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55 results about "Instantaneous power theory" patented technology
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The instantaneous power theory, or “the p-q theory,” makes clear the physical meaning of what instantaneous real and imaginary power is in a three-phase circuit. Moreover, it provides insight into how energy flows from a source to a load, or circulates between phases, in a three-phase circuit.
Microgrid inverter multi-loop control method based on virtual synchronous generator
ActiveCN105914778ARealize no static difference controlImprove voltage waveformSingle network parallel feeding arrangementsVirtual synchronous generatorSynchronous motor
The invention discloses a microgrid inverter multi-loop control method based on a virtual synchronous generator, and the method comprises power control of an outer loop and voltage current control of an inner loop. The power control of the outer loop comprises the following steps: measuring the three-phase voltage and current of an output side of an inverter, calculating active power and reactive power according to the instantaneous power theory, carrying out calculation and regulation through an active power-frequency equation, a reactive frequency equation, a torque inertia equation and an electromagnetic transient equation of a synchronous motor, obtaining the amplitude of an output voltage and a phase angle given value, and then carrying out modulation through voltage and current double loops. The method can achieve the non-corresponding control of voltage size and frequency well, outputs active and reactive power, can achieve precise manual control, and has the characteristics of V / F and PQ control. When a fault happens to a power grid, the method can simulate the primary modulation, primary voltage regulation and inertia characteristics of the synchronous generator, participates in the power grid adjustment, provides frequency and voltage support, and facilitates the stabilization of the power grid.
Owner:SOUTHEAST UNIV
Model prediction current control method based on NPC topology grid connected inverter under asymmetric voltage
ActiveCN105375804AGet the positive and negative sequence components directlyImprove tracking accuracyAc-dc conversionCapacitor voltageWeight coefficient
The invention discloses a model prediction current control method based on an NPC topology grid connected inverter under asymmetric voltage, introducing the model prediction current control technology into the NPC grid connected inverter control. The model prediction current control method disclosed by the invention comprises steps of introducing decoupling double synchronization reference coordinate system phase-locked loop (DDSRF-PLL) phase lock technology to perform tracking on a positive sequence voltage phase angle in order to accurately track the positive sequence voltage phase angle under the condition that the power system has the asymmetric fault, on the basis, utilizing the DDSRF-PLL to decouple to obtain fundamental frequency voltage positive and negative sequence components, realizing a model prediction current control with the inhibition of the negative sequence current component, the active power oscillation and the reactive power oscillation as the control goal by combining with a instantaneous power theory, and adding a weight coefficient item into a cost function in order to guarantee the capacitor voltage balance on the DC side of the NPC grid connected inverter in the control process. In the whole control process, the invention reduces the usage of the PI controller, enhances the responding speed of the system, and enables the two sides of the grid connected inverter to have higher electric energy quality and stability.
Owner:FUZHOU UNIV
Fault protection and ride-through control system and method for virtual synchronous machine
ActiveCN105978042AImprove anti-disturbance abilityImprove failure resilienceSingle network parallel feeding arrangementsAc network load balancingControl theoryPower system stabiliser
The invention discloses a fault protection and ride-through control system and method for a virtual synchronous machine. The fault protection and ride-through control method for the virtual synchronous machine comprises the following steps of measuring the three-phase voltage and current on the inverter output side, and calculating the active power according to an instantaneous power theory; if an asymmetric voltage drop fault occurs, extracting the voltage positive sequence component of the power grid to obtain a switching signal, and calculating the correction amount when the active power and the reactive power need to be output; if the voltage drop depth of the power grid exceeds a preset value, obtaining a supporting voltage through a power system stabilizer; and performing calculation and regulation through an active equation, a reactive equation, a torque inertia equation, and an electromagnetic torque equation to obtain the amplitude value and the phase angle setting value of the output voltage, and performing PWM modulation. According to the fault protection and ride-through control system and method, an energy storage unit is adopted for performing voltage-stabilizing control; and the direct bus voltage is stabilized while it is ensured that overcurrent does not occur, so that huge voltage fluctuation is avoided, and the performance degradation of the system is prevented.
