CN104218658B - A kind of micro-capacitance sensor mixed energy storage system control method - Google Patents

Abstract

The present invention relates to a kind of micro-capacitance sensor mixed energy storage system control method, to the buck/boost changed power device in micro-capacitance sensor mixed energy storage system, choose inductive currenti _L And capacitance voltageu _c For state variable, energy-storage units voltageu _i And load currenti _Load For input variable, establish the small-signal model of the buck/boost power inverter controlled based on PWM complementation, and separately designed the control circuit of accumulator and ultracapacitor, use the discharge and recharge of single current loop control accumulator, stabilize the low frequency component in synthetic load；Ultracapacitor stabilizes the difference of synthetic load power and battery power, adds power feedforward in Double closed-loop of voltage and current, it is suppressed that the fluctuation of DC bus-bar voltage.Consider each load power in micro-capacitance sensor, use multiple control modes to stabilize the high-frequency fluctuation of power, the fluctuation of suppression DC bus-bar voltage, maintain stablizing of DC bus-bar voltage work.

Description

A kind of micro-capacitance sensor mixed energy storage system control method

Technical field

The present invention relates to a kind of grid control method, particularly to a kind of micro-capacitance sensor mixed energy storage system control method.

Background technology

In order to ensure the stability that micro-capacitance sensor runs, keep realtime power for electric equilibrium, need to mixed energy storage system in addition Reasonably control.Microgrid power is distributed as shown in Figure 1.In system, energy-storage units (accumulator and ultracapacitor) all passes through Buck/boost power inverter is connected with dc bus, it is achieved the two-way flow of power.

At present, both at home and abroad the control strategy of micro-grid energy storage system is expanded research.Chen Yizhe proposes based on short-term The micro-grid energy storage system active control strategies of load prediction, in the case of considering that accumulator capacity, discharge and recharge number of times limit, According to the result of load prediction, the discharge and recharge of control accumulator actively, optimize the charging and discharging curve of accumulator.Zhang Guoju etc. adopt With ultracapacitor as the energy-storage units of micro-capacitance sensor, establish the small signal equivalent model that complementary PWM controls, apply two close cycles Control and power feedforward link achieves stablizing of DC bus-bar voltage.But single energy-storage units tends not to well hold concurrently Turn round and look at micro-capacitance sensor for energy and the requirement of power.Dougal R A etc. proposes the general of accumulator-super capacitor mixed energy storage Read, and demonstrate mixed energy storage system superiority in performance theoretically.Dai Yongxi etc., for pulse-type load, devise A kind of active mixing energy storage connected mode, optimizes the discharge condition of accumulator.Wang Hongfu etc. use accumulator-super capacitor Device mixing energy-storage system, accumulator and ultracapacitor stabilize the power swing of low frequency and high frequency respectively according to respective characteristic, flat Slide grid-connected honourable active power, improve the grid-connected quality of power supply.The existing research to hybrid energy-storing, focuses primarily upon flat Press down the control strategy of grid-connected power, and less to the electricity Real-time Balancing of independent operating micro-capacitance sensor and the research of voltage stabilization.

Summary of the invention

The present invention be directed to the electricity Real-time Balancing of independent operating micro-capacitance sensor, the problem of voltage stabilization, it is proposed that Yi Zhongwei Electrical network mixed energy storage system control method, based on complementary PWM small-signal model, gives accumulator and ultracapacitor designs respectively Control circuit, accumulator uses single electric current loop well to stabilize the low-frequency fluctuation of power, and ultracapacitor uses band feedforward Double-loop control, stabilizes the high-frequency fluctuation of power, and effectively maintains stablizing of DC bus-bar voltage.

The technical scheme is that a kind of micro-capacitance sensor mixed energy storage system control method, to micro-capacitance sensor hybrid energy-storing system Buck/boost changed power device in system, chooses inductive current i_LWith capacitance voltage u_cFor state variable, energy-storage units voltage u_i With load current i_LoadFor input variable, establish the small-signal of the buck/boost power inverter controlled based on PWM complementation Model, and separately designed the control circuit of accumulator and ultracapacitor, use the discharge and recharge of single current loop control accumulator, Stabilize the low frequency component in synthetic load；Ultracapacitor stabilizes the difference of synthetic load power and battery power, voltage- Current double closed-loop adds power feedforward in controlling, it is suppressed that the fluctuation of DC bus-bar voltage.

