CN115632400A - Harmonic suppression method for satellite time service synchronous power distribution transformer area inverter - Google Patents
Harmonic suppression method for satellite time service synchronous power distribution transformer area inverter Download PDFInfo
- Publication number
- CN115632400A CN115632400A CN202211297520.4A CN202211297520A CN115632400A CN 115632400 A CN115632400 A CN 115632400A CN 202211297520 A CN202211297520 A CN 202211297520A CN 115632400 A CN115632400 A CN 115632400A
- Authority
- CN
- China
- Prior art keywords
- current
- synchronous
- voltage
- time service
- harmonic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000001360 synchronised effect Effects 0.000 title claims abstract description 65
- 230000001629 suppression Effects 0.000 title claims abstract description 49
- 238000000034 method Methods 0.000 title claims abstract description 43
- 238000011217 control strategy Methods 0.000 claims abstract description 16
- 230000005540 biological transmission Effects 0.000 claims abstract description 10
- 238000001914 filtration Methods 0.000 claims abstract description 8
- 238000004891 communication Methods 0.000 claims description 12
- 230000010354 integration Effects 0.000 claims description 6
- 238000004364 calculation method Methods 0.000 claims description 4
- 230000003068 static effect Effects 0.000 claims description 4
- 238000012545 processing Methods 0.000 claims description 3
- 238000012546 transfer Methods 0.000 claims description 3
- 230000000694 effects Effects 0.000 claims 1
- 238000001514 detection method Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 7
- 238000005259 measurement Methods 0.000 description 6
- 238000013461 design Methods 0.000 description 3
- 238000012795 verification Methods 0.000 description 3
- 230000033228 biological regulation Effects 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000000452 restraining effect Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
Images
Classifications
-
- 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
-
- 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
- H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
- H02J13/00004—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by the power network being locally controlled
-
- 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
- H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
- H02J13/00006—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment
- H02J13/00022—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment using wireless data transmission
-
- 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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
-
- 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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
-
- 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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/40—Synchronising a generator for connection to a network or to another generator
-
- 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
Abstract
A harmonic suppression method for an inverter of a satellite time service synchronous power distribution station belongs to the technical field of grid connection of power distribution stations. S1, connecting a microgrid in a power distribution area to a public bus; s2, acquiring the synchronous voltage and current state information of the whole station area by adopting Beidou satellite/GPS synchronous time service; s3, enabling phase angles of output currents of all DG units to be consistent based on a current synchronous control strategy; s4, the inverter performs high-frequency filtering by adopting an LCL filter and then is connected to a power grid/load; and S5, the microgrid control unit of the power distribution area is provided with a front communication software module for reading PMU transmission data. The invention can effectively inhibit system harmonic waves, improve the voltage waveform quality of a nonlinear load distribution area, effectively improve the operation efficiency of the grid-connected inverter, obtain stable and reliable output voltage, keep the Total Harmonic Distortion (THD) of the voltage below 3 percent and effectively improve the electric energy quality.
Description
Technical Field
A harmonic suppression method for an inverter of a satellite time service synchronous power distribution station belongs to the technical field of grid connection of power distribution stations.
Background
Renewable energy sources such as photovoltaic energy, wind energy and the like become important points for research and utilization of carbon emission reduction, and with the access of large-scale new energy sources, great challenges are brought to safe and stable operation of a power system and safe and stable operation of a power distribution area. Distributed Generation (DG) system composed of high-proportion new energy and inverters is low in inertia, and the problems that the power-angle stability, interconnection control of multiple regions is difficult to achieve, diversity loads are difficult to adapt and the like exist when a traditional phasor synchronous control strategy is adopted.
Because the distribution transformer area mainly comprises a photovoltaic power generation system, an energy storage system, wind power and a 100% inverter, and the initiative and the flexibility of a DG unit inverter are considered, a global uniform time coordinate can be constructed by using a Beidou satellite/GPS time service signal, a phase-locked signal in a voltage control loop is output by the inverter instead, a fixed frequency control method is formed, and the microgrid is enabled to run at a fixed frequency. The control strategy can adopt U-I (voltage-current) droop control or power-phase angle droop control, meanwhile, nonlinear loads can exist in a power distribution area, 6n +/-1 (n is a natural number) subharmonic currents are caused, and the existence of the harmonic currents can influence the U-I droop control and the distribution of active power and reactive power.
The method is characterized in that the synchronization fixed-frequency current control principle of an island operation microgrid is verified [ J ] through document Xuanquan, xuanbo, zhao Yangren, and the like, the automation of a power system is 2019,43 (15): 132-143, the distribution problem of active power and reactive power according to the inverter capacity proportion is realized by utilizing satellite time service signal synchronization and adopting I-U droop control, the power-angle stability problem is solved, and the output voltage of the system is seriously distorted in a nonlinear load state.