Owner:SOUTHEAST UNIV
Photovoltaic grid-connected and electric energy quality management unified control strategy
ActiveCN105281368AIncrease profitReduce investmentSingle network parallel feeding arrangementsReactive power adjustment/elimination/compensationPower inverterPower flow
The invention discloses a photovoltaic grid-connected and electric energy quality management unified control strategy comprising the following steps that 1) photovoltaic component output is detected in real time, and the operation mode of a photovoltaic grid-connected system is adjusted; when the active grid-connected conditions are not met, the photovoltaic grid-connected system operates in an electric energy quality management mode, and when the active grid-connected conditions are met, the photovoltaic grid-connected system operates in an active grid-connected and electric energy quality management unified mode; and 2) when the photovoltaic grid-connected system operates in the active grid-connected and electric energy quality management unified mode, the photovoltaic grid-connected system allocates residual capacity of the photovoltaic grid-connected system according to priority of reactive power and harmonic compensation firstly and then integrates command current based on the instantaneous power theory. Compared with conventional methods, the photovoltaic grid-connected system is enabled to have a function of actively participating in power gird electric energy quality management on the basis of maintaining the original functions so that utilization rate of an inverter is enhanced, use of an electric energy quality management device is reduced and cost is saved.
Owner:CEEC JIANGSU ELECTRIC POWER DESIGN INST
Direct power prediction control method of three-level grid-connected inverter model
InactiveCN107104604ASmall amount of calculationReduce the required powerAc-dc conversionSingle network parallel feeding arrangementsThree levelPower inverter
The invention discloses a direct power prediction control method of a three-level grid-connected inverter model. The method comprises the following steps that 1) synthesis of three vectors is used in a three-level spatial vector modulation method, and an objective function is determined according to an instantaneous power theory and a direct power prediction control method; 2) a virtual vector is constructed, a large sector position where the virtual vector is positioned is determined, and a value of the virtual vector is calculated; 3) a small sector position where the virtual vector is positioned is determined; 4) action time of each of three vectors in the next switching period is calculated; and 5) and a switching sequence is determined according to balance of a mid-point voltage. The method is low in computational complexity, ripples of active and reactive power of the grid-connected inverter are low, the dynamic and static performances are high, and a harmonic wave inhibition effect is good.
Owner:SOUTH CHINA UNIV OF TECH
Control method for high-power reactive and harmonic dynamic hybrid compensation system
ActiveCN104362631AImprove robustnessHigh control precisionReactive power adjustment/elimination/compensationReactive power compensationEnvironmental resistanceHybrid logic
The invention discloses a control method for high-power reactive and harmonic dynamic hybrid compensation method. The hybrid compensation system comprises an SVG (static var generator), a TSF (thyristor switched filter) group and a controller, and the SVG and TSFs are parallelly connected to a grid. The three-phase current of the grid between the SVG and the TSFs is taken as a detection object, voltage and current values collected by sensors are processed through the controller, switching signals of the TSFs are acquired according to hybrid logic judgment, most of the reactive power of loads is compensated in a graded manner, and specific subharmonic is filtered out; control parameters of the SVG are acquired according to an instantaneous-power theory, and the surplus reactive power and harmonic of the loads are continuously compensated. A cost-effective scheme for rapid continuous compensation of the high-power reactive and harmonic is provided, impact of switching of passive equipment on the grid can be completely avoided, and harmonic current is avoided flowing to the grid, so that the control method is energy saving, emission reducing, green, environment friendly, good in social and economical effectiveness, wide in application range and especially applicable to the field of oil drilling.
