CN107154630A - A kind of hybrid power electrical substation - Google Patents

Abstract

The invention relates to a hybrid power electronic substation, which is characterized in that: it includes a primary system; the primary system includes a hybrid power electronic transformer and a switchgear for a substation; the high voltage side of the hybrid power electronic transformer passes through the high voltage AC busbar and The incoming line is connected, and the low-voltage side is divided into a traditional low-voltage AC outlet, a customized low-voltage AC outlet and a low-voltage DC outlet, and the traditional low-voltage AC outlet is connected to the input side of the traditional low-voltage AC busbar, and the customized low-voltage AC outlet is connected to the customized low-voltage AC busbar. The outlet is connected to the low-voltage DC busbar, and each low-voltage busbar is connected to various AC and DC load outlets and DC input and output interfaces to provide corresponding power for them. The invention can be widely used in the construction of power electronic substations.

Description

A Hybrid Power Electronic Substation

technical field

The invention relates to the field of planning and design of substations in distribution networks, in particular to a hybrid power electronic substation.

Background technique

With the increase of user-side information equipment (such as data centers, computers and microprocessors, communication system equipment, intelligent terminals, sensors and sensor networks), electric vehicle power batteries, semiconductor lighting and other DC power equipment, AC sensitive loads (Mainly refers to personal computers, programmable logic devices, adjustable speed drives, AC contactors, high-pressure gas discharge lamps, and finishing automatic devices or complex machinery for cutting, drilling and metal processing, etc. ) The improvement of power quality requirements, and the wide application of various distributed renewable energy power generation (biomass energy, wind energy, water energy, solar energy, etc.) The power supply mode is transformed from the AC input of the grid to the AC output of the user side, and has transformed into a complex power deployment mode that requires access to distributed power generation, electric vehicles, energy storage and other equipment, and provides customized power for AC-sensitive users. , Direct hybrid distribution network. However, since the traditional AC distribution network cannot provide DC input and output interfaces and high-quality power for new-type power users, new-type power users have to install converters or filtering equipment at the connection with the distribution network. However, these commutation or filter devices that meet the individual needs of users for electricity consumption and operate in a decentralized manner have the problems of low overall efficiency and difficulty in regulating them by the distribution network.

The substation in the distribution network, as a bridge connecting the upper-level power grid and power users, can provide AC and DC power for power users when new transformer (including the function of current conversion) equipment and diversified wiring methods are used in the station. The most important thing is to accept the control of the distribution network control center. This will greatly improve the overall operation level and security stability at the distribution network level, and at the same time meet the needs of power users to customize power and access convenience and friendliness. For this reason, the power electronic substation is gradually advancing towards the demonstration project from the previous conceptual design. The core equipment in the power electronic substation, the power electronic transformer, adopts the AC/DC/AC/DC/AC five-level conversion topology, and its cost is extremely expensive. This is a problem that has to be seriously considered for commercial power companies.

It should be pointed out that the majority of power users have very different requirements for power supply or access. It is mainly manifested in the fact that new power users hope that the distribution network can provide high-quality power, or a convenient DC interface, but most traditional power users still use traditional AC power. In this case, if the distribution network generally uses expensive power electronic transformers in substations, although it can provide high-quality electric energy or convenient DC input and output interfaces for some new power users. However, due to the high equipment cost, it will affect the electricity price level, which may lead to a general increase in electricity costs. This is extremely unreasonable for traditional power users who have no special electricity needs. For power companies, the economics of power electronic substation construction is also questionable.

Contents of the invention

In view of the above problems, the purpose of the present invention is to provide a hybrid power electronic substation, which can provide different interfaces and high-quality electric energy for users with diversified power demands, and ensure that the investment and construction of substations in the distribution network conform to commercial operation concept.

