CN106026658A - Two-way energy storage converter analysis and control method related to nonlinear factors - Google Patents

Abstract

The invention discloses a two-way energy storage converter analysis and control method related to nonlinear factors. Influences of the dead-zone effect, power tube saturated pressure drop and other nonlinear factors on a system are considered, storage battery voltage, power tube saturated pressure drop and the duty ratio of a dead zone serve as external variables, the error voltage caused by the nonlinear factors is calculated, the obtained error voltage serves as disturbance quantity and is introduced into voltage current double closed-loop control, expressions of open-circuit voltage, output impedance and a controlled voltage source in an equivalent circuit are calculated, and the direct current microgrid two-way energy storage converter equivalent circuit related to the nonlinear factors is obtained. The error voltage caused by the nonlinear factors are compensated, the equivalent circuit is approximate to the equivalent circuit in an actual direct current microgrid two-way energy storage converter, precision of the equivalent circuit is improved, and the method can be used for analyzing the parallel-connection uniform current distribution property of a multi-energy-storage converter.

Description

The bidirectional energy-storage changer of a kind of meter and non-linear factor is analyzed and control method

Technical field

The present invention relates to new forms of energy distributed power generation, direct-current grid field, a kind of meter and non-linear factor Bidirectional energy-storage changer is analyzed and control method.

Background technology

Along with the continuous exhaustion of fossil energy, new forms of energy distributed generation technology is increasingly subject to people's attention, micro-electricity Net also arises at the historic moment.Compared to exchange micro-capacitance sensor, direct-current grid is by distributed power generation, energy storage device, energy converter The system formed with load etc., both can be incorporated into the power networks with bulk power grid, it is also possible to isolated operation.DC micro power grid system has knot The advantages such as structure is simple, and energy conversion times is few, it is not necessary to consider frequency, phase place and reactive-load compensation equipment, and power supply quality is high, promote The fast development of direct-current grid.When studying many energy storage changer parallel current-sharing characteristic, existing document is not all examined when modeling Consider dead time effect and the impact on system of the IGBT saturation voltage drop.

Summary of the invention

The technical problem to be solved is, not enough for prior art, it is provided that a kind of meter and non-linear factor Bidirectional energy-storage changer is analyzed and control method.

For solving above-mentioned technical problem, the technical solution adopted in the present invention is: a kind of meter and non-linear factor two-way Energy storage changer is analyzed and control method, and the method is:

1) in the starting point in each sampling period, to energy storage changer DC bus capacitor C₁The voltage u at two ends_dc1, flow through line Road impedance Z_line1Electric current i₁With flow through inductance L₁Electric current i_L1Sample respectively, by the data after a/d converter is changed Give dsp controller by parallel interface to process；

2) by DC side reference voltage u_refAnd with capacitance voltage feedback factor H_uEnergy storage changer DC side electricity after being multiplied Hold C₁The voltage u at two ends_dc1Subtract each other, obtain difference e_u, wherein, H_uSpan is 0.01 < H_u<0.02；

3) by difference e_uTransmission function G with outer loop voltag PI controller_uS () is multiplied, obtain instruction current i^* _L1, wherein, The transmission function G of outer loop voltag PI controller_uS the expression formula of () is G_u(s)=k_p+k_i/ s, wherein, k_pIt it is the ratio of PI controller Coefficient, k_pSpan is 0.1≤k_p≤ 20, k_iIt is the integral coefficient of PI controller, k_iSpan is 0.001≤k_i≤ 0.1, S=j ω, j are imaginary part unit symbols, and ω is electrical network angular frequency；

4) by instruction current i^* _L1And with inductor current feedback coefficient H_iInductance L is flow through after being multiplied₁Electric current i_L1Subtract each other, Obtain difference e_i, wherein, H_iSpan is 0.09 < H_i<0.11；

5) by difference e_iTransmission function G with interior circular current P controller_iS () is multiplied, obtain modulating wave u_t, wherein, internal ring The transmission function G of electric current P controller_iS the expression formula of () is G_iS ()=k, k are the proportionality coefficients of P controller, k span is 0.1≤k≤1.5；