Owner:江苏辰午节能科技股份有限公司
Method for controlling output current peak values of photovoltaic inverter during temporary asymmetric voltage drop
ActiveCN103956770ARealize grid-connected operation controlEliminate potential safety hazardsSingle network parallel feeding arrangementsPhotovoltaic energy generationCurrent limitingVoltage drop
The invention discloses a method for controlling output current peak values of a photovoltaic inverter during temporary asymmetric voltage drop, and belongs to the field of photovoltaic power generation control technology. The method comprises the steps of calculating the reference value of the output current of the photovoltaic inverter under the condition of temporary asymmetric voltage drop on the basis of an instantaneous power theory; calculating the output current peak values of the photovoltaic inverter and the possible maximum current peak value; putting forward the restrictive measures for the output current peak values according to a current peak value expression; designing an output current control structure of the photovoltaic inverter under the condition of the temporary asymmetric voltage drop. The method for controlling the output current peak values of the photovoltaic inverter during the temporary asymmetric voltage drop has the advantages that grid connection current control of the photovoltaic inverter during the temporary asymmetric voltage drop can be achieved effectively, the fact that the output currents of the photovoltaic inverter under the condition of the temporary asymmetric voltage drop cannot exceed the maximum current limiting value is guaranteed, and therefore the potential safety hazards brought to operation of a photovoltaic system by enlargement of the current peak values are eliminated.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING)
Fractional calculus-based PWM rectifier modeling method
InactiveCN105608266ATrue description of actual dynamic behaviorReflect the essential characteristicsSpecial data processing applicationsCapacitanceMathematical model
The invention discloses a fractional calculus-based PWM rectifier modeling method, and according to the method, a precise mathematic model of a single-phase PWM rectifier can be established on the basis of a fractional calculus theory and an instantaneous power theory defined by Caputo. The method comprises the following steps: firstly determining a voltage equation and a current equation of the single-phase PWM rectifier in a rest frame; defining and establishing a fractional order inductance equation and a fractional order capacitance equation of the single-phase PWM rectifier, and giving an input instantaneous power equation and an output instantaneous power equation of the single-phase PWM rectifier; and finally giving a direct-current component equation and an alternating-current component equation in an input instantaneous power and an output instantaneous power, and verifying the precision of the fractional calculus-based single-phase PWM rectifier fractional order model established on the basis of numerical simulation. According to the method, the fact that the capacitance and inductance are fractional orders in essence is considered in the modeling process, so that the modeling precision of the single-phase PWM rectifier.
Owner:HENAN POLYTECHNIC UNIV
Current mode inverting control strategy for inhibiting current harmonic waves and three phase imbalance in micro grid
ActiveCN104201679AMeet the output requirementsGovernance of power quality problemsPolyphase network asymmetry elimination/reductionPolyphase network asymmetry reductionHarmonicPower theory
The invention discloses a current mode inverting control strategy for inhibiting current harmonic waves and three phase imbalance in a micro grid. The current mode inverting control strategy for inhibiting the current harmonic waves and the three phase imbalance in the micro grid includes: superposing d axis and positive sequence voltage of a load for Park transformation based on a traditional instant power theory so as to measure a harmonic current of the load; obtaining fundamental voltage of the load and fundamental voltage of a micro source inverter output port, which are equal to each other due to the fact that load is connected with a micro source side in parallel; accordingly, adding a micro source power control link based on harmonic detection control, and enabling a detected current signal to contain a power current signal output by a micro source; enabling an inverter output current to track the current signal through current hysteresis control, and thereby meeting output requirements of the micro source, and managing power quality problems in the micro grid.
Owner:STATE GRID CORP OF CHINA +2
Power-current coordination control method for virtual synchronous generator under unbalanced power grid
ActiveCN108964040AGuaranteed uptimeRealize coordinated controlPower oscillations reduction/preventionVirtual synchronous generatorNew energy
The invention relates to a power-current coordination control method for a virtual synchronous generator under an unbalanced power grid, and belongs to the field of new energy power generation. The method calculates a negative sequence current reference value in a static coordinate system according to the instantaneous power theory, and establishes a unified analytical expression of three controltargets of constant active, reactive and current balance to realize the power-current coordination control of the virtual synchronous generator under the unbalanced power grid. The problems such as power oscillation and current imbalance under the unbalanced power grid can be solved, and the system performance is improved. The method does not need complicated trigonometric function calculation, has small calculation amount and a simple control structure, and can realize corresponding control objectives according to different requirements of the power grid.
Owner:HENAN POLYTECHNIC UNIV
Method for additional function control for modularized multilevel current converter
InactiveCN103730898AReduce Harmonic PollutionImprove power qualityActive power filteringAc-dc conversionHarmonicClosed loop
The invention discloses a method for additional function control for a modularized multilevel current converter. The method comprises the steps that alternating voltages and alternating currents at the load side are collected; based on the instantaneous power theory, a harmonic current instantaneous value at the load side is calculated; a harmonic current instantaneous calculation value is adjusted by a closed loop so that an additional control voltage order can be obtained; the additional control voltage order and the power control voltage order are added together to serve as a voltage control order of the modularized multilevel current converter; alternating voltages and alternating currents at the load side are collected again. Under the condition that a filter device is not additionally arranged, harmonic pollution, caused by a harmonic source, of a connected alternating current system is effectively reduced, the power grid power quality is improved, and the stability and the quality of the system are improved.