The method is characterized in that the method is based on the literature of Yangmuning, zhao Yangren Lei, wang Kui, and the like, a synchronous fixed-frequency microgrid control strategy based on no-difference voltage regulation U-I droop is researched [ J ] modern electronic technology, 2021,44 (21): 144-148, and the microgrid control strategy based on the U-I droop is adopted, so that the problems of active and reactive decoupling and power distribution among DG units of different transformer areas are effectively solved, but only simulation verification is carried out, and real experimental verification is not carried out.
The method comprises the following steps of (1) designing a U-I droop curve based on virtual resistors, and realizing reasonable distribution of power in DG units by adjusting the virtual resistors, wherein the control strategy is only suitable for low-voltage microgrid occasions.
The patent of Huangyue, the quality control of electric energy of microgrid with multiple inverters several key technical researches [ D ] Hunan university, 2016, and Huangyue, roan, wangyuan. A harmonic flexible control method of three-phase grid-connected inverter without harmonic detection [ J ] electrotechnical Committee, 2016,31 (24): 213-222), which proposes a control method of grid-connected inverter without harmonic current detection, but does not consider the problem of power distribution.
A new method for separating positive and negative sequence components of a base wave voltage during unbalanced network voltage and harmonic distortion [ J ] motor and control application, 2017,44 (10): 94-101, provides a U-I droop control strategy, eliminates frequency deviation, but still has voltage deviation.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method for restraining the harmonic waves of the satellite time service synchronous power distribution station inverter can effectively restrain system harmonic waves, improve the voltage waveform quality of a nonlinear load power distribution station and effectively improve the operation efficiency of a grid-connected inverter.
The technical scheme adopted by the invention for solving the technical problems is as follows: the harmonic suppression method for the satellite time service synchronous power distribution transformer area inverter is characterized by comprising the following steps: the method comprises the following steps:
s1, under the control of a fixed-frequency synchronous signal, a power distribution station micro-grid is connected to a public bus;
s2, synchronously measuring electrical information of DG units in different transformer areas by adopting Beidou satellite/GPS synchronous time service, and acquiring synchronous voltage and current state information of the whole transformer area;
s3, based on a current synchronization control strategy, enabling the phase angles of the output currents of the DG units to be consistent, and achieving the suppression of the circulation currents among the DGs in the transformer area;
s4, the inverter adopts an LCL filter to carry out high-frequency filtering, then is connected to a power grid/load, and a current double closed loop structure of an output current outer loop and a filtering capacitance current inner loop is adopted for harmonic suppression;
and S5, the microgrid control unit of the power distribution area is provided with a front communication software module for reading PMU transmission data.
Preferably, the step of acquiring the voltage and current state information of the whole cell synchronization is as follows:
s2.1, a voltage transformer and a current transformer respectively measure a voltage signal and a current signal of a DG unit to be measured;
s2.2, comparing the zero-crossing time of the voltage and current signals to be measured according to a unified time standard provided by the Beidou satellite/GPS, and obtaining a corresponding phase difference;
s2.3, acquiring synchronous phasor information of the measured voltage and current signals;
s2.4, the A/D converter converts the synchronous phasor information into a digital signal according to the synchronous signal and sends the digital signal to the microprocessor;
s2.5, obtaining corresponding amplitude and phase angle information of the voltage and the current after processing and calculation by the microprocessor;
s2.6, marking information with a time tag according to the Beidou satellite/GPS signal;
and S2.7, sending the synchronous data into a communication module to output the synchronous data to a corresponding external system and carrying out local control.
Preferably, the method further comprises referencing the d-axis current to a signal i qref Setting the value of =0 as a control target, and designing a current synchronous controller based on an integral closed-loop control idea as follows:
θ ref ＝k θ ∫(i qref -i q )dt；
wherein, theta ref Is the phase angle of the output voltage, k θ To output electricityPhase angle of pressure adjustment parameter, i qref Is the current reference value of the current loop dq axis, i q The dq-axis current component of the current is output for the cell unit DG 1.
Preferably, the method further includes that the active output power P of each DG unit in the transformer area is n And reactive power Q n Respectively as follows:
wherein, U PCC 、θ PCC Respectively the amplitude and phase angle of the voltage at the point of common connection, I n Is the output current amplitude of the DGn cell of the distribution substation area.
Preferably, the method further comprises, without considering the influence of the line impedance, the relationship between the droop coefficient and the current amplitude of each land area is as follows:
γ 1 I 1 ＝γ 2 I 2 ＝…＝γ i I i (i＝1,2,…n)；
wherein gamma is a U-I droop control coefficient.
Preferably, the method further includes setting a U-I amplitude droop control coefficient of each DG unit in the power distribution substation area according to the capacity of each DG unit in an inverse proportional relationship.
Preferably, the inner ring comprises a fundamental wave control branch and a harmonic suppression branch, the fundamental wave control branch adopts a PI regulator under a fundamental wave positive sequence two-phase dq rotation coordinate system, and the output current tracks the fundamental wave current without static error; an nth harmonic quasi-resonant controller is used to track the nth + -1 harmonic component without a dead-lag.
