The improvement self adaptation droop control method of shunt chopper in a kind of low pressure micro-capacitance sensor
Technical field
The present invention relates to micro-capacitance sensor field, especially relate to the improvement self adaptation of shunt chopper in a kind of low pressure micro-capacitance sensor
Droop control method.
Background technology
With the development of distributed energy, power supply quality, power supply reliability, power system capacity etc. are had higher by power distribution network side
Requirement.And multiple inverter parallel can increase system power, after composition micro-capacitance sensor, high-quality electricity can be provided the user
Can, increase the power supply reliability of system.Inverter parallel technology, is divided into and has interconnection and no control interconnections mode.There is connection
Winding thread mode, main by the information of each parallel module in detecting system, host computer send instruction and complete parallel connection.It is main
Shortcoming is that order wire Louis occurs postponing, if communication line breaks down, then micro-grid system will face paralysis.Droop control belongs to
In no control interconnection mode, and the control of shunt chopper meets sagging output characteristics, therefore, it is possible to bent according to meritorious-frequency droop
Line and idle-voltage sagging curve go to simulate the external characteristics of synchronous generator in bulk power grid.
Through finding the retrieval of existing document, Chen Jie published thesis " municipal rail train in " Beijing Jiaotong University " in 2013
Auxiliary power supply system high-quality waveform controls and arcless breaking key technology research " draw virtual complex impedance, make low pressure micro-
In electrical network, the output equivalent impedance of shunt chopper is perception, but the problem not solving voltage accuracy.
Sun Xiaofeng, Yang Yalin, Zhao Wei, Shen Hong, Tan Guangjun. publishing thesis in " electric power network technique " in 2014, " micro-capacitance sensor is inverse
Become device self adaptation droop control strategy " propose self adaptation droop control strategy, weak point is load sharing and output voltage
The intrinsic contradictions of quality are difficult to compromise and consider.
Summary of the invention
It is an object of the invention to provide the improvement self adaptation of shunt chopper in a kind of low pressure micro-capacitance sensor for the problems referred to above
Droop control method.
The purpose of the present invention can be achieved through the following technical solutions:
The improvement self adaptation droop control method of shunt chopper in a kind of low pressure micro-capacitance sensor, described method includes following step
Rapid:
1) introducing virtual complex impedance makes the equivalent output impedance of shunt chopper be perception, obtains droop control equation;
2) introduce the linear function item of power and sagging coefficient, replace the sagging coefficient in droop control equation, obtain certainly
Adapt to droop control equation;
3) consider to introduce the Voltage Drop that virtual complex impedance brings, obtain improving self adaptation droop control equation, by changing
Enter self adaptation droop control method and realize the improvement self adaptation droop control of shunt chopper.
Described droop control equation is:
Wherein, w1And E1It is respectively voltage angle frequency and amplitude, the w of inverter output0And E0It is respectively rated voltage angular frequency
Rate and amplitude, P1And Q1Being respectively active power and the reactive power of inverter output, m is the sagging of meritorious-frequency droop curve
Coefficient, n is the sagging coefficient of idle-voltage sagging curve.
Described power includes active power and the linear function item of sagging coefficient and nothing with the linear function item of sagging coefficient
Merit power and the linear function item of sagging coefficient.
Described self adaptation droop control equation is:
Wherein, m1For the linear function item of active power Yu sagging coefficient, n1A letter for reactive power Yu sagging coefficient
Several.
Described m1Meet:
Described n1Meet:
Wherein, P0And Q0It is respectively specified active power and reactive power.
Described improvement self adaptation droop control equation particularly as follows:
Wherein, the resistance of the equivalent output impedance of inverter and inductance after R and X respectively introduces virtual complex impedance;U0For
The equivalent output voltage of inverter.
Compared with prior art, the method have the advantages that
(1) add Voltage Drop to compensate, solve the Voltage Drop problem after introducing virtual complex impedance, it is achieved that be in parallel
The compromise of inverter load sharing and output voltage considers.