Owner:ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD +1
Integrated flexible arc extinguishing method of single-phase grounding fault of power distribution network
ActiveCN111130088AAchieve independent controlImprove utilization efficiencyReactive power adjustment/elimination/compensationEmergency protective arrangements for limiting excess voltage/currentControl theoryElectric power
The invention relates to an integrated flexible arc extinguishing method of a single-phase grounding fault of a power distribution network. Multiple functions of arc extinguishing of the single-phasegrounding fault of the power distribution network, active power and reactive power control of a load and the like are realized by using multi-level converter integration. Independent control of activepower, reactive power and zero-sequence power is achieved through current decoupling control under a rotating coordinate system. The control of the active power and the reactive power of the load isrealized by utilizing an instantaneous power theory, and the control of zero-sequence power is realized by a flexible arc extinguishing algorithm of the single-phase grounding fault. For problems thatan existing active arc extinguishing device is single in function; and cost performance is low due to high cost, in the invention, the same set of power electronic equipment has the multiple functions of active power control, reactive power control, single-phase grounding fault arc extinguishing and the like, utilization efficiency of the power electronic equipment is greatly improved, capacity expansion is easy, and dispersion localization of grounding fault arc extinguishing and reactive power compensation can be realized.
Owner:FUZHOU UNIV
Prediction control method of constant switch frequency model of tri-level grid connected inverter
InactiveCN106972773ASmall amount of calculationReduce the required powerAc-dc conversionSingle network parallel feeding arrangementsReference vectorHarmonic mitigation
The invention discloses a prediction control method of a constant switch frequency model of a tri-level grid connected inverter. The method comprises following steps of firstly, adopting tri-vector synthesis in a tri-level space vector modulation method, and determining a target function according to a transient power theory and a direct power prediction control method; step 2, according to the target function, taking the smallest value to determine a small section position where a reference vector is located; step 3, calculating respective action time of three vectors in one switch period; and step 4, according to central point voltage balance, determining a switch sequence. According to the invention, calculated amount of power control of the tri-level grid connected inverter can be greatly reduced; ripple waves of active power and reactive power of the grid connected inverter are reduced; better dynamic and static performance is achieved; constant switch frequency can be achieved; and good harmonic wave inhibition effects are achieved.
Owner:SOUTH CHINA UNIV OF TECH
On-line diagnosis method for turn-to-turn short circuit fault of double redundancy permanent magnet synchronous motor coil
ActiveCN108566131AElectronic commutation motor controlAC motor controlPermanent magnet synchronous motorEngineering
The invention discloses an on-line diagnosis method for a turn-to-turn short circuit fault of a non-electromagnetic coupling low-thermal coupling double redundancy permanent magnet synchronous motor coil among each winding based on an instantaneous power principle. When a coil turn-to-turn short circuit of a certain set of three-phase winding occurs, corresponding equivalent resistance, equivalentinductance and equivalent induction electromotive force of the phase where the fault coil is located change, fault winding parameters are differed from normal three-phase winding parameters when 3 / 2static coordinate system switching is conducted, currents of the two three-phase winding are almost the same, and therefore the situation where instantaneous active power or instantaneous reactive power is consumed by the fault three-phase winding is differed from the normal three-phase winding. According to the method, the motor is in a braking state or an electric state, the absolute value and the average value of the difference of the instantaneous active power or the difference of the instantaneous reactive power of the two windings, whether the absolute value or the average value is positive or negative and the forward or reverse rotation state of a motor within the latest limited sampling control periods are calculated in real time to judge coil turn-to-turn short circuit fault occurs on which three-phase winding on line.
Owner:TIANJIN UNIV
PWM rectifier model prediction method and device based on fixed vector synthesis
ActiveCN106329967AEasy to controlImprove versatilityAc-dc conversionVoltage vectorMathematical model
The invention discloses a PWM rectifier model prediction method and device based on fixed vector synthesis. According to a mathematical model and an instantaneous power theory of a rectifier, complex power Sk at the k moment, a complex power prediction value Sk+1 at the k+1 moment and a complex power reference value Sref are solved; according to the complex power prediction value Sk+1 and the complex power reference value Sref, a reference voltage vector vref is obtained; according to the reference voltage vector vref, SVPWM duty cycle information is obtained through prediction and control of a PWM rectifier model using fixed vector synthesis, and action time tx of a non-zero vector Vx and action time t0'' of a zero vector V0' of a double-vector method are obtained; according to the action time tx of the non-zero vector Vx and the action time t0'' of the zero vector V0', a drive signal of each switch tube of the whole rectifier is constructed. Thus, the method and device do not need a lot of enumeration calculation processes, is based on fixed vector synthesis SVPWM and has the function of freely switching between SVPWM and double vectors.