Preferably, the method further comprises the transfer function of the PI regulator is:
wherein k is p Is the proportionality coefficient, k, of a PI regulator i Is the integration time constant of the PI regulator,
representing the integration element.
Preferably, the method further comprises the step of the nth harmonic quasi-resonant controller:
wherein k is nr Is the resonant gain, ω nc Is the cut-off frequency, ω n Is the natural angular frequency.
Preferably, the method further comprises outputting a command signal I of the current harmonic suppression branch h Comprises the following steps:
wherein, I L The local load current is sensed for the sensor.
Compared with the prior art, the invention has the beneficial effects that:
according to the harmonic suppression method for the satellite time service synchronous power distribution transformer area inverter, double current inner loop control of output current and network access current is adopted, a PI regulator of a fundamental wave control branch circuit and an n-th harmonic quasi-resonance controller of a harmonic suppression branch circuit are respectively designed, a harmonic compensation mode and a harmonic suppression mode can be flexibly selected by a system according to the output capacity of the transformer area inverter, and therefore system harmonics can be effectively suppressed, the voltage waveform quality of a nonlinear load power distribution transformer area can be improved, and the operation efficiency of a grid-connected inverter can be effectively improved. No matter the grid-connected system of the power distribution area runs in full load or light load, and no matter the grid-connected system runs in a grid-connected mode or in an isolated island mode, stable and reliable output voltage can be obtained, the Total Harmonic Distortion (THD) of the voltage can be kept below 3%, and the quality of electric energy is effectively improved through the control strategy.
In order to solve the synchronous grid-connected operation and harmonic suppression of the power distribution area inverter, a voltage and current double-closed-loop control strategy of the power distribution area micro-grid inverter is designed based on a Beidou satellite/GPS synchronous time service and current synchronous U-I amplitude droop control scheme. In order to analyze the 26865 protocol special for the PMU, the microgrid control unit of the power distribution area is provided with a front communication software module for reading PMU transmission data. The consistency of output current phase angles of Distributed Generation (DG) in the transformer area is realized, and circulating currents among DG units in the transformer area are restrained. The synchronization of the output current of each DG unit and the grid-connected/isolated island stable operation of the output voltage are realized.
In order to solve the synchronous grid-connected operation and harmonic suppression of the inverter of the power distribution transformer area, a voltage and current double closed-loop control strategy of the micro-grid inverter of the power distribution transformer area is designed based on a Beidou satellite/GPS synchronous time service and current synchronous U-I amplitude droop control scheme, the consistency of output current phase angles of Distributed Generation (DG) of each transformer area is realized, and the circulation current among DG units of the transformer area is suppressed. In order to solve the problems of current tracking, harmonic detection, harmonic suppression and the like, a harmonic compensation and harmonic suppression strategy without harmonic detection is provided, a PI regulator of a fundamental wave control branch circuit and an n-order harmonic quasi-resonance controller of a harmonic suppression branch circuit are respectively designed by adopting double-current inner-loop control of output current and network access current, and the operation efficiency of a grid-connected inverter and the electric energy quality of a power distribution area are effectively improved.
Drawings
Fig. 1 is a structure diagram of a microgrid in a power distribution station area.
FIG. 2 is a structural block diagram of a PMU based on Beidou satellite/GPS synchronous time service.
Fig. 3 is a block diagram of current-synchronized U-I droop control.
Fig. 4 is a control block diagram of a harmonic-free detection current loop.
Fig. 5 is a general architecture diagram of preamble communication.
Fig. 6 is a communication flow chart.
Detailed Description
Fig. 1 to 6 show preferred embodiments of the present invention, and the present invention will be further described with reference to fig. 1 to 6.
The harmonic suppression method for the satellite time service synchronous power distribution transformer area inverter is characterized by comprising the following steps: the method comprises the following steps:
s1, under the control of a fixed-frequency synchronous signal, a power distribution station micro-grid is connected to a public bus;
s2, synchronously measuring electrical information of DG units in different transformer areas by adopting Beidou satellite/GPS synchronous time service, and acquiring synchronous voltage and current state information of the whole transformer area;
s3, based on a current synchronization control strategy, enabling the phase angles of the output currents of the DG units to be consistent, and achieving the suppression of the circulation currents among the DGs in the transformer area;
s4, the inverter adopts an LCL filter to carry out high-frequency filtering and then is connected to a power grid/load, and harmonic suppression adopts a current double closed loop structure of an output current outer loop and a filter capacitor current inner loop;
and S5, the microgrid control unit of the power distribution area is provided with a front communication software module for reading PMU transmission data.
