CN106712115A - Virtual synchronous generator controller without using current feedback - Google Patents

Abstract

The present invention provides a virtual synchronous generator controller without using current feedback. The virtual synchronous generator controller comprises the following parts of: 1) a rotor motion equation: a virtual rotor angular frequency and phase are obtained through calculation, and the virtual rotor angular frequency is adopted as the angular frequency of an inverter; 2) voltage control: synchronous generator excitation control and reactive voltage drop characteristics are simulated to control the output voltage amplitude of the inverter; 3) an inverter output power calculation equation: a power transmission line transmission power calculation method is adopted to calculate the reactive power and virtual electromagnetic torque of the inverter, wherein the inverter output power calculation equation is characterized in that calculation can be performed with no current quantity required; and 4) a dq transformation unit and a dq inverse transformation unit: and the angular frequency and phase of the rotor motion equation are adopted as a reference phase angle. The above parts are integrated so as to form the virtual synchronous generator controller without using current feedback. Compared with existing methods, the virtual synchronous generator controller without using current feedback of the present invention does not need current feedback, so that a control algorithm can be simplified; and a current sensor is omitted, and the construction cost of the inverter can be reduced.

Description

A kind of virtual synchronous engine controller without current feedback

Technical field

The present invention relates to micro-capacitance sensor and distributed power generation field, the virtual synchronous generator control of more particularly to a kind of inverter Device processed.

Background technology

With the increase of intermittence clean energy resource proportion in power system such as wind, light, intelligent grid is particularly micro- Electric network consecutive turns into the study hotspot of power domain.Inverter in micro-capacitance sensor is the grid-connected major way of clean energy resource, therefore Its control strategy just becomes the key technology of micro-capacitance sensor operation.Conventional control strategy for inverter in micro-capacitance sensor multi-inverter simultaneously Voltage, frequency support cannot be provided in the case of network operation for micro-grid system, it is also difficult to reasonably distribute between each inverter Power output, as restriction micro-capacitance sensor development problem.Synchronous generator has pressure regulation, frequency modulation special in conventional electric power system Property, and rotor inertia to multiple unit operation when power adjusting characteristic.Simulate the inverter control of above-mentioned synchronous generator characteristic Technology, i.e. virtual synchronous generator techniques turn into the focus of research at present.

Existing virtual synchronous engine controller is required for measuring simultaneously the voltage and electric current of inverter output end.And The control computing for carrying out complexity using voltage, electric current could be controlled to inverter.

The content of the invention

The invention provides it is a kind of do not need current feedback virtual synchronous engine controller.

To achieve the above object, the present invention is realized using following technical method：

As described in a kind of virtual synchronous engine controller without current feedback of the invention, the present invention is only defeated to inverter Go out voltage to be sampled.Clear and definite two concepts are needed exist for, inverter output voltage connects LC wave filters rear end by inverter Voltage on electric capacity, inversion bridge output voltage is the output voltage at filter front end power electronic devices.Obtaining three-phase The dq components U of inverter output voltage is obtained after output voltage sampled value by dq conversion_d、U_q。

Control method is specifically realized with following 3 steps：

(1) voltages control：According to above-mentioned inverter output voltage dq axle components U_d、U_q, with given Voltage Reference V_ref, And the given Q of reactive power_setWith inverter output reactive power Q.Consider simultaneously control and the reactive power of voltage magnitude with it is inverse Become the sagging relation of device output voltage, the controlled quentity controlled variable of inverter output voltage is calculated using the following differential equation：

In above formula, K_aVoltage magnitude gain；n_qIt is idle sagging gain；U_oIt is inverter output voltage amplitude, it calculates public Formula is as follows：

Obtain the controlled quentity controlled variable E of inverter output voltage_qAfterwards, as PWM voltage q axle components, and polishing is identical In zero d axle components E_dWith 0 axle component E₀, by obtaining PWM three-phase modulations ripples after dq inverse transformations, inverter bridge way switch is entered Row control.

Above-mentioned dq conversion refers to angular frequency with needed for dq inverse transformations_rCalculated by equation of rotor motion with phase.Turn The sub- equation of motion is the 2nd step for realizing controller of the present invention.Above-mentioned inverter output reactive power Q is inverse by the 3rd step Become device power output calculating equation to be calculated.Subsequent step is specific as follows.

(2) equation of rotor motion：The equation of rotor motion of synchronous generator can be described with following formula.

Wherein H is rotor inertia time constant, T_mAnd T_eRespectively machine torque and electromagnetic torque, ω_rIt is virtual rotor Angular velocity of rotation, angular frequency is referred to as dq conversion with dq inverse transformations, on the premise of inverter bridge path loss consumption is ignored, ω_r The as angular frequency of inversion bridge output voltage.Machine torque T_mCan be asked for synchronous generator speed regulator Mathematical Modeling, calculated Formula is as follows.