Owner:NORTH CHINA UNIVERSITY OF TECHNOLOGY
Voltage source-type energy storage micro grid power quality improvement predictive control method
ActiveCN105826922AImprove power qualityImprove voltage stabilityAc network voltage adjustmentReactive power compensationVoltage sourceEnergy storage
The invention relates to a voltage source-type energy storage micro grid power quality improvement predictive control method. The energy storage system serves as an important part of the micro grid, and research on multiple usages of the energy storage system in the micro grid plays an important role in improving the utilization efficiency. On the basis of analyzing the feasibility of using voltage source-type energy storage to realize harmonic current compensation, a multiple predictive control method of improving micro grid voltage and frequency dynamic stability and compensating the harmonic current by the energy storage system is researched. Firstly, based on an ip-iq detection method for the harmonic current and an instantaneous power theory and in combination with a GM (1,1) gray model, a comprehensive instruction current compensation predictive method for multifunctional control of the energy storage device is researched and realized; then, based on a dynamic model for voltage source-type converter output current, through building an optimal switch selection function for the converter, a predictive control strategy for tracking the comprehensive instruction current based on the optimal switch mode is provided for an energy storage system grid-connected converter; and finally, effectiveness of the provided switch control strategy is verified.
Owner:WUHAN UNIV
Three-level active power filter (APF) reference current detection method suitable for distorted or unbalanced situation
InactiveCN104122432AGood compensation characteristicsGuaranteed to workCurrent/voltage measurementThree levelReference current
The invention discloses a three-level active power filter (APF) reference current detection method suitable for a distorted or unbalanced situation, relates to the field of three-level parallel APF reference current detection under a power grid distorted or unbalanced situation, and solves the problem of low detection accuracy of the APF reference current detection method based on an instantaneous power theory under the non-sine or unbalanced situation of power grid voltage. The method is used for performing resonant current separation. The detection method can run effectively in an alpha-beta coordinate system under a voltage distorted or unbalanced situation, and high compensation characteristic is realized for an APF. Based on a high-selectivity filter (HSF), the method can be applied to a distorted or unbalanced power grid environment, and resonant compensation and power factor correction can be effectively performed through the APF, thereby increasing the reference current detection accuracy and ensuring that the power grid current and the power grid voltage are at the same phase. The method is suitable for detecting the reference current of a three-level APF under a distorted or unbalanced situation.
Owner:哈尔滨同为电气股份有限公司
Selection analysis method for equivalent capacitance at DC side of UPFC (Unified Power Flow Controller)
The invention provides a selection analysis method for equivalent capacitance at the DC side of a UPFC (Unified Power Flow Controller), which explains a relation between the active power flowing through a series-side converter and the power of a line inductor in the transient process of UPFC power flow control. Certain active power transmission is generated in the UPFC in the power flow control, the parallel-side capacity can be low when a DC-side capacitor provides transient power and the parallel side only provides steady-state power; and the capacity of a parallel-side converter should comprise the sum of the transient and steady state power in order to stabilize the DC-side voltage. Therefore, the selection analysis method provides a basis for capacitance selection analysis for the UPFC.
Owner:JIANGSU ELECTRIC POWER CO +2
Multi-vector fast model predictive control method under non-ideal power grid condition
ActiveCN110297446AReduce computational complexityCalculation speedProgramme controlComputer controlVoltage vectorCapacitor voltage
The invention provides a multi-vector fast model predictive control method under a non-ideal power grid condition. The three-phase voltage on the grid side, the three-phase current on the grid side and the capacitor voltage on the direct-current side are collected, and the abc coordinate system of the three-phase voltage on the grid side and the three-phase current on the grid side is converted into an alpha-beta coordinate system through Clarke conversion, so as to obtain the voltage and the current under a two-phase static coordinate system; a grid side complex power vector is defined basedon the instantaneous power theory; derivation conducting is carried out on the grid side complex power vector; derivation conducting is carried out by taking a negative conjugated complex power vectoras a control variable; discretizing is carried out on the formula of the change rate of the negative conjugated complex power vector, and the power error is obtained; the phase angle and the amplitude value of the error vector caused by the zero voltage vector are calculated; the power size needing to be compensated is calculated; and the action time under each voltage vector is calculated separately, and the operation of a PWM rectifier is controlled under a non-ideal power grid condition according to a switch signal. The method disclosed by the invention has the advantages that the calculation complexity is relatively low, the calculation speed is relatively high, and the control precision is high.
