0056] (a) The power supply system using transformer waste heat in the substation of the present application effectively recovers the low-grade heat source of the transformer, and the conversion and utilization mode is simple and efficient. Considering the huge total amount of transformers in the power grid system, the energy saving and carbon reduction benefits brought by the present application are considerable;

[0057] (b) Compared with the traditional power supply mode, the power supply system using transformer waste heat in the substation of the present application is more compact and delicate, and there is no multi-stage power supply conversion unit, which can reduce the risk of large-area influence on instrument equipment work caused by single device failure, improve the energy utilization rate of the substation, and improve the instrument power supply reliability while using energy in a fine way. It is conducive to the demand for equipment safety, stability and reliability, and also promotes the green and energy-saving development of the industry;

[0058] (c) The power supply system in the substation using transformer waste heat of the present application solves the two technical problems of difficulty in effectively utilizing low-grade waste heat generated by transformer operation and complex transformer detection instrument power supply scheme, based on the principle of semiconductor thermoelectric power generation, the low-grade waste heat generated by the transformer during operation is converted into electric energy, the transformer body is used as an energy source, and the output voltage is adjusted in real time according to the transformer operating condition and ambient temperature change, so as to provide stable and reliable power supply to various low-power instruments of the transformer in a simple loop.

[0059] (d) The power supply system in the substation using transformer waste heat of the present application effectively utilizes the low-grade waste heat generated by the transformer during operation, opens up the path for waste heat utilization of transformer and other heat-generating electrical equipment from the bottom principle, fine energy utilization, improves the energy utilization rate, has considerable energy saving and carbon reduction benefits from the perspective of total equipment quantity, and also provides a convenient solution for power supply of various distributed instruments;

[0060] (e) The power supply system in the substation using transformer waste heat of the present application uses the main equipment body (transformer) to supply power to the instrument, and improves the flexibility and reliability of the transformer oil level meter, transformer oil surface temperature meter and transformer winding temperature meter;

[0061] (f) The power supply system in the substation using transformer waste heat of the present application adjusts the state of the power supply system in real time according to the set voltage value to meet the power supply demand of the instrument.

[0062] A power supply system in a substation using transformer waste heat

[0063] The present application provides a power supply system in a substation using transformer waste heat, which comprises a transformer shell 1, a semiconductor thermoelectric generator 2, a boost circuit 3 and a transformer instrument 4, one end of the semiconductor thermoelectric generator 2 is connected with the transformer shell 1 by a heat-conducting material, the other end of the semiconductor thermoelectric generator 2 is connected with the input end of the boost circuit 3, and the output end of the boost circuit 3 is connected with the transformer instrument 4; preferably, the heat-conducting material comprises heat-conducting silicone grease 24.

[0064] The semiconductor thermoelectric generator 2 is configured to receive waste heat generated by the transformer shell 1 and generate electromotive force by utilizing temperature difference, and the boost circuit 3 is used to boost the voltage output by the semiconductor thermoelectric generator 2 to a constant target voltage required by the transformer instrument 4, so as to maintain the normal work of the transformer instrument 4.

[0065] Preferably, the semiconductor thermoelectric generator 2 comprises a plurality of N-type semiconductors 21 and P-type semiconductors 22 connected in series. The heat-conducting silicone grease 24 is located between the transformer shell 1 and the N-type semiconductors 21 and P-type semiconductors 22.

[0066] Preferably, the semiconductor thermoelectric generator 2 further comprises a copper bar 23 and the thermal conductive silicone grease 24.

[0067] Preferably, the input end of the boost circuit 3 comprises a positive end of the boost circuit and a negative end of the boost circuit, the positive end of the boost circuit is connected with the P-type semiconductor 22, and the negative end of the boost circuit is connected with the N-type semiconductor 21.

[0068] Preferably, the boost circuit 3 is a Boost converter, and the boost circuit comprises an energy storage inductor 31, a switch tube 32, a diode 33 and a filter capacitor 34.

[0069] Preferably, the system further comprises a feedback control loop configured to enable the semiconductor thermoelectric generator 2 to provide the transformer instrument 4 with a constant target voltage required, and the feedback control loop comprises an input current detection unit 5, a micro-processing control circuit 6 and an output voltage detection unit 7. Preferably, the input current detection unit 5 is used to detect the current value of the energy storage inductor 31 of the input boost circuit, and the output voltage detection unit 7 is used to detect the output voltage of the output end of the boost circuit 3.

[0070] Preferably, the micro-processing control circuit 6 comprises a PID controller configured to adjust the on and off time of the switch tube 32 according to the set voltage value.

