CN113725856B - Multifunctional electric energy quality control device based on hybrid energy storage and thyristors - Google Patents
Multifunctional electric energy quality control device based on hybrid energy storage and thyristors Download PDFInfo
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- 238000003908 quality control method Methods 0.000 title claims abstract description 15
- 230000002457 bidirectional effect Effects 0.000 claims abstract description 74
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- 230000001629 suppression Effects 0.000 claims abstract description 3
- 238000007599 discharging Methods 0.000 claims description 9
- 238000011217 control strategy Methods 0.000 claims description 7
- 238000013016 damping Methods 0.000 claims description 6
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- 230000001105 regulatory effect Effects 0.000 claims description 4
- 238000013461 design Methods 0.000 claims description 3
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- 238000010586 diagram Methods 0.000 description 7
- 238000004088 simulation Methods 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 3
- 238000002955 isolation Methods 0.000 description 3
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
- H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
- H02J7/345—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering using capacitors as storage or buffering devices
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks
Abstract
The invention discloses a multifunctional electric energy quality control device based on hybrid energy storage and thyristors, belonging to the field of electric energy quality control; the multifunctional electric energy quality management device based on the hybrid energy storage and the thyristors comprises a hybrid energy storage module, an inversion module, a bidirectional thyristor module and a control module, and can be applied to complex environments with precise sensitive and/or harmonic loads such as banks, hospitals, chip manufacturing bases, electric vehicle charging stations and the like, the precise sensitive load voltage is kept constant when the power grid voltage is subjected to long-time dip/interruption, and harmonic suppression/reactive compensation/three-phase imbalance compensation and power factor improvement are performed when the power grid voltage is normal, so that various electric energy quality problems can be solved at the same time with lower economic cost; the super capacitor module and the storage battery module are integrated in the energy storage module to exert respective advantages, and the super capacitor module and the storage battery module are switched in the voltage and current quality control mode through the switching bidirectional thyristor, so that the super capacitor module and the storage battery module have high practical value.
Description
Technical Field
The invention belongs to the field of electric energy quality control, and particularly relates to a multifunctional electric energy quality control device based on hybrid energy storage and thyristors.
Background
Along with the continuous development of the current technology and the development of the modern technology, on one hand, electric equipment sensitive to the electric energy quality is continuously popularized, and the requirement of users on the electric energy quality is higher and higher; on the other hand, the factors causing the problem of power quality are increasing, and the reactive power and harmonic problems of the power grid are more serious along with the access of a plurality of nonlinear loads, and the popularization of distributed new energy power generation in recent years also brings new challenges to the power quality. At present, the electric energy quality mainly comprises the problems of voltage sag/sag, harmonic pollution, low power factor, three-phase imbalance and the like, and corresponding solutions mainly comprise a Dynamic Voltage Restorer (DVR), an Uninterruptible Power Supply (UPS), a static var compensator (SVG), an active power filter and the like, but the problems of various electric energy quality are difficult to solve by the solutions.
At present, in the field of electric energy quality management, an energy storage link is often needed to provide long-term reliable power supply for precise sensitive loads, and if a storage battery is used as the energy storage link, the defects of insufficient power density, low response speed and influence on the service life due to frequent charge and discharge of the storage battery under the voltage fluctuation working condition exist; if the super capacitor is used as an energy storage link, the energy density is not high enough, and the voltage compensation requirement under the long-time voltage interruption working condition is difficult to meet. If the storage battery and the super capacitor are combined to be used as the hybrid energy storage unit and an appropriate control strategy is adopted, the advantages of the storage battery and the super capacitor can be combined, the economic cost is reduced, the service life is prolonged, and the working performance is improved.
At present, in the field of electric energy quality control, a power frequency transformer with huge volume and higher price is often required to be configured to play a role in electric isolation, and the electric isolation is realized by switching the bidirectional thyristor, so that the economic cost and the occupied area can be greatly reduced.
