CN106803683A - A kind of two-way AC/DC convertor model prediction current control method - Google Patents

Abstract

The invention discloses a kind of two-way AC/DC convertor model prediction current control method, step is as follows, step S1, defines on off state S_i；S2, obtains output voltage vector U_jWith on off state S_iExpression formula；S3, constructs secondary power forecast model and output current quadratic forecast model；S4, calculates output current reference value i_αrefAnd i_βref；S5, construction cost function g；S6, initialization；S7, gathers line voltage and output current；S8, calculates the output voltage U under current switch states_j；S9, calculates first time output current predicted value and first time power prediction value；S10, calculates second output current predicted value and second power prediction value；S11, calculates output current reference value i_αrefAnd i_βref；S12, calculates cost function g；The size of S13, relative value function g and comparison variable m, and minimum value is assigned to comparison variable m；S14, judges and exports.The present invention carries out two-staged prediction by power output, and optimal voltage vector is calculated in advance, and effective compensation is carried out to algorithm time delay, reduces the influence that delay on system performance is produced.

Description

A kind of two-way AC/DC convertor model prediction current control method

Technical field

The invention belongs to intelligent power grid technology field, and in particular to a kind of two-way AC/DC convertor model prediction electric current control Method processed.

Background technology

In recent years, the access of various distributed DC powers such as photovoltaic generation, fuel cell, battery so that two-way friendship Direct current energy is converted into the major issue for continuing to solve.Direct current distributed power source is general by setting up direct-current micro-grid, with big electricity Net is connected, and forms distributed generation system.By two-way AC/DC convertor and EMS between power network and dc bus, Realize two-way flow of the energy between power network and distributed generation system.

At present, most control strategies on two-way AC/DC convertor are to use pulsewidth modulation, the control of external electrical pressure ring DC voltage is constant, internal current ring control ac-side current waveform.Under unbalanced electric grid voltage, two-way ac-dc conversion The traditional control method of device is, by line voltage and electric current, positive-negative sequence separation to be carried out using PHASE-LOCKED LOOP PLL TECHNIQUE, for positive sequence and negative Order components are respectively controlled, and amount of calculation is larger, and control is complicated.

The content of the invention

The present invention is to solve the control strategy amount of calculation of the use pulsewidth modulation of existing two-way AC/DC convertor compared with Greatly, complicated technical problem is controlled, so as to provide a kind of two-way AC/DC convertor model prediction current control method.

In order to solve the above technical problems, the technical solution adopted in the present invention is as follows：

A kind of two-way AC/DC convertor model prediction current control method, step is as follows,

Step S1, defines the on off state S of two-way AC/DC convertor_i；

Wherein, i is the phase of AC network, and i ∈ (a, b, c)；

S2, obtains the output voltage vector U of two-way AC/DC convertor under α β two-phase static coordinates_jWith on off state S_i's Expression formula.

Concretely comprise the following steps, S2.1, under abc three-phase static coordinate systems, obtain the output voltage of two-way AC/DC convertor With on off state S_iComputing formula, it is specific as follows：

Wherein, U_dcIt is DC bus-bar voltage, u_anIt is a phase output voltages of two-way AC/DC convertor；u_bnFor two-way friendship is straight The b phase output voltages of current converter；u_cnIt is the c phase output voltages of two-way AC/DC convertor；S_aIt is the on off state value of a phases； S_bIt is the on off state value of b phases；S_cIt is the on off state value of c phases.

S2.2, Clark conversion is carried out to the formula 2 in step S2.1, obtains two-way alternating current-direct current under α β two-phase static coordinates Converter output voltage U_jWith on off state S_iExpression formula, it is specific as follows：

Wherein, u_αIt is the α components of output voltage；u_βIt is the β components of output voltage；U_dcIt is DC bus-bar voltage, S_aIt is a phases On off state value；S_bIt is the on off state value of b phases；S_cIt is the on off state value of c phases.

S3, constructs two-way AC/DC convertor and output voltage vector U_jRelevant power prediction model；

Concretely comprise the following steps, S3.1, according to Kirchhoff's law, obtain shape of the combining inverter under three-phase static coordinate system State equation；

Wherein, u_anIt is a phase output voltages of two-way AC/DC convertor；u_bnFor the b phases of two-way AC/DC convertor are exported Voltage；u_cnIt is the c phase output voltages of two-way AC/DC convertor；i_aIt is a phase output currents of two-way AC/DC convertor；i_bFor The b phase output currents of two-way AC/DC convertor；i_cIt is the c phase output currents of two-way AC/DC convertor；e_aIt is power network a phases electricity Pressure；e_bIt is power network b phase voltages；e_cIt is power network c phase voltages；L is inductance；R is resistance；

S3.2, Clark conversion is carried out to the formula 4 in step S3.1, obtains the state equation under α β two-phase static coordinates； It is specific as follows：

Wherein, L is inductance；R is resistance；e_αIt is the α components of line voltage；e_βIt is the β components of line voltage；i_αFor two-way The α components of the output current of AC/DC convertor；i_βIt is the β components of the output current of two-way AC/DC convertor；u_αIt is output electricity The α components of pressure；u_βIt is the β components of output voltage；

S3.3, carries out discretization and arranges to the formula 5 in step S3.2, obtains two-way AC/DC convertor in t_k+1When Carve predicted current：

In formula, i_α(k+1) it is t_k+1The α components of moment output current predicted value；i_β(k+1) it is t_k+1Moment output current is pre- The β components of measured value；i_αK () is t_kThe α components of moment output current；i_βK () is t_kThe β components of moment output current；e_αK () is t_k The α components of moment line voltage；e_βK () is t_kThe β components of moment line voltage；u_αK () is t_kThe α components of moment output voltage； u_βK () is t_kThe β components of moment output voltage；L is inductance；R is resistance；T_sIt is sample frequency；

S3.4, the formula 6 in step S3.3, obtains t_k+2Moment, two-way AC/DC convertor was in t_k+2Moment prediction electricity Stream；

In formula, i_α(k+1) it is t_k+1The α components of moment output current predicted value；i_β(k+1) it is t_k+1Moment output current is pre- The β components of measured value；i_α(k+2) it is t_k+2The α components of moment output current；i_β(k+2) it is t_k+2The β components of moment output current；e_α It is the α components of line voltage；e_βIt is the β components of line voltage；u_α(k+1) it is t_k+1The α components of moment output voltage；u_β(k+1) It is t_k+1The β components of moment output voltage；L is inductance；R is resistance；T_sIt is sample frequency；

S3.5, according to instantaneous power theory, obtains the computing formula of the active power p and reactive power q of grid side, specifically For：

In formula：e_αIt is the α components of line voltage；e_βIt is the β components of line voltage；i_αIt is the α components of output current；i_βFor The β components of output current；P is active power, and q is reactive power；

S3.6, for three-phase equilibrium power network, as sample frequency T_sWhen higher, have：

S3.7, during the formula 9 in step S3.6 substituted into the formula 8 of step S3.5, obtains t_k+1Moment, two-way alternating current-direct current became The power prediction model of parallel operation：

In formula, P (k+1) is t_k+1Moment active power predicted value；Q (k+1) is t_k+1Moment reactive power predicted value；P(k) It is t_kMoment active power predicted value；Q (k) is t_kMoment reactive power predicted value；i_αK () is t_kMoment output current predicted value α components；i_βK () is t_kThe β components of moment output current predicted value；e_αIt is the α components of line voltage；e_βIt is the β of line voltage Component；u_αK () is t_kThe α components of moment output voltage；u_βK () is t_kThe β components of moment output voltage；L is inductance；T_sIt is sampling Frequency；

S3.8, the formula 10 in step S3.7 obtains t_k+2Moment combining inverter and output voltage U_jRelevant work( Rate forecast model；Specially：

Wherein, P (k+1) is t_k+1Moment active power predicted value；Q (k+1) is t_k+1Moment reactive power predicted value；P(k+ 2) it is t_k+2Moment active power predicted value；Q (k+2) is t_k+2Moment reactive power predicted value；i_α(k+1) it is t_k+1Moment exports The α components of current forecasting value；i_β(k+1) it is t_k+1The β components of moment output current predicted value；e_αIt is the α components of line voltage；e_β It is the β components of line voltage；u_α(k+1) it is t_k+1The α components of moment output voltage；u_β(k+1) it is t_k+1The β of moment output voltage Component；L is inductance；T_sIt is sample frequency；