6) by modulating wave u_tTransmission function G with pulse width modulator_pwmIt is multiplied, with energy storage changer DC bus capacitor C₁Two ends Voltage u_dc1Subtract each other, then the error voltage Δ u caused with non-linear factor_eSubtract each other, obtain the output voltage u of energy storage changer₁, Wherein, G_pwm=U_b1/U_c, U_b1It is battery tension meansigma methods, U_b1Span is 700≤U_b1≤ 720, U_cIt it is triangular carrier Amplitude, U_cSpan is 1≤U_c≤10。

Described step 6) in, the error voltage Δ u that non-linear factor causes_eExpression formula be:

Δu_e=(u_b1D_d+u_Q1)sign(i_L1)

Wherein, u_b1It is battery tension, u_Q1It is power tube saturation voltage drop, D_dIt is the dutycycle in dead band,

Compared with prior art, the present invention had the beneficial effect that the present invention relates to a kind of meter and non-linear because of The bidirectional energy-storage changer of element is analyzed and control method.Consider that dead time effect and power tube saturation pressure degradation non-linear factor are to being The impact of system, by battery tension, the dutycycle in power tube saturation voltage drop and dead band, as external variable, calculates because of non-linear The error voltage that factor causes, introduces the error voltage obtained in Double closed-loop of voltage and current as disturbance quantity, calculates In equivalent circuit, open-circuit voltage, output impedance and the expression formula of controlled voltage source, counted and the DC micro-electric of non-linear factor Net bidirectional energy-storage changer equivalent circuit.The present invention compensate for the error voltage caused because of non-linear factor, approaches actual DC The equivalent circuit of micro-capacitance sensor bidirectional energy-storage changer, improves the accuracy of equivalent circuit, can be used to analyze many energy storage conversion Device parallel current-sharing characteristic.

Accompanying drawing explanation

Fig. 1 is the structure chart of energy-storage system；

Fig. 2 is one embodiment of the invention i_L1> 0 time drive signal and the output voltage u of energy storage changer₁Waveform；

Fig. 3 is the control block diagram of one embodiment of the invention energy-storage system；

Fig. 4 is the equivalent circuit of one embodiment of the invention energy storage changer；

Energy storage changer DC bus capacitor C when Fig. 5 (a) is not consider non-linear factor₁The voltage u at two ends_dc1Emulation ripple Shape；Energy storage changer DC bus capacitor C when Fig. 5 (b) is to consider non-linear factor₁The voltage u at two ends_dc1Simulation waveform.

Detailed description of the invention

Fig. 1 is the structure chart of energy-storage system, Buck/Boost changer, also known as energy storage changer, it is achieved energy bidirectional flow Dynamic, DC/AC inverter uses single-phase bridge circuit and LC wave filter, has both avoided control that the circuit structure of complexity brings and stable Sex chromosome mosaicism, plays again bigger attenuation to high-frequency harmonic electric current, loads and is connect resistive load simulation by DC/AC inverter.Its In, power tube Q₁、Q₂, diode D₁、D₂With inductance L₁Constitute energy storage changer, power tube Q₃-Q₆Constitute single-phase bridge circuit, electricity Sense L_f1With electric capacity C_f1Constitute LC wave filter, u_b1And i_b1It is battery tension and electric current respectively, u₁It it is the output electricity of energy storage changer Pressure, u_dc1It is energy storage changer DC bus capacitor C₁The voltage at two ends, u_load1And i_load1It is that DC/AC inverter direct-flow side is defeated respectively Enter voltage and current, u_o1And i_o1It is to flow through resistive load R respectively₁Voltage and current, i_L1And i_Lf1It is inductance L respectively₁And L_f1 Electric current, i_C1And i_Cf1It is electric capacity C respectively₁And C_f1Electric current, i₁It it is line impedance Z_line1Electric current.