In order to achieve the above object, the present invention adopts the following technical solutions: a hybrid power electronic substation, characterized in that: it includes a primary system; the primary system includes a hybrid power electronic Substation switchgear; the high-voltage side of the hybrid power electronic transformer is connected to the incoming line of the upper power grid through the high-voltage AC bus, and the low-voltage side is connected to various AC and DC load outlets and DC input and output interfaces through the low-voltage bus; the low-voltage bus It includes a traditional low-voltage AC busbar, a custom-made low-voltage AC busbar and a low-voltage DC busbar, and the input side of the traditional low-voltage AC busbar is connected to the traditional low-voltage AC outlet of the hybrid power electronic transformer, and the output side is connected to each parallel traditional low-voltage AC load The input side of the customized low-voltage AC bus is connected with the customized low-voltage AC outlet of the hybrid power electronic transformer, and the output side is connected with each parallel customized low-voltage AC load outlet; the input side of the low-voltage DC bus is connected with the The hybrid power electronic transformer is connected to the low-voltage DC outlet, and the output side is connected to each parallel low-voltage DC load outlet and each DC input and output interface.

The hybrid power electronic transformer includes a traditional transformer and a converter; and the traditional transformer and the converter adopt the same secondary winding form or each adopt an independent secondary winding form.

The use of the same secondary winding form means: the traditional transformer and the converter adopt the same secondary winding; that is, the primary side of the traditional transformer is connected to the AC power supply to form a primary side alternating current, and the The primary-side alternating current forms a secondary-side output AC voltage V _out1 on the secondary side of the traditional transformer, which serves as the traditional low-voltage AC outlet of the hybrid power electronic transformer; the AC/DC converter in the converter The AC power used is directly obtained from the secondary side of the traditional transformer, and the AC/DC converter converts the secondary side output AC voltage V _out1 into a low-voltage direct current V _out2 as the hybrid power electronic transformer the low-voltage direct current outlet; the DC/AC converter in the converter converts the low-voltage direct current V _out2 obtained from the output end of the AC/DC converter into a customized low-voltage alternating current V _out3 , which is used as the hybrid power electronic transformer Custom low voltage AC outlets.

The use of an independent secondary winding means that: the traditional transformer and the converter respectively use different secondary windings; the primary side of the traditional transformer is connected to an AC power source to form an alternating current on the primary side, and the The primary-side alternating current forms a secondary-side output AC voltage V _out1 on the secondary side of the traditional transformer, which serves as the traditional low-voltage AC outlet of the hybrid power electronic transformer; The secondary side output AC voltage V' _out1 is formed on the secondary winding of the converter, and the AC/DC converter in the converter converts the secondary side output AC voltage V' _out1 into a low-voltage direct current V _out2 , as the hybrid The low-voltage direct current outlet of the power electronic transformer; the direct current used by the DC/AC converter in the converter is obtained from the output terminal of the AC/DC converter, and the low-voltage direct current V _out2 is converted into a low-voltage sensitive alternating current V _out3 as Custom low voltage AC outlets for the hybrid power electronic transformer.

The substation also includes a substation automation system, which is used to control all the equipment in the substation.

The substation switchgear includes several circuit breakers and several isolating switches arranged at both ends of each of the circuit breakers, each of the circuit breakers and isolating switches is connected to the substation automation system through a signal line, and is controlled by the substation automation system .

The circuit breaker includes two high-voltage AC circuit breakers, several low-voltage AC circuit breakers and several low-voltage DC circuit breakers, wherein the two high-voltage AC circuit breakers are respectively arranged at the connection between the high-voltage AC busbar and the incoming line of the upper-level power grid and with the The input side connection of the hybrid power electronic transformer; each of the low-voltage AC circuit breakers is respectively set at the connection between the traditional low-voltage AC busbar and the traditional low-voltage AC outlet of the hybrid power electronic transformer and each of the traditional low-voltage AC The load outlet connection, and the customized low-voltage AC outlet connection between the customized low-voltage AC bus bar and the hybrid power electronic transformer, and each of the customized low-voltage AC load outlet connections; each of the low-voltage DC circuit breakers is respectively set at the The connection between the low-voltage DC bus bar and the low-voltage DC outlet of the hybrid power electronic transformer and the connection between each of the low-voltage DC load outlets and each DC input and output interface.

On-site measurement and control equipment is also connected to the traditional low-voltage AC bus. The on-site measurement and control equipment includes inductive current-limiting reactors connected in series to limit the fault current and ensure the voltage level on the traditional low-voltage AC bus. power compensator.