S4, calculates the output current reference value i under α β static coordinates_αrefAnd i_βref；

Concretely comprise the following steps, S4.1, under unbalanced power grid, line voltage e, the positive-sequence component of output current i are calculated respectively And negative sequence component；

In formula：ω is dq coordinate system angular velocity of rotations,It is line voltage in the positive-sequence component of α β coordinate systems；For Negative sequence component of the line voltage in α β coordinate systems；It is line voltage in the positive-sequence component of dq coordinate systems；It is line voltage In the negative sequence component of dq coordinate systems；It is output current in the positive-sequence component of α β coordinate systems；It is output current in α β coordinates The negative sequence component of system；It is output current in the positive-sequence component of dq coordinate systems；It is output current in the negative phase-sequence of dq coordinate systems Component；e_d ⁺It is line voltage in the d axle positive-sequence component numerical value of dq coordinate systems；e_q ⁺It is line voltage in the q axle positive sequences of dq coordinate systems Component values；e_d ^-It is line voltage in the d axle negative sequence component numerical value of dq coordinate systems；e_q ^-It is line voltage in the q axles of dq coordinate systems Negative sequence component numerical value；i_d ⁺It is output current in the d axle positive-sequence component numerical value of dq coordinate systems；i_q ⁺It is output current in dq coordinate systems Q axle positive-sequence component numerical value；i_d ^-It is output current in the d axle negative sequence component numerical value of dq coordinate systems；i_q ^-For output current is sat in dq Mark the q axle negative sequence component numerical value of system；

S4.2, obtains the active power under dq coordinates and the relational expression between reactive power and positive and negative order components；

Concretely comprise the following steps：S4.2.1, according to instantaneous power theory, grid side power is expressed as follows：

S=ei^*=p+jq (14)；

In formula：

Wherein, p is active power, and q is reactive power；p₀It is a reference value of active power；p_c2It is the cosine of active power Flutter component；p_s2It is the sinuous pulsation component of active power；q₀It is a reference value of reactive power；q_c2It is the cosine arteries and veins of reactive power Dynamic component；q_s2It is the sinuous pulsation component of reactive power；

S4.2.2, formula 12 in step S4.1 and formula 13 are substituted into the formula 15 in step S4.2.1, are calculated and are arranged, and are obtained Active power under to dq coordinates and the relational expression between reactive power and positive and negative order components：

In formula：p₀It is a reference value of active power；p_c2It is the cosine flutter component of active power；p_s2For active power just String flutter component；q₀It is a reference value of reactive power；q_c2It is the cosine flutter component of reactive power；q_s2It is the sine of reactive power Flutter component；e_d ⁺It is line voltage in the d axle positive-sequence component numerical value of dq coordinate systems；e_q ⁺It is line voltage in the q axles of dq coordinate systems Positive-sequence component numerical value；e_d ^-It is line voltage in the d axle negative sequence component numerical value of dq coordinate systems；e_q ^-It is line voltage in dq coordinate systems Q axle negative sequence component numerical value；i_d ⁺It is output current in the d axle positive-sequence component numerical value of dq coordinate systems；i_q ⁺For output current is sat in dq Mark the q axle positive-sequence component numerical value of system；i_d ^-It is output current in the d axle negative sequence component numerical value of dq coordinate systems；i_q ^-For output current exists The q axle negative sequence component numerical value of dq coordinate systems；

S4.3, obtains under α β rest frames, active power p, reactive power q and line voltage, output current and electricity 90 ° of postpones signals of net voltage, 90 ° of relational expressions of postpones signal of output current.

Comprise the following steps that：S4.3.1, under α β rest frames, calculates between 90 ° of postpones signals and positive and negative order components Relation：

Assuming that the variable under α β rest frames is x, then its 90 ° of postpones signals are expressed as x ', postpones signal and positive-negative sequence Relation between component is：

X '=x_αβ ^+′+x_αβ ^-′=-jx_αβ ⁺+jx_αβ ^-(17)；

Then x, x ' are expressed as with the relation of positive and negative order components：

S4.3.2, inverts and can obtain to the formula 18 in step S4.3.1：

After arrangement, the relation obtained between the positive and negative order components of dq rotating coordinate systems and α β rest frames is：

S4.3.3, with reference to formula 19 and formula 20 in step S4.3.2, obtains positive and negative order components and α β under dq coordinate systems Expression formula under coordinate between variable and postpones signal：

S4.3.4, the formula 21 in step S4.3.3 is substituted into the formula 16 in step S4.2, obtains having under dq coordinates Relational expression between work(power and reactive power and positive and negative order components：

Wherein：

In formula：i_αIt is the α components of output current；i_βIt is the β components of output current；i_α' prolong for 90 ° of output current α components Slow signal；i_β' it is 90 ° of postpones signals of output current β components；e_αIt is the α components of line voltage；e_βIt is β points of line voltage Amount；e_α' it is 90 ° of postpones signals of line voltage α components；e_β' it is 90 ° of postpones signals of line voltage β components.

S4.4, to eliminate the secondary pulsation of two-way AC/DC convertor power, is divided into secondary pulsation and the nothing of active power The secondary pulsation of work(power；

To eliminate the secondary pulsation of active power, the stabilization output of two-way AC/DC convertor active power, order are realized：

Formula 22 and the solution formula 24 of formula 23 in step S4.3, obtain output current reference value and wattful power Rate, the α components of line voltage, the expression formula between β components and postpones signal：

In formula, i_αrefIt is the α components of output current reference value；i_βrefIt is the β components of output current reference value；e_αIt is power network The α components of voltage；e_βIt is the β components of line voltage；e_α' it is 90 ° of postpones signals of line voltage α components；e_β' it is line voltage β 90 ° of postpones signals of component；p_refIt is active power set-point；

To eliminate the secondary pulsation of reactive power, the stabilization output of two-way AC/DC convertor reactive power, order are realized：

Formula 22 and the solution formula 26 of formula 23 in step S4.3, output current reference value and reactive power, electricity The α components of net voltage, the expression formula between β components and postpones signal：

In formula, i_αrefIt is the α components of output current reference value；i_βrefIt is the β components of output current reference value；e_xIt is power network The α components of voltage；e_βIt is the β components of line voltage；e_α' it is 90 ° of postpones signals of line voltage α components；e_β' it is line voltage β 90 ° of postpones signals of component；q_refIt is active power set-point；

S5, construction cost function g；

Wherein, i_αrefIt is the α components of output current reference value；i_βrefIt is the β components of output current reference value；λ is weight system Number；i_α(k+2) it is t_k+2The α components of moment output current；i_β(k+2) it is t_k+2The β components of moment output current；P (k+2) is t_k+2 Moment active power predicted value；Q (k+2) is t_k+2Moment reactive power predicted value；

S6, initialization gives the comparison variable m of cost function g, and to comparison variable m and on off state S_iAssign initial value；

S7, collection line voltage e_a、e_b、e_c, carry out the α components e that Clark conversion obtains line voltage_αWith β components e_β, and To the α components e of line voltage_α, line voltage β components e_β90 ° of delays are carried out respectively, and obtain line voltage α components 90 ° prolong 90 ° of postpones signals of slow signal and line voltage β components；Gather the output current i of two-way AC/DC convertor_a、i_b、i_cGo forward side by side Row Clark conversion obtains the α components i of two-way AC/DC convertor output current_αWith β components i_β, and to the α components of output current i_αWith β components i_βCarry out 90 ° of delays respectively, obtain output current α components 90 ° of postpones signals and 90 ° of output current β components Postpones signal；

S8, the output voltage U of the two-way AC/DC convertor under current switch states is calculated with reference to step S2 and S7_j；

S9, the first time output current predicted value and first of two-way AC/DC convertor is calculated with reference to step S3 and step S8 Secondary power prediction value；

S10, second output current prediction of two-way AC/DC convertor is calculated with reference to step S3, step S8 and step S9 Value and second power prediction value；

S11, the output current reference value i under α β static coordinates is calculated with reference to step S4 and step S7_αrefAnd i_βref；

S12, cost function g is calculated with reference to step S5, step S9 and step S10；

The size of S13, relative value function g and comparison variable m, and minimum value is assigned to comparison variable m；

S14, judges whether cycle-index reaches setting value, when cycle-index is less than setting value, changes on off state value, Repeat step S7-S13；When cycle-index is equal to setting value, the output voltage vector corresponding to minimum value function g is exported U_j；Output voltage vector U_jCorresponding on off state is applied to subsequent time, realizes direct Power Control.