Specifically, as shown in fig. 1, the distribution grid area microgrid architecture is composed of n distributed power Supplies (DGs) and corresponding loads thereof, wherein the DGs 1 and the DGs 2 \8230areadopted, and a DGn module is respectively composed of a primary side energy system (new energy or an energy storage device and the like), a direct current bus, a power electronic inverter and an LCL filter, and is connected to a Common bus (PCC) under the control of a fixed frequency synchronous signal to realize power supply or grid-connected operation of a local load.
Fig. 2 shows a PMU (phasor measurement unit) control block diagram based on the Beidou satellite/GPS synchronous time service, and a phase measurement device adopts the high-precision Beidou satellite/GPS synchronous time service to realize the synchronous measurement of electrical information of DG units in different transformer areas, obtain information such as the amplitude value and the phase angle of voltage and current of each node in the same time coordinate axis, and further obtain the state information of the voltage and current synchronized in the whole transformer area. By reading PMU measurement information of each node, the central controller of the distribution network of the distribution station can obtain the real-time state of the circuit of the whole distribution station without carrying out complicated load flow calculation, and the mode can greatly improve the reliability of the control of the distribution network of the distribution station and provide convenience for adjusting the running state of the DG unit in real time.
The steps of acquiring the synchronous voltage and current state information of the whole station area are as follows:
s2.1, a voltage transformer and a current transformer respectively measure a voltage signal and a current signal of a DG unit to be measured;
s2.2, comparing the zero-crossing time of the voltage and current signals to be measured according to a unified time standard provided by the Beidou satellite/GPS, and obtaining a corresponding phase difference;
s2.3, obtaining synchronous phasor information of the measured voltage and current signals;
s2.4, the A/D converter converts the synchronous phasor information into a digital signal according to the synchronous signal and sends the digital signal to the microprocessor;
s2.5, obtaining corresponding amplitude and phase angle information of the voltage and the current after processing and calculation by the microprocessor;
s2.6, marking information with a time tag according to the Beidou satellite/GPS signal;
and S2.7, sending the synchronous data into a communication module to output the synchronous data to a corresponding external system and carrying out local control.
Under the influence of the parameters of the transmission line, the phase angle deviation of the output current among the DG units of each transformer area can cause the occurrence of circulation, and the system operation efficiency of the microgrid of the transformer area and the power distribution among the DGs are influenced. To solve this problem, a current-synchronized U-I droop control strategy is proposed, as shown in fig. 3.
The control strategy mainly comprises three parts: the device comprises a voltage and current double closed-loop control part, a U-I amplitude droop control module and a current synchronization control module. Based on a current synchronization control strategy, the phase angles of the output currents of all DG units are consistent, the loop current among the DGs in the transformer area is suppressed, the power distribution among the DGs is effectively improved, and the system operation efficiency is improved. In FIG. 3, i d 、 i q A dq-axis current component of the output current for the unit DG1 of the transformer area; i all right angle C Is the capacitance current i 01 Is the output current of the DG1 cell; u. u 01 、U 01 Respectively DG1 no-load output voltage and amplitude thereof; u. of PCC Is the voltage of the connection point, gamma is the droop control coefficient of U-I, k θ For the output voltage phase angle adjustment parameter, theta ref 、U ref Reference values for phase angle and amplitude, u, of the output voltage, respectively dref 、 u qref Voltage reference value, i, of the voltage ring dq axis dref 、i qref Is an electric currentCurrent reference value of loop dq axis.
Since the phase angles of the output currents of the DG units are the same, that is, the phase angles of the output currents of the DG units are 0 with respect to the d-axis, the d-axis current reference signal iqref =0 is set as a control target, and a current synchronization controller designed based on an integral closed-loop control idea is as follows:
θ ref ＝k θ ∫(i qref -i q )dt； (1)
if the system operation state is instantaneously suddenly changed, i is enabled qref -i q Not equal to 0, then the current synchronization control loop will continuously adjust θ according to equation (1) ref Up to i q And =0. The DG units of each transformer area are synchronously timed by the Beidou satellite/GPS (global positioning system), namely the rise edge of the timing second pulse of the Beidou satellite/GPS is consistent with the d axis of the two-phase rotating dq coordinate system, so that the i of the DG units in the transformer area is consistent with the d axis of the two-phase rotating dq coordinate system q If =0, the output currents of the DG units can be synchronized.
After the system is stable, the phase angle of the output current of each DG unit in the transformer area is 0, and the active output power P of each DG unit in the transformer area can be obtained by assuming that the line loss is ignored n And reactive power Q n Respectively is as follows:
wherein, U PCC 、θ PCC Is the magnitude and phase angle of the voltage at the point of common connection, I n The output current amplitude of the DGn unit of the power distribution station area is known from the voltage vector relation, and the output power factor of the DG unit is consistent with the load power factor when the DG unit works in a steady state, so that the circulating current suppression is very favorable, and the power distribution among the DG units can be effectively improved. In addition, the current synchronization control module adopts an integral controller, has low-pass filtering characteristics, can effectively reduce the influence of harmonic current on a q axis of a rotating coordinate system on a phase angle reference signal, and effectively reduces the influence of reference signal fluctuation on output voltage distortion.