(2) introduce the linear function item of power and sagging coefficient, solve traditional droop control method and be limited to fix
Sagging parameter.
(3) virtual complex impedance is introduced so that the equivalent output impedance of shunt chopper is perception so that shunt chopper
Traditional droop control method can be used to be controlled.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of shunt chopper in embodiment;
Fig. 2 is the meritorious-frequency droop performance diagram of tradition droop control;
Fig. 3 is droop control schematic diagram;
Fig. 4 is equivalent circuit diagram after the virtual complex impedance of introducing;
Fig. 5 is the inverter equivalent output impedance Bode diagram before and after the virtual complex impedance of introducing;
Fig. 6 is m when taking different numerical value, the droop characteristic of active power and frequency;
Fig. 7 is the simulation waveform figure in the present embodiment, and wherein, (7a) is the A phase dynamic current ripple that back loading in parallel is uprushed
Shape figure, (7b) is to gain merit 1KW load lower inverter parallel moment to divide equally oscillogram, and (7c) is that the A phase that back loading in parallel is uprushed is moved
State current waveform figure, shunt chopper output voltage oscillogram when (7d) is load changing;
Fig. 8 is experimental waveform after employing improvement droop control algorithm, and wherein, (8a) is shunt chopper load sharing electric current
Waveform, (8b) is that shunt chopper loads output dynamic current waveform when uprushing.
Fig. 9 is the method flow diagram of the present invention.
Detailed description of the invention
The present invention is described in detail with specific embodiment below in conjunction with the accompanying drawings.The present embodiment is with technical solution of the present invention
Premised on implement, give detailed embodiment and concrete operating process, but protection scope of the present invention be not limited to
Following embodiment.
As it is shown in figure 9, the invention provides the improvement self adaptation droop control of shunt chopper in a kind of low pressure micro-capacitance sensor
Method, the method comprises the following steps:
1) virtual complex impedance is introduced:
In tradition three ring droop controls, inverter output voltage expression formula is:
U0=G (s) uref-I0(s)Z(s)
What in formula, G (s) described is that controlled voltage source is to output voltage urefThe tracking performance of instruction, Z (s) is equivalent to inverse
Become device output impedance, be made up of two parts: virtual impedance ZDThe output impedance Z of (s) and current and voltage feedback equivalence0 *(s).When
When virtual impedance value is pure perception, i.e. ZD(s)=sL.Introduce after virtual impedance, equivalent circuit diagram as shown in Figure 4, at low frequency
Section, equivalent output impedance Z (s) is in perception, according to the droop characteristic of traditional sagging formula, it is possible to realize the decoupling of P, Q.At high frequency
Switching frequency harmonic wave section, equivalent output impedance is resistive.As it is shown in figure 5, flow through the pressure drop u after virtual impedance by electric currentDSimulation
Go out the pressure drop on virtual impedance of connecting, droop characteristic show that output voltage instructs E*After, by uDDeduct, finally draw correction
After the given instruction of outfan contravarianter voltage: uref=E*-uD;Thus, after introducing virtual complex impedance so that shunt chopper
Equivalent output impedance is perception, obtains droop control equation:
Wherein, w1And E1It is respectively voltage angle frequency and amplitude, the w of inverter output0And E0It is respectively rated voltage angular frequency
Rate and amplitude, P1And Q1Being respectively active power and the reactive power of inverter output, m is the sagging of meritorious-frequency droop curve
Coefficient, n is the sagging coefficient of idle-voltage sagging curve, meritorious-frequency droop characteristic curve such as Fig. 2 of tradition droop control
Shown in, traditional droop control schematic diagram is as shown in Figure 3;
2) the linear function item of power and sagging coefficient, i.e. active power and the linear function item of sagging coefficient and nothing are introduced
Merit power and the linear function item of sagging coefficient, replace the sagging coefficient in droop control equation, obtain self adaptation droop control
Equation:
Wherein, m1For the linear function item of active power Yu sagging coefficient, n1A letter for reactive power Yu sagging coefficient
Several.