The small-signal model of described buck/boost power inverter based on PWM complementation control is:

PWM complementation is used to control, metal-oxide-semiconductor S1, S2 of dc bus two ends shunt capacitance C and two series connection, two metal-oxide-semiconductor S1, S2 upper each inverse parallel fast recovery diode D1, D2, two metal-oxide-semiconductor S1, S2 are connected in series and a little connect accumulation power supply positive pole by inductance L, Accumulation power supply negative pole connects dc bus negative pole, if metal-oxide-semiconductor and diode s₂/d₂ON time is than for d, s₁/d₁The time ratio of conducting For 1-d, if inductive current i_L, dc-link capacitance voltage u_CFor state variable；If accumulation power supply voltage u_iWith load current i_Load For input variable, i_oFor through transistor boost after electric current, if i_L、u_c、u_i、i_load、i_o, steady-state component corresponding for d be I_L、U_C、 U_I、I_O、I_Load、D；

At steady operation point, system is added disturbance: u_C=U_C+Δu_C, i_L=I_L+Δi_L, i_load=I_Load+Δi_load, d =D+ Δ d, u_i=U_I+Δu_iIgnore second order components, and consider I_O=I_Load, can obtain small-signal model after linearisation:

${\mathrm{\Δi}}_o=\frac{U_I-{2r}_L{I}_L}{U_C}{\mathrm{\Δi}}_L+\frac{I_L}{U_C}{\mathrm{\Δu}}_i-\frac{I_{\mathrm{Load}}}{U_C}{\mathrm{\Δu}}_C.$

The design on control circuit of described accumulator:

Using single current loop control, battery current following object current value changes, according to reference to charging/discharging current instruction i_{bat_ref}Control the discharge and recharge of accumulator, the low-frequency fluctuation of suppression synthetic load；

G_cS () is that electric current loop compensates network transfer function, G_pwmS () is that PWM pulse width modulator transmits function, G_id(s) be Buck/boost changed power device dutycycle extremely exports the transmission function of electric current, and H (s) is that current sample transmits function, output electricity Stream is by H (s) and i_{bat_ref}Ask difference through the G of series connection_c(s)、G_pwm(s)、G_idExport after (s)；

Wherein electric current loop compensates network transfer function G_cS () employing pole zero compensation model is:

$G_c\left(s\right)=G_{\mathrm{CO}}\frac{(1+\frac{s}{{\mathrm{\ω}}_{z1}})(1+\frac{s}{{\mathrm{\ω}}_{z2}})}{s(1+\frac{s}{{\mathrm{\ω}}_{p1}})(1+\frac{s}{{\mathrm{\ω}}_{p2}})}$

G in formula_COFor DC current gain；ω_z1、ω_z2For compensating zero point；ω_p1、ω_p2For compensating zero point.

The ultracapacitor design on control circuit of described band power feedforward: ultracapacitor uses based on power feedforward voltage Outer shroud adds current inner loop double-loop control；

Current inner loop transmission function is:

${\mathrm{\Δi}}_L=\frac{G_{\mathrm{iC}}{G}_{\mathrm{pwm}}[(1-D)I_L+{\mathrm{CU}}_{c}s]{\mathrm{\Δi}}_{L\_\mathrm{ref}}+{\mathrm{Cs\Δu}}_i+(1-D){\mathrm{\Δi}}_{\mathrm{load}}}{G_{\mathrm{iC}}{G}_{\mathrm{pwm}}[(1-D)I_L+{\mathrm{CU}}_{c}s]H_i+[{\mathrm{LCs}}^2+r_L\mathrm{Cs}+{(1-D)}^2]}$

For controlling the transmission function to inductive current；Transmission function for input voltage to inductive current；For the transmission function of load current to inductive current, H_vS () is outer voltage sample transfer function, G_icS () is electric current in Ring compensates network function, G_vcS () is that outer voltage compensates transmission function, G_ic(s) and G_vcS () all uses PI to compensate control；

