The bidirectional power controller that is used for superconducting energy storage
Technical field
The present invention relates to a kind of bidirectional power controller that is used for superconducting energy storage, belong to superconductor applications
Technical field.
Background technology
Along with the discovery of high temperature superconducting materia and the fast development of power electronic technology, superconducting energy storage (SMES) is installed in application on power system more and more widely.Superconducting magnetic energy storage not only can be used for the leveling load, increases the transmission power limit of transmission line, can also improve stability of power system, suppresses mains frequency and voltage fluctuation, alleviates the sub-synchronous oscillation of generator, shortens failure recovery time etc.The used power control unit of SMES is the energy exchange device of superconducting coil and electrical network, is connected with electrical network by transformer, and it can independently control the active power and the reactive power exchange of superconducting coil and electric power system.In early days, the power control unit among the SMES adopts silicon-controlled device, and the power factor in the system always lags behind, and has a large amount of low-order harmonics.Therefore, present superconducting energy storage (SMES) is the voltage source type converter that is made of the electronic power switch element with the power control unit majority, by voltage source type converter output voltage amplitude and phase place are controlled, make it active power, the reactive power (comprising harmonic wave) of regulating system apace.
We learn about first, the operation principle of bidirectional power controller in superconductive energy storage system.
In order to realize that superconducting energy storage inductance and power control unit are (as static reacance generator, active power filter, dynamic electric voltage recovery device or the like) bidirectional power transmission, must there be one can finish the device that magnetic field energy in the superconducting energy storage inductance and voltage-source type converting means is carried out the two-way exchange of energy, generally be referred to as two-way chopper (BI-DIRECTIONAL CHOPPER FORSMES) abroad, and we are with its called after bidirectional power controller (BI-DIRECTIONAL POWERREGULATOR FOR SMES), and it in the position of the superconductive energy storage system that is used for electric power system as shown in Figure 1.
When superconductive energy storage system absorbs active power from electrical network, the dc capacitor (referring among Fig. 2 shown in the C) that plays the voltage supporting role is gone up voltage and will be raise, bidirectional power controller is operated in charging modes, make this part meritorious store energy in the superconducting energy storage inductance, keep voltage constant on the dc capacitor.And when superconductive energy storage system sends active power in electrical network, play that voltage will reduce on the dc capacitor of voltage supporting role, bidirectional power controller is operated in discharge mode, makes the meritorious energy that is stored in the superconducting energy storage inductance discharge dc capacitor, keeps voltage constant on the dc capacitor.
Have a look citation form and the operation principle of existing superconducting energy storage again with two-way chopper circuit.
Existing superconducting energy storage with the citation form of two-way chopper circuit as shown in Figure 2, it is synthetic by two unidirectional choppers: electronic power switch T1 and diode D1 constitute first chopper, electronic power switch T2 and diode D2 constitute second chopper, Lsc represents the superconducting energy storage inductance among the figure, arrow is represented the sense of current, and C represents dc capacitor.Its operation principle is by turning on and off the time of control electronic power switch T1, T2, to realize electric current and the upward control of voltage of dc capacitor C to flowing through superconducting energy storage inductance L sc.When T1, T2 opened simultaneously, direct voltage was added on the superconducting energy storage inductance L sc, and voltage direction is identical with the sense of current, and two-way chopper is operated in charge mode.When T1, T2 disconnected simultaneously, direct voltage oppositely was added on the superconducting energy storage inductance L sc, and the energy among the superconducting energy storage inductance L sc discharges to dc capacitor C, and two-way chopper is operated in discharge mode.And when having only one to open among T1, the T2, the output voltage of two-way chopper is zero, and energy remains unchanged among the superconducting energy storage inductance L sc.
The circuit structure of two-way chopper is simple, and the station service power electronic component is also less, but its shortcoming is also very obvious.At first, powerful electronic power switch element is directly connected with the superconducting energy storage inductance, bear the electric current identical with the superconducting energy storage inductance, and the electric current ability to bear of superconducting energy storage inductance causes superconducting energy storage efficient to be suppressed considerably beyond present powerful power electronic element (can reach thousands of even tens thousand of amperes).Secondly, for reaching the requirement of the high-power exchange of large-scale superconductive energy storage system, power electronic element be should bear higher voltage (thousands of volt).And existing two-way chopper is very low owing to switching frequency, thereby causes the voltage fluctuation of DC voltage side violent, must adopt other complicated voltage stabilizing devices to solve, and makes circuit structure very complicated, and efficient also reduces greatly.Simultaneously, above-mentioned reason has also limited the more realization of high power super conductive energy-storage system.At present, two-way chopper has obtained application in small-sized superconducting magnetic energy storage, but effect is unsatisfactory.
Summary of the invention
Technical problem to be solved by this invention is, overcomes the shortcoming of existing two-way chopper, and a kind of bidirectional power controller that the is used for superconducting energy storage high power super conductive energy storage, the control dc voltage stability that is easy to realize is provided.
The technical solution adopted for the present invention to solve the technical problems is as follows: a kind of bidirectional power controller that is used for superconducting energy storage, it is characterized in that by voltage source inverter, low-frequency transformer and thyristor converter are formed, electric power control is connected with the DC side of voltage-source type converting means in the DC side of described voltage source inverter and the superconductive energy storage system, its AC side is connected with the former limit of described low-frequency transformer, the secondary of low-frequency transformer is connected with the AC side of described thyristor converter, and the DC side of thyristor converter is connected with the superconducting energy storage inductance.