The U-I amplitude droop control module outputs a voltage amplitude U according to the DG no-load 01 And d-axis current amplitude is solved to obtain a voltage amplitude reference signal, so that stable operation of output voltage is ensured, and the output of each DG unit in the transformer area can be distributed in proportion according to the capacity of the DG unit. i.e. i q When =0, i d Namely, the amplitude of the power frequency component of the DG unit output current of the power distribution area, so that the power distribution area can be used for reducing the power frequency component of the DG unit output currentU-IThe amplitude droop control is designed as:
U ref ＝U 01 -γi d ； (3)
as can be seen from equation (3), if the U of each DG unit in the distribution area is equal to or greater than the U of the corresponding DG unit 01 Is completely identical, without considering the influence of line impedance, there are:
γ 1 I 1 ＝γ 2 I 2 ＝…＝γ i I i (i＝1,2,…n)； (4)
according to the formula (4), as long as each DG unit in the power distribution area sets the U-I amplitude droop control coefficient according to the capacity of the DG unit per se in an inverse proportion relation, the reasonable power sharing and the synchronous regulation of active power and reactive power can be realized.
Taking a DG1 unit in a distribution substation area as an example, a designed harmonic suppression system of a harmonic-free detection inverter is shown in fig. 4, wherein the inverter adopts an LCL filter for high-frequency filtering and then is connected to a power grid/load, and the harmonic suppression adopts an output current (or an in-grid current i) 1 ) Outer loop and filter capacitance current (i) C ) The current double closed loop structure of the inner loop. The inner ring is used for restraining peak resonance in the LCL and improving the reliability and stability of the DG unit, the composition of the network access current outer ring is different from that of a traditional harmonic detection circuit, and the inner ring is composed of two branches in parallel connection: fundamental wave control branch road and harmonic suppression branch road, this loop design 2 way input signal simultaneously: the output current fundamental wave control branch circuit only presents high gain at the output current fundamental wave frequency and presents limited gain at the output current harmonic wave frequency; the output current harmonic suppression branch is just opposite to the output current harmonic suppression branch. The ingenious design of the branch can realize current tracking and harmonic detection on the basis of not increasing a current sensor (or a mutual inductor).
In view of the design idea, the output current fundamental wave control branchThe PI regulator under a fundamental wave positive sequence two-phase dq rotation coordinate system is adopted, the output current can realize the non-static tracking of the fundamental wave current and the reference value I of the fundamental wave current f Given by the output of the voltage loop, the transfer function of the PI regulator is:
in the formula (5), k p Is the proportionality coefficient of PI regulators, k i Is the integration time constant of the PI regulator,
representing the integration element.
Under a fundamental wave positive sequence two-phase dq rotating coordinate system, three-phase positive sequence alternating current components of n +1 harmonic waves and three-phase negative sequence alternating current components of n-1 harmonic waves in network access current are converted into n harmonic wave alternating current components. Therefore, for the output current harmonic suppression branch, as long as the n-th harmonic quasi-resonance controller is adopted, the n +/-1 harmonic component can be tracked without static error, and the n-th harmonic quasi-resonance controller is as follows:
in the formula (6), k nr Is the resonant gain, ω nc Is the cut-off frequency, ω n When the natural angular frequency is n =6, the suppression of 5 th harmonic and 7 th harmonic in the output current of the DG inverter can be realized; when n =12, suppression of the 11 th harmonic and the 13 th harmonic in the DG inverter output current can be achieved; when n =18, the suppression of the 17 th harmonic and the 19 th harmonic in the DG inverter output current can be realized, and how 4 the control block diagram shows.
The selection switch in the figure can lead the system to flexibly select a harmonic compensation mode and a harmonic suppression mode according to the output capacity of the transformer area inverter, thereby effectively controlling the harmonic of the system.
Harmonic suppression mode of operation: when the DG inverter is operated in a full-load or heavy-load stateThe command signal I of the output current harmonic suppression branch circuit h The value is set to '0', so that the main subharmonic can be effectively inhibited, and high-quality current output can be realized.
Harmonic compensation mode of operation: when the DG inverter operates in a light load state, the local load current I can be detected through the sensor L Command signal I as output current harmonic suppression branch h And the compensation control of the local load harmonic current is realized.
In summary, the designed command signal I of the output current harmonic suppression branch h Comprises the following steps:
in order to analyze the 26865 protocol special for the PMU, the microgrid control unit of the power distribution area is provided with a front communication software module for reading PMU transmission data. The overall architecture of the front-end communication software is shown in fig. 5.
The front-end communication software receives the messages from the PMU substation through the network, analyzes the messages according to the protocol to obtain the measurement data collected by the PMU, stores the measurement data in the real-sequence library and provides data sources for WAMS advanced application, interface display, a third-party system and the like.