Fig. 2 is i_L1> 0 time drive signal and the output voltage u of energy storage changer₁Waveform, it is assumed that flow through inductance L₁Electric current i_L1Flowing to dc bus is that just it is negative for flowing to energy storage changer from dc bus.With i_L1> as a example by 0, q₁And q₂It is not consider respectively Power tube Q during non-linear factor₁And Q₂Drive signal, q₁₁And q₂₂Power tube Q when being to consider non-linear factor respectively₁And Q₂ Drive signal, u₁And u₁₁It is the output voltage considering the energy storage changer before and after non-linear factor respectively, t_dIt is Dead Time, t_on And t_offIt is turn on delay time and the turn-off delay time of power tube respectively, negligible, T_sIt is switch periods, u_Q1And u_D2 It is the saturation voltage drop of power tube and diode respectively, general u_Q1And u_D2Size be sufficiently close to, i.e. u_Q1=u_D2。

Fig. 3 is the control block diagram of energy-storage system, in the starting point in each sampling period, to energy storage changer DC bus capacitor C₁The voltage u at two ends_dc1, flow through line impedance Z_line1Electric current i₁With flow through inductance L₁Electric current i_L1Sample respectively, will be through Cross the data after a/d converter conversion to give dsp controller by parallel interface and process.

By DC side reference voltage u_refAnd with capacitance voltage feedback factor H_uEnergy storage changer DC bus capacitor after being multiplied C₁The voltage u at two ends_dc1Subtract each other, obtain difference e_u, wherein, H_uSpan is 0.01 < H_u<0.02。

By difference e_uTransmission function G with outer loop voltag PI controller_uS () is multiplied, obtain instruction current i^* _L1, wherein, outward The transmission function G of loop voltag PI controller_uS the expression formula of () is G_u(s)=k_p+k_i/ s, wherein, k_pIt it is the ratio system of PI controller Number, k_pSpan is 0.1≤k_p≤ 20, k_iIt is the integral coefficient of PI controller, k_iSpan is 0.001≤k_i≤ 0.1, s =j ω, j are imaginary part unit symbols, and ω is electrical network angular frequency.

By instruction current i^* _L1And with inductor current feedback coefficient H_iInductance L is flow through after being multiplied₁Electric current i_L1Subtract each other, To difference e_i, wherein, H_iSpan is 0.09 < H_i<0.11。

By difference e_iTransmission function G with interior circular current P controller_iS () is multiplied, obtain modulating wave u_t, wherein, internal ring electricity The transmission function G of stream P controller_iS the expression formula of () is G_iS ()=k, k are the proportionality coefficients of P controller, k span is 0.1 ≤k≤1.5。

By modulating wave u_tTransmission function G with pulse width modulator_pwmIt is multiplied, with energy storage changer DC bus capacitor C₁Two ends Voltage u_dc1Subtract each other, then the error voltage Δ u caused with non-linear factor_eSubtract each other, obtain the output voltage u of energy storage changer₁, its In, G_pwm=U_b1/U_c, U_b1It is battery tension meansigma methods, U_b1Span is 700≤U_b1≤ 720, U_cIt it is the width of triangular carrier Value, U_cSpan is 1≤U_c≤ 10, the error voltage Δ u that non-linear factor causes_eExpression formula be:

Δu_e=(u_b1D_d+u_Q1)sign(i_L1)

In formula, u_b1It is battery tension, u_Q1It is power tube saturation voltage drop, D_dIt is the dutycycle in dead band,

Fig. 4 is the equivalent circuit of energy storage changer, R_eIt is the DC/AC inverter equivalent load that connects resistive load, controlled electricity Potential source Δ u₁Expression formula be:

${\mathrm{\&Delta;u}}_1=\frac{(u_{b1}{D}_d+u_{Q1})sign\left(i_{L1}\right)}{1+G_u\left(s\right)G_i\left(s\right)G_{pwm}{H}_u}$

Open-circuit voltage E₁Expression formula be:

$E_1=\frac{G_u\left(s\right)G_i\left(s\right)G_{pwm}}{1+G_u\left(s\right)G_i\left(s\right)G_{pwm}{H}_u}{u}_{ref}$

Output impedance Z_L1Expression formula be:

$Z_{L1}=\frac{{\mathrm{sL}}_1+r_d+H_i{G}_i\left(s\right)G_{pwm}}{1+G_u\left(s\right)G_i\left(s\right)G_{pwm}{H}_u}$