The low-voltage DC input and output interfaces connected to the output side of the low-voltage DC bus include wind power generation and photovoltaic power generation inlet interfaces, and electric vehicles, energy storage devices or other corresponding equipment with bidirectional characteristics of power generation and power consumption.

The other end of each customized low-voltage AC load outgoing line connected to the output side of the customized low-voltage AC bus bar provides customized power to each AC-sensitive user.

The present invention has the following advantages due to the adoption of the above technical scheme: 1) The present invention forms a hybrid power electronic transformer due to the use of traditional transformers and converters. Converting traditional low-voltage AC power to low-voltage DC or customized low-voltage AC power can simultaneously meet the power needs of diverse power users. 2) Because the hybrid power electronic substation of the present invention can directly provide various types of power users with required traditional low-voltage alternating current, customized low-voltage alternating current or direct current, and does not need to use other converters or filtering equipment when supplying power to various types of power users, the substation All equipment can be uniformly controlled by the substation automation system, which greatly increases the flexibility and controllability of power electronic substation operation, and solves the problem of low overall efficiency and power distribution caused by the connection of converter or filter equipment in the prior art. It is difficult to regulate the network. 3) In the present invention, since the hybrid power electronic transformer is composed of traditional transformers and converters, and the traditional transformers and converters and other equipment have passed the long-term operation test, they have high reliability, low price and good performance, which effectively reduces the The construction cost of the substation system. Therefore, the present invention can be widely used in the construction of power electronic substations.

Description of drawings

Fig. 1 is the main wiring diagram of the hybrid power electronic substation of the present invention;

Fig. 2 (a) is the structural schematic diagram of the hybrid power electronic transformer adopting the shared secondary winding form of the present invention;

Fig. 2 (b) is the structure schematic diagram of the hybrid power electronic transformer adopting independent secondary winding form of the present invention;

Fig. 3 is a structural diagram of the control system of the hybrid power electronic substation of the present invention.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in FIG. 1 , the hybrid power electronic substation of the present invention includes a primary system; the primary system includes a hybrid power electronic transformer 1 and a substation switchgear 2 composed of several circuit breakers and isolating switches. Among them, the high-voltage side of the hybrid power electronic transformer 1 is connected to the incoming line 4 of the upper power grid through the high-voltage AC bus 3 , and the low-voltage side is connected to various AC and DC load outlets and various DC input and output interfaces through the low-voltage bus 5 . The low-voltage busbar 5 includes a traditional low-voltage AC busbar 51, a custom-made low-voltage AC busbar 52 and a low-voltage DC busbar 53, and the input side of the traditional low-voltage AC busbar 51 is connected to the traditional low-voltage AC outlet of the hybrid power electronic transformer 1, and the output side is connected to each parallel connected The traditional low-voltage AC load outlet 6 is connected; the input side of the customized low-voltage AC bus 52 is connected with the customized low-voltage AC outlet of the hybrid power electronic transformer 1, and the output side is connected with each parallel customized low-voltage AC load outlet 7; the input side of the low-voltage DC bus 53 The output side is connected to the low-voltage DC outlet of the hybrid power electronic transformer 1 , and the output side is connected to each parallel low-voltage DC load outlet 8 and each DC input and output interface 9 .

As shown in Fig. 2(a) and Fig. 2(b), the hybrid power electronic transformer 1 in the primary system includes a traditional transformer and a converter. Among them, the traditional transformer and the converter adopt the same secondary winding form (as shown in Figure 2(a)) or each adopt independent secondary winding forms (as shown in Figure 2(b)). Specifically, the form of the same secondary winding is: the traditional transformer and the converter use the same secondary winding, and the primary side of the traditional transformer (a ₁ , a ₂ in Figure 2(a)) is connected to the AC power supply u _i to form a primary side alternating current, the primary side alternating current forms the secondary side output AC voltage V _out1 on the secondary side of the traditional transformer (b ₁ , b ₂ in Fig. 2(a), as the traditional low-voltage AC outlet. The converter and the traditional transformer share the same secondary side, that is, the AC power used by the AC/DC converter in the converter is directly obtained from the secondary side of the traditional transformer, and the AC/DC converter outputs the AC power from the secondary side. The voltage V _out1 is converted into a low-voltage direct current V _out2 , which serves as the low-voltage direct current outlet of the hybrid power electronic transformer 1 . The direct current used by the DC/AC converter in the converter is obtained from the output terminal of the AC/DC converter, and the low-voltage direct current V _out2 is converted into a customized low-voltage alternating current V _out3 , which serves as a customized low-voltage AC outlet of the hybrid power electronic transformer 1 .