The prepositive communication software receives PMU data from the substation according to a data transmission protocol between the main station and the substation and a communication flow, analyzes PMU data messages, stores the PMU data messages into a time sequence library, and provides a function of inquiring data, messages and communication states. The communication flow is shown in fig. 6.
In the invention, the format of the communication message between the front-end communication module and the PMU is defined as follows:
the 2-byte data transmission byte order is: the upper 8 bits are interchanged with the lower 8 bits.
For example: UINT16 type, the original data in the controller is 0x0B0A, and the data received by the server is: 0x0A0B
The 4-byte data transmission byte order is as follows: for example: the data in the controller are: 0x0D0C 0B0A, and the server receives the data as follows: 0x0A0B 0C0D.
In the invention, data exchanged between the microgrid control unit and the PMU in the distribution station area mainly comprises electric quantities such as voltage amplitude and phase angle, current amplitude and phase angle, active power, reactive power and the like of each measuring point.
In the front-end communication module, the format and definition of the request message are shown in table 1. In the front-end communication module, the format and definition of the response message are shown in table 2.
TABLE 1 request message Format and Definitions
| Serial number | Definition of | Data type | Byte number | Description of the |
| 1 | Verification information | UINT16 | 2 | Default values are as follows: 0x0000+1 |
| 2 | Type of protocol | UINT16 | 2 | Default values are as follows: 0x0000 |
| 3 | Device address | UINT16 | 2 | The default value is as follows: 0x0001 |
| 4 | Function code | UINT16 | 2 | Default values are as follows: 0x0003 |
| 5 | Message length | UINT16 | 2 | Default values are as follows: 0x000A |
TABLE 2 response message Format and Definitions
The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention will still fall within the protection scope of the technical solution of the present invention.
Claims (10)
1. The harmonic suppression method for the satellite time service synchronous power distribution transformer area inverter is characterized by comprising the following steps: the method comprises the following steps:
s1, under the control of a fixed-frequency synchronous signal, a power distribution station micro-grid is connected to a public bus;
s2, synchronously measuring DG unit electrical information of different transformer areas by adopting Beidou satellite/GPS synchronous time service, and acquiring synchronous voltage and current state information of the whole transformer area;
s3, based on a current synchronization control strategy, enabling the phase angles of the output currents of the DG units to be consistent, and achieving the suppression of the circulation currents among the DGs in the transformer area;
s4, the inverter adopts an LCL filter to carry out high-frequency filtering, then is connected to a power grid/load, and a current double closed loop structure of an output current outer loop and a filtering capacitance current inner loop is adopted for harmonic suppression;
and S5, the microgrid control unit in the power distribution area is provided with a front communication software module for reading PMU transmission data.
2. The harmonic suppression method for the satellite time service synchronous distribution substation inverter according to claim 1, is characterized in that: the steps of obtaining the synchronous voltage and current state information of the whole station area are as follows:
s2.1, a voltage transformer and a current transformer respectively measure a voltage signal and a current signal of a DG unit to be measured;
s2.2, comparing the measured voltage and current signals with the zero-crossing time according to a unified time standard provided by the Beidou satellite/GPS, and obtaining a corresponding phase difference;
s2.3, acquiring synchronous phasor information of the measured voltage and current signals;
s2.4, converting the synchronous phasor information into a digital signal by the A/D converter according to the synchronous signal and sending the digital signal to the microprocessor;
s2.5, obtaining corresponding amplitude and phase angle information of the voltage and the current after processing and calculation by the microprocessor;
s2.6, marking information with a time tag according to the Beidou satellite/GPS signal;
and S2.7, sending the synchronous data into a communication module to output the synchronous data to a corresponding external system and carrying out local control.
3. The harmonic suppression method for the satellite time service synchronous distribution substation inverter according to claim 1, is characterized in that: the method further comprises referencing the d-axis current to a signal i qref Setting the value of =0 as a control target and based on the idea of integral closed-loop controlThe designed current synchronous controller comprises:
θ ref ＝k θ ∫(i qref -i q )dt；
wherein, theta ref Is the phase angle of the output voltage, k θ Adjusting parameters for the output voltage phase angle, i qref Is the current reference value of the current loop dq axis, i q The dq-axis current component of the current is output for the cell unit DG 1.
4. The harmonic suppression method for the satellite time service synchronous distribution transformer area inverter according to claim 3, characterized by comprising the following steps: the method also comprises the step that the active output power P of each DG unit in the transformer area n And reactive power Q n Respectively as follows:
wherein, U PCC 、θ PCC Respectively the amplitude and phase angle of the common node voltage, I n Is the output current amplitude of the DGn cell of the distribution substation area.