In view of the above, it is particularly important to invent a low-cost multifunctional power quality control device capable of simultaneously solving the problems of voltage quality and power quality.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a multifunctional power quality control device based on hybrid energy storage and thyristors, which can solve various power quality problems at the same time with lower economic cost.
The aim of the invention can be achieved by the following technical scheme:
a multifunctional electric energy quality control device based on hybrid energy storage and thyristors comprises a hybrid energy storage module, a bidirectional thyristor module, an inversion module and a control module;
further, a bidirectional thyristor is arranged in the bidirectional thyristor module, the bidirectional thyristor is positioned between the power grid and the harmonic wave and/or the sensitive load, the hybrid energy storage module is connected with a direct current bus of the inversion module, the output end of the inversion module is connected in parallel between the bidirectional thyristor and the harmonic wave and/or the sensitive load, and the input end of the bidirectional thyristor is connected with a system power supply.
Further, the bidirectional thyristor module is composed of the bidirectional thyristor and a drive protection circuit.
Further, the inversion module comprises a three-phase inverter and a passive filter.
Further, the passive filter adopts an LCL filter, and a current and voltage sensor is arranged on the passive filter and fed back to the control module.
Further, the passive filter adopts a passive damping or active damping scheme to ensure the stability of the LCL filter, and the inductance parameter design of the passive filter on the power grid side should take the inductance voltage drop into account to ensure the voltage compensation capability of the passive filter.
Further, the hybrid energy storage module comprises a storage battery module, a super capacitor module and a bidirectional DC-DC module; the super capacitor module is formed by connecting super capacitor monomers in series and parallel, and the storage battery module is formed by connecting storage battery packs in series and parallel; the bidirectional DC-DC module is responsible for respectively connecting the storage battery module and the super capacitor module with a direct current bus of the voltage source type inverter.
Furthermore, rated power and capacity of the storage battery module, the super capacitor module and the bidirectional DC-DC module are determined according to preset rated power and voltage interruption maximum compensation time.
Further, the control module comprises a DSP control chip, a sampling circuit and a drive protection circuit, and is responsible for realizing a control algorithm and carrying out coordination control on the inversion module, the hybrid energy storage module and the bidirectional thyristor module.
Further, the control method of the control module includes:
s1: collecting signals of each sensor, including power grid side voltage, load side current, super capacitor and storage battery end voltage in the hybrid energy storage module, bidirectional DC-DC module current and device temperature;
s2: judging whether the electric energy quality problem exists at the moment according to the acquired signals, switching the working modes according to the sequence of solving the voltage quality problem and then the current quality problem, and switching the device into a standby state if the electric energy quality problem does not exist at the moment;
s3: when the control module detects the voltage quality problem, the bidirectional thyristor is forced to be turned off, the inversion module supplies power to the sensitive load reliably for a long time, and meanwhile, the hybrid energy storage module is controlled to maintain the constant voltage of the DC bus of the inversion module; when the duration time of voltage sag/sag is shorter, the direct current bus voltage of the inversion module is maintained to be constant only by the super capacitor module and the corresponding bidirectional DC-DC module, and the storage battery module does not participate in discharging; when the voltage sag/sag duration is longer and the end voltage of the super capacitor module is reduced to a certain threshold value, the storage battery module is used for discharging again and maintaining the DC bus of the inversion module constant, and when the end voltage of the hybrid energy storage module is lower than a certain safety threshold value, the device stops processing.
S4: when the control module of the device does not detect the voltage quality problem and only detects the current quality problem, the bidirectional thyristor is closed at the moment, the device works in a harmonic suppression/reactive power control or three-phase imbalance control mode, the voltage source type inverter outputs compensation current through the passive filter to offset harmonic/reactive power/imbalance components in load current, and meanwhile, the voltage of a bus at the direct current side of the inversion module is regulated;
under the harmonic wave and reactive power control mode, the control module judges the states of the bidirectional DC-DC module and the storage battery module in the hybrid energy storage module according to the sampling signal, and if the terminal voltages of the super capacitor module and the storage battery module are not in the rated range, the bidirectional DC-DC module is used for adjusting; if the super capacitor module and the storage battery module are restored to the rated range, locking the bidirectional DC-DC module;
s5: when the device is in an environment without the problem of power quality, the device is in a standby state, and the bidirectional thyristor is kept on, so that the normal power supply of a sensitive load is ensured.
