CN104716886B - based on virtual impedance voltage type converter virtual synchronous motor control method - Google Patents

Abstract

Virtual impedance Voltage type converter virtual synchronous motor control method is based on the invention discloses one kind, by electrically and mechanically two major parts for simulating synchronous motor, wherein electric part includes new virtual impedance simulation algorithm, traditional current transformer current inner loop and modulation strategy, mechanical part includes power computation module, rotor mechanical equation and automatic virtual blocks module, and realizing control voltage type current transformer output voltage electric current has the characteristic of synchronous motor.The present invention is based on virtual impedance Voltage type converter virtual synchronous motor control method, the differential term that it need not introduce output current of converter is capable of achieving winding reactance simulation, overcome influence of the extra low pass filter to impedance simulation, and do not sacrifice the current inner loop control of grid-connected converter, so that alternating current is controlled, there are current fluctuation, the excessively stream even ability of impact resisted, it is not required that control in quick current inner loop, it is possible to while simulating salient-pole machine and non salient pole machine.

Description

Based on virtual impedance Voltage type converter virtual synchronous motor control method

Technical field：

Patent of the present invention belongs to virtual synchronous Motor Control Field, and in particular to one kind is based on virtual impedance voltage-type unsteady flow Device virtual synchronous motor control method.

Background technology：

Distributed new generator unit is most of to access power distribution network, is close to load.As distributed new is accessed Ratio is improved, and power distribution network is developed from traditional vertical stratification to network structure.The power distribution network most typically feature of network structure is to send out Electric unit is no longer traditional a small number of Large Copacities, but most low capacities.Most of distribution generator unit is all by electricity in addition Power electronic inverter is grid-connected, therefore its grid-connected characteristic is subject to the control method of current transformer to determine.Usual distributed new is grid-connected When, current transformer uses current source control model, that is, inject the active and idle alternating current reality by controlling current transformer of power network It is existing.Compared with conventional rotary synchronous generator, grid-connected converter active reactive fast response time, output impedance are small, used without rotating The characteristics of amount.These cause that power distribution network faces some new problems：One is reliability, stability of the power distribution network to whole network system Increased with safety effects, especially there is standard regulation distributed power source to be automatically exited from electric network fault, further aggravated The unbalanced power of system transient modelling process；Two be new energy intermittent feature brought to the power distribution network of high impedance it is serious Voltage pulsation problem, three is distribution power flow two-way by what is simply unidirectionally thickened, have impact on power distribution network voltage control, Relay protection, network loss and the quality of power supply.In order to give full play to the advantage of distributed energy, diminuendo distributed power source is to power distribution network With the influence of transmission network, power network is allowed to dissolve more distributed energy, distributed power source necessarily participates in power distribution network and transmission network Frequency modulation and pressure regulation process, the potential assistant service of distributed power source must be excavated fully, and distributed power source must be provided to power network Necessary assistant service.

For the shortcoming of new energy power grid, there is scholar to propose the control thought of virtual synchronous motor, i.e., by control Algorithm processed, make new energy power supply have with traditional grid-connected characteristic of rotary power source identical, be actively engaged in power system frequency modulation and voltage modulation Process, be power network provided auxiliary service.Virtual synchronous motor concept is proposed that the Dutch energy grinds by J.Driesen scholar earliest Study carefully the units such as center (Energy research Centre of Netherlands), TU Delft University of Science and Technology to exist VSYNC plans are set up within 2007, virtual synchronous motor technology is studied, by increasing the virtual inertia of distributed generation unit, reached To the purpose of electric power grid frequency stabilization.Hereafter, domestic and foreign scholars have done numerous studies work, and there is China Electric Power Research Institute the country Sheng Wanxing scholar, HeFei University of Technology Zhang Xinghe Soviet Union build emblem scholar, there are German Lao Kesi tal fibres polytechnical university Ralf in foreign countries Person, the Zhong Qingchang scholar of Univ Sheffield UK, U.S. Hussam Alatrash scholars etc..