Model predictive control method is applied to the present invention the two-way AC/DC convertor under unbalanced power grid, in traditional mould On the basis of type predictive-current control, electricity is expressed using the voltage under α β rest frames, electric current and their 90 ° of postpones signals Stream reference value, is used to eliminate active power pulsation or reactive power pulsation, reduces current distortion.Using two-staged prediction, advanced meter Optimal voltage vector is calculated, effective compensation is carried out to algorithm time delay, reduce the influence that delay on system performance is produced.Add time delay After compensation, when sample frequency is higher, control strategy of the present invention can be substantially reduced power swing.

Brief description of the drawings

Fig. 1 is two-way AC/DC convertor failure tolerant structural representation of the invention.

Fig. 2 is Model Predictive Control structural representation of the present invention.

Specific embodiment

As shown in Figure 1-2, a kind of two-way AC/DC convertor model prediction current control method, step is as follows,

Step S1, defines the on off state S of two-way AC/DC convertor_i；

Wherein, i is the phase of AC network, and i ∈ (a, b, c)；

S2, obtains the output voltage vector U of two-way AC/DC convertor under α β two-phase static coordinates_jWith on off state S_i's Expression formula.

Concretely comprise the following steps, S2.1, under abc three-phase static coordinate systems, obtain the output voltage of two-way AC/DC convertor With on off state S_iComputing formula, it is specific as follows：

Wherein, U_dcIt is DC bus-bar voltage, u_anIt is a phase output voltages of two-way AC/DC convertor；u_bnFor two-way friendship is straight The b phase output voltages of current converter；u_cnIt is the c phase output voltages of two-way AC/DC convertor；S_aIt is the on off state value of a phases； S_bIt is the on off state value of b phases；S_cIt is the on off state value of c phases.

S2.2, Clark conversion is carried out to the formula 2 in step S2.1, obtains two-way alternating current-direct current under α β two-phase static coordinates Converter output voltage U_jWith on off state S_iExpression formula, it is specific as follows：

Wherein, u_αIt is the α components of output voltage；u_βIt is the β components of output voltage；U_dcIt is DC bus-bar voltage, S_aIt is a phases On off state value；S_bIt is the on off state value of b phases；S_cIt is the on off state value of c phases.

S3, constructs two-way AC/DC convertor and output voltage vector U_jRelevant power prediction model；

Concretely comprise the following steps, S3.1, according to Kirchhoff's law, obtain shape of the combining inverter under three-phase static coordinate system State equation；

Wherein, u_anIt is a phase output voltages of two-way AC/DC convertor；u_bnFor the b phases of two-way AC/DC convertor are exported Voltage；u_cnIt is the c phase output voltages of two-way AC/DC convertor；i_aIt is a phase output currents of two-way AC/DC convertor；i_bFor The b phase output currents of two-way AC/DC convertor；i_cIt is the c phase output currents of two-way AC/DC convertor；e_aIt is power network a phases electricity Pressure；e_bIt is power network b phase voltages；e_cIt is power network c phase voltages；L is inductance；R is resistance；

S3.2, Clark conversion is carried out to the formula 4 in step S3.1, obtains the state equation under α β two-phase static coordinates； It is specific as follows：

Wherein, L is inductance；R is resistance；e_αIt is the α components of line voltage；e_βIt is the β components of line voltage；i_αFor two-way The α components of the output current of AC/DC convertor；i_βIt is the β components of the output current of two-way AC/DC convertor；u_αIt is output electricity The α components of pressure；u_βIt is the β components of output voltage；

S3.3, carries out discretization and arranges to the formula 5 in step S3.2, obtains two-way AC/DC convertor in t_k+1When Carve predicted current：

In formula, i_α(k+1) it is t_k+1The α components of moment output current predicted value；i_β(k+1) it is t_k+1Moment output current is pre- The β components of measured value；i_αK () is t_kThe α components of moment output current；i_βK () is t_kThe β components of moment output current；e_αK () is t_k The α components of moment line voltage；e_βK () is t_kThe β components of moment line voltage；u_αK () is t_kThe α components of moment output voltage； u_βK () is t_kThe β components of moment output voltage；L is inductance；R is resistance；T_sIt is sample frequency；

S3.4, the formula 6 in step S3.3, obtains t_k+2Moment, two-way AC/DC convertor was in t_k+2Moment prediction electricity Stream；

In formula, i_α(k+1) it is t_k+1The α components of moment output current predicted value；i_β(k+1) it is t_k+1Moment output current is pre- The β components of measured value；i_α(k+2) it is t_k+2The α components of moment output current；i_β(k+2) it is t_k+2The β components of moment output current；e_α It is the α components of line voltage；e_βIt is the β components of line voltage；u_α(k+1) it is t_k+1The α components of moment output voltage；u_β(k+1) It is t_k+1The β components of moment output voltage；L is inductance；R is resistance；T_sIt is sample frequency；

S3.5, according to instantaneous power theory, obtains the computing formula of the active power p and reactive power q of grid side, specifically For：

In formula：e_αIt is the α components of line voltage；e_βIt is the β components of line voltage；i_αIt is the α components of output current；i_βFor The β components of output current；P is active power, and q is reactive power；

S3.6, for three-phase equilibrium power network, as sample frequency T_sWhen higher, have：

S3.7, during the formula 9 in step S3.6 substituted into the formula 8 of step S3.5, obtains t_k+1Moment, two-way alternating current-direct current became The power prediction model of parallel operation：

In formula, P (k+1) is t_k+1Moment active power predicted value；Q (k+1) is t_k+1Moment reactive power predicted value；P(k) It is t_kMoment active power predicted value；Q (k) is t_kMoment reactive power predicted value；i_αK () is t_kMoment output current predicted value α components；i_βK () is t_kThe β components of moment output current predicted value；e_αIt is the α components of line voltage；e_βIt is the β of line voltage Component；u_αK () is t_kThe α components of moment output voltage；u_βK () is t_kThe β components of moment output voltage；L is inductance；T_sIt is sampling Frequency；

S3.8, the formula 10 in step S3.7 obtains t_k+2Moment combining inverter and output voltage U_jRelevant work( Rate forecast model；Specially：

Wherein, P (k+1) is t_k+1Moment active power predicted value；Q (k+1) is t_k+1Moment reactive power predicted value；P(k+ 2) it is t_k+2Moment active power predicted value；Q (k+2) is t_k+2Moment reactive power predicted value；i_α(k+1) it is t_k+1Moment exports The α components of current forecasting value；i_β(k+1) it is t_k+1The β components of moment output current predicted value；e_αIt is the α components of line voltage；e_β It is the β components of line voltage；u_α(k+1) it is t_k+1The α components of moment output voltage；u_β(k+1) it is t_k+1The β of moment output voltage Component；L is inductance；T_sIt is sample frequency；

S4, calculates the output current reference value i under α β static coordinates_αrefAnd i_βref；

Concretely comprise the following steps, S4.1, under unbalanced power grid, line voltage e, the positive-sequence component of output current i are calculated respectively And negative sequence component；

In formula：ω is dq coordinate system angular velocity of rotations,It is line voltage in the positive-sequence component of α β coordinate systems；For Negative sequence component of the line voltage in α β coordinate systems；It is line voltage in the positive-sequence component of dq coordinate systems；It is line voltage In the negative sequence component of dq coordinate systems；It is output current in the positive-sequence component of α β coordinate systems；It is output current in α β coordinates The negative sequence component of system；It is output current in the positive-sequence component of dq coordinate systems；It is output current in the negative phase-sequence of dq coordinate systems Component；e_d ⁺It is line voltage in the d axle positive-sequence component numerical value of dq coordinate systems；e_q ⁺It is line voltage in the q axle positive sequences of dq coordinate systems Component values；e_d ^-It is line voltage in the d axle negative sequence component numerical value of dq coordinate systems；e_q ^-It is line voltage in the q axles of dq coordinate systems Negative sequence component numerical value；i_d ⁺It is output current in the d axle positive-sequence component numerical value of dq coordinate systems；i_q ⁺It is output current in dq coordinate systems Q axle positive-sequence component numerical value；i_d ^-It is output current in the d axle negative sequence component numerical value of dq coordinate systems；i_q ^-For output current is sat in dq Mark the q axle negative sequence component numerical value of system；