Further, when the storage battery participates in discharging and maintains the constant of the direct current bus of the inversion module, the given value of the power required to be output by the hybrid energy storage module is calculated, the low-frequency component of the given value of the power is used as the given value of the output power of the storage battery and the corresponding bidirectional DC-DC module, the control strategy of the outer ring current inner ring of the voltage is adopted to control the storage battery pack and the corresponding bidirectional DC-DC module, the high-frequency component of the given value of the power of the hybrid energy storage module is used as the given value of the output power of the super capacitor and the corresponding bidirectional DC-DC module, the response speed of the high-frequency component of the given value of the power is improved through the control strategy of the single current ring, and the constant voltage of the direct current bus of the inversion module is maintained.
The invention has the beneficial effects that:
1. the multifunctional electric energy quality control device based on the hybrid energy storage and the thyristors has the advantages that the voltage sag compensation time is long, the voltage interruption compensation function is realized, the bidirectional thyristors are adopted to realize the electric isolation of the device and the power distribution network, and a power frequency transformer required by a traditional dynamic voltage restorer is not needed, so that the economic cost is reduced.
2. The device can be switched to different working modes after judging the type of the electric energy quality, and can perform harmonic wave/reactive power/unbalanced current compensation when the voltage of the power grid is normal, and perform voltage compensation when the voltage of the power grid is reduced/interrupted, so that the control is flexible.
3. The hybrid energy storage module of the device has the advantages of both the super capacitor and the storage battery, the overall economic cost is lower, when the voltage of the power grid rises temporarily, the super capacitor module and the corresponding bidirectional DC-DC module react rapidly, high-power energy is output in a short time, the reliable power supply of the device to sensitive load is ensured, and the storage battery module is prevented from working to ensure the service life of the storage battery; after the voltage of the end of the super capacitor module is lower than a threshold value after the duration of the voltage sag/rise of the power grid lasts for a period of time, the storage battery module and the corresponding bidirectional DC-DC module are put into operation and serve as main energy sources of the device, and the super capacitor module and the bidirectional DC-DC module are only responsible for stabilizing high-frequency fluctuation of the DC bus of the inverter, so that frequent charge and discharge of the storage battery module are avoided, and the service life of the storage battery is prolonged.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to those skilled in the art that other drawings can be obtained according to these drawings without inventive effort.
FIG. 1 is a schematic diagram of a abatement apparatus in accordance with an embodiment of the present invention;
FIG. 2 is a circuit topology of a abatement device in accordance with an embodiment of the present invention;
fig. 3 (a) and fig. 3 (b) are schematic circuit diagrams of the super capacitor unit series-parallel connection and the lithium battery pack parallel connection according to the embodiment of the invention;
FIG. 4 is a schematic diagram of a hybrid energy storage module according to an embodiment of the present invention;
FIG. 5 is a schematic view of the operation mode of the abatement apparatus according to the embodiment of the present invention
FIG. 6 is a schematic diagram of a passive filter according to an embodiment of the invention;
FIG. 7 is a cooperative control block diagram of the battery and supercapacitor according to an embodiment of the present invention when they are simultaneously involved in discharging;
FIG. 8 is a control block diagram of a harmonic/reactive abatement mode of an embodiment of the invention;
FIG. 9 is a control block diagram of a voltage compensation mode of an embodiment of the present invention;
FIG. 10 is a simulated waveform of a voltage compensation mode of an embodiment of the present invention;
FIG. 11 is a simulated waveform of a harmonic/reactive abatement mode of an embodiment of the invention;
fig. 12 is a simulation waveform of the super capacitor module according to the embodiment of the present invention, which maintains the constant voltage of the DC bus of the inverter module by charging and discharging the bi-directional DC-DC module.