According to the common recognition of numerous scholars, grid-connected converter simulation synchronous motor characteristic is becoming for following grid-connected converter control Gesture.The electromagnetism and mechanical property for simulating synchronous motor simultaneously are most common ways, and specific implementation can be by pure algorithm reality Can now be realized by hardware again.Wherein electromagnetic property is all based on model stator winding by the way of impedance simulation, including Voltage-type and current mode scheme, but each scheme has the shortcomings that its is intrinsic：All voltage-type impedance simulation modes, due to calculating The voltage instruction for going out all is that, by the direct control bridge wall voltage of PWM, the current loop control pattern of conventional current transformer is all sacrificial Domestic animal, alternating current is not directly controlled, and this can cause alternating current the even impact of fluctuation, excessively stream occur, especially in grid entry point electricity When net voltage magnitude or phase are undergone mutation, the normal operation of current transformer is had a strong impact on；And current mode impedance simulation side Formula, the impedance operator of synchronous machine is simulated due to replicating completely, existing obvious delayed in impedance simulation link, in order to ensure The retardance of overall control is within the specific limits it is necessary to make the response speed requirement of current regulator very high.But existing electricity Stream ring control strategy is all unable to reach requirement so high, causes control method retardance larger, and electric current regulation is not prompt enough, control Effect processed is poor.

The content of the invention：

Defect of the present invention for virtual synchronous motor technology, there is provided one kind is empty based on virtual impedance Voltage type converter Intend synchronous motor control method.

To achieve the above object, the present invention is adopted the following technical scheme that：

Based on virtual impedance Voltage type converter virtual synchronous motor control method, it is characterised in that comprise the following steps：

1) equation of rotor motion of synchronous machine is simulated, the active power of output instruction P according to Voltage type converter_refWith reality Border active power of output P_eDifference P_err, and it is calculated virtual synchronous motor with the automatic virtual blocks that proportional component is represented Frequency perunit value ω^*, using the frequency perunit value ω of synchronous motor^*Phase theta needed for calculating coordinate transform；

2) simulation synchronous reactance part, using step 1) in phase theta needed for the coordinate transform that obtains, current transformer is exported Voltage instruction and actual output voltage transform to dq coordinate systems respectively, and virtual impedance matrix is designed under dq coordinate systems, with virtual Current transformer output voltage is instructed impedance matrix and actual output voltage carries out computing, obtains the instruction of current transformer dq axles output currentWith

3) design current inner ring, using step 1) in phase theta needed for the coordinate transform that obtains, by output current of converter Dq coordinate systems are transformed to, poor for being instructed with current transformer dq axles output current under dq coordinate systems, its difference is by PI controls Device, is calculated current transformer dq axle modulated signals, and then obtains exporting the switch controlling signal of converter switches network, so that with In driving switch network.

The present invention is further improved, step 1) in, the active power of output instruction P of voltage converter_refWith reality Active power of output P_eDiffer from, its difference by generating set reference capacity P_basePerunit, the result after perunit is divided by 2 times Synchronous motor inertia time constant H is simultaneously integrated to result, obtains the frequency perunit value ω of synchronous motor^*, specific formula is as follows：

In formula：S is integral operator；

Frequency perunit value ω^*Multiplied by with frequency reference value ω_RAnd result is integrated, obtain design current transformer voltage x current double Phase theta needed for closed-loop control ring, specific formula is as follows：

It is again target to simulate the damping effect in actual synchronization rotor rotary course, what design proportion link was represented Automatic virtual blocks are used as feedback element, frequency perunit value ω^*After making difference with reference frequency perunit value 1, it is multiplied with this link and is hindered Buddhist nun's power, by Damping Power and the power difference P of current transformer_errIt is poor in real time, for corrected power difference P_err, and then correct this The output phase of link, the phase theta needed for obtaining coordinate transform.