Owner:WUHAN UNIV
Multi-loop control method of microgrid inverter based on virtual synchronous generator
ActiveCN105914778BRealize no static difference controlImprove voltage waveformSingle network parallel feeding arrangementsVirtual synchronous generatorMulti loop control
Owner:SOUTHEAST UNIV
Direct power boundary control method based on three-phase three-throw two-level rectifier
The invention relates to a direct power boundary control method based on a three-phase three-throw two-level rectifier. A mathematical model of the three-phase three-throw two-level rectifier in a two-phase synchronous rotating coordinate system is established; a power model of the rectifier in the rotating coordinate system is established by combining an instantaneous power theory and a voltage orientation principle; a standard phase plane is established by taking the DC side voltage as the transverse axis and the AC side current as the longitudinal axis, and change of a natural trajectory ofthe rectifier when the AC-side current of the rectifier is decreased and increased in the standard phase plane is analyzed; and on the basis of the power amount, a boundary control condition is usedto crease novel direct power control, a natural switching side of boundary control is selected by taking the natural trajectory of the rectification system, when the AC-side current is decreased and increased, as basis, the natural switching side is used to update output rule of direct power control in a power hysteresis comparator, and finally a direct power boundary control method is obtained. The dynamic performance in the DC side of the three-phase three-throw two-level rectifier can be improved effectively aimed at the abrupt load change in practical application.
Owner:CHINA THREE GORGES UNIV
Zero-dynamic DC output voltage control method and system of current source converter
ActiveCN111181428AImprove the quality of power supplyAchieve zero dynamic adjustmentAc-dc conversionAc network voltage adjustmentSource transformationSmall-signal model
The invention discloses a zero-dynamic DC output voltage control method and system of a current source converter. According to the invention, a power grid voltage feedforward control item and a DC side output current feedforward control item are effectively calculated through the instantaneous power theory, the small signal model analysis, the superposition theorem and other methods; the zero-dynamic DC output voltage control method of the current source converter is provided on such basis, and by adopting the DC output voltage and power grid voltage feedforward control technology, the methodcan realize stable DC output voltage, and can realize zero-dynamic adjustment of the output voltage under the condition that the power grid voltage fluctuates; furthermore, no matter under the condition of balanced drop or unbalanced drop of the power grid voltage, zero dynamic adjustment of the DC output voltage can be realized by adopting the method, the power supply quality of the current source converter is effectively improved, and the method is simple in implementation process and has a great practical engineering application value.
Owner:YANSHAN UNIV
Control method with fault diagnosis and automatic restoration function for hybrid compensation system
ActiveCN105071391AImprove robustnessReduce post-maintenance costsReactive power adjustment/elimination/compensationReactive power compensationHarmonicEconomic benefits
The invention discloses a control method with fault diagnosis and automatic restoration functions for a hybrid compensation system. According to the control method for the hybrid compensation system, power grid three-phase currents between an SVG and a TSF group as well as output three-phase currents of the TSF group are regarded as detection objects, voltage and current values acquired by sensors are processed through a controller, the TSFs are controlled to compensate most of reactive power of a load in a graded manner and filter out specific subharmonic waves by using a diagnostic control module, when one of the TSFs fails, the faulty TSF is diagnosed and cut off automatically, and the normal TSFs are reconfigured on demand and put into service, so that the hybrid compensation system has the automatic restoration function; in addition, control parameters of the SVG are obtained according to an instantaneous power theory, so as to achieve continuous compensation of residual reactive power and harmonic waves of the load. The control method ensures stable and reliable operation of the hybrid compensation system in normal and fault states of the TSFs, greatly increases system operating efficiency, and reduces system later-stage maintenance cost. The control method for the hybrid compensation system saves energy, reduces emission, is green and environmentally friendly, has good social and economic benefits, and is particularly suitable to be used in the petroleum drilling field with high damage rate of the TSF due to harsh environment.