[0071] When the switch tube 32 is turned on, the semiconductor thermoelectric generator 2 charges the energy storage inductor 31, and the diode 33 is in a closed state at this time to prevent the filter capacitor 34 from discharging; when the switch tube 32 is turned off, the energy storage inductor 31 discharges the filter capacitor and the transformer instrument, the inductor current begins to decrease slowly, and the output voltage U o = U i + U L , wherein U L is the voltage of the energy storage inductor, U o is the output voltage of the boost circuit, and U i is the input voltage of the boost circuit.

[0072] In order to make the purpose, technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings. It should be understood that these are only some examples that the present application can take for the reader, but are not intended to limit the scope of the present application.

[0073] Example 1

[0074] As Figure 1As shown, the application provides a power supply system using transformer waste heat in a transformer substation. The system is a transformer instrument power supply system based on the principle of semiconductor thermoelectric power generation, which includes: a semiconductor thermoelectric generator 2, a boost circuit 3, an input current detection unit 5, an output voltage detection unit 7, a micro-processing control circuit 6 (in this embodiment, the micro-processing control circuit 6 is a PID controller), a transformer housing 1, a transformer instrument 4. Among them, the transformer housing 1 provides the energy source for the power supply system, and the transformer instrument 4 is the load of the power supply system. All the above devices are arranged around the transformer. As shown in the figure Figure 2 The boost circuit 3 is a Boost converter, which includes an energy storage inductor 31, a switch tube 32, a diode 33 and a filter capacitor 34.

[0075] The semiconductor thermoelectric generator 2 is attached to one end of the transformer housing 1 and connected to the boost circuit 3 at the other end. Because of the fixed temperature difference between the two ends of the semiconductor, an electromotive force is formed. Considering the many factors affecting the ambient temperature and the temperature change of the transformer housing 1 (the shell), and the transformer instrument 4 needs a relatively stable voltage power supply, the boost circuit 3 is responsible for stabilizing the output voltage.

[0076] In this embodiment, the input current detection unit 5 is used to detect the current value of the energy storage inductor 31 input to the boost circuit 3, and the output voltage detection unit 7 is used to detect the output voltage of the output end of the boost circuit 3. The output voltage value of the output end of the boost circuit 3 detected by the output voltage detection unit 7 and a fixed reference voltage value constitute a voltage outer loop negative feedback regulation, and the input current detection unit 5 is used to detect the current value of the energy storage inductor 31 input to the boost circuit 3 and the voltage outer loop regulation output value (i.e. the target current value) to constitute a current inner loop negative feedback regulation. The voltage and current negative feedback regulation control is realized by the micro-processing control circuit 6 (built with operational amplifier, resistor and capacitor), and appropriate PID (proportional integral derivative) parameters are set according to the characteristics of the system, so as to continuously provide a stable voltage source for the transformer instrument 4 and achieve the purpose of reusing transformer waste heat.

[0077] According to the set voltage value, the PID controller adjusts the on and off time of the switch tube 32. When the switch tube 32 is turned on, the semiconductor thermoelectric generator 2 charges the energy storage inductor 31, and the diode 33 is in the off state at this time to prevent the filter capacitor 34 from discharging; when the switch tube 32 is turned off, the energy storage inductor 31 discharges the filter capacitor 34 and the transformer instrument 4, and the inductor current begins to decrease slowly, and the output voltage U o = U i + U L .

[0078] For the inductor, when the switch tube 32 is turned on, U on = U i , and when the switch tube 32 is turned off, Uoff = U o i = U i * T D = (U o - U i ) * (T S - T D ). Wherein, Ts refers to the total time of switch tube 32 turn-on and turn-off, T D refers to the time of 32 tube conduction, D = T D / T S , U o is the output voltage of the boost circuit, U i is the input voltage of the boost circuit.

[0079] Therefore, U o is simplified as U o = U i / (1-D), the output voltage of the semiconductor thermoelectric generator U i = ∑α ab *(T1-T2), as described in detail below.

[0080] The structure of the semiconductor thermoelectric generator 2 of the present application is shown in Figure 3 , which constitutes N-type semiconductor 21, P-type semiconductor 22, flow guide copper bar 23, and heat-conducting silicone grease 24, and the figure also shows the transformer shell 1. When the semiconductor thermoelectric generator 2 is attached to the transformer body (i.e. the transformer shell 1), the heat-conducting silicone grease 24 can not only achieve effective conduction of the transformer waste heat, but also can insulate the closed current loop of the thermoelectric generator from the transformer shell to reduce the impact on the main equipment. N-type semiconductor 21 and P-type semiconductor 22 constitute a pair of thermocouples. According to the thermoelectric principle, the thermoelectric electromotive force △U = α ab *(T1-T2),

[0081] α ab is the Seeback coefficient of N-type semiconductor 21 and P-type semiconductor 22, unit: V / K;

[0082] T1, T2 are the temperatures at the heat source (transformer shell) and the cold source (environment), unit: K.