T_m≈P_set+D_p(f_n-ω_r/(2π)) (4)

Wherein P_setFor active power of output is given, D_pIt is droop characteristic coefficient, f_nIt is mains frequency.

Electromagnetic torque T in formula (3)_eIt is calculated by the 3rd step inverter output power equation, it is specific as follows.

(3) inverter output powers accounting equation：As described above with E_qAs PWM voltage q axle components, and polishing Perseverance is 0 d axle components E_dWith 0 axle component E₀, with ω_rAs dq conversion angular frequency is referred to dq inverse transformations.Ignoring inverter bridge On the premise of path loss consumes, it is believed that inversion bridge output voltage amplitude is E_q.With inverter bridge output voltage phase as reference Phase, then inverter output voltage can be asked for by following formula with inversion bridge output voltage phase difference δ：

Inverter active power of output P can be asked for idle work(using the computing formula of transmission line of electricity power transmission equation Rate Q.Using existing conclusion in synchronous generator steady-state analysis, because rotating speed is basic near synchronous rotational speed, output work can be made Rate is equal to electromagnetic power, i.e. electromagnetic torque T_e.Therefore, the electromagnetic torque T for being wanted needed for step (2) equation of rotor motion_eCan be with defeated Electric line power transmission equation is asked for.Specific formula is as follows：

Wherein R_fIt is the equivalent resistance in inverter LC filter inductances, X_fIt is LC filter inductance induction reactance.

Similarly, reactive power Q computing formula is as follows：

Compared with prior art, advantages of the present invention is embodied in：Inverter is calculated using transmission line of electricity power transmission equation Power output, i.e. electromagnetic torque here and reactive power, calculating do not need current value.Therefore current feedback can be omitted, Inverter need not install current sensor, save construction cost.It is sagging with reactive power that voltage control considers voltage Relation, takes into account the control of reactive power while control voltage stabilization.

Brief description of the drawings

Fig. 1 is a kind of overall construction drawing of virtual synchronous engine controller without current feedback of the invention；

Fig. 2 is voltage control and inverter output power accounting equation part-structure；

Fig. 3 is equation of rotor motion module detailed construction.

Specific embodiment

Specific embodiment of the invention is described below in conjunction with the accompanying drawings, so as to those skilled in the art preferably Understand the present invention.Requiring particular attention is that, in the following description, when known function and design detailed description perhaps When can desalinate main contents of the invention, these descriptions will be ignored herein.

Fig. 1 is a kind of overall construction drawing of virtual synchronous engine controller without current feedback of the invention, including master Circuit, inverter output power accounting equation, voltage control, equation of rotor motion, dq conversion, dq inverse transformations these part structures Into.Lower mask body introduces Each part：

1) main circuit part, including IGBT three-phase full-bridge inverting circuits (IGBT Bridge) and LC wave filters and voltage are passed Sensor.L_fIt is LC filter inductances, R_fIt is L_fUpper equivalent resistance, C_fIt is LC filter capacities.Z_LIt is networking line impedance, v_bIt is net Side voltage.U_a、U_b、U_cFor the three-phase voltage that voltage sensor measurement is obtained.

2) dq conversion and dq inverse transformation units, perform dq conversion and the reference angular frequency required for dq inverse transformations_rAnd phase Position is provided by equation of rotor motion part.The three-phase voltage U that the input of dq converter units is obtained for voltage sensor measurement_a、U_b、 U_c, by obtaining three-phase voltage dq axle components U after conversion_d、U_q.The input of dq inverse transformation units is voltage control division point output E_q, As q axle components, and polishing perseverance is 0 d axle components E_dWith 0 axle component E₀, three-phase PWM modulating wave is obtained after inverse transformation, control IGBT Bridge work processed.

3) inverter output power equation part, inverter output power accounting equation dotted line in its detailed construction such as Fig. 2 Shown in frame portion point.The part calculates inverter output reactive power Q and virtual using the method for transmission line of electricity power transmission equation Electromagnetic torque T_e.It is three-phase voltage dq axle components U to be input into_d、U_qAnd E_q.T is calculated by below equation_eAnd Q.And by T_eMake For equation of rotor motion part is input into, Q is used as voltage control division point input.

4) voltage control division point, its detailed construction is as shown in voltage control dotted box portion in Fig. 2.The input of the part is Three-phase voltage dq axle components U_d、U_q, the given V of voltage_ref, the given Q of reactive power_setCalculated with inverter output power equation part The reactive power Q for obtaining.The part may be used to lower differential equation its Mathematical Modeling.