Beneficial effect of the present invention is as follows: at first, adopt bidirectional power controller scheme of the present invention can realize the power control of powerful superconductive energy storage system.Voltage source inverter is made up of controlled electronic power switch element, when adopting multilevel converter or inverter cascade innovation type circuit form just can utilize the electronic power switch element of operating current lower (in the hundreds of ampere) to constitute powerful voltage source inverter, lower operating current makes the electronic power switch element can work under the very high switching frequency.By adopting the high frequency carrier modulation technique, voltage source inverter outgoing carrier frequency height and the alternating current of base frequency low (as the 50Hz/60Hz power frequency), through offering thyristor converter after low-frequency transformer (frequency is generally 50Hz or the 60Hz power frequency) step-down, by choosing suitable low-frequency transformer no-load voltage ratio, can make voltage source inverter work in the operating mode of the little electric current of high voltage, and thyristor converter work in the operating mode of low-voltage and high-current.A kind of power electronic element that controllable silicon is a present capacity maximum (can reach more than the 8000V/8000A), technology is the most ripe, have the characteristics simple, high efficiency of controlling, be particularly suitable for the application of big capacity controllable rectification/inversion, but that its shortcoming is a control frequency is low, and can not be from turn-offing.Directly the two-way control that the superconducting energy storage inductance carries out power is just in time met the characteristics that the thyristor electric current is big, frequency is low with thyristor converter.In addition, utilize multi-form series, parallel technology, can realize the more high power capacity formed by a plurality of voltage source inverters, low-frequency transformer and thyristor converter and the superconducting energy storage bidirectional power controller of bigger electric current.In theory, such superconducting energy storage, can reach more than the 100MW/10KA owing to be not subjected to the restriction of power electronic element capacity with the capacity of bidirectional power controller.
Secondly, the dc voltage stability control performance that adopts bidirectional power controller scheme of the present invention to realize ideal.As described above, the voltage source inverter that links to each other with DC voltage side is because operating current is lower, the electronic power switch element can be operated under the very high switching frequency, therefore can realize the high frequency control to direct voltage, and direct voltage will show as the fluctuation of high-frequency, short arc like this.Not needing increases other stable-pressure device, and circuit structure is simple, and efficient also improves greatly.
In a word, bidirectional power controller scheme of the present invention is than existing two-way chopper, and it is big to have power, and the advantage that control performance is good meets the development trend that current superconducting energy storage is used big capacity, big electric current.
Description of drawings
Fig. 1 is the superconductive energy storage system theory diagram that is used for electric power system.
Fig. 2 is the two-way chopper electrical schematic diagram of prior art.
Fig. 3 is used for the bidirectional power controller theory diagram of superconducting energy storage for the present invention.
Fig. 4 is the embodiment of the invention 1 electrical schematic diagram.
Fig. 5 is the embodiment of the invention 2 electrical schematic diagrams.
Fig. 6 is the embodiment of the invention 3 electrical schematic diagrams.
Embodiment
With reference to the accompanying drawings and in conjunction with three embodiment the present invention is further described.
Embodiment 1 as shown in Figure 4 is the low power bidirectional power controller that is used for superconducting energy storage of 100KW/1000A, and it is made up of one two level three-phase voltage source inverter INV, three-phase main-frequency transformer (frequency is a 50Hz or 60Hz) Tr and a three-phase common cathode controllable silicon half-bridge converter SCR.Wherein two level three-phase voltage source inverter INV output line voltages are 400V, and output current phase is 150A.Industrial Frequency Transformer Tr is D/Y
0The 100KVA three-phase transformer of connection.The output dc voltage of three-phase common cathode controllable silicon half-bridge converter SCR be 100V (during inversion for-100V), output current is 1000A.C is a dc capacitor among the figure, and Lsc is the superconducting energy storage inductance.
Embodiment 2 as shown in Figure 5 is the bidirectional power controller that is used for superconducting energy storage of 500KW/2000A mid power, and it is made up of one three level three-phase voltage source inverter TLI, a three-phase main-frequency transformer Tr and a three-phase controllable silicon full-bridge converter SCR.Wherein the output line voltage of three level three-phase voltage source inverter TLI is 1000V, and output current phase is 300A.Industrial Frequency Transformer Tr is D/Y
0The 500KVA three-phase transformer of connection.The output dc voltage of three-phase controllable silicon full-bridge converter be 250V (during inversion for-250V), output current is 2000A.C1, C2 are dc capacitor among the figure, and Lsc is the superconducting energy storage inductance.
Embodiment 3 as shown in Figure 6 is the powerful bidirectional power controller that is used for superconducting energy storage of 1000KW/2000A, and it is made up of two three level three-phase voltage source inverter TLI1 and TLI2, a double winding Industrial Frequency Transformer Tr and a three-phase controllable silicon full-bridge converter SCR.Wherein each three level three-phase voltage source inverter output line voltage is 1000V, and output current phase is 300A.Industrial Frequency Transformer Tr is the 1000KVA three-phase two winding transformer of Y/Y/D connection.The output dc voltage of three-phase controllable silicon full-bridge converter SCR be 500V (during inversion for-500V), output current is 2000A.C11, C12, C21, C22 are dc capacitor among the figure, and Lsc is the superconducting energy storage inductance.
For more powerful superconductive energy storage system, controller of the present invention can be connected to form by three and above high-power voltage source inverter, three and above low-frequency transformer and three and above thyristor converter thereof, realization power is synthetic, finishes the two-way control of high power super conductive energy storage.High-power voltage source inverter can be voltage with multiple levels source inventer, cascade type DC-to-AC converter etc., and low-frequency transformer can be three windings or multi winding transformer.