Outer voltage based on power feedforward transmission function:

${\mathrm{\Δu}}_c=\frac{G_{\mathrm{vc}}K\frac{(U_I-{2r}_L{I}_L)}{U_C}{\mathrm{\Δu}}_{c\_\mathrm{ref}}+({\mathrm{KK}}_1-1){\mathrm{\Δi}}_{\mathrm{load}}+({\mathrm{KK}}_2\frac{I_L}{U_C}-\frac{I_L}{U_C}){\mathrm{\Δu}}_i}{G_{\mathrm{vc}}K\frac{(U_I-{2r}_L{I}_L)}{U_C}{H}_v+\frac{I_{\mathrm{Load}}}{U_C}+\mathrm{Cs}}.$

The beneficial effects of the present invention is: micro-capacitance sensor mixed energy storage system fuzzy control method of the present invention, consider micro- Each load power in electrical network, uses multiple control modes to stabilize the high-frequency fluctuation of power, suppresses the fluctuation of DC bus-bar voltage, Maintain stablizing of DC bus-bar voltage work.

Accompanying drawing explanation

Fig. 1 is microgrid power scattergram；

Fig. 2 is buck/boost power converter construction figure of the present invention；

Fig. 3 is accumulator control block diagram of the present invention；

Fig. 4 is ultracapacitor control block diagram of the present invention；

Fig. 5 is present invention ultracapacitor based on power feedforward control block diagram；

Fig. 6 is that the present invention mixes energy-storage system emulation main structure chart；

Fig. 7 is open-loop transfer function Bode diagram before rechargeable battery control circuit of the present invention compensates；

Fig. 8 is open-loop transfer function Bode diagram after rechargeable battery control circuit of the present invention compensates；

Fig. 9 is the open loop frequency performance plot of ultracapacitor control system of the present invention；

Figure 10 is active power curves figure of the present invention；

Figure 11 is DC bus-bar voltage curve chart of the present invention.

Detailed description of the invention

In independent micro-grid, the control of hybrid energy-storing is for buck/boost changed power device, chooses inductive current i_LAnd electric capacity Voltage u_cFor state variable, energy-storage units voltage u_iWith load current i_LoadFor input variable, establish and control based on PWM complementation The small-signal model of buck/boost power inverter, and separately designed the control circuit of accumulator and ultracapacitor, Using the discharge and recharge of single current loop control accumulator, stabilize the low frequency component in synthetic load, ultracapacitor is stabilized comprehensive negative Lotus power and the difference of battery power, add power feedforward, it is suppressed that dc bus in voltage-to-current double-closed-loop control The fluctuation of voltage.

One, Control System Design

Buck/boost reversible transducer assume responsibility for the discharge and recharge task of accumulator and ultracapacitor, and 2-way state switches Frequently, before accumulator and ultracapacitor are controlled design, buck/boost reversible transducer and PWM regulation need to be obtained The transmission function of device.The present invention establishes the reversible transducer small-signal model controlled based on complementary PWM, designs on this basis The control system of energy-storage units.

1, the switch converters small-signal model controlled based on complementary PWM

For avoiding frequently switching a large amount of switching losses that switch causes and the smooth steady control realizing inductive current, this Invention uses PWM complementation to control.In Fig. 2, metal-oxide-semiconductor S1, S2 of dc bus two ends shunt capacitance C and two series connection, two metal-oxide-semiconductors S1, S2 upper each inverse parallel fast recovery diode D1, D2, two metal-oxide-semiconductor S1, S2 are connected in series and are a little just connecing accumulation power supply by inductance L Pole, accumulation power supply negative pole connects dc bus negative pole.If metal-oxide-semiconductor and diode s₂/d₂ON time is than for d, s₁/d₁Conducting time Between than be 1-d.If inductive current i_L, dc-link capacitance voltage u_CFor state variable；If accumulation power supply voltage u_iAnd load current i_LoadFor input variable.Wherein s₁With s₂Can be metal oxide semiconductcor field effect transistor MOSFET or insulated gate bipolar Transistor IGBT.