Voltage controls the specific work process to be：By V_refWith U_oDifference be multiplied by gain K_aValue and Q_setDifference with Q is multiplied by gain n_qValue be added.Then it is integrated and is exported after amplitude limit, that is, obtains the controlled quentity controlled variable E of inverter output voltage_q.As PWM Modulation voltage q axle components, and it is 0 that d axles, 0 axle component are permanent.While E_qFeed back to inverter output power accounting equation and participate in meter Calculate.

5) equation of rotor motion part, the part detailed construction is as shown in Figure 3.Its working principle is, first by power network frequently Rate f_nSubtract inverter frequency f_r, f_r=ω_r/2π.The difference for obtaining is multiplied by droop characteristic coefficient D_p.Along with active power of output Given P_set, by the i.e. virtual machine torque T of the value that is obtained after amplitude limit link_m.By T_mWith inverter output power equation part The electromagnetic torque T for obtaining_eSubtract each other, the value as inversion bridge output voltage obtained divided by inertia time constant 2H, then after integrating Angular frequency_r, to ω_rIntegration can obtain its phase theta.

In summary to the description of each several part, a kind of virtual synchronous without current feedback that can be obtained as shown in Figure 1 generate electricity The general structure of machine controller.

Specific embodiment：

Shown below is a kind of design parameter of circuit control device of the present invention.

Inverter parameters：Three-phase inverter, rated frequency f_n=50Hz；Rated output power 50kW；Rated voltage V_refFor 380V；Rated output power Q_setIt is 0var.Specified DC terminal voltage is 700V.Filter segment parameter is L_f=2mH is right The X for answering_f=0.628 Ω；R_f=0.1 Ω；C_f=13 μ F.Sagging coefficient D_p=100 000, n_qIt is 0.15, voltage magnitude gain K_a =20.Rotor inertia time constant H=2.

Although being described to illustrative specific embodiment of the invention above, in order to the technology of the art Personnel understand the present invention, it should be apparent that the invention is not restricted to the scope of specific embodiment, to the common skill of the art For art personnel, as long as various change is in appended claim restriction and the spirit and scope of the present invention for determining, these Change is it will be apparent that all utilize the innovation and creation of present inventive concept in the row of protection.

Claims (2)

1. a kind of virtual synchronous engine controller without current feedback, by equation of rotor motion, voltage control, dq conversion, Dq inverse transformation units and these parts of inverter output power accounting equation are constituted.It is characterized in that：Inverter output work Rate accounting equation part calculates electromagnetic torque T using equation below_eWith inverter output reactive power Q：

$T_e=\frac{U_o\[R_f(E_{q}cos\mathrm{\δ}-U_o)+X_f{E}_{q}sin\mathrm{\δ}\]}{R_f^2+X_f^2}---\left(1\right)$

$Q=\frac{U_o\[X_f(E_{q}cos\mathrm{\δ}-U_o)-R_f{E}_{q}sin\mathrm{\δ}\]}{R_f^2+X_f^2}---\left(2\right)$

Wherein R_fIt is the equivalent resistance in inverter LC filter inductances；X_fIt is LC filter inductance induction reactance；E_qBefore LC wave filters Terminal voltage amplitude, i.e. inversion bridge output voltage amplitude, are calculated by voltage control division point；U_oIt is LC wave filters rear end electric capacity On voltage magnitude, i.e. inverter output voltage amplitude, computing formula is as follows：

$U_o=\sqrt{U_d^2+U_q^2}---\left(3\right)$

Wherein U_d、U_qIt is the dq components of inverter output voltage.

δ in formula (1), (2) is inversion bridge output voltage and the phase difference of inverter output voltage, and computing formula is as follows：

$\mathrm{\δ}=\arctan \left(\frac{U_d}{U_q}\right)---\left(4\right)$

It is further characterized in that：Electromagnetic torque is calculated using formula (1), (2) and reactive power does not need current feedback, i.e. inverter Also without current sensor in main circuit.

2. a kind of virtual synchronous engine controller without current feedback according to claim 1, it is characterised in that：By The following differential equation carries out voltage control：

$\frac{{\mathrm{dE}}_q}{dt}=K_a(V_{ref}-U_o)+n_q(Q_{set}-Q)---\left(5\right)$

The equation considers the control of voltage magnitude and the sagging relation of reactive power and output voltage simultaneously.With burning voltage While control the idle output of inverter advantage.

In formula (5), V_refIt is the inverter output reference voltage amplitude for giving；K_aVoltage magnitude gain；Q_setFor reactive power is given It is fixed；Q is inverter output reactive power；n_qIt is idle sagging gain；Output E_qAs PWM voltage q axle components, and polishing The d axles of identically vanishing and 0 axle component, by obtaining PWM three-phase modulations ripples after dq inverse transformations, control to inverter bridge way switch System.Under the hypothesis for ignoring the loss of inverter bridge way switch, it is believed that E_qEqual to the amplitude of inversion bridge output voltage.