[0083] The voltage and current output by a single thermocouple are relatively small. The system of the present application increases the output voltage and current of the semiconductor thermoelectric generator 2 by combining multiple thermocouple units in series and parallel. According to the volt-second balance principle, the output voltage value U o = U i / (1-D), as described above.

[0084] U i ​For BOOST input voltage, unit: V / K;

[0085] D is the modulation duty cycle outputted by microprocessor control circuit 6, which ranges from 0 to 1.

[0086] The power supply system of the present application outputs voltage U o =∑α ab *(T1-T2) / (1-D), which can be adjusted according to the parameters of transformer instrument 4 to meet its 24V power supply requirements.

[0087] A large number of technical features are described in the specification of the present application, which are distributed in various technical solutions. If all possible combinations of technical features (i.e. technical solutions) of the present application are listed, the specification will be too long. In order to avoid this problem, each technical feature disclosed in the above invention content, each technical feature disclosed in the following embodiments and examples, and each technical feature disclosed in the drawings can be freely combined to form various new technical solutions (these technical solutions are considered to have been described in the specification), unless such combination of technical features is technically infeasible. For example, features A+B+C are disclosed in one example, features A+B+D+E are disclosed in another example, features C and D are equivalent technical means that play the same role, and only one of them can be used technically, and feature E can be combined with feature C technically. Therefore, the scheme of A+B+C+D should not be considered as having been described because it is technically infeasible, and the scheme of A+B+C+E should be considered as having been described.

[0088] All documents mentioned in the present application are considered to be included in the disclosure of the present application as a whole, so that they can be used as a basis for modification if necessary. In addition, it should be understood that those skilled in the art can make various modifications or modifications to the present application after reading the above disclosure of the present application, and these equivalent forms also fall within the scope of the present application.

Claims

1. A power supply system using waste heat of a transformer in a substation, characterized by, The system comprises: a transformer housing (1), a semiconductor thermoelectric generator (2), a voltage boosting circuit (3) and a transformer instrument (4), one end of the semiconductor thermoelectric generator (2) is connected with the transformer housing (1) by a heat-conducting material, the other end of the semiconductor thermoelectric generator (2) is connected with the input end of the voltage boosting circuit (3), the output end of the voltage boosting circuit (3) is connected with the transformer instrument (4); the semiconductor thermoelectric generator (2) is configured to receive waste heat generated by the transformer housing (1) and generate electromotive force by temperature difference, the voltage boosting circuit (3) is used to boost the voltage output by the semiconductor thermoelectric generator (2) to a constant target voltage required by the transformer instrument (4), so as to maintain the normal work of the transformer instrument (4).

2. The system of claim 1, wherein, The heat-conducting material comprises heat-conducting silicone grease (24).

3. The system of claim 2, wherein, The semiconductor thermoelectric generator (2) comprises a plurality of N-type semiconductors (21) and P-type semiconductors (22) connected in series.

4. The system of claim 3, wherein, The heat-conducting silicone grease is located between the transformer housing and the N-type semiconductors (21) and P-type semiconductors (22).

5. The system of claim 4, wherein, The input end of the voltage boosting circuit (3) comprises a positive electrode end of the voltage boosting circuit and a negative electrode end of the voltage boosting circuit, the positive electrode end of the voltage boosting circuit is connected with the P-type semiconductor (22), and the negative electrode end of the voltage boosting circuit is connected with the N-type semiconductor (21).

6. The system of claim 1, wherein, The voltage boosting circuit comprises an energy storage inductor (31), a switching tube (32), a diode (33) and a filter capacitor (34).

7. The system of claim 6, wherein, The system further comprises a feedback control loop, which is configured to enable the semiconductor thermoelectric generator (2) to provide the constant target voltage required by the transformer instrument (4), and the feedback control loop comprises an input current detection unit (5), a micro-processing control circuit (6) and an output voltage detection unit (7).

8. The system of claim 7, wherein, The input current detection unit (5) is used to detect the current value input to the energy storage inductor (31) of the voltage boosting circuit, and the output voltage detection unit (7) is used to detect the output voltage of the output end of the voltage boosting circuit (3).

9. The system of claim 8, wherein, The output voltage at the output of the voltage boosting circuit (3) is U o =∑α ab *(T1-T2) / (1-D), wherein a ab Seeback coefficient of N-type semiconductor and P-type semiconductor, unit: V / K; T1 is the temperature at the transformer housing, and T2 is the temperature at the environment, both in K; D is the modulation duty cycle output by the micro-processing control circuit, which ranges from 0 to 1.

10. The system of claim 1, wherein, The power generated by the semiconductor thermoelectric generator (2) matches the power required by the transformer instrument, the power generated by the semiconductor thermoelectric generator (2) is about 20 W, and the power required by the transformer instrument ranges from several watts to tens of watts.

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