S4.2, obtains the active power under dq coordinates and the relational expression between reactive power and positive and negative order components；

Concretely comprise the following steps：S4.2.1, according to instantaneous power theory, grid side power is expressed as follows：

S=ei^*=p+jq (14)；

In formula：

Wherein, p is active power, and q is reactive power；p₀It is a reference value of active power；p_c2It is the cosine of active power Flutter component；p_s2It is the sinuous pulsation component of active power；q₀It is a reference value of reactive power；q_c2It is the cosine arteries and veins of reactive power Dynamic component；q_s2It is the sinuous pulsation component of reactive power；

S4.2.2, formula 12 in step S4.1 and formula 13 are substituted into the formula 15 in step S4.2.1, are calculated and are arranged, and are obtained Active power under to dq coordinates and the relational expression between reactive power and positive and negative order components：

In formula：p₀It is a reference value of active power；p_c2It is the cosine flutter component of active power；p_s2For active power just String flutter component；q₀It is a reference value of reactive power；q_c2It is the cosine flutter component of reactive power；q_s2It is the sine of reactive power Flutter component；e_d ⁺It is line voltage in the d axle positive-sequence component numerical value of dq coordinate systems；e_q ⁺It is line voltage in the q axles of dq coordinate systems Positive-sequence component numerical value；e_d ^-It is line voltage in the d axle negative sequence component numerical value of dq coordinate systems；e_q ^-It is line voltage in dq coordinate systems Q axle negative sequence component numerical value；i_d ⁺It is output current in the d axle positive-sequence component numerical value of dq coordinate systems；i_q ⁺For output current is sat in dq Mark the q axle positive-sequence component numerical value of system；i_d ^-It is output current in the d axle negative sequence component numerical value of dq coordinate systems；i_q ^-For output current exists The q axle negative sequence component numerical value of dq coordinate systems；

S4.3, obtains under α β rest frames, active power p, reactive power q and line voltage, output current, power network 90 ° of postpones signals of voltage, 90 ° of relational expressions of postpones signal of output current.

Comprise the following steps that：S4.3.1, under α β rest frames, calculates between 90 ° of postpones signals and positive and negative order components Relation：

Assuming that the variable under α β rest frames is x, then its 90 ° of postpones signals are expressed as x ', postpones signal and positive-negative sequence Relation between component is：

X '=x_αβ ^+′+x_αβ ^-′=-jx_αβ ⁺+jx_αβ ^-(17)；

Then x, x ' are expressed as with the relation of positive and negative order components：

S4.3.2, inverts and can obtain to the formula 18 in step S4.3.1：

After arrangement, the relation obtained between the positive and negative order components of dq rotating coordinate systems and α β rest frames is：

S4.3.3, with reference to formula 19 and formula 20 in step S4.3.2, obtains positive and negative order components and α β under dq coordinate systems Expression formula under coordinate between variable and postpones signal：

S4.3.4, the formula 21 in step S4.3.3 is substituted into the formula 16 in step S4.2, obtains having under dq coordinates Relational expression between work(power and reactive power and positive and negative order components：

Wherein：

In formula：i_αIt is the α components of output current；i_βIt is the β components of output current；i_α' prolong for 90 ° of output current α components Slow signal；i_β' it is 90 ° of postpones signals of output current β components；e_αIt is the α components of line voltage；e_βIt is β points of line voltage Amount；e_α' it is 90 ° of postpones signals of line voltage α components；e_β' it is 90 ° of postpones signals of line voltage β components.

S4.4, to eliminate the secondary pulsation of two-way AC/DC convertor power, is divided into secondary pulsation and the nothing of active power The secondary pulsation of work(power；

To eliminate the secondary pulsation of active power, the stabilization output of two-way AC/DC convertor active power, order are realized：

Formula 22 and the solution formula 24 of formula 23 in step S4.3, obtain output current reference value and wattful power Rate, the α components of line voltage, the expression formula between β components and postpones signal：

In formula, i_αrefIt is the α components of output current reference value；i_βrefIt is the β components of output current reference value；e_xIt is power network The α components of voltage；e_βIt is the β components of line voltage；e_α' it is 90 ° of postpones signals of line voltage α components；e_β' it is line voltage β 90 ° of postpones signals of component；p_refIt is active power set-point；

To eliminate the secondary pulsation of reactive power, the stabilization output of two-way AC/DC convertor reactive power, order are realized：

Formula 22 and the solution formula 26 of formula 23 in step S4.3, output current reference value and reactive power, electricity The α components of net voltage, the expression formula between β components and postpones signal：

In formula, i_αrefIt is the α components of output current reference value；i_βrefIt is the β components of output current reference value；e_xIt is power network The α components of voltage；e_βIt is the β components of line voltage；e_α' it is 90 ° of postpones signals of line voltage α components；e_β' it is line voltage β 90 ° of postpones signals of component；q_refIt is active power set-point；

S5, construction cost function g；

Wherein, i_αrefIt is the α components of output current reference value；i_βrefIt is the β components of output current reference value；λ is weight system Number；i_α(k+2) it is t_k+2The α components of moment output current；i_β(k+2) it is t_k+2The β components of moment output current；P (k+2) is t_k+2 Moment active power predicted value；Q (k+2) is t_k+2Moment reactive power predicted value；

S6, initialization gives the comparison variable m of cost function g, and to comparison variable m and on off state S_iAssign initial value；

S7, collection line voltage e_a、e_b、e_c, carry out the α components e that Clark conversion obtains line voltage_αWith β components e_β, and To the α components e of line voltage_α, line voltage β components e_β90 ° of delays are carried out respectively, and obtain line voltage α components 90 ° prolong 90 ° of postpones signals of slow signal and line voltage β components；Gather the output current i of two-way AC/DC convertor_a、i_b、i_cGo forward side by side Row Clark conversion obtains the α components i of two-way AC/DC convertor output current_αWith β components i_β, and to the α components of output current i_αWith β components i_βCarry out 90 ° of delays respectively, obtain output current α components 90 ° of postpones signals and 90 ° of output current β components Postpones signal；

S8, the output voltage U of the two-way AC/DC convertor under current switch states is calculated with reference to step S2 and S7_j；

S9, the first time output current predicted value and first of two-way AC/DC convertor is calculated with reference to step S3 and step S8 Secondary power prediction value；

S10, second output current prediction of two-way AC/DC convertor is calculated with reference to step S3, step S8 and step S9 Value and second power prediction value；

S11, the output current reference value i under α β static coordinates is calculated with reference to step S4 and step S7_αrefAnd i_βref；

S12, cost function g is calculated with reference to step S5, step S9 and step S10；

The size of S13, relative value function g and comparison variable m, and minimum value is assigned to comparison variable m；

S14, judges whether cycle-index reaches setting value, when cycle-index is less than setting value, changes on off state value, Repeat step S7-S13；When cycle-index is equal to setting value, the output voltage vector corresponding to minimum value function g is exported U_j；Output voltage vector U_jCorresponding on off state is applied to subsequent time, realizes direct Power Control.

The voltage utilized under α β rest frames of the invention, electric current and its 90 ° of postpones signals, without traditional positive-negative sequence Control is separated, improved model prediction Current Control Strategy is devised, active power or reactive power pulsation is eliminated, electric current is reduced Distortion.

And to improve control system performance, time delay is compensated using two-staged prediction method.t_kInstance sample is simultaneously applied Current time on off state, t_k+1The beginning that moment predicted value is predicted as all on off states, to t_k+2The power at moment is carried out Prediction, selects the on off state for making cost function minimum, treats t_k+1Moment updates.Although increased t_k+2The power prediction at moment, But can immediately update on off state after sampling every time.Both contrasts, have more preferable real-time control performance after compensation of delay.

Claims (4)

1. a kind of two-way AC/DC convertor model prediction current control method, it is characterised in that：Step is as follows,

Step S1, defines the on off state S of two-way AC/DC convertor_i；

Wherein, i is the phase of AC network, and i ∈ (a, b, c)；

S2, obtains the output voltage vector U of two-way AC/DC convertor under α β two-phase static coordinates_jWith on off state S_iExpression Formula, it is specific as follows：

$U_j=\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right]=\frac{\sqrt{6}{U}_{dc}}{9}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}2S_a-S_b-S_c\\ -S_a+2S_b-S_c\\ -S_a-S_b+2S_c\end{array}\right]---\left(3\right);$

Wherein, u_αIt is the α components of output voltage；u_βIt is the β components of output voltage；U_dcIt is DC bus-bar voltage, S_aIt is opening for a phases Off status value；S_bIt is the on off state value of b phases；S_cIt is the on off state value of c phases；

S3, constructs two-way AC/DC convertor and output voltage vector U_jRelevant secondary power forecast model and output current two Secondary forecast model；

Output current quadratic forecast model is,

$\left[\begin{array}{c}{i}_{\mathrm{\α}}(k+2)\\ i_{\mathrm{\β}}(k+2)\end{array}\right]=\frac{T_s}{L}\left[\begin{array}{c}{u}_{\mathrm{\α}}(k+1)-e_{\mathrm{\α}}\\ u_{\mathrm{\β}}(k+1)-e_{\mathrm{\β}}\end{array}\right]+(1-\frac{{\mathrm{RT}}_s}{L})\left[\begin{array}{c}{i}_{\mathrm{\α}}(k+1)\\ i_{\mathrm{\β}}(k+1)\end{array}\right]---\left(7\right);$

In formula, i_α(k+1) it is t_k+1The α components of moment output current predicted value；i_β(k+1) it is t_k+1Moment output current predicted value β components；i_α(k+2) it is t_k+2The α components of moment output current；i_β(k+2) it is t_k+2The β components of moment output current；e_αIt is electricity The α components of net voltage；e_βIt is the β components of line voltage；u_α(k+1) it is t_k+1The α components of moment output voltage；u_β(k+1) it is t_k+1 The β components of moment output voltage；L is inductance；R is resistance；T_sIt is sample frequency；

Secondary power forecast model,

$\left[\begin{array}{c}P\left(k+2\right)\\ Q\left(k+2\right)\end{array}\right]=\frac{T_s}{L}\left[\begin{array}{cc}{e}_{\mathrm{\α}}& e_{\mathrm{\β}}\\ e_{\mathrm{\β}}& -e_{\mathrm{\α}}\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{\α}}(k+1)-e_{\mathrm{\α}}-{\mathrm{Ri}}_{\mathrm{\α}}(k+1)\\ u_{\mathrm{\β}}(k+1)-e_{\mathrm{\β}}-{\mathrm{Ri}}_{\mathrm{\β}}(k+1)\end{array}\right]+\left[\begin{array}{c}P\left(k+1\right)\\ Q\left(k+1\right)\end{array}\right]---\left(11\right);$

Wherein, P (k+1) is t_k+1Moment active power predicted value；Q (k+1) is t_k+1Moment reactive power predicted value；P (k+2) is t_k+2Moment active power predicted value；Q (k+2) is t_k+2Moment reactive power predicted value；i_α(k+1) it is t_k+1Moment output current The α components of predicted value；i_β(k+1) it is t_k+1The β components of moment output current predicted value；e_αIt is the α components of line voltage；e_βIt is electricity The β components of net voltage；u_α(k+1) it is t_k+1The α components of moment output voltage；u_β(k+1) it is t_k+1The β components of moment output voltage； L is inductance；T_sIt is sample frequency；

S4, calculates the output current reference value i under α β static coordinates_αrefAnd i_βref；

The output current reference value i relevant with active power_αrefAnd i_βrefComputing formula it is as follows；

$\left\{\begin{array}{c}{i}_{\mathrm{\α}ref}=\frac{e_{\mathrm{\β}}^{\′}}{e_{\mathrm{\α}}{e}_{\mathrm{\β}}^{\′}-e_{\mathrm{\α}}^{\′}{e}_{\mathrm{\β}}}{p}_{ref}\\ i_{\mathrm{\β}ref}=\frac{-e_{\mathrm{\α}}^{\′}}{e_{\mathrm{\α}}{e}_{\mathrm{\β}}^{\′}-e_{\mathrm{\α}}^{\′}{e}_{\mathrm{\β}}}{p}_{ref}\end{array}\right.---\left(25\right);$

In formula, i_αrefIt is the α components of output current reference value；i_βrefIt is the β components of output current reference value；e_xIt is line voltage α components；e_βIt is the β components of line voltage；e_α' it is 90 ° of postpones signals of line voltage α components；e_β' it is line voltage β components 90 ° of postpones signals；p_refIt is active power set-point；

The output current reference value i relevant with reactive power_αrefAnd i_βrefComputing formula it is as follows；

$\left\{\begin{array}{c}{i}_{\mathrm{\α}ref}=\frac{-e_{\mathrm{\α}}^{\′}}{e_{\mathrm{\α}}{e}_{\mathrm{\β}}^{\′}-e_{\mathrm{\α}}^{\′}{e}_{\mathrm{\β}}}{q}_{ref}\\ i_{\mathrm{\β}ref}=\frac{-e_{\mathrm{\β}}^{\′}}{e_{\mathrm{\α}}{e}_{\mathrm{\β}}^{\′}-e_{\mathrm{\α}}^{\′}{e}_{\mathrm{\β}}}{q}_{ref}\end{array}\right.---\left(27\right);$

In formula, i_αrefIt is the α components of output current reference value；i_βrefIt is the β components of output current reference value；e_αIt is line voltage α components；e_βIt is the β components of line voltage；e_α' it is 90 ° of postpones signals of line voltage α components；e_β' it is line voltage β components 90 ° of postpones signals；q_refIt is active power set-point；

S5, construction cost function g；

Wherein, i_αrefIt is the α components of output current reference value；i_βrefIt is the β components of output current reference value；λ is weight coefficient； i_α(k+2) it is t_k+2The α components of moment output current；i_β(k+2) it is t_k+2The β components of moment output current；P (k+2) is t_k+2When It is carved with work(power prediction value；Q (k+2) is t_k+2Moment reactive power predicted value；

S6, initialization gives the comparison variable m of cost function g, and to comparison variable m and on off state S_iAssign initial value；

S7, collection line voltage e_a、e_b、e_c, carry out the α components e that Clark conversion obtains line voltage_αWith β components e_β, and to electricity The α components e of net voltage_α, line voltage β components e_β90 ° of delays are carried out respectively, and obtain line voltage α components 90 ° postpone letter Number and line voltage β components 90 ° of postpones signals；Gather the output current i of two-way AC/DC convertor_a、i_b、i_cAnd carry out Clark conversion obtains the α components i of two-way AC/DC convertor output current_αWith β components i_β, and to the α components i of output current_α With β components i_β90 ° of delays are carried out respectively, obtain 90 ° of postpones signals of output current α components and 90 ° of output current β components prolong Slow signal；

S8, the output voltage U of the two-way AC/DC convertor under current switch states is calculated with reference to step S2 and S7_j；

S9, the first time output current predicted value and first time work(of two-way AC/DC convertor are calculated with reference to step S3 and step S8 Rate predicted value；

S10, with reference to step S3, step S8 and step S9 calculate two-way AC/DC convertor second output current predicted value and Second power prediction value；

S11, the output current reference value i under α β static coordinates is calculated with reference to step S4 and step S7_αrefAnd i_βref；

S12, cost function g is calculated with reference to step S5, step S9 and step S10；

The size of S13, relative value function g and comparison variable m, and minimum value is assigned to comparison variable m；

S14, judges whether cycle-index reaches setting value, when cycle-index is less than setting value, changes on off state value, repeats Step S7-S13；When cycle-index is equal to setting value, the output voltage vector U corresponding to minimum value function g is exported_j；It is defeated Go out voltage vector U_jCorresponding on off state is applied to subsequent time, realizes direct Power Control.

2. two-way AC/DC convertor model prediction current control method according to claim 1, it is characterised in that：In step In rapid S2, concretely comprise the following steps, S2.1, under abc three-phase static coordinate systems, obtain the output voltage of two-way AC/DC convertor with On off state S_iComputing formula, it is specific as follows：

$\left[\begin{array}{c}{u}_{an}\\ u_{bn}\\ u_{cn}\end{array}\right]=\frac{U_{dc}}{3}\left[\begin{array}{ccc}2& -1& -1\\ -1& 2& -1\\ -1& -1& 2\end{array}\right]\left[\begin{array}{c}{S}_a\\ S_b\\ S_c\end{array}\right]---\left(2\right);$

Wherein, U_dcIt is DC bus-bar voltage, u_anIt is a phase output voltages of two-way AC/DC convertor；u_bnFor two-way alternating current-direct current becomes The b phase output voltages of parallel operation；u_cnIt is the c phase output voltages of two-way AC/DC convertor；S_aIt is the on off state value of a phases；S_bIt is b The on off state value of phase；S_cIt is the on off state value of c phases；

S2.2, Clark conversion is carried out to the formula 2 in step S2.1, obtains two-way ac-dc conversion under α β two-phase static coordinates Device output voltage U_jWith on off state S_iExpression formula, it is specific as follows：

$U_j=\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right]=\frac{\sqrt{6}{U}_{dc}}{9}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}2S_a-S_b-S_c\\ -S_a+2S_b-S_c\\ -S_a-S_b+2S_c\end{array}\right]---\left(3\right);$

Wherein, u_αIt is the α components of output voltage；u_βIt is the β components of output voltage；U_dcIt is DC bus-bar voltage, S_aIt is opening for a phases Off status value；S_bIt is the on off state value of b phases；S_cIt is the on off state value of c phases.