The present invention is further improved, step 2) in, using step 1) middle gained phase theta, to output voltage instruction Dq conversion is carried out with reality output three-phase voltage, the virtual excitation electric gesture E of current transformer dq axles is respectively obtained_d、E_qWith current transformer dq Axle actual output voltage v_d、v_q, respectively by E_dWith v_dMake difference and obtain d shaft voltage errors v_{d_err}, E_qWith v_qMake difference and obtain q shaft voltages mistake Difference v_{q_err}；D shaft voltage errors v_{d_err}With q shaft voltage errors v_{q_err}After for the virtual impedance link for simulating synchronous reactance, Obtain the instruction of dq axles output currentWithWherein virtual impedance link only simulates the power frequency characteristic of three-phase symmetrical inductance, will The differential term of inductive current is cast out, and casts out resistive component, obtains the equation of virtual impedance：

Wherein, i_{L_d}、u_{L_d}Respectively d shaft currents voltage, i_{L_q}、u_{L_q}Respectively q shaft currents voltage, w_RIt is synchronous angular frequency Rate, L is inductance value.

The present invention is further improved, step 3) in, using step 1) middle gained phase, actual output current is entered Row dq is converted, and obtains dq axle actual output currents i_{c_d}And i_{c_q}, by the instruction of dq axles output currentWithRespectively with dq axle realities Border output current i_{c_d}And i_{c_q}Differ from, its difference is modulated by obtaining current transformer dq axle modulated signals after the computing of PI controllers Signal by PWM or SVM modulators, obtains exporting the switch controlling signal of converter switches network again, so that for driving Switching network.

Compared with prior art, the present invention is excellent based on virtual impedance Voltage type converter virtual synchronous motor control method Point is embodied in：

The differential term that it need not introduce output current of converter is capable of achieving winding reactance simulation, overcomes extra low pass filtered Influence of the ripple device to impedance simulation, and the current inner loop control of grid-connected converter is not sacrificed so that alternating current is controlled, resists The ability that current fluctuation, excessively stream are even impacted, it is not required that quick current inner loop control so that conventional current ring can be used for Without causing larger delay sex chromosome mosaicism in virtual synchronous motor control algorithms, so that virtual synchronous motor control algorithms Become feasible under existence conditions, it is possible to while simulating salient-pole machine and non salient pole machine.

Brief description of the drawings：

Fig. 1 is the control block diagram based on virtual impedance Voltage type converter virtual synchronous motor control method；

Fig. 2 is the control block diagram for simulating synchronous machine rotor portion；

Fig. 3 is virtual impedance control block diagram；

Fig. 4 is traditional PI current inner loop control block diagram；

The current transformer power output that Fig. 5 is carried under control method by synchronous machine when electric network voltage phase is mutated and the present invention is rung Answer waveform；

Fig. 6 is carried the current transformer A phase current ripples under control method by synchronous machine when electric network voltage phase is mutated and the present invention Shape；

Fig. 7 is carried the current transformer output voltage under control method by synchronous machine when electric network voltage phase is mutated and the present invention Frequency changes waveform.

Specific embodiment：

The present invention is described in further details with specific embodiment below in conjunction with the accompanying drawings

As shown in figure 1, the present invention is based on virtual impedance Voltage type converter virtual synchronous motor control method, including it is following Step：

1) equation of rotor motion of synchronous machine is simulated, the active power of output instruction P according to Voltage type converter_refWith reality Border active power of output P_eDifference P_errAnd the frequency of virtual synchronous motor is calculated with the automatic virtual blocks that proportional component is represented Rate perunit value ω^*, using the frequency perunit value ω of synchronous motor^*Phase theta needed for calculating coordinate transform, as shown in Figure 2；

In the step, the active power of output instruction P of voltage converter_refWith reality output active-power P_eDiffer from, it is poor It is worth by the reference capacity P of generating set_basePerunit, result after perunit divided by 2 times synchronous motor inertia time constant H simultaneously Result is integrated, the frequency perunit value ω of synchronous motor is obtained^*, specific formula is as follows：

In formula：S is integral operator；

Frequency perunit value ω^*Multiplied by with frequency reference value ω_RAnd result is integrated, obtain design current transformer voltage x current double Phase theta needed for closed-loop control ring, specific formula is as follows：

It is again target to simulate the damping effect in actual synchronization rotor rotary course, what design proportion link was represented Automatic virtual blocks are used as feedback element, frequency perunit value ω^*After making difference with reference frequency perunit value 1, it is multiplied with this link and is hindered Buddhist nun's power, by Damping Power and the power difference P of current transformer_errIt is poor in real time, for corrected power difference P_err, and then correct this The output phase of link.