Detailed Description
The following description of embodiments of the invention will be made with reference to the accompanying drawings and a voltage class 380V, with a capacity of 15kVA, it being evident that the examples described are only some, but not all, examples of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 1, the multifunctional electric energy quality management device based on the hybrid energy storage and the thyristors provided by the invention structurally comprises a hybrid energy storage module, a bidirectional thyristor module, an inversion module and a control module; the hybrid energy storage module comprises a super capacitor module, a storage battery module and a bidirectional DC-DC module, wherein the bidirectional DC-DC module is responsible for respectively connecting the storage battery module and the super capacitor module with a direct current bus of the voltage source type inverter; the bidirectional thyristor module consists of a bidirectional thyristor and a drive protection circuit, and the inversion module comprises a passive filter and a three-phase inverter;
specific embodiments of the components of the present invention are described below:
as shown in fig. 2, when the treatment device is applied to a three-phase four-wire system distribution network, a two-level capacitor split topology can be adopted, the midpoint of a direct current bus of an inversion module is connected with a system neutral line, a neutral point of a passive filter is connected with the system neutral line, and a software and hardware scheme is adopted to keep the voltage balance of the midpoint of the direct current bus.
The hybrid energy storage module is connected with a direct current bus of the inversion module in parallel, the bidirectional thyristor module is arranged between the power grid and the harmonic and/or sensitive load, the alternating current output end of the inversion module is connected between the bidirectional thyristor and the harmonic and/or sensitive load in parallel, and the input end of the bidirectional thyristor is connected with the system power supply. When the treatment device is in reactive power/harmonic wave/three-phase unbalanced compensation mode, the bidirectional thyristor is in a closed state, and when voltage sag/sag occurs, the bidirectional thyristor is forced to be turned off, and the inverter module supplies power to the load.
As shown in fig. 3, the super capacitor module in the hybrid energy storage module adopts a scheme of performing series-parallel connection on super capacitor monomers so as to improve the total capacity and terminal voltage of the super capacitor module, and the storage battery module is formed by connecting storage battery packs in parallel;
as shown in fig. 4, the capacity and power of the storage battery and the super capacitor in the hybrid energy storage module can be selected and configured according to the requirements of the embodiment, and the rated capacity of the embodiment is 15 kVA. According to the rated capacity provided by the embodiment, under the aim of ensuring reliable power supply for continuously supplying the sensitive load for 1 hour, the hybrid energy storage module can select three 'BMOD 0165P 048C 01' super capacitor modules produced by MAXWELL company in series to meet the power demand of 15kW output in a short time, and the capacity of the super capacitor module is limited, the electric quantity of the super capacitor module can only be maintained for about half a minute under the condition of continuously outputting 15kW power, so that the lead-acid storage battery module with high cost performance and stability and reliability is adopted to meet the energy demand of the treatment device for reliably supplying the sensitive load, and if the rated voltage is 48V, the storage battery module with the capacity of 400AH can support the load with the rated power of 15kW for more than 1 hour. From the aspects of cost and stability, if the storage battery of the hybrid energy storage module in the treatment device adopts a lead-acid storage battery, the advantages of lower price, larger capacity, support of floating charge and longer cycle life compared with a lithium battery can be obtained; and when the treatment device is applied to occasions with higher requirements on the occupied area, such as banks, the economy can be sacrificed, and the lithium battery with higher energy density is adopted to reduce the whole volume of the device.