3. two-way AC/DC convertor model prediction current control method according to claim 1, it is characterised in that：In step In rapid S3, concretely comprise the following steps, S3.1, according to Kirchhoff's law, obtain shape of the combining inverter under three-phase static coordinate system State equation；

$L\frac{d}{dt}\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]+R\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]=\left[\begin{array}{c}{u}_{an}\\ u_{bn}\\ u_{cn}\end{array}\right]-\left[\begin{array}{c}{e}_a\\ e_b\\ e_c\end{array}\right]---\left(4\right);$

Wherein, u_anIt is a phase output voltages of two-way AC/DC convertor；u_bnIt is the b phase output voltages of two-way AC/DC convertor； u_cnIt is the c phase output voltages of two-way AC/DC convertor；i_aIt is a phase output currents of two-way AC/DC convertor；i_bFor two-way The b phase output currents of AC/DC convertor；i_cIt is the c phase output currents of two-way AC/DC convertor；e_aIt is power network a phase voltages；e_b It is power network b phase voltages；e_cIt is power network c phase voltages；L is inductance；R is resistance；

S3.2, Clark conversion is carried out to the formula 4 in step S3.1, obtains the state equation under α β two-phase static coordinates；Specifically It is as follows：

$L\frac{d}{dt}\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]+R\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]=\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right]-\left[\begin{array}{c}{e}_{\mathrm{\α}}\\ e_{\mathrm{\β}}\end{array}\right]---\left(5\right);$

Wherein, L is inductance；R is resistance；e_αIt is the α components of line voltage；e_βIt is the β components of line voltage；i_αFor two-way friendship is straight The α components of the output current of current converter；i_βIt is the β components of the output current of two-way AC/DC convertor；u_αIt is output voltage α components；u_βIt is the β components of output voltage；

S3.3, carries out discretization and arranges to the formula 5 in step S3.2, obtains two-way AC/DC convertor in t_k+1Moment is pre- Survey electric current：

$\left[\begin{array}{c}{i}_{\mathrm{\α}}(k+1)\\ i_{\mathrm{\β}}(k+1)\end{array}\right]=\frac{T_s}{L}\left[\begin{array}{c}{u}_{\mathrm{\α}}\left(k\right)-e_{\mathrm{\α}}\left(k\right)\\ u_{\mathrm{\β}}\left(k\right)-e_{\mathrm{\β}}\left(k\right)\end{array}\right]+(1-\frac{{\mathrm{RT}}_s}{L})\left[\begin{array}{c}{i}_{\mathrm{\α}}\left(k\right)\\ i_{\mathrm{\β}}\left(k\right)\end{array}\right]---\left(6\right);$

In formula, i_α(k+1) it is t_k+1The α components of moment output current predicted value；i_β(k+1) it is t_k+1Moment output current predicted value β components；i_αK () is t_kThe α components of moment output current；i_βK () is t_kThe β components of moment output current；e_αK () is t_kMoment The α components of line voltage；e_βK () is t_kThe β components of moment line voltage；u_αK () is t_kThe α components of moment output voltage；u_β(k) It is t_kThe β components of moment output voltage；L is inductance；R is resistance；T_sIt is sample frequency；

S3.4, the formula 6 in step S3.3, obtains t_k+2Moment, two-way AC/DC convertor was in t_k+2Moment predicted current；

$\left[\begin{array}{c}{i}_{\mathrm{\α}}(k+2)\\ i_{\mathrm{\β}}(k+2)\end{array}\right]=\frac{T_s}{L}\left[\begin{array}{c}{u}_{\mathrm{\α}}(k+1)-e_{\mathrm{\α}}\\ u_{\mathrm{\β}}(k+1)-e_{\mathrm{\β}}\end{array}\right]+(1-\frac{{\mathrm{RT}}_s}{L})\left[\begin{array}{c}{i}_{\mathrm{\α}}(k+1)\\ i_{\mathrm{\β}}(k+1)\end{array}\right]---\left(7\right);$

In formula, i_α(k+1) it is t_k+1The α components of moment output current predicted value；i_β(k+1) it is t_k+1Moment output current predicted value β components；i_α(k+2) it is t_k+2The α components of moment output current；i_β(k+2) it is t_k+2The β components of moment output current；e_αIt is electricity The α components of net voltage；e_βIt is the β components of line voltage；u_α(k+1) it is t_k+1The α components of moment output voltage；u_β(k+1) it is t_k+1 The β components of moment output voltage；L is inductance；R is resistance；T_sIt is sample frequency；

S3.5, according to instantaneous power theory, obtains the computing formula of the active power p and reactive power q of grid side, specially：

$\left\{\begin{array}{c}p=e_{\mathrm{\α}}{i}_{\mathrm{\α}}+e_{\mathrm{\β}}{i}_{\mathrm{\β}}\\ q=e_{\mathrm{\β}}{i}_{\mathrm{\α}}-e_{\mathrm{\α}}{i}_{\mathrm{\β}}\end{array}\right.---\left(8\right);$

In formula：e_αIt is the α components of line voltage；e_βIt is the β components of line voltage；i_αIt is the α components of output current；i_βIt is output electricity The β components of stream；P is active power, and q is reactive power；

S3.6, for three-phase equilibrium power network, as sample frequency T_sWhen higher, have：

$\left\{\begin{array}{c}{e}_{\mathrm{\α}}(k+1)=e_{\mathrm{\α}}\left(k\right)\\ e_{\mathrm{\β}}(k+1)=e_{\mathrm{\β}}\left(k\right)\end{array}\right.---\left(9\right);$

S3.7, during the formula 9 in step S3.6 substituted into the formula 8 of step S3.5, obtains t_k+1Moment two-way AC/DC convertor Power prediction model：

$\left[\begin{array}{c}P\left(k+1\right)\\ Q\left(k+1\right)\end{array}\right]=\frac{T_s}{L}\left[\begin{array}{cc}{e}_{\mathrm{\α}}& e_{\mathrm{\β}}\\ e_{\mathrm{\β}}& -e_{\mathrm{\α}}\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{\α}}\left(k\right)-e_{\mathrm{\α}}-{\mathrm{Ri}}_{\mathrm{\α}}\left(k\right)\\ u_{\mathrm{\β}}\left(k\right)-e_{\mathrm{\β}}-{\mathrm{Ri}}_{\mathrm{\β}}\left(k\right)\end{array}\right]+\left[\begin{array}{c}P\left(k\right)\\ Q\left(k\right)\end{array}\right]---\left(10\right);$

In formula, P (k+1) is t_k+1Moment active power predicted value；Q (k+1) is t_k+1Moment reactive power predicted value；P (k) is t_k Moment active power predicted value；Q (k) is t_kMoment reactive power predicted value；i_αK () is t_kThe α of moment output current predicted value points Amount；i_βK () is t_kThe β components of moment output current predicted value；e_αIt is the α components of line voltage；e_βIt is the β components of line voltage； u_αK () is t_kThe α components of moment output voltage；u_βK () is t_kThe β components of moment output voltage；L is inductance；T_sIt is sample frequency；

S3.8, the formula 10 in step S3.7 obtains t_k+2Moment combining inverter and output voltage U_jRelevant power prediction Model；Specially：

$\left[\begin{array}{c}P\left(k+2\right)\\ Q\left(k+2\right)\end{array}\right]=\frac{T_s}{L}\left[\begin{array}{cc}{e}_{\mathrm{\α}}& e_{\mathrm{\β}}\\ e_{\mathrm{\β}}& -e_{\mathrm{\α}}\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{\α}}(k+1)-e_{\mathrm{\α}}-{\mathrm{Ri}}_{\mathrm{\α}}(k+1)\\ u_{\mathrm{\β}}(k+1)-e_{\mathrm{\β}}-{\mathrm{Ri}}_{\mathrm{\β}}(k+1)\end{array}\right]+\left[\begin{array}{c}P\left(k+1\right)\\ Q\left(k+1\right)\end{array}\right]---\left(11\right);$

Wherein, P (k+1) is t_k+1Moment active power predicted value；Q (k+1) is t_k+1Moment reactive power predicted value；P (k+2) is t_k+2Moment active power predicted value；Q (k+2) is t_k+2Moment reactive power predicted value；i_α(k+1) it is t_k+1Moment output current The α components of predicted value；i_β(k+1) it is t_k+1The β components of moment output current predicted value；e_αIt is the α components of line voltage；e_βIt is electricity The β components of net voltage；u_α(k+1) it is t_k+1The α components of moment output voltage；u_β(k+1) it is t_k+1The β components of moment output voltage； L is inductance；T_sIt is sample frequency.