5. The harmonic suppression method for the satellite time service synchronous distribution substation inverter according to claim 4, is characterized in that: the method further includes, without considering the line impedance effect, the droop coefficient versus current magnitude for each land as follows:
γ 1 I 1 ＝γ 2 I 2 ＝…＝γ i I i (i＝1,2,…n)；
wherein gamma is a U-I droop control coefficient.
6. The harmonic suppression method for the satellite time service synchronous distribution transformer area inverter according to claim 1 or 5, characterized in that: the method also comprises the step that each DG unit in the power distribution area carries out U-I amplitude droop control coefficient setting according to the capacity of the DG unit per se in an inverse proportion relation.
7. The harmonic suppression method for the satellite time service synchronous distribution substation inverter according to claim 1, is characterized in that: the inner ring comprises a fundamental wave control branch and a harmonic suppression branch, the fundamental wave control branch adopts a PI regulator under a fundamental wave positive sequence two-phase dq rotating coordinate system, and output current does not have static tracking on fundamental wave current; an nth harmonic quasi-resonant controller is used to track the nth + -1 harmonic component without dead-beat.
8. The harmonic suppression method for the satellite time service synchronous distribution transformer area inverter according to claim 7, characterized in that: the method further comprises the transfer function of the PI regulator is:
wherein k is p Is the proportionality coefficient, k, of a PI regulator i Is the integration time constant of the PI regulator,
representing the integration element.
9. The harmonic suppression method for the satellite time service synchronous distribution transformer area inverter according to claim 7, characterized in that: the method further comprises the step that the nth harmonic quasi-resonance controller is as follows:
wherein k is nr Is the resonant gain, ω nc Is the cut-off frequency, ω n Is the natural angular frequency.
10. The harmonic suppression method for the satellite time service synchronous distribution transformer area inverter according to claim 1, characterized by comprising the following steps: the method also comprises outputting a command signal I of the current harmonic suppression branch h Comprises the following steps:
wherein, I L The local load current is sensed for the sensor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211297520.4A CN115632400A (en) | 2022-10-22 | 2022-10-22 | Harmonic suppression method for satellite time service synchronous power distribution transformer area inverter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211297520.4A CN115632400A (en) | 2022-10-22 | 2022-10-22 | Harmonic suppression method for satellite time service synchronous power distribution transformer area inverter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115632400A true CN115632400A (en) | 2023-01-20 |
Family
ID=84906770
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211297520.4A Pending CN115632400A (en) | 2022-10-22 | 2022-10-22 | Harmonic suppression method for satellite time service synchronous power distribution transformer area inverter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115632400A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117175665A (en) * | 2023-11-02 | 2023-12-05 | 深圳海辰储能科技有限公司 | Wave-transmitting synchronous system, method and related equipment for PCS (process control system) multi-machine parallel connection |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102142694A (en) * | 2011-03-18 | 2011-08-03 | 浙江大学 | Rotational coordinate transformation based current decoupling control method for three-phase grid-connected inverter |
| CN103560690A (en) * | 2013-11-07 | 2014-02-05 | 湖南大学 | Harmonic wave damping control method for one-phase LCL type grid-connected inverter |
| CN205484576U (en) * | 2015-11-05 | 2016-08-17 | 国网黄石供电公司运维检修部（检修分公司） | Nuclear phase testing arrangement that dead line is wireless |
| CN107482682A (en) * | 2017-09-14 | 2017-12-15 | 湖南大学 | Active filter and distributed power source cooperative control method under a kind of off-network pattern |
| CN108448630A (en) * | 2018-04-24 | 2018-08-24 | 上海电力学院 | The Z-source inverter grid-connected control method controlled based on monocycle and double-current ring |
| CN109599868A (en) * | 2018-11-28 | 2019-04-09 | 广州锐翔电力科技有限公司 | A kind of control system and method for active filter output electric current |
| CN111917131A (en) * | 2020-08-04 | 2020-11-10 | 西安热工研究院有限公司 | Harmonic suppression method for photovoltaic LCL grid-connected inverter based on PI and MPR |
| CN211979046U (en) * | 2020-01-15 | 2020-11-20 | 杭州北赫电力科技有限公司 | Grounding device shunting vector test system based on GPS and wireless synchronization technology |
| CN113036764A (en) * | 2021-03-08 | 2021-06-25 | 山东科汇电力自动化股份有限公司 | Synchronous fixed-frequency current control method based on virtual harmonic resistance |
| CN113839388A (en) * | 2021-11-29 | 2021-12-24 | 湖北工业大学 | Current double-loop control method of active power filter based on hybrid load |
-
2022
- 2022-10-22 CN CN202211297520.4A patent/CN115632400A/en active Pending