The form of independent secondary winding is: the traditional transformer and the converter use different secondary windings respectively, the primary side of the traditional transformer is connected with the AC power supply u _i to form the primary side alternating current, and the primary side alternating current is in the secondary side of the traditional transformer The secondary side output AC voltage V _out1 is formed on the side winding as the traditional low-voltage AC outlet of the hybrid power electronic transformer 1 . The primary-side alternating current forms the secondary-side output AC voltage V′ _out1 on the secondary winding of the converter (c ₁ , c ₂ in Figure 2(b)), and the AC/DC converter in the converter converts the secondary The side output AC voltage V′ _out1 is converted into a low-voltage DC voltage V _out2 , which serves as the low-voltage DC outlet of the hybrid power electronic transformer 1 . The direct current used by the DC/AC converter in the converter is obtained from the output terminal of the AC/DC converter, and the low-voltage direct current V _out2 is converted into a customized low-voltage alternating current V _out3 , which serves as a customized low-voltage AC outlet of the hybrid power electronic transformer 1 .

The substation switchgear 2 includes several circuit breakers 21 and several isolating switches 22 arranged at both ends of each circuit breaker 21. Each circuit breaker 21 and isolating switch 22 are connected to the substation automation system through signal lines and controlled by the substation automation system. The circuit breaker 21 includes two high-voltage AC circuit breakers 211, several low-voltage AC circuit breakers 212 and several low-voltage DC circuit breakers 213, wherein the two high-voltage AC circuit breakers 211 are respectively arranged at the connection between the high-voltage AC busbar 3 and the incoming line 4 of the upper-level grid and Connection with the input side of the hybrid power electronic transformer 1; each low-voltage AC circuit breaker 212 is respectively set at the connection between the traditional low-voltage AC busbar 51 and the traditional low-voltage AC outlet of the hybrid power electronic transformer 1 and the connection of each traditional low-voltage AC load outlet 6 , and the customized low-voltage AC outlet connection between the customized low-voltage AC bus 52 and the hybrid power electronic transformer 1 and the connection of each customized low-voltage AC load outlet 7; each low-voltage DC circuit breaker 213 is respectively arranged on the low-voltage DC bus 53 and the hybrid power electronic The connection of the low-voltage DC outlet of the transformer 1 and the connection of each low-voltage DC load outlet 8 and each DC input and output interface 9 .

As shown in FIG. 3 , the hybrid power electronic substation of the present invention also includes a substation automation system for controlling all equipment in the whole substation. The design of the substation automation system refers to the design method of the traditional substation automation system. Two-way communication between layers, mutual coordination. The substation dispatching layer is used to monitor and control all the controlled equipment in the substation, as well as communicate with the dispatching center. The inter-equipment coordination protection layer is used for on-site monitoring and control of all controlled equipment in this interval, as well as coordination and control with the substation dispatching layer. The single-device control protection layer is used for data collection, automatic monitoring and control of the controlled device at the process layer, as well as coordination and control with the coordination protection layer between devices. Among them, the controlled equipment includes hybrid power electronic transformers, various AC/DC circuit breakers, various isolating switches, inductive current-limiting reactors, reactive power compensation capacitors, electric vehicles, energy storage equipment, wind power generation, photovoltaic power generation interfaces, etc. .

In the above embodiment, the traditional low-voltage AC bus 51 is also connected with local measurement and control equipment, and the local measurement and control equipment includes inductive current limiting devices connected in series to limit the fault current and ensure the voltage level on the traditional low-voltage AC bus. Reactors and reactive power compensators.

In each of the above-mentioned embodiments, the low-voltage DC input and output interfaces 9 connected to the output side of the low-voltage DC bus 53 include wind power generation and photovoltaic power generation inlet interfaces, and electric vehicles, energy storage devices, or other corresponding equipment with bidirectional characteristics of power generation and power consumption. outgoing interface.

When the invention is in use, the high-voltage alternating current sent from the upper-level power grid enters the high-voltage side of the hybrid power electronic transformer in the primary system through the incoming line through the high-voltage alternating current bus.

The function of the hybrid power electronic transformer 1 includes two parts. One is the traditional AC transformer, which is used to realize the conversion of AC from high voltage to low voltage. DC conversion, and further DC to AC conversion. Among them, the converter is a conversion circuit composed of power electronic devices IGBT, and its control is realized by pulse-width-modulation (PWM, pulse-width-modulation), so as to ensure that the output DC and AC can meet the specified requirements. Such as ripple voltage, harmonic content, etc., with power flow control and power quality adjustment capabilities.

The present invention takes the same secondary winding form as an example. The traditional transformer in the hybrid power electronic transformer first steps down the high-voltage alternating current, reducing the high-voltage alternating current to low-voltage alternating current V _out1 , and then divides it into two circuits, one of which is used as the traditional low-voltage AC outlet, and provide traditional low-voltage AC power for various traditional low-voltage loads through traditional low-voltage AC busbars. The other low-voltage alternating current completes the AC/DC/AC commutation through the converter, and outputs high-quality customized low-voltage AC from the AC side of the converter, namely V _out3 , as the customized low-voltage AC outlet, and through the customized low-voltage AC busbar as Various customized low-voltage AC loads provide customized AC power. Output low-voltage direct current from the direct-current side of the converter, that is, V _out2 , as a low-voltage direct-current outlet, and connect with various direct-current loads or direct-current interface devices through a low-voltage direct-current bus.

The substation automation system monitors all the controlled equipment in the substation, and transmits the monitoring information through the communication mode (such as optical fiber or LAN) in the substation through layered control, and finally implements control according to the proposed control and protection strategy to ensure the operation of the whole station reliability and flexibility. When the substation fails or is overhauled, the substation automation system controls and switches the circuit breaker 21 and the isolating switch 22 in the substation switchgear 2, and then cuts off the substation and the upper-level power grid, or the hybrid power electronic transformer 1 and the high-voltage AC bus 3 and each low-voltage bus 5, or the electrical connection between all connected objects on the low-voltage side and the substation to ensure the safety of operation in the substation. Considering the electrical safety factor, when the circuit breaker is disconnected, the isolating switches on both sides must act to form a physically obvious disconnection point to ensure the personal safety of the operation and maintenance personnel.

The above-mentioned embodiments are only used to illustrate the present invention, wherein the structure, connection mode and manufacturing process of each component can be changed to some extent, and any equivalent transformation and improvement carried out on the basis of the technical solution of the present invention should not excluded from the protection scope of the present invention.

Claims (10)

1. A hybrid power electronic substation is characterized in that: it includes a primary system; the primary system includes a hybrid power electronic transformer and a substation switchgear composed of several circuit breakers and isolating switches; The high-voltage side of the hybrid power electronic transformer is connected to the incoming line of the upper power grid through a high-voltage AC bus, and the low-voltage side is connected to various AC and DC load outlets and DC input and output interfaces through a low-voltage bus; the low-voltage bus includes traditional low-voltage AC Busbar, customized low-voltage AC busbar and low-voltage DC busbar, and the input side of the traditional low-voltage AC busbar is connected to the traditional low-voltage AC outlet of the hybrid power electronic transformer, and the output side is connected to each parallel traditional low-voltage AC load outlet; The input side of the customized low-voltage AC bus is connected to the customized low-voltage AC outlet of the hybrid power electronic transformer, and the output side is connected to each parallel customized low-voltage AC load outlet; the input side of the low-voltage DC bus is connected to the hybrid power electronic transformer. The low-voltage DC outlet of the electronic transformer is connected, and the output side is connected with each parallel-connected low-voltage DC load outlet and each DC input and output interface. 2. A kind of hybrid power electronic substation as claimed in claim 1, characterized in that: said hybrid power electronic transformer comprises a traditional transformer and a converter; and between said traditional transformer and converter The same secondary winding form or independent secondary winding forms. 3. A hybrid power electronic substation as claimed in claim 2, characterized in that: the use of the same secondary winding form means: the traditional transformer and the converter use the same secondary winding; That is, the primary side of the traditional transformer is connected to an AC power source to form a primary-side alternating current, and the primary-side alternating current forms a secondary-side output AC voltage V _out1 on the secondary side of the traditional transformer, as the hybrid The traditional low-voltage AC outlet of the power electronic transformer; the AC power used by the AC/DC converter in the converter is directly obtained from the secondary side of the traditional transformer, and the AC/DC converter converts the secondary The side output AC voltage V _out1 is converted into low-voltage direct current V _out2 as the low-voltage direct-current outlet of the hybrid power electronic transformer; the DC/AC converter in the converter will be obtained from the output terminal of the AC/DC converter The low-voltage direct current V _out2 is converted into a customized low-voltage alternating current V _out3 , which serves as a customized low-voltage AC outlet of the hybrid power electronic transformer. 4. A hybrid power electronic substation as claimed in claim 2, characterized in that: the use of independent secondary windings means that the traditional transformer and the converter use different secondary windings ; The primary side of the traditional transformer is connected to an AC power supply to form a primary side alternating current, and the primary side alternating current forms a secondary side output AC voltage V _out1 on the secondary side of the traditional transformer, as the hybrid The traditional low-voltage AC outlet of the power electronic transformer; the primary-side alternating current forms a secondary-side output AC voltage _V'out1 on the secondary winding of the converter, and the AC/DC converter in the converter will The secondary-side output AC voltage V' _out1 is converted into low-voltage direct current V _out2 as the low-voltage direct current outlet of the hybrid power electronic transformer; the direct current used by the DC/AC converter in the converter is obtained from the AC/DC The output terminal of the converter obtains and converts the low-voltage direct current V _out2 into a low-voltage sensitive alternating current V _out3 , which serves as a customized low-voltage AC outlet of the hybrid power electronic transformer. 5. A hybrid power electronic substation according to claim 1, characterized in that: said substation further comprises a substation automation system, and said substation automation system is used to control all equipment in the whole substation. 6. A kind of hybrid power electronic substation as claimed in claim 1, characterized in that: said substation switchgear comprises several circuit breakers and several isolating switches arranged at both ends of each said circuit breaker, each said circuit breaker and The isolating switches are all connected to the substation automation system through signal lines and controlled by the substation automation system. 7. A hybrid power electronic substation as claimed in claim 6, wherein said circuit breakers include two high-voltage AC circuit breakers, several low-voltage AC circuit breakers and several low-voltage DC circuit breakers, wherein the two high-voltage The AC circuit breakers are respectively arranged at the connection between the high-voltage AC bus and the incoming line of the upper-level power grid and at the connection with the input side of the hybrid power electronic transformer; the low-voltage AC circuit breakers are respectively arranged at the connection between the traditional low-voltage AC bus The traditional low-voltage AC outlet connection of the hybrid power electronic transformer and each of the traditional low-voltage AC load outlet connections, as well as the customized low-voltage AC busbar and the customized low-voltage AC outlet connection of the hybrid power electronic transformer and each The customized low-voltage AC load outlet connection; each of the low-voltage DC circuit breakers is respectively arranged at the connection between the low-voltage DC busbar and the low-voltage DC outlet of the hybrid power electronic transformer and each of the low-voltage DC load outlets and each DC Input and output interface connection. 8. A hybrid power electronic substation according to claim 1, characterized in that: said traditional low-voltage AC bus is also connected with on-site measurement and control equipment, and the on-site measurement and control equipment includes series-connected Inductive current-limiting reactors and reactive power compensators that limit fault current and ensure voltage levels on traditional low-voltage AC buses. 9. A hybrid power electronic substation according to claim 1, characterized in that: the low-voltage DC input and output interfaces connected to the output side of the low-voltage DC bus include wind power generation and photovoltaic power generation inlet interfaces, electric vehicles, energy storage The inlet/outlet interface of the device or other corresponding equipment with bidirectional characteristics of power generation and power consumption. 10. A hybrid power electronic substation according to claim 1, characterized in that: the other end of each customized low-voltage AC load outgoing line connected to the output side of the customized low-voltage AC bus provides customized power to each AC-sensitive user.