Wherein, r_dFor inductance equivalent series resistance, r_dSpan is 2.5≤r_d≤3.5。

Fig. 5 (a), Fig. 5 (b) are energy storage changer DC bus capacitor C₁The voltage u at two ends_dc1Simulation waveform, Fig. 5 (a) is Do not consider energy storage changer DC bus capacitor C during non-linear factor₁The voltage u at two ends_dc1Simulation waveform, Fig. 5 (b) be consider Energy storage changer DC bus capacitor C during non-linear factor₁The voltage u at two ends_dc1Simulation waveform, can from Fig. 5 (a), Fig. 5 (b) To find out, the present invention compensate for the error voltage caused because of non-linear factor, reduces energy storage changer DC bus capacitor C₁Two The voltage u of end_dc1Fluctuation, the equivalent circuit derived more approaches the equivalence of actual DC micro-capacitance sensor bidirectional energy-storage changer Circuit, improves the accuracy of equivalent circuit.

Claims (6)

1. the bidirectional energy-storage changer of a meter and non-linear factor is analyzed and control method, it is characterised in that include following step Rapid:

1) in the starting point in each sampling period, to energy storage changer DC bus capacitor C₁The voltage u at two ends_dc1, flow through circuit resistance Anti-Z_line1Electric current i₁With flow through inductance L₁Electric current i_L1Sample respectively, sampled data is sent after a/d converter is changed Process to dsp controller；

2) by DC side reference voltage u_refAnd with capacitance voltage feedback factor H_uEnergy storage changer DC bus capacitor C after being multiplied₁ The voltage u at two ends_dc1Subtract each other, obtain difference e_u；

3) by difference e_uTransmission function G with outer loop voltag PI controller_uS () is multiplied, obtain instruction current i^* _L1；

4) by instruction current i^* _L1And with inductor current feedback coefficient H_iInductance L is flow through after being multiplied₁Electric current i_L1Subtract each other, poor Value e_i；

5) by difference e_iTransmission function G with interior circular current P controller_iS () is multiplied, obtain modulating wave u_t；

6) by modulating wave u_tTransmission function G with pulse width modulator_pwmIt is multiplied, product and energy storage changer DC bus capacitor C₁Two ends Voltage u_dc1Subtract each other, the error voltage Δ u that difference causes with non-linear factor again_eSubtract each other, obtain the output electricity of energy storage changer Pressure u₁, wherein, G_pwm=U_b1/U_c, U_b1It is battery tension meansigma methods, U_b1Span is 700≤U_b1≤ 720, U_cIt is that triangle carries The amplitude of ripple, U_cSpan is 1≤U_c≤10。

The bidirectional energy-storage changer of meter the most according to claim 1 and non-linear factor is analyzed and control method, its feature It is, step 2) in, H_uSpan is 0.01 < H_u<0.02。

The bidirectional energy-storage changer of meter the most according to claim 1 and non-linear factor is analyzed and control method, its feature It is, step 3) in, the transmission function G of outer loop voltag PI controller_uS the expression formula of () is G_u(s)=k_p+k_i/ s, wherein, k_pIt is The proportionality coefficient of PI controller, k_pSpan is 0.1≤k_p≤ 20, k_iIt is the integral coefficient of PI controller, k_iSpan is 0.001≤k_i≤ 0.1, s=j ω, j are imaginary part unit symbols, and ω is electrical network angular frequency.

The bidirectional energy-storage changer of meter the most according to claim 1 and non-linear factor is analyzed and control method, its feature It is, step 4) in, H_iSpan is 0.09 < H_i<0.11。

The bidirectional energy-storage changer of meter the most according to claim 1 and non-linear factor is analyzed and control method, its feature It is, step 5) in, the transmission function G of interior circular current P controller_iS the expression formula of () is G_iS ()=k, k are the ratios of P controller Example coefficient, k span is 0.1≤k≤1.5.

The bidirectional energy-storage changer of meter the most according to claim 1 and non-linear factor is analyzed and control method, its feature It is, step 6) in, the error voltage Δ u that non-linear factor causes_eExpression formula be:

Δu_e=(u_b1D_d+u_Q1)sign(i_L1)；

Wherein, u_b1It is battery tension, u_Q1It is power tube saturation voltage drop, D_dIt is the dutycycle in dead band,