2) simulation synchronous reactance part, virtual excitation electric gesture E_dAnd E_qMake with current transformer dq axles actual output voltage respectively Difference, by virtual impedance matrix, is calculated the instruction of current transformer dq axles output currentWithAs shown in Figure 3；

Wherein, virtual impedance realizes under dq coordinates, with versatility, can simulate any form of impedance, including pure Perceptual, pure capacitive, resistance sense and capacitance-resistance, also including the asymmetric inductance of ac-dc axis, and it is micro- to avoid the electric current of conventional method The introducing of subitem and extra use low pass filter；

In the step, using step 1) middle gained phase, dq is carried out to output voltage instruction and reality output three-phase voltage Conversion, respectively obtains virtual excitation electric gesture E_d、E_qWith current transformer dq axle actual output voltages v_d、v_q, respectively by E_dWith v_dDiffer from Obtain d shaft voltage errors v_{d_err}, E_qWith v_qMake difference and obtain q shaft voltage errors v_{q_err}；D shaft voltage errors v_{d_err}Missed with q shaft voltages Difference v_{q_err}After for the virtual impedance link for simulating synchronous reactance, the instruction of dq axles output current is obtainedWithWherein Virtual impedance link only simulates the power frequency characteristic of three-phase symmetrical inductance, and the differential term of inductive current is cast out, and casts out resistance point Amount, obtains the equation of virtual impedance：

Wherein, i_{L_d}, u_{L_d}It is d shaft current voltages, i_{L_q}, u_{L_q}It is q shaft current voltages, w_RIt is synchronization

Angular frequency, L is inductance value.

3) design current inner ring, the instruction of current transformer dq axles output currentWithIt is actually defeated with current transformer dq axles respectively Go out electric current i_{c_d}And i_{c_q}Differ from, its difference is calculated current transformer dq axle modulated signals, and then exported by PI controllers The switch controlling signal of converter switches network, for driving switch network, as shown in Figure 4；

In the step, using step 1) middle gained phase, actual output current is carried out into dq conversion, obtain dq axles actually defeated Go out electric current i_{c_d}And i_{c_q}, by the instruction of dq axles output currentWithRespectively with dq axle actual output currents i_{c_d}And i_{c_q}Differ from, Its difference is modulated by PWM or SVM again by obtaining current transformer dq axle modulated signals, modulated signal after the computing of PI controllers Device, obtains exporting the switch controlling signal of converter switches network, for driving switch network.

Embodiment：

In the case where electric network voltage phase is mutated, the contrast present invention puies forward the unsteady flow under the control of virtual impedance simulation algorithm Device operational effect and grade capacity synchronous motor operational effect.At the 10s moment, electric network voltage phase increases suddenly 15 degree；In 20s Carve, electric network voltage phase declines suddenly 15 degree.Its power response waveform as shown in figure 5, A phase currents change waveform as shown in fig. 6, Electric voltage frequency change waveform is as shown in Figure 7.Can be found by simulation result, when electric network voltage phase mutation is tackled, institute of the present invention Proposing the current transformer power output under algorithm control, alternating current and frequency fluctuation will be significantly less than synchronous motor.Demonstrate this Invention puies forward the superiority of virtual impedance algorithm.The design parameter of emulation is set referring to Tables 1 and 2：

The grid-connected converter of table 1 and virtual synchronous Motor control parameters

The parameter of synchronous machine of table 2

Claims (4)

1. virtual impedance Voltage type converter virtual synchronous motor control method is based on, it is characterised in that comprised the following steps：

1) equation of rotor motion of synchronous machine is simulated, the active power of output instruction P according to Voltage type converter_refIt is defeated with actual Go out active-power P_eDifference P_err, and the frequency that virtual synchronous motor is calculated with the automatic virtual blocks that proportional component is represented Perunit value ω^*, using the frequency perunit value ω of synchronous motor^*Phase theta needed for calculating coordinate transform；

2) simulation synchronous reactance part, using step 1) in phase theta needed for the coordinate transform that obtains, by current transformer output voltage Instruction and actual output voltage transform to dq coordinate systems respectively, and virtual impedance matrix is designed under dq coordinate systems, use virtual impedance Current transformer output voltage is instructed matrix and actual output voltage carries out computing, obtains the instruction of current transformer dq axles output current With

3) design current inner ring, using step 1) in phase theta needed for the coordinate transform that obtains, output current of converter is converted To dq coordinate systems, poor for being instructed with current transformer dq axles output current under dq coordinate systems, its difference is by PI controllers, meter Calculation obtains current transformer dq axle modulated signals, and then obtains exporting the switch controlling signal of converter switches network, so that for driving Dynamic switching network.