As shown in fig. 5, when the abatement device works, analog-to-digital conversion (ADC) sampling is performed first, including the grid-side voltage, the load-side current, the super capacitor and battery terminal voltage in the hybrid energy storage module, the bidirectional DC-DC module current in the hybrid energy storage module, and the device temperature. Judging whether the electric energy quality problems such as voltage sag/sag and current harmonic/reactive power exist at the moment or not according to the collected load current and power grid voltage signals, and if the electric energy quality problems do not exist at the moment, enabling the device to be in a standby state; if the power quality problem exists at this time, the power quality problem is solved according to the priority of firstly solving the voltage quality problem, ensuring the normal power supply of the sensitive load and then inhibiting the current harmonic wave/reactive component at the load side. When the device is in an Uninterruptible Power Supply (UPS) mode and is responsible for solving the voltage quality problem, the bidirectional thyristor is forced to be turned off, the bidirectional DC-DC module transmits the energy of the super capacitor/storage battery to the DC side capacitor of the inverter, and a Digital Signal Processor (DSP) controller forms closed-loop control according to the voltage acquired by a load side and the inductance current acquired by a passive filter, so that the voltage stability of the load side is ensured; when the harmonic/reactive power management mode is in, the bidirectional thyristor is kept in a conducting state, the bidirectional DC-DC module is dynamically regulated to keep the voltage of the storage battery and the super capacitor within a rated range, when the voltage of the end of the hybrid energy storage module is normal, the bidirectional DC-DC module is kept in a blocking state to reduce energy loss, the DSP controller calculates reactive/harmonic components of current at the moment according to current collected by a load side and forms a control closed loop with inductance current collected by a passive filter, so that the management device outputs current with the same amplitude and opposite phase to the harmonic/reactive current at the moment, the harmonic content of power supply current is reduced, and the power factor of the system is improved.
As shown in fig. 6, to enable the passive filter in the inverter module to have the capability of voltage quality control and current quality control at the same time, an LCL filter may be selected, where the parameter design requirements are as follows:
(1) The switching subharmonic can be effectively inhibited;
(2) The control device can normally output low-order harmonic current in the harmonic control mode, so that compensation current output by the control device in the harmonic control mode can be counteracted with harmonic components in load current, harmonic components in power supply current are reduced, and the power factor of a power grid is improved;
(3) If the passive filter is an LCL filter, the inductance of the power grid side of the passive filter is not excessively large so as to limit the inductance voltage drop of the passive filter and ensure the voltage control precision of the treatment device in a voltage compensation mode.
Meanwhile, the LCL filter needs to adopt an active damping scheme as shown in fig. 6 (a) or a passive damping scheme as shown in fig. 6 (b) to ensure stability, and simultaneously collect the load side voltage u L And the device outputs a compensation current i c Closed loop control is performed.
As shown in fig. 7, when the voltage drop time is long so that the voltage at the end of the super capacitor drops too much, a scheme of co-charging and discharging the storage battery and the super capacitor should be adopted. The battery is not overcharged due to its limited cycle life, so that a high-frequency component of a given power value needs to be distributed to the supercapacitor module by means of a high-pass filter, and a low-frequency component of a given power value needs to be distributed to the battery module by means of a low-pass filter. The basic purpose of the control of the storage battery module is to stabilize the voltage of the direct-current bus terminal, and the maintenance management device provides long-time electric energy support, so that the basic control strategy selects closed-loop control of a voltage outer ring and a current outer ring; the basic purpose of the super capacitor module control is to respond to the high-frequency component of the target power of the hybrid energy storage module, so that the response speed is improved by adopting single-current loop closed-loop control. In this embodiment, the battery modules are connected in parallel by using the battery pack to increase the output power, so that the droop control is used to suppress the circulation.
As shown in fig. 8, when the abatement device is in the harmonic abatement mode, the load side current i is first of all applied to La,b,c Perform dq conversion and apply the dq axis component i thereto Ld,q Low-pass filtering to obtain DC component i on dq axis Ldf,qf If the current is subjected to dq inverse transformation, a fundamental component in the load current can be obtained; meanwhile, the direct-current side capacitor voltage of the treatment device is also regulated through a PI regulator on the d axis. The load current is subtracted from the fundamental component of the load current and the output of the PI controller corresponding to the DC capacitance voltage to obtain the current given value i of the treatment device in the harmonic treatment mode abcref The current which is subtracted from the current which is actually output by the treatment device at the moment is processed by a PI regulator to obtain a modulation signal; when the DSP has higher main frequency and stronger operation capability, the PI regulator can be replaced by a multiple PR controller under the condition of not changing the synchronous rotation coordinate system, and a plurality of synchronous rotation coordinate systems with different rotation frequencies can be set on the premise of only using the PI regulator so as to simultaneously inhibit current harmonics under a plurality of frequencies.