4. two-way AC/DC convertor model prediction current control method according to claim 1, it is characterised in that：In step In rapid S4, concretely comprise the following steps, S4.1, under unbalanced power grid, calculate respectively line voltage e, the positive-sequence component of output current i and Negative sequence component；

$\left\{\begin{array}{c}e={e_{\mathrm{\α}\mathrm{\β}}}^{+}+{e_{\mathrm{\α}\mathrm{\β}}}^{-}={e_{dq}}^{+}{e}^{j\mathrm{\ω}t}+{e_{dq}}^{-}{e}^{-j\mathrm{\ω}t}\\ i={i_{\mathrm{\α}\mathrm{\β}}}^{+}+{i_{\mathrm{\α}\mathrm{\β}}}^{-}={i_{dq}}^{+}{e}^{j\mathrm{\ω}t}+{i_{dq}}^{-}{e}^{-j\mathrm{\ω}t}\end{array}\right.---\left(12\right);$

$\left\{\begin{array}{c}{e_{dq}}^{+}={e_d}^{+}+{{\mathrm{je}}_q}^{+}\\ {e_{dq}}^{-}={e_d}^{-}+{{\mathrm{je}}_q}^{-}\\ {i_{dq}}^{+}={i_d}^{+}+{{\mathrm{ji}}_q}^{+}\\ {i_{dq}}^{-}={i_d}^{-}+{{\mathrm{ji}}_q}^{-}\end{array}\right.---\left(13\right);$

In formula：ω is dq coordinate system angular velocity of rotations,It is line voltage in the positive-sequence component of α β coordinate systems；It is power network Negative sequence component of the voltage in α β coordinate systems；It is line voltage in the positive-sequence component of dq coordinate systems；It is line voltage in dq The negative sequence component of coordinate system；It is output current in the positive-sequence component of α β coordinate systems；It is output current in α β coordinate systems Negative sequence component；It is output current in the positive-sequence component of dq coordinate systems；It is output current in the negative sequence component of dq coordinate systems； e_d ⁺It is line voltage in the d axle positive-sequence component numerical value of dq coordinate systems；e_q ⁺It is line voltage in the q axle positive-sequence components of dq coordinate systems Numerical value；e_d ^-It is line voltage in the d axle negative sequence component numerical value of dq coordinate systems；e_q ^-It is line voltage in the q axle negative phase-sequences of dq coordinate systems Component values；i_d ⁺It is output current in the d axle positive-sequence component numerical value of dq coordinate systems；i_q ⁺It is output current in the q axles of dq coordinate systems Positive-sequence component numerical value；i_d ^-It is output current in the d axle negative sequence component numerical value of dq coordinate systems；i_q ^-It is output current in dq coordinate systems Q axle negative sequence component numerical value；

S4.2, obtains the active power under dq coordinates and the relational expression between reactive power and positive and negative order components；

Concretely comprise the following steps：S4.2.1, according to instantaneous power theory, grid side power is expressed as follows：

S=ei^*=p+jq (14)；

In formula：

$\left\{\begin{array}{c}p=p_0+p_{c2}cos\left(2\mathrm{\ω}t\right)+p_{s2}sin\left(2\mathrm{\ω}t\right)\\ q=q_0+q_{c2}cos\left(2\mathrm{\ω}t\right)+q_{s2}\sin \left(2\mathrm{\ω}t\right)\end{array}\right.---\left(15\right);$

Wherein, p is active power, and q is reactive power；p₀It is a reference value of active power；p_c2For the cosine of active power is pulsed Component；p_s2It is the sinuous pulsation component of active power；q₀It is a reference value of reactive power；q_c2It is the cosine pulsation point of reactive power Amount；q_s2It is the sinuous pulsation component of reactive power；

S4.2.2, formula 12 in step S4.1 and formula 13 are substituted into the formula 15 in step S4.2.1, are calculated and are arranged, and obtain dq The relational expression between active power and reactive power and positive and negative order components under coordinate：

$\left\{\begin{array}{c}{p}_0={e_d}^{+}{i_d}^{+}+{e_q}^{+}{i_q}^{+}+{e_d}^{-}{i_d}^{-}+{e_q}^{-}{i_q}^{-}\\ p_{c2}={e_d}^{+}{i_d}^{-}+{e_q}^{+}{i_q}^{-}+{e_d}^{-}{i_d}^{+}+{e_q}^{-}{i_q}^{+}\\ p_{s2}={e_d}^{+}{i_q}^{-}-{e_q}^{+}{i_d}^{-}+{e_d}^{-}{i_d}^{+}-{e_q}^{-}{i_q}^{+}\\ q_0={e_q}^{+}{i_d}^{+}-{e_d}^{+}{i_q}^{+}+{e_q}^{-}{i_d}^{-}-{e_d}^{-}{i_q}^{-}\\ q_{c2}={e_q}^{+}{i_d}^{-}-{e_d}^{+}{i_q}^{-}+{e_q}^{-}{i_d}^{-}-{e_d}^{-}{i_q}^{+}\\ q_{s2}={e_d}^{+}{i_d}^{-}+{e_q}^{+}{i_q}^{-}-{e_d}^{-}{i_d}^{+}-{e_q}^{-}{i_q}^{+}\end{array}\right.---\left(16\right);$

In formula：p₀It is a reference value of active power；p_c2It is the cosine flutter component of active power；p_s2It is the positive taut pulse of active power Dynamic component；q₀It is a reference value of reactive power；q_c2It is the cosine flutter component of reactive power；q_s2It is the sinuous pulsation of reactive power Component；e_d ⁺It is line voltage in the d axle positive-sequence component numerical value of dq coordinate systems；e_q ⁺It is line voltage in the q axle positive sequences of dq coordinate systems Component values；e_d ^-It is line voltage in the d axle negative sequence component numerical value of dq coordinate systems；e_q ^-It is line voltage in the q axles of dq coordinate systems Negative sequence component numerical value；i_d ⁺It is output current in the d axle positive-sequence component numerical value of dq coordinate systems；i_q ⁺It is output current in dq coordinate systems Q axle positive-sequence component numerical value；i_d ^-It is output current in the d axle negative sequence component numerical value of dq coordinate systems；i_q ^-For output current is sat in dq Mark the q axle negative sequence component numerical value of system；

S4.3, obtains under α β rest frames, active power p, reactive power q and line voltage, output current and power network electricity 90 ° of postpones signals, 90 ° of relational expressions of postpones signal of output current of pressure.