Row write state equation is as follows:

Work as s₂/d₂During conducting, state equation is:

$\left\{\begin{array}{c}C\frac{{\mathrm{du}}_c}{\mathrm{dt}}=-i_{\mathrm{load}}\\ L\frac{{\mathrm{di}}_L}{\mathrm{dt}}=-r_L{i}_L+u_i\end{array}\right.---\left(12\right)$

In formula: r_LFor boost inductance equivalent resistance

The form of matrix of being write as arranges and is:

Order

Work as s₁/d₁During conducting, state equation is:

$\left\{\begin{array}{c}C\frac{{\mathrm{du}}_c}{\mathrm{dt}}=i_L-i_{\mathrm{load}}\\ L\frac{{\mathrm{di}}_L}{\mathrm{dt}}=-r_L{i}_L-u_C+u_i\end{array}\right.---\left(14\right)$

The form of matrix of being write as arranges and is:

Order

Utilization State-space Averaging Principle:

A=DA+ (1-D) A (16)

B=DB+ (1-D) B (17)

$\stackrel{.}{x}=\mathrm{Ax}+\mathrm{By}---\left(18\right)$

In formula: D is the conducting dutycycle of transistor.

Simultaneous formula (15), (16), (17) solve:

Substitute into quiescent point state equation 0=Ax+By, if i_L、u_c、u_i、i_load、i_o, steady-state component corresponding for d be I_L、 U_C、U_I、I_O、I_Load、D.Wherein i_oFor through transistor boost after electric current, from accompanying drawing 2, i₀≈i_load, obtain:

Solving quiescent point is:

$\left\{\begin{array}{c}{U}_C=\frac{1}{1-D}{U}_I-\frac{r_L}{{(1-D)}^2}{I}_{\mathrm{Load}}\\ I_L=\frac{1}{1-D}{I}_{\mathrm{Load}}\end{array}\right.---\left(21\right)$

From formula (21):

Work as U_I-(1-D)U_CDuring ＞ 0: I_L＞ 0, therefore DC/DC power inverter is operated in discharge condition (boost).

Work as U_I-(1-D)U_CDuring ＜ 0: I_L＜ 0, therefore DC/DC power inverter is operated in charged state (buck).

Work as U_I-(1-D)U_CWhen=0: I_L=0, therefore DC/DC power inverter is operated in zero energy swap status.

By above formula it can also be seen that the size of regulation dutycycle D can control inductive current.

At steady operation point, system is added disturbance: u_C=U_C+Δu_C, i_L=I_L+Δi_L, i_load=I_Load+Δi_load, d =D+ Δ d, u_i=U_I+Δu_iIgnore second order components, and consider I_O=I_Load, small-signal model after linearisation, can be obtained.

Solve:

By Laplace transform it is:

Again because power-balance has:

$u_i\·i_L-r_L\·i_L^2=u_C\·i_o---\left(25\right)$

Substitution microvariations obtain:

${\mathrm{\Δi}}_o=\frac{U_I-{2r}_L{I}_L}{U_C}{\mathrm{\Δi}}_L+\frac{I_L}{U_C}{\mathrm{\Δu}}_i-\frac{I_{\mathrm{Load}}}{U_C}{\mathrm{\Δu}}_C---\left(26\right)$

Δi_oIt is i_oMicrovariations, state averaging method is usually used in the dynamic modeling of DC/DC changer.

2, the design on control circuit of accumulator:

Accumulator mainly undertakes the low-frequency fluctuation of synthetic load, and the present invention uses single current loop control, electric power storage Pond current tracking target current value change, according to reference to charging/discharging current instruction i_{bat_ref}Control the discharge and recharge of accumulator.Store The control block diagram of battery is as it is shown on figure 3, G_cS () is that electric current loop compensates network transfer function, available pole zero point shown in formula (28) Compensate control realization；G_pwmS () is that PWM pulse width modulator transmits function, can be tried to achieve by formula (27)；G_idS () is buck/boost merit Rate variator dutycycle is to the transmission function exporting electric current；H (s) is that current sample transmits function.In Fig. 4, battery current is real Measured value i_batWith reference current i_{bat_ref}Between difference, by pole zero compensation actuator produce voltage control quantity u, voltage control Amount processed is made comparisons with the sawtooth waveforms amplitude of PWM controller, produces duty cycle, delta and triggers on buck/boost reversible transducer brachium pontis Switch S1 or S2, controls battery current.

G_idS () is the transmission function that dutycycle extremely exports electric current,

Tried to achieve by formula (24): $G_{\mathrm{id}}\left(s\right)=\frac{{\mathrm{\Δi}}_L}{\mathrm{\Δd}}=(1-D)I_L+{\mathrm{CU}}_{C}s$

$G_{\mathrm{pwm}}\left(s\right)=\frac{1}{V_M}---\left(27\right)$

In formula: V_MFor PWM ripple triangular wave amplitude.

Electric current loop compensates network transfer function G_cS () uses shown in pole zero compensation model such as formula (28).

$G_c\left(s\right)=G_{\mathrm{CO}}\frac{(1+\frac{s}{{\mathrm{\ω}}_{z1}})(1+\frac{s}{{\mathrm{\ω}}_{z2}})}{s(1+\frac{s}{{\mathrm{\ω}}_{p1}})(1+\frac{s}{{\mathrm{\ω}}_{p2}})}---\left(28\right)$

In formula: G_COFor DC current gain；ω_z1、ω_z2For compensating zero point；ω_p1、ω_p2For compensating zero point；

3, the ultracapacitor design on control circuit of band power feedforward

Ultracapacitor fast response time, it is provided that synthetic load power and the difference power of battery power, and maintain system Stablizing of system DC bus-bar voltage so that accumulator is in optimization charging and discharging state all the time, extends the service life of accumulator.This Literary composition ultracapacitor uses outer voltage-current inner loop double-loop control, and ultracapacitor control block diagram is as shown in Figure 4.H in figure_i S () is current inner loop sampling network function, H_vS () is outer voltage sample transfer function, G_icS () is that current inner loop compensates network Function, G_vcS () is that outer voltage compensates transmission function, G_ic(s) and G_vcS () all uses PI to compensate control.

By Fig. 6 set up current inner loop transmission function:

${\mathrm{\Δi}}_L=\frac{C_{\mathrm{iC}}{G}_{\mathrm{pwm}}{G}_{i_{L}d}{\mathrm{\Δi}}_{L\_\mathrm{ref}}+G_{i_L{u}_i}{\mathrm{\Δu}}_i+G_{i_L{i}_{\mathrm{load}}}{\mathrm{\Δi}}_{\mathrm{load}}}{1+G_{\mathrm{iC}}{G}_{\mathrm{pwm}}{G}_{i_{L}d}{H}_i}---\left(29\right)$

In formula:

For controlling the transmission function to inductive current；

Transmission function for input voltage to inductive current；

Transmission function for load current to inductive current.

$G_{i_{L}d}\left(s\right)=i_L\left(s\right)/d\left(s\right)=\frac{(1-D)I_L+{\mathrm{CU}}_{C}s}{{\mathrm{LCs}}^2+r_L\mathrm{CS}+{(1-D)}^2}---\left(30\right)$

$G_{i_L{u}_i}\left(s\right)=i_L\left(s\right)/u_i\left(s\right)=\frac{\mathrm{Cs}}{{\mathrm{LCs}}^2+r_L\mathrm{CS}+{(1-D)}^2}---\left(31\right)$

$G_{i_L{u}_{\mathrm{load}}}\left(s\right)=i_L\left(s\right)/u_{\mathrm{load}}\left(s\right)=\frac{\mathrm{Cs}}{{\mathrm{LCs}}^2+r_L\mathrm{CS}+{(1-D)}^2}---\left(32\right)$

Wushu (30), (31), (32) substitute in formula (29) and obtain

${\mathrm{\Δi}}_L=\frac{G_{\mathrm{iC}}{G}_{\mathrm{pwm}}[(1-D)I_L+{\mathrm{CU}}_{c}s]{\mathrm{\Δi}}_{L\_\mathrm{ref}}+{\mathrm{Cs\Δu}}_i+(1-D){\mathrm{\Δi}}_{\mathrm{load}}}{G_{\mathrm{iC}}{G}_{\mathrm{pwm}}[(1-D)I_L+{\mathrm{CU}}_{c}s]H_i+[{\mathrm{LCs}}^2+r_L\mathrm{Cs}+{(1-D)}^2]}---\left(23\right)$