M, n then calculate according to traditional droop control, and voltage minimum typically takes uref90%-95%, the fluctuation of frequency
Degree general control is within 2%.The linear function increased is at m1、n1Value on the basis of numerical value.By sagging Coefficient m1It is taken at
0.43m/P0With 0.68m/P0Between, as shown in Figure 6;n1It is taken at 0.43n/Q0With 0.68n/Q0Between.I.e. m1Meet:
n1Meet:
Wherein, P0And Q0It is respectively specified active power and reactive power;
3) compensate owing to drawing the Voltage Drop that virtual complex impedance brings,
After introducing virtual impedance feedback, the sag of chain of voltage magnitude inevitably enlarges, under the output voltage precision of system is incited somebody to action
Fall;When additionally the load in shunt chopper is undergone mutation, reference voltage or sagging coefficient need bigger change to realize
The power-sharing of each inverter.Therefore the load sharing performance in time taking into account inverter parallel and control voltage accuracy two side
From the point of view of face controls requirement, need to compensate the voltage drop owing to using virtual impedance to bring, by traditional fixing sagging factor design
For dynamically changeable, thus can obtain improving self adaptation droop control equation:
Wherein, the resistance of the equivalent output impedance of inverter and inductance after R and X respectively introduces virtual complex impedance;U0For
The equivalent output voltage of inverter.
Embodiment 1
Using Simulink as emulation platform, two three-phase inverters are connected on same section of ac bus altogether, its equivalence
Mathematical model figure is as shown in Figure 1.The main circuit major parameter of shunt chopper is: input direct voltage is 700V, output voltage
220V/50Hz, the specified active power of single inverter is 1.7KW, and rated reactive power is 500Var, filter inductance
3.14mL, filter capacitor is 100uF, and the corner frequency of power filter is 20rad/s.Taking one group of sagging Coefficient m is
0.00004, n is 0.0012.Simulation waveform figure is as it is shown in fig. 7, in (7a) and (7b), two shunt chopper stable operations
After, it is the 0.06s moment at t, unexpected increase common load to 2.6KW, it can be seen that improve droop control algorithm and introduce dynamically tune
After integral coefficient, current waveform change is very mild, when the output electric current of two inverters is climbed to 2A by 1A, and parallel inverter
Device shows preferable load sharing and dynamic property.(7c) in, it is the 0.18s moment at t, starts inverter 1 band 1KW and bear
Carry, be the 0.195s moment at t, start inverter 2 and start working, it can be seen that inverter parallel moment exists circulation, but passes through
After about 1/4 power frequency period, two inverter output power reach unanimity, and side light improves droop control algorithm can be by parallel connection
The FREQUENCY CONTROL of inverter reaches unanimity, it is achieved load sharing.And in inverter 2 moment in parallel, impact the least, enter stable
Running status is the mildest.(7d) be after shunt chopper even running, the 0.22s moment uprush resistive load by 0.5KW to
1KW, it can be seen that shunt chopper output voltage amplitude will not be fallen, and stability is fine.Illustrate to improve droop control algorithm
Preferable to the voltage landing compensation effect caused after introducing virtual impedance.
Embodiment 2
Three-phase two-level inverter using two 1.7KW is in parallel as experiment porch.Control system uses
TMS320FM2812 control chip, switching frequency is set to 12.8KHz, adds the resistive line impedance of 1 Ω, simulation tradition in experiment
Impedance on low-voltage power line.Experiment parameter is consistent with emulation.Load current during available shunt chopper stable operation
Divide equally waveform, the 0.06s moment load uprush time shunt chopper electric current dynamic experiment waveform.Experimental waveform as shown in Figure 8,
Illustrate to be used improvement droop control algorithm, can preferably realize bearing power when two inverter parallels and divide equally, and
During load changing, the dynamic property of output electric current is preferable.Demonstrate the effectiveness improving control algolithm.