2. according to claim 1 based on virtual impedance Voltage type converter virtual synchronous motor control method, its feature It is, step 1) in, the active power of output instruction P of voltage converter_refWith reality output active-power P_eDiffer from, its difference By the reference capacity P of generating set_basePerunit, result after perunit is divided by 2 times of synchronous motor inertia time constant H and right Result is integrated, and obtains the frequency perunit value ω of synchronous motor^*, specific formula is as follows：

${\mathrm{\ω}}^{*}=\frac{(P_{\mathrm{ref}}-P_e)}{P_{\mathrm{base}}}\·\frac{1}{2\mathrm{Hs}}---\left(1\right)$

In formula：S is integral operator；

Frequency perunit value ω^*Multiplied by with frequency reference value ω_RAnd result is integrated, obtain designing current transformer voltage and current double closed-loop Phase theta needed for control ring, specific formula is as follows：

$\mathrm{\θ}={\mathrm{\ω}}^{*}\·\frac{{\mathrm{\ω}}_R}{s}---\left(2\right)$

It is again target to simulate the damping effect in actual synchronization rotor rotary course, it is virtual that design proportion link is represented Damping is used as feedback element, frequency perunit value ω^*After making difference with reference frequency perunit value 1, it is multiplied with this link and obtains damping work( Rate, by Damping Power and the power difference P of current transformer_errIt is poor in real time, for corrected power difference P_err, and then correct this link Output phase, the phase theta needed for obtaining coordinate transform.

3. according to claim 1 based on virtual impedance Voltage type converter virtual synchronous motor control method, its feature It is, step 2) in, using step 1) middle gained phase theta, dq changes are carried out to output voltage instruction and reality output three-phase voltage Change, respectively obtain the virtual excitation electric gesture E of current transformer dq axles_d、E_qWith current transformer dq axle actual output voltages v_d、v_q, respectively will E_dWith v_dMake difference and obtain d shaft voltage errors v_{d_err}, E_qWith v_qMake difference and obtain q shaft voltage errors v_{q_err}；D shaft voltage errors v_{d_err}With Q shaft voltage errors v_{q_err}After for the virtual impedance link for simulating synchronous reactance, the instruction of dq axles output current is obtainedWithWherein virtual impedance link only simulates the power frequency characteristic of three-phase symmetrical inductance, and the differential term of inductive current is cast out, and house Resistive component is removed, the equation of virtual impedance is obtained：

$\left[\begin{array}{cc}0& -\frac{1}{w_{R}L}\\ \frac{1}{w_{R}L}& 0\end{array}\right]\left[\begin{array}{c}{u}_{L-d}\\ u_{L-q}\end{array}\right]=\left[\begin{array}{c}{i}_{L-d}\\ i_{L-q}\end{array}\right]---\left(3\right)$

Wherein, i_{L_d}、u_{L_d}Respectively d shaft currents voltage, i_{L_q}、u_{L_q}Respectively q shaft currents voltage, w_RIt is synchronous angular frequency, L is Inductance value.

4. according to claim 1 based on virtual impedance Voltage type converter virtual synchronous motor control method, its feature It is, step 3) in, using step 1) middle gained phase, actual output current is carried out into dq conversion, obtain dq axle reality outputs Electric current i_{c_d}And i_{c_q}, by the instruction of dq axles output currentWithRespectively with dq axle actual output currents i_{c_d}And i_{c_q}Differ from, its Difference is modulated by PWM or SVM again by obtaining current transformer dq axle modulated signals, modulated signal after the computing of PI controllers Device, obtains exporting the switch controlling signal of converter switches network, so as to be used for driving switch network.