Owing to the numerical value of inductance L and electric capacity C is the least, generally 10^-3The order of magnitude, D is dutycycle, and 1-D is between 0 and 1. Δi_loadWith Δ u_iCoefficient relative Δ i_{L_ref}For be negligible, therefore Δ i can be ignored_loadWith Δ u_iTo electric current loop Impact.In the case of ignoring system delay, electric current loop can be equivalent to proportional component K=1/H_i。

Outer voltage transmission function the most as shown in Figure 6:

${\mathrm{\Δu}}_c=\frac{G_{\mathrm{vc}}K(U_I-{2r}_L{I}_L){\mathrm{\Δu}}_{c\_\mathrm{ref}}+I_L{\mathrm{\Δu}}_i-U_C{\mathrm{\Δi}}_{\mathrm{load}}}{G_{\mathrm{vc}}K(U_I-{2r}_L{I}_L)H_v+I_{\mathrm{Load}}+\mathrm{Cs}}---\left(34\right)$

For outer voltage, have using Isobarically Control:

Δu_{c_ref}=0 (35)

Formula (35) is substituted into (34) obtain:

${\mathrm{\Δu}}_c=\frac{I_L{\mathrm{\Δu}}_i-U_C{\mathrm{\Δi}}_{\mathrm{load}}}{G_{\mathrm{vc}}K(U_I-{2r}_L{I}_L)H_v+I_{\mathrm{Load}}+\mathrm{Cs}}---\left(36\right)$

By formula (36) it can be seen that under Isobarically Control strategy, the fluctuation of DC bus-bar voltage is mainly by supply voltage Δ u_iWith load current Δ i_loadFluctuation causes.In order to effectively suppress the fluctuation of DC bus-bar voltage, present invention introduces power feedforward Control.After introducing the feedforward, ultracapacitor control block diagram is as shown in Figure 5.

By Fig. 7 can set up outer voltage based on power feedforward transmission function:

${\mathrm{\Δu}}_c=\frac{G_{\mathrm{vc}}K\frac{(U_I-{2r}_L{I}_L)}{U_C}{\mathrm{\Δu}}_{c\_\mathrm{ref}}+({\mathrm{KK}}_1-1){\mathrm{\Δi}}_{\mathrm{load}}+({\mathrm{KK}}_2\frac{I_L}{U_C}-\frac{I_L}{U_C}){\mathrm{\Δu}}_i}{G_{\mathrm{vc}}K\frac{(U_I-{2r}_L{I}_L)}{U_C}{H}_v+\frac{I_{\mathrm{Load}}}{U_C}+\mathrm{Cs}}---\left(37\right)$

K is proportional component coefficient, K₁And K₂It is respectively current feed-forward ring and the penalty coefficient of electric voltage feed forward ring.

Understood under Isobarically Control by formula (37), if KK₁-1=0 and KK₂-1=0, the most just can eliminate load electricity The impact that system is produced by stream and input voltage fluctuation, dc bus keeps transient stability.

Two, sample calculation analysis

1, simulation parameter

For verifying the correctness of above-mentioned control strategy, matlab/simulink builds mixing energy storage phantom and enters Row emulation, emulation agent structure is as shown in Figure 6.Accumulator capacity 4 × 320Ah, rated voltage 220V, rated current 100A；Super Level condenser capacity 63F, rated voltage 100V.

Other relevant parameter is: accumulator shunt inductance 5mH, internal resistance 0.3 Ω；Ultracapacitor shunt inductance 5mH, 0.3 Ω；Electric capacity of voltage regulation 5mF；Dc bus rated voltage 400V；Buck/boost reversible transducer switching frequency 10kHz.Accumulator State-of-charge interval be [0.35,0.9], the state-of-charge interval of ultracapacitor is [0.5,0.95], accumulator and super The state-of-charge initial value of capacitor is all set to 0.5, and the initial time constant T of low pass filter is set to 50s, i.e. synthetic load power The medium frequency power less than 0.02Hz, distributes to accumulator, and the high frequency power higher than 0.02Hz distributes to ultracapacitor.