As shown in fig. 9, when the abatement device is in the UPS mode, the control accuracy is improved by adopting a dual closed loop control strategy of a voltage outer loop and a current inner loop, firstly, the dq-axis transformation is performed on the load side voltage, and the dq-axis transformation is compared with a preset given value of the dq-axis component of the load side voltage, after dq decoupling, a given value of the current inner loop is obtained, and a closed loop is formed by the given value and the current output by the abatement device through a PI controller.
As shown in the simulation waveforms of FIG. 10, the abatement device has a voltage sag at the gridThe response capability of falling time is that the power grid voltage u is in the period of 0 to 0.1s sa ,u sb ,u sc In a normal state, the bidirectional thyristor trigger signal is kept on, the power grid voltage is subjected to voltage sag in a time period of 0.1 to 0.2s, when the power grid voltage is subjected to sag, the treatment device is switched into a UPS mode, and at the moment, the energy of the hybrid energy storage module is transmitted to a load side through the bidirectional DC-DC module and the inverter to keep the load side voltage u La ,u Lb ,u Lc Constant.
As shown in the simulation waveform of fig. 11, the abatement device has harmonic/reactive abatement capability under the normal working condition of the power grid, and is in a harmonic abatement mode when the power grid voltage is in the normal working condition within the period of 0 to 0.1s, and the abatement device outputs the compensation current i ca ,i cb, i cc Suppressing load-side current i La ,i Lb ,i Lc Such that the supply current i sa ,i sb ,i sc The sine is kept, so that the power factor of the power grid is improved, and the loss is reduced.
As shown in the simulation waveform of fig. 12, when the 0.1s grid voltage drops, the direct current voltage u of the inversion module dc Rapidly drop to detect the DC bus voltage u dc After falling, the super capacitor and the corresponding bidirectional DC-DC module are put into operation, and the DC bus voltage u dc Quickly recover to a given value in a short time, and the super capacitor voltage u sc It is always in a slowly descending state. The bidirectional DC-DC module adopts complementary PWM modulation and works in a continuous conduction mode, and inductance current i of the bidirectional DC-DC module dc Is limited to a safe range due to the clipping effect of the PI controller.
In the description of the present specification, the descriptions of the terms "one embodiment," "example," "specific example," and the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims.
Claims (6)
1. The multifunctional electric energy quality management device based on the hybrid energy storage and the thyristors is characterized by comprising a hybrid energy storage module, a bidirectional thyristor module, an inversion module and a control module;
the bidirectional thyristor module is internally provided with a bidirectional thyristor, the bidirectional thyristor is positioned between a power grid and harmonic waves and/or sensitive loads, the hybrid energy storage module is connected with a direct current bus of the inversion module, the output end of the inversion module is connected between the bidirectional thyristor and the harmonic waves and/or sensitive loads in parallel, and the input end of the bidirectional thyristor is connected with a system power supply;
the hybrid energy storage module comprises a storage battery module, a super capacitor module and a bidirectional DC-DC module; the super capacitor module is formed by connecting super capacitor monomers in series and parallel, and the storage battery module is formed by connecting storage battery packs in series and parallel; the bidirectional DC-DC module is responsible for respectively connecting the storage battery module and the super capacitor module with a direct current bus of the voltage source type inverter;
the rated power and capacity of the storage battery module, the super capacitor module and the bidirectional DC-DC module are determined according to preset rated power and voltage interruption maximum compensation time;
the control method of the control module comprises the following steps:
s1: collecting signals of each sensor, including power grid side voltage, load side current, super capacitor and storage battery end voltage in the hybrid energy storage module, bidirectional DC-DC module current and device temperature;
s2: judging whether the electric energy quality problem exists at the moment according to the acquired signals, switching the working modes according to the sequence of solving the voltage quality problem and then the current quality problem, and switching the device into a standby state if the electric energy quality problem does not exist at the moment;