Owner:江苏辰午节能科技股份有限公司
A control method for a high-power reactive power and harmonic dynamic hybrid compensation system
ActiveCN104362631BImprove robustnessHigh control precisionReactive power adjustment/elimination/compensationReactive power compensationHybrid logicEngineering
The invention discloses a control method for high-power reactive and harmonic dynamic hybrid compensation method. The hybrid compensation system comprises an SVG (static var generator), a TSF (thyristor switched filter) group and a controller, and the SVG and TSFs are parallelly connected to a grid. The three-phase current of the grid between the SVG and the TSFs is taken as a detection object, voltage and current values collected by sensors are processed through the controller, switching signals of the TSFs are acquired according to hybrid logic judgment, most of the reactive power of loads is compensated in a graded manner, and specific subharmonic is filtered out; control parameters of the SVG are acquired according to an instantaneous-power theory, and the surplus reactive power and harmonic of the loads are continuously compensated. A cost-effective scheme for rapid continuous compensation of the high-power reactive and harmonic is provided, impact of switching of passive equipment on the grid can be completely avoided, and harmonic current is avoided flowing to the grid, so that the control method is energy saving, emission reducing, green, environment friendly, good in social and economical effectiveness, wide in application range and especially applicable to the field of oil drilling.
Owner:江苏辰午节能科技股份有限公司
A predictive control method for voltage source energy storage to improve the power quality of microgrid
ActiveCN105826922BImprove power qualityImprove voltage stabilityAc network voltage adjustmentReactive power compensationMicrogridPredictive methods
The invention relates to a voltage source-type energy storage micro grid power quality improvement predictive control method. The energy storage system serves as an important part of the micro grid, and research on multiple usages of the energy storage system in the micro grid plays an important role in improving the utilization efficiency. On the basis of analyzing the feasibility of using voltage source-type energy storage to realize harmonic current compensation, a multiple predictive control method of improving micro grid voltage and frequency dynamic stability and compensating the harmonic current by the energy storage system is researched. Firstly, based on an ip-iq detection method for the harmonic current and an instantaneous power theory and in combination with a GM (1,1) gray model, a comprehensive instruction current compensation predictive method for multifunctional control of the energy storage device is researched and realized; then, based on a dynamic model for voltage source-type converter output current, through building an optimal switch selection function for the converter, a predictive control strategy for tracking the comprehensive instruction current based on the optimal switch mode is provided for an energy storage system grid-connected converter; and finally, effectiveness of the provided switch control strategy is verified.
Owner:WUHAN UNIV
Current limiting method suitable for grounding fault in alternating-current microgrid
InactiveCN112086953AIncrease asymmetryHarmonic reductionEmergency protective arrangements for limiting excess voltage/currentAc network circuit arrangementsMicrogridLoop control
The invention relates to a current limiting method suitable for a grounding fault in an AC microgrid. The method comprises the following steps of S1, improving the design of optimal parameters of droop control, constructing a Bode diagram according to a droop control transfer function equation containing a washout filter, and selecting optimal parameters through simulation comparison; S2, an instantaneous power theory being improved, specifically, based on the fact that a traditional instantaneous power theory is only suitable for a single-phase earth fault, the instantaneous power theory containing a double rated current amplitude limiting link being constructed, wherein the instantaneous power theory can be suitable for a two-phase earth fault and a three-phase earth fault; S3, voltage and current double-loop control, utilizing the static error-free tracking performance of a quasi-PR controller, and utilizing quasi-PR control to realize accurate tracking of reference voltage by an outer loop; aiming at a problem that traditional passive control is greatly influenced by parameter disturbance, an inner loop adopts improved passive control to realize accurate tracking of filter inductance current, and voltage and current control is carried out on a converter in a microgrid in combination with an SPWM modulation algorithm. Compared with the prior art, the method has the advantages of being good in fault current asymmetry degree, high in fault recovery speed and the like.
Owner:STATE GRID HEBEI ELECTRIC POWER CO LTD +2
MMC AC side near-end asymmetric fault short-circuit current calculation method
PendingCN114268120AEmergency protective circuit arrangementsElectric power transfer ac networkMathematical modelAC - Alternating current
The invention provides an MMC alternating-current side near-end asymmetric fault short-circuit current calculation method. The method comprises the steps that alternating-current voltage and current at a PCC are decomposed into positive-sequence dq-axis components and negative-sequence dq-axis components through a phase sequence separation module; calculating real-time active power and reactive power transmitted by the MMC when an asymmetric fault occurs according to an instantaneous power theory; judging the type of a power outer loop controller, calculating a positive sequence dq-axis current instruction value, and converting the positive sequence dq-axis current instruction value into a positive sequence dq-axis current instruction value and a negative sequence dq-axis current instruction value; according to the MMC mathematical model of the positive and negative sequence dq-axis components and the mathematical model of the positive and negative sequence decoupling inner loop current controller, solving a transfer function of the positive and negative sequence current output by the MMC and the instruction value of the positive and negative sequence dq-axis current; and calculating the short-circuit current fed into the short-circuit point by the MMC according to the positive and negative sequence current. According to the method, reference is provided for MMC controller parameter setting and alternating current system relay protection parameter setting, and the method can be used for analyzing the active power and reactive power characteristics of MMC transmission after an asymmetric fault occurs on the near-end alternating current side of the MMC.
Owner:STATE GRID FUJIAN POWER ELECTRIC CO ECONOMIC RES INST
Comprehensive control method for micro-grid power fluctuation stabilization and electric energy quality treatment based on energy storage converter
PendingCN114884058ASolve the problem of working mode switchingImprove dynamic response performanceElectric power transfer ac networkSingle network parallel feeding arrangementsElectrical batteryGrid based
The invention discloses a comprehensive control method for power fluctuation stabilization and electric energy quality treatment of a micro-grid based on an energy storage converter, and the method comprises the steps: firstly, calculating the power of a grid-connected point based on an instantaneous power theory according to two output modes of power fluctuation stabilization and electric energy quality treatment of the energy storage converter; a main and auxiliary mode switching control strategy of the energy storage converter is determined by comparing the power required by the local load and the energy storage residual power; in order to prolong the service life of the energy storage system, an energy storage capacity distribution strategy based on reactive power / harmonic wave / three-phase imbalance priority is also provided, compensation priorities are set for three electric energy quality problems existing in the micro-grid, and the electric energy quality problem with a higher compensation level is preferentially compensated according to the residual capacity of the energy storage system. According to the invention, an energy storage converter main and auxiliary mode switching control strategy and a reactive / harmonic / three-phase unbalanced priority energy storage capacity distribution strategy are effectively combined, the problems of grid connection and electric energy quality of a micro-grid are greatly improved, and the operation economy of an energy storage battery is improved.
Owner:STATE GRID HENAN ELECTRIC POWER ELECTRIC POWER SCI RES INST
Three-level PWM (Pulse-Width Modulation) rectifier direct power control method
InactiveCN102545665BEliminate reactive power uncontrollable areasEasy to analyzeAc-dc conversionThree levelMathematical model
The invention discloses a three-level PWM (Pulse-Width Modulation) rectifier direct power control method, which comprises the following steps of: deducing an instantaneous power control model of a rectifier by utilizing a high frequency mathematical model and an instantaneous power theory of the three-level rectifier; substituting basic vectors corresponding to 27 groups of switch statuses of a three-level converter into the instantaneous power control model, and carrying out normalization to obtain formulas of active power variation rate and reactive power variation rate under the action of the basic vectors; calculating the active power variation rate and the reactive power variation rate corresponding to each basic vector in a whole vector space, and classifying basic vectors according to the types of the vectors, the active and the reactive power variation trends and the variation rates; and quantizing the reactive power variation rate needed to be tracked into two levels, quantizing the active power variation rate into four levels, and building a switch list controlled by rectifier direct power. The method can realize network side unit power factors, quickly stabilize direct current bus voltage and balanced midpoint potential, and is more effective for fast tracking the instantaneous active power and reactive power.
Owner:TIANJIN UNIV
Three-phase unbalanced load current active compensation control method
PendingCN110994649AQuick extractionAccurate extractionFlexible AC transmissionSingle network parallel feeding arrangementsElectric power systemHemt circuits
The invention relates to a three-phase unbalanced load current active compensation control method, and belongs to the field of electric energy treatment. Instantaneous power is improved according to abasic structure and a working principle of the two-level SVG, and current is decomposed to a synchronous rotating coordinate system instead of directly decomposing the power according to a traditional instantaneous power theory. Aiming at the extraction of instruction current, a software phase-locked loop phase-locked method based on a single synchronous coordinate system is adopted, an SPLL linearized model is obtained based on a dq coordinate transformation principle, and a novel three-phase SPLL is realized through PI control. For a current control algorithm, a current control method basedon model predictive control is adopted. The three-phase unbalanced circuit can be compensated in real time, and can be conveniently applied to an actual power system. The method is flexible, simple and high in accuracy. The method has the advantages of being scientific, reasonable, high in applicability, high in reliability and good in effect.
Owner:NORTHEAST DIANLI UNIVERSITY +1
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