2, the asking for of control circuit penalty function

1) the compensation network G of first calculating accumulator and ultracapacitor control circuit_c(s) and G_ve(s)。

From the figure 3, it may be seen that system open loop transmission function is before accumulator controls loop compensation:

$T_b\left(s\right)=G_{\mathrm{id}}\left(s\right)G_{\mathrm{pwm}}\left(s\right)H\left(s\right)=\frac{(1-D)I_L+{\mathrm{CU}}_{C}s}{{\mathrm{LCs}}^2+r_L\mathrm{CS}+{(1-D)}^2}\·\frac{1}{V_M}---\left(38\right)$

Substituting into relevant parameter, taking PWM pulse width modulator and obtaining the peak value of triangular wave is V_M=10V, feedback network transfer function H S ()=1 is calculated:

$T_b\left(s\right)=\frac{0.2s+5.5}{2.5\×{10}^{-5}{s}^2+1.5\×{10}^{-3}s+0.3}---\left(39\right)$

As shown in Figure 7, before compensating, open loop Bode diagram low-frequency range is relatively flat, and steady-state error is bigger.Use pole zero compensation Controlling, its transmission function is:

$G_c\left(s\right)=G_{\mathrm{CO}}\frac{(1+\frac{s}{{\mathrm{\ω}}_{z1}})(1+\frac{s}{{\mathrm{\ω}}_{z2}})}{s(1+\frac{s}{{\mathrm{\ω}}_{p1}})(1+\frac{s}{{\mathrm{\ω}}_{p2}})}---\left(40\right)$

Compensate network G_cS () two zero frequency are designed as and initial circuit function T_b(s) two close pole frequency phases Deng, so make in the frequency range higher than dual pole frequency, open-loop transfer function is to decline with-20dB/dec.I.e.

$f_{p0}=\frac{1}{2\mathrm{\π}\sqrt{\mathrm{LC}}}=16\mathrm{Hz}---\left(41\right)$

f_z1=f_z2=f_p0=16Hz (42)

Use f_p1Offset the low-limit frequency that original transfer function zero point occurs, it may be assumed that

f_p1=f_z0=27.5Hz (43)

By f_p2It is placed at a little higher than cross-over frequency, to reduce output high frequency switching ripple.That is:

f_p2≥1.5f_c=3000Hz (44)

Trying to achieve compensation network transfer function is:

$G_c\left(s\right)=100\frac{(1+\frac{s}{100})(1+\frac{s}{100})}{s(1+\frac{s}{180})(1+\frac{s}{18000})}---\left(45\right)$

After compensation, system open loop transmission function is:

T′_b(s)=G_c(s)·G_id(s)·G_pwm(s)·H(s) (46)

Substituting into relevant parameter, Bode diagram is as shown in Figure 8.After compensation, the Phase margin of open-loop transfer function is 41.7 °.Pass through Frequency is 1.55kHz, low-frequency range be improved significantly, eliminate steady-state error, meet system stability requirement.

From above analyzing, in super capacitor control circuit, electric current loop can regard proportional component as, and coefficient is K= 1/H_i, take again K₁=K₂=1/K=1.

Before compensating, the open-loop transfer function of outer voltage is:

$T\left(s\right)=K\·\frac{U_I-{2r}_L{I}_L}{U_C}\·\frac{1}{\mathrm{CS}}---\left(47\right)$

If outer voltage PI control and compensation transmission function is:

$G_{\mathrm{vc}}\left(s\right)=20(1+\frac{1}{2s})---\left(48\right)$

Open-loop transfer function frequency characteristic Bode diagram such as Fig. 9 of ultracapacitor control circuit.Improve after compensation and pass through Frequency, improves the response speed of system.After compensation, the phase margin of system is 90 °, and cross-over frequency is 1.6kHz, meets system Design requirement.

3, analysis of simulation result

One day synthetic load power and energy-storage units exert oneself as shown in Figure 10, due to distributed power source generating random Property, synthetic load power swing is the most violent.Synthetic load power is just, represents that generated output has deficiency, and vacancy power is by storing up Can unit compensation；Synthetic load power is negative, represents that power has surplus, unnecessary electricity to be stored in accumulator and ultracapacitor Between.It can be seen that the charge and discharge power of accumulator is more mild, effectively inhibit the low frequency part of synthetic load power, and Acutely, discharge and recharge switching frequently, effectively inhibits the high frequency waves of synthetic load electric current to the fluctuation of ultracapacitor charge-discharge electric power Dynamic, the input of ultracapacitor makes battery-operated under the charging and discharging state optimized, and extends its service life.

Figure 11 show the DC bus-bar voltage curve before and after introducing power feedforward, and before introducing power feedforward, direct current is female The voltage pulsation of line is relatively big, and especially when synthetic load power is changed between positive and negative, DC bus-bar voltage exists violent Fluctuation；After introducing power feedforward, feed-forward loop reduces supply voltage and the load fluctuation impact on dc bus, dc bus Voltage is more stable so that the fluctuation of DC bus-bar voltage maintains in the range of 5%, meets system reliability requirement.

Claims (3)

1. a micro-capacitance sensor mixed energy storage system control method, becomes the buck/boost power in micro-capacitance sensor mixed energy storage system Parallel operation, chooses inductive current i_LWith capacitance voltage u_cFor state variable, energy-storage units voltage u_iWith load current i_LoadBecome for input Amount, establishes the small-signal model of the buck/boost power inverter controlled based on PWM complementation, and has separately designed electric power storage Pond and the control circuit of ultracapacitor, use the discharge and recharge of single current loop control accumulator, stabilize the low frequency in synthetic load Component；Ultracapacitor stabilizes the difference of synthetic load power and battery power, increases in voltage-to-current double-closed-loop control Power feedforward, it is suppressed that the fluctuation of DC bus-bar voltage, it is characterised in that the described buck/ controlled based on PWM complementation The small-signal model of boost power inverter is: use PWM complementation to control, dc bus two ends shunt capacitance C and two series connection Metal-oxide-semiconductor S1, S2, two metal-oxide-semiconductor S1, S2 upper each inverse parallel fast recovery diode D1, D2, two metal-oxide-semiconductor S1, S2 are connected in series a little logical Crossing inductance L and connect accumulation power supply positive pole, accumulation power supply negative pole connects dc bus negative pole, if metal-oxide-semiconductor and diodeON time Than being,The time ratio of conducting isIf, inductive current, dc-link capacitance voltageFor state variable；If energy storage Supply voltageAnd load currentFor input variable,For through transistor boost after electric current, if、、、、、 Corresponding steady-state component is、、、、、；

At steady operation point, system is added disturbance:,,,,Ignore second order components, and consider, small-signal mould after linearisation, can be obtained Type:

, wherein r_LFor the electricity in buck/boost power inverter Sense equivalent resistance.

Micro-capacitance sensor mixed energy storage system control method the most according to claim 1, it is characterised in that the control of described accumulator Circuit design:

Using single current loop control, battery current following object current value changes, according to reference to charging/discharging current instructionControl the discharge and recharge of accumulator, the low-frequency fluctuation of suppression synthetic load；

Network transfer function is compensated for electric current loop,Function is transmitted for PWM pulse width modulator,For buck/ Boost changed power device dutycycle extremely exports the transmission function of electric current,Transmitting function for current sample, output electric current passes throughWithAsk difference through series connection、、Rear output；

Wherein electric current loop compensates network transfer functionEmploying pole zero compensation model is:

In formulaFor DC current gain；、For compensating zero point；、For compensating zero point.

Micro-capacitance sensor mixed energy storage system control method the most according to claim 2, it is characterised in that described band power feedforward Ultracapacitor design on control circuit: ultracapacitor uses and adds current inner loop double-loop control based on power feedforward outer voltage；

Current inner loop transmission function is:

For controlling the transmission function to inductive current；Transmission function for input voltage to inductive current；For Load current to the transmission function of inductive current,For outer voltage sample transfer function,Compensate for current inner loop Network function,Transmission function is compensated for outer voltage,WithAll use PI to compensate to control；

Outer voltage based on power feedforward transmission function:

。