s3: when the control module detects the voltage quality problem, the bidirectional thyristor is forced to be turned off, the inversion module supplies power to the sensitive load reliably for a long time, and meanwhile, the hybrid energy storage module is controlled to maintain the constant voltage of the DC bus of the inversion module; when the duration time of voltage sag/sag is shorter, the direct current bus voltage of the inversion module is maintained to be constant only by the super capacitor module and the corresponding bidirectional DC-DC module, and the storage battery module does not participate in discharging; when the voltage sag/sag duration is longer and the end voltage of the super capacitor module is reduced to a certain threshold value, the storage battery module is used for discharging again and maintaining the DC bus of the inversion module constant, and when the end voltage of the hybrid energy storage module is lower than a certain safety threshold value, the device stops processing;
s4: when the control module of the device does not detect the voltage quality problem and only detects the current quality problem, the bidirectional thyristor is closed at the moment, the device works in a harmonic suppression/reactive power control or three-phase imbalance control mode, the voltage source type inverter outputs compensation current through the passive filter to offset harmonic/reactive power/imbalance components in load current, and meanwhile, the voltage of a bus at the direct current side of the inversion module is regulated;
under the harmonic wave and reactive power control mode, the control module judges the states of the bidirectional DC-DC module and the storage battery module in the hybrid energy storage module according to the sampling signal, and if the terminal voltages of the super capacitor module and the storage battery module are not in the rated range, the bidirectional DC-DC module is used for adjusting; if the super capacitor module and the storage battery module are restored to the rated range, locking the bidirectional DC-DC module;
s5: when the device is in an environment without the problem of power quality, the device is in a standby state, and the bidirectional thyristor is kept on, so that the normal power supply of a sensitive load is ensured;
when the storage battery participates in discharging and maintains the constant of the direct current bus of the inversion module, the given value of the power required to be output by the hybrid energy storage module is calculated, the low-frequency component of the given value of the power is used as the given value of the output power of the storage battery and the corresponding bidirectional DC-DC module, the control strategy of the voltage outer ring current inner ring is adopted to control the storage battery pack and the corresponding bidirectional DC-DC module, the high-frequency component of the given value of the power of the hybrid energy storage module is used as the given value of the output power of the super capacitor and the corresponding bidirectional DC-DC module, the response speed is improved through the control strategy of the single current ring, and the constant voltage of the direct current bus of the inversion module is maintained.
2. The multifunctional power quality management device based on the hybrid energy storage and the thyristors according to claim 1, wherein the bidirectional thyristor module is composed of the bidirectional thyristors and a driving protection circuit.
3. The multifunctional power quality management device based on hybrid energy storage and thyristors according to claim 1, wherein the inverter module comprises a three-phase inverter and a passive filter.
4. A multifunctional power quality management device based on hybrid energy storage and thyristors according to claim 3, wherein the passive filter is an LCL filter, and current and voltage sensors are installed on the passive filter and fed back to the control module.
5. The multifunctional power quality management device based on hybrid energy storage and thyristors according to claim 4, wherein the passive filter parameter design needs to consider the power grid side inductance voltage drop to ensure the effect of voltage compensation of the management device, and the passive filter adopts a passive damping or active damping scheme to ensure the stability of the LCL filter.
6. The multifunctional power quality control device based on the hybrid energy storage and the thyristor as claimed in claim 5, wherein the control module comprises a DSP control chip, a sampling circuit and a driving protection circuit, and is responsible for realizing a control algorithm and carrying out coordinated control on the inversion module, the hybrid energy storage module and the bidirectional thyristor module.
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