Comprise the following steps that：S4.3.1, under α β rest frames, calculates the pass between 90 ° of postpones signals and positive and negative order components System：

Assuming that the variable under α β rest frames is x, then its 90 ° of postpones signals are expressed as x ', postpones signal and positive and negative order components Between relation be：

X '=x_αβ ⁺′+x_αβ ^-'=- jx_αβ ⁺+jx_αβ ^-(17)；

Then x, x ' are expressed as with the relation of positive and negative order components：

$\left[\begin{array}{c}x\\ x^{\′}\end{array}\right]=\left[\begin{array}{cc}1& 1\\ -j& j\end{array}\right]\left[\begin{array}{c}{x}_{\mathrm{\α}\mathrm{\β}}^{+}\\ x_{\mathrm{\α}\mathrm{\β}}^{-}\end{array}\right]---\left(18\right).$

S4.3.2, inverts and can obtain to the formula 18 in step S4.3.1：

$\left[\begin{array}{c}{x}_{\mathrm{\α}\mathrm{\β}}^{+}\\ x_{\mathrm{\α}\mathrm{\β}}^{-}\end{array}\right]=\frac{1}{2}\left[\begin{array}{cc}1& j\\ 1& -j\end{array}\right]\left[\begin{array}{c}x\\ x^{\′}\end{array}\right]---\left(19\right);$

After arrangement, the relation obtained between the positive and negative order components of dq rotating coordinate systems and α β rest frames is：

$\left[\begin{array}{c}{x}_{dq}^{+}\\ x_{dq}^{-}\end{array}\right]=\left[\begin{array}{cc}{e}^{-j\mathrm{\ω}t}& 0\\ 0& e^{j\mathrm{\ω}t}\end{array}\right]\left[\begin{array}{c}{x}_{\mathrm{\α}\mathrm{\β}}^{+}\\ x_{\mathrm{\α}\mathrm{\β}}^{-}\end{array}\right]---\left(20\right).$

S4.3.3, with reference to formula 19 and formula 20 in step S4.3.2, obtains positive and negative order components and α β coordinates under dq coordinate systems Lower expression formula between variable and postpones signal：

$\left[\begin{array}{c}{x}_{dq}^{+}\\ x_{dq}^{-}\end{array}\right]=\frac{1}{2}\left[\begin{array}{cc}{e}^{-j\mathrm{\ω}t}& {\mathrm{je}}^{-j\mathrm{\ω}t}\\ e^{j\mathrm{\ω}t}& -{\mathrm{je}}^{j\mathrm{\ω}t}\end{array}\right]\left[\begin{array}{c}x\\ x^{\′}\end{array}\right]---\left(21\right).$

S4.3.4, the formula 21 in step S4.3.3 is substituted into the formula 16 in step S4.2, obtains the wattful power under dq coordinates Relational expression between rate and reactive power and positive and negative order components：

$\left\{\begin{array}{c}{p}_0=\frac{1}{2}(i_{\mathrm{\α}}{e}_{\mathrm{\α}}+i_{\mathrm{\β}}{e}_{\mathrm{\β}}+{i_{\mathrm{\α}}}^{\′}{e_{\mathrm{\α}}}^{\′}+{i_{\mathrm{\β}}}^{\′}{e_{\mathrm{\β}}}^{\′})\\ p_{c2}=\frac{1}{2}\[k_{1}cos\left(2\mathrm{\ω}t\right)+k_{2}sin\left(2\mathrm{\ω}t\right)\]\\ p_{s2}=\frac{1}{2}\[-k_{2}cos\left(2\mathrm{\ω}t\right)+k_{1}sin\left(2\mathrm{\ω}t\right)\]\\ q_0=\frac{1}{2}(i_{\mathrm{\α}}{e}_{\mathrm{\β}}-i_{\mathrm{\β}}{e}_{\mathrm{\α}}+{i_{\mathrm{\α}}}^{\′}{e_{\mathrm{\β}}}^{\′}-{i_{\mathrm{\β}}}^{\′}{e_{\mathrm{\α}}}^{\′})\\ q_{c2}=\frac{1}{2}\[k_3\cos \left(2\mathrm{\ω}t\right)+k_4\sin \left(2\mathrm{\ω}t\right)\]\\ q_{s2}=\frac{1}{2}\[-k_{4}cos\left(2\mathrm{\ω}t\right)+k_3\sin \left(2\mathrm{\ω}t\right)\]\end{array}\right.---\left(22\right);$

Wherein：

$\left\{\begin{array}{c}{k}_1=i_{\mathrm{\α}}{e}_{\mathrm{\α}}+i_{\mathrm{\β}}{e}_{\mathrm{\β}}-{i_{\mathrm{\α}}}^{\′}{e_{\mathrm{\α}}}^{\′}-{i_{\mathrm{\β}}}^{\′}{e_{\mathrm{\β}}}^{\′}\\ k_2=i_{\mathrm{\α}}{e_{\mathrm{\α}}}^{\′}+i_{\mathrm{\β}}{e_{\mathrm{\β}}}^{\′}+{i_{\mathrm{\α}}}^{\′}{e}_{\mathrm{\α}}+{i_{\mathrm{\β}}}^{\′}{e}_{\mathrm{\β}}\\ k_3=i_{\mathrm{\α}}{e}_{\mathrm{\β}}-i_{\mathrm{\β}}{e}_{\mathrm{\α}}-{i_{\mathrm{\α}}}^{\′}{e_{\mathrm{\β}}}^{\′}+{i_{\mathrm{\β}}}^{\′}{e_{\mathrm{\α}}}^{\′}\\ k_4=i_{\mathrm{\α}}{e_{\mathrm{\β}}}^{\′}-i_{\mathrm{\β}}{e_{\mathrm{\α}}}^{\′}+{i_{\mathrm{\α}}}^{\′}{e}_{\mathrm{\β}}-{i_{\mathrm{\β}}}^{\′}{e}_{\mathrm{\α}}\end{array}\right.---\left(23\right);$

In formula：i_αIt is the α components of output current；i_βIt is the β components of output current；i_α' it is 90 ° of delay letters of output current α components Number；i_β' it is 90 ° of postpones signals of output current β components；e_αIt is the α components of line voltage；e_βIt is the β components of line voltage；e_α′ It is 90 ° of postpones signals of line voltage α components；e_β' it is 90 ° of postpones signals of line voltage β components.

S4.4, to eliminate the secondary pulsation of two-way AC/DC convertor power, is divided into the secondary pulsation of active power and idle work( The secondary pulsation of rate；

To eliminate the secondary pulsation of active power, the stabilization output of two-way AC/DC convertor active power, order are realized：

$\left\{\begin{array}{c}{p}_0=p_{ref}\\ q_0=0\\ k_1=0\\ k_2=0\end{array}\right.---\left(24\right);$

Formula 22 and the solution formula 24 of formula 23 in step S4.3, obtain output current reference value and active power, electricity The α components of net voltage, the expression formula between β components and postpones signal：

$\left\{\begin{array}{c}{i}_{\mathrm{\α}ref}=\frac{e_{\mathrm{\β}}^{\′}}{e_{\mathrm{\α}}{e}_{\mathrm{\β}}^{\′}-e_{\mathrm{\α}}^{\′}{e}_{\mathrm{\β}}}{p}_{ref}\\ i_{\mathrm{\β}ref}=\frac{-e_{\mathrm{\α}}^{\′}}{e_{\mathrm{\α}}{e}_{\mathrm{\β}}^{\′}-e_{\mathrm{\α}}^{\′}{e}_{\mathrm{\β}}}{p}_{ref}\end{array}\right.---\left(25\right);$

In formula, i_arefIt is the α components of output current reference value；i_βrefIt is the β components of output current reference value；e_αIt is line voltage α components；e_βIt is the β components of line voltage；e_α' it is 90 ° of postpones signals of line voltage α components；e_β' it is line voltage β components 90 ° of postpones signals；p_refIt is active power set-point；

To eliminate the secondary pulsation of reactive power, the stabilization output of two-way AC/DC convertor reactive power, order are realized：

$\left\{\begin{array}{c}{p}_0=0\\ q_0=q_{ref}\\ k_3=0\\ k_4=0\end{array}\right.---\left(26\right);$

Formula 22 and the solution formula 26 of formula 23 in step S4.3, output current reference value and reactive power, power network electricity The α components of pressure, the expression formula between β components and postpones signal：

$\left\{\begin{array}{c}{i}_{\mathrm{\α}ref}=\frac{-e_{\mathrm{\α}}^{\′}}{e_{\mathrm{\α}}{e}_{\mathrm{\β}}^{\′}-e_{\mathrm{\α}}^{\′}{e}_{\mathrm{\β}}}{q}_{ref}\\ i_{\mathrm{\β}ref}=\frac{-e_{\mathrm{\β}}^{\′}}{e_{\mathrm{\α}}{e}_{\mathrm{\β}}^{\′}-e_{\mathrm{\α}}^{\′}{e}_{\mathrm{\β}}}{q}_{ref}\end{array}\right.---\left(27\right);$

In formula, i_αrefIt is the α components of output current reference value；i_βrefIt is the β components of output current reference value；e_αIt is line voltage α components；e_βIt is the β components of line voltage；e_α' it is 90 ° of postpones signals of line voltage α components；e_β' it is line voltage β components 90 ° of postpones signals；q_refIt is active power set-point.