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102142694A (en) * | 2011-03-18 | 2011-08-03 | 浙江大学 | Rotational coordinate transformation based current decoupling control method for three-phase grid-connected inverter |
| CN103560690A (en) * | 2013-11-07 | 2014-02-05 | 湖南大学 | Harmonic wave damping control method for one-phase LCL type grid-connected inverter |
| CN205484576U (en) * | 2015-11-05 | 2016-08-17 | 国网黄石供电公司运维检修部（检修分公司） | Nuclear phase testing arrangement that dead line is wireless |
| CN107482682A (en) * | 2017-09-14 | 2017-12-15 | 湖南大学 | Active filter and distributed power source cooperative control method under a kind of off-network pattern |
| CN108448630A (en) * | 2018-04-24 | 2018-08-24 | 上海电力学院 | The Z-source inverter grid-connected control method controlled based on monocycle and double-current ring |
| CN109599868A (en) * | 2018-11-28 | 2019-04-09 | 广州锐翔电力科技有限公司 | A kind of control system and method for active filter output electric current |
| CN211979046U (en) * | 2020-01-15 | 2020-11-20 | 杭州北赫电力科技有限公司 | Grounding device shunting vector test system based on GPS and wireless synchronization technology |
| CN111917131A (en) * | 2020-08-04 | 2020-11-10 | 西安热工研究院有限公司 | Harmonic suppression method for photovoltaic LCL grid-connected inverter based on PI and MPR |
| CN113036764A (en) * | 2021-03-08 | 2021-06-25 | 山东科汇电力自动化股份有限公司 | Synchronous fixed-frequency current control method based on virtual harmonic resistance |
| CN113839388A (en) * | 2021-11-29 | 2021-12-24 | 湖北工业大学 | Current double-loop control method of active power filter based on hybrid load |
Non-Patent Citations (2)
| Title |
|---|
| 徐化博等: "孤岛微电网电流同步U-I下垂控制方法", 《电测与仪表》, pages 1 - 8 * |
| 黄媛等: "一种无谐波检测的三相并网逆变器谐波灵活控制方法", 《电工技术学报》, vol. 31, no. 24, pages 213 - 222 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117175665A (en) * | 2023-11-02 | 2023-12-05 | 深圳海辰储能科技有限公司 | Wave-transmitting synchronous system, method and related equipment for PCS (process control system) multi-machine parallel connection |
| CN117175665B (en) * | 2023-11-02 | 2024-01-26 | 深圳海辰储能科技有限公司 | Wave-transmitting synchronous system, method and related equipment for PCS (process control system) multi-machine parallel connection |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104836258B (en) | Microgrid control method having functions of voltage unbalance compensation and harmonic suppression | |
| Geng et al. | A novel low voltage ride through control method for current source grid-connected photovoltaic inverters | |
| CN105743091B (en) | A kind of double close-loop decoupling control method of Active Power Filter-APF | |
| CN101814893A (en) | Method for inhibiting stator current imbalance of doubly-fed wind turbine generator set | |
| CN108418231A (en) | A kind of mixing multiport railway power inverter and its power coordination control method | |
| CN115632400A (en) | Harmonic suppression method for satellite time service synchronous power distribution transformer area inverter | |
| Kong et al. | Phase-locked strategy of photovoltaic connected to distribution network with high proportion electric arc furnace | |
| Teng et al. | Review on grid-forming converter control methods in high-proportion renewable energy power systems | |
| Pan et al. | Stability comparison between grid-forming and grid-following based wind farms integrated MMC-HVDC | |
| Gupta et al. | Power quality assessment of a solar photovoltaic two-stage grid connected system: Using fuzzy and proportional integral controlled dynamic voltage restorer approach | |
| CN108512247A (en) | Photovoltaic virtual synchronous control method based on Lagrange's interpolation prediction | |
| Cao et al. | Research on PQ control strategy for PV inverter in the unbalanced grid | |
| Jiang et al. | A novel pre-synchronization control strategy for microgrid connections based on improved droop control | |
| CN111969650A (en) | Micro-grid improved droop control strategy based on power decoupling | |
| Babaei et al. | Voltage unbalance compensation based on optimal current injection by SSTs | |
| CN114744626A (en) | On-grid/off-grid seamless switching control method and device for renewable energy hydrogen production system | |
| Jiapei et al. | A Control Strategy for Single-phase Grid-Connected Inverter with Power Quality Regulatory Function | |
| Wang et al. | Strategy for the seamless mode transfer of an inverter in a master-slave control independent microgrid | |
| Chen et al. | Research of low voltage ride through control strategy in photovoltaic (PV) grid | |
| Jing et al. | Network topology and operation control of DC distribution network with AC DC converter | |
| Saifudheen et al. | A droop controller based active power sharing of parallel inverter islanded microgrid | |
| CN116094069B (en) | VSG parallel operation control strategy and system based on frequency voltage compensation | |
| Yang et al. | Research on fault ride-through control strategy for microgrid with wind farms and storages | |
| Wu et al. | Research on Harmonic Compensation Control Strategy Considering Capacity Limitation of PV Grid-connected Inverter | |
| CN203826981U (en) | Distributed generation connected controller |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |