CN105896546A - Control method capable of restraining impact load based on hybrid energy storage system - Google Patents

Abstract

The invention discloses a control method capable of restraining impact load based on a hybrid energy storage system. The control method comprises the steps of I, establishing an inverter control model; II, establishing a value objective function; and III, establishing a simulation model. Compared with a control method for V/f control by singly adopting an energy storage system, the system voltage and frequency fluctuations, after the impact load is tracked and compensated are all within the allowable range, obtained by the control method provided by the invention so as to ensure the steady operation of the system; and in addition, due to the control method provided by the invention, the harmonic content of the output current of the inverter is relatively increased, so that the electric energy quality output by the inverter is improved.

Description

A kind of hybrid energy-storing stabilizes the control method of impact load

Technical field

The present invention relates to a kind of control method, a kind of hybrid energy-storing stabilizes the control of impact load Method.

Background technology

There is the features such as intermittence, undulatory property and randomness due to photovoltaic generation, for the micro-electricity containing photovoltaic generation Net system, for guaranteeing power-balance in system, stability, quality of power supply etc., the most in systems equipped with Corresponding energy-storage system.Currently, accumulator has the advantage that energy density is big, can provide for load the long period Electric energy, but have and recycle the shortcomings such as the life-span is low, power density is low；Super capacitor have power density big, Have extended cycle life, the advantageous properties such as efficiency for charge-discharge height, fast response time, it is possible to achieve instantaneous power receives Or release, but electric energy can not be provided for load for a long time.In order to realize the high-energy-density of energy-storage system simultaneously And high power density, accumulator can be combined with super capacitor, form accumulator and mix storage with super capacitor Energy system (hybrid energy storage system, HESS), is equipped with corresponding management scheme and control System strategy, it is achieved stable, the economical operation of micro-grid system.

But, have the most different from bulk power grid, micro-grid system inertia is little, underdamping, does not possess big The Ability of Resisting Disturbance of electrical network, in the moment of energy requirement change, distributed power source cannot meet needs, therefore, Ability to bear and stability containing impact load micro-capacitance sensor is had higher requirement.At city micro-capacitance sensor In, elevator is load type more typically, and the startup of elevator, braking and acceleration and deceleration can produce bigger impact electricity Stream, when micro-capacitance sensor is under islet operation pattern, owing to losing the support of bulk power grid, dash current can make Obtain the voltage of micro-grid system, frequency produces bigger fluctuation, thus affects system stable operation.Along with distribution The fast development of formula generation technology, micro-capacitance sensor will quickly be popularized.It would therefore be highly desirable to a kind of economy of research Hybrid energy-storing technology, solve micro-capacitance sensor stable operation problem.

Summary of the invention

In order to solve the above-mentioned deficiency in the presence of prior art, the present invention provides a kind of hybrid energy-storing to stabilize impact The control method of property load.

The control method that the present invention provides includes:

I, set up inverter control model；

II, set up value goal function；

III, structure phantom.

Preferably, described step I inverter exports electric current under static α β coordinate system and is shown below:

$\left\{\begin{array}{c}L\frac{{\mathrm{di}}_{\mathrm{\α}}}{dt}=u_{\mathrm{\α}}-e_{\mathrm{\α}}-{\mathrm{Ri}}_{\mathrm{\α}}\\ L\frac{{\mathrm{di}}_{\mathrm{\β}}}{dt}=u_{\mathrm{\β}}-e_{\mathrm{\β}}-{\mathrm{Ri}}_{\mathrm{\β}}\end{array}\right.---\left(1\right)$

In formula, R: resistance, L: inductance, i_α、i_βRepresent that three-phase inverter output electric current is in α β coordinate system respectively Lower α component and β component；u_α、u_βRespectively represent three-phase inverter output voltage under α β coordinate system α component and β component；e_α、e_βRepresent system common point voltage α component and β component under α β coordinate system respectively.

Preferably, the on off state S of described step I inverter_iIt is shown below:

In formula, i represents a, b, c；

Described inverter output voltage component u under α β coordinate system_α、u_βIt is calculated as follows respectively:

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

In formula, DC bus-bar voltage U_dc。

Preferably, output current equation is carried out sliding-model control to be shown below:

$\left\{\begin{array}{c}L\frac{i_{\mathrm{\α}}(k+1)-i_{\mathrm{\α}}\left(k\right)}{T_S}=u_{\mathrm{\α}}\left(k\right)-e_{\mathrm{\α}}\left(k\right)-{\mathrm{Ri}}_{\mathrm{\α}}\left(k\right)\\ L\frac{i_{\mathrm{\β}}(k+1)-i_{\mathrm{\β}}\left(k\right)}{T_S}=u_{\mathrm{\β}}\left(k\right)-e_{\mathrm{\β}}\left(k\right)-{\mathrm{Ri}}_{\mathrm{\β}}\left(k\right)\end{array}\right.---\left(4\right)$

In formula, T_S: sampling period, R: resistance, L: inductance, i_α(k+1)、i_β(k+1) three-phase is represented respectively The α component in inverter output current k+1 moment under α β coordinate system and β component；i_α(k)、i_βK () represents respectively The α component in three-phase inverter output electric current k moment under α β coordinate system and β component；u_α(k)、u_β(k) difference Represent three-phase inverter output voltage k moment α component and β component under α β coordinate system；e_α(k)、e_β(k) point Biao Shi system common point voltage k moment α component and β component under α β coordinate system；

The inverter output current d axle and the q axle component that dope are shown below:

$\left\{\begin{array}{c}{i}_d(k+1)=i_{\mathrm{\α}}(k+1)\cos \mathrm{\θ}+i_{\mathrm{\β}}(k+1)\sin \mathrm{\θ}\\ i_q(k+1)=-i_{\mathrm{\α}}(k+1)\sin \mathrm{\θ}+i_{\mathrm{\β}}(k+1)\cos \mathrm{\θ}\end{array}\right.---\left(5\right)$

In formula, θ: system space angle, R: resistance, L: inductance, i_α(k+1)、i_β(k+1) represent respectively The α component in three-phase inverter output electric current k+1 moment under α β coordinate system and β component.

Preferably, shown step II value goal function is shown below:

$g={\[i_d^{*}-i_d(k+1)\]}^2+{\[i_q^{*}-i_q(k+1)\]}^2---\left(6\right)$

In formula, i^* _dAnd i^* _qRepresent currently practical sample rate current d axle under dq coordinate system and q axle component respectively； G: current flow sampled value and the difference of predicted current value.

Preferably, described step III applies to the phantom of super capacitor system；

Described super capacitor system includes: photovoltaic array, batteries to store energy, super capacitor energy-storage, load and phase The changer answered；

Described photovoltaic array, batteries to store energy and super capacitor energy-storage are existed by respective three-phase inverter and wave filter AC parallel connection is load supplying.

Preferably, described photovoltaic array is incorporated to dc bus by the control of DC transformer (DC/DC), to light Volt uses maximal power tracing technology (MPPT), then by DC/AC inverter incoming transport bus, use meritorious, Idle control (P/Q)；

Described batteries to store energy, uses bidirectional, dc current transformer (DC/DC), by DC/AC inverter incoming transport Bus, uses constant voltage, constant frequency (V/f) to control；

Described super capacitor energy-storage, uses two-way DC converter (DC/DC), DC/AC inverter access and hand over Stream bus, uses meritorious, idle control (P/Q).

Preferably, use the super capacitor in described super capacitor system in threephase asynchronous start-up course Watt current and reactive current quickly follow the tracks of.

Preferably, described step I inverter includes two level three-phase voltage-type inverters；

Both ends of power is arranged in parallel switch, and described switch includes brachium pontis and lower brachium pontis, on described brachium pontis and under Arranging a little between brachium pontis, described point is provided with inductance and the resistance of series connection with load between being connected.

Compared with prior art, the method have the advantages that

(1) hybrid energy-storing of the present invention stabilizes the control method of impact load, and individually uses energy-storage system Carrying out V/f to control to compare, the fluctuation that impact load is tracked the system voltage after compensating and frequency can In allowed limits, it is ensured that the stable operation of system.

(2) compared with traditional PI control method, humorous at inverter output current of the control method of the present invention Ripple content aspect has greatly improved, and improves the quality of power supply of inverter output.

Accompanying drawing explanation

Fig. 1 is the two level three-phase inverter principle schematic of the present invention；

Fig. 2 is the flow chart of model current predictive control algorithm；

Fig. 3 is photovoltaic/energy storage micro-grid system structured flowchart；

System voltage amplitude change curve schematic diagram when Fig. 4 is tracing compensation.

Detailed description of the invention

In order to be more fully understood that the present invention, below in conjunction with Figure of description and example, present disclosure is done into one The explanation of step.

The present invention proposes a kind of hybrid energy-storing and stabilizes the control method of impact load.This control method, has good Good dynamic response, it is possible to quickly follow the tracks of the dash current that impact load produces, maintain system voltage and frequency Stable.It addition, the electric current linear controller given up in this control method in traditional control method and pulsewidth modulation Module, control algolithm is simple, and digital signal processing chip implements very easy, easy to implement in engineering.

The technical solution adopted for the present invention to solve the technical problems is as follows:

Model current predictive control algorithm is number limited (8) based on the combination of three-phase inverter switch function, Such that it is able to by being combined the prediction mould that the relation between its controlled volume is constituted by three-phase inverter switch function Type, uses the form calculus of traversal to go out the three-phase inverter under all 8 switch functions combination effects respectively Controlled volume predictive value, selects the switch function compound action making the system function optimization functional value minimum of structure in three Phase inverter.

For invention process approach, shown in accompanying drawing 2, it is described in further detail below:

The first step: set up inverter control model

Three-phase inverter is two level three-phase voltage-type inverters, its system architecture diagram as shown in Figure 1: electricity Two ends, source are parallel with switch S respectively_a、S_bAnd S_c, its breaker in middle S_aIncluding upper arm S1 and underarm S4, switch S_b Including upper arm S3 and underarm S6, switch S_cIncluding upper arm S5 and underarm S2, switch S_a、S_bAnd S_cUpper arm And between underarm, it is respectively arranged with a point, b point and c point, it is in series with inductance at these 3 on load connecting line L and resistance R.

Three-phase inverter output electric current dynamical equation under static α β coordinate system is:

$\left\{\begin{array}{c}L\frac{{\mathrm{di}}_{\mathrm{\α}}}{dt}=u_{\mathrm{\α}}-e_{\mathrm{\α}}-{\mathrm{Ri}}_{\mathrm{\α}}\\ L\frac{{\mathrm{di}}_{\mathrm{\β}}}{dt}=u_{\mathrm{\β}}-e_{\mathrm{\β}}-{\mathrm{Ri}}_{\mathrm{\β}}\end{array}\right.---\left(1\right)$

In formula, R represents that resistance, L represent inductance, i_α、i_βRepresent that three-phase inverter output electric current is at α β respectively α component and β component under coordinate system；u_α、u_βRepresent three-phase inverter output voltage α under α β coordinate system respectively Component and β component；e_α、e_βRepresent system common point voltage α component and β component under α β coordinate system respectively.

In every phase brachium pontis of three-phase inverter, have two kinds of switching modes, i.e. go up brachium pontis conducting or lower brachium pontis is led Logical, therefore have 8 kinds of switch combinations.Unipolarity two-valued function switch function is utilized to describe three-phase inverter switch State, it may be assumed that

According to DC bus-bar voltage U_dcOn off state S with three-phase inverter_a、S_b、S_c, inversion can be obtained Device output voltage α, β component under α β coordinate system is respectively u_α、u_β。

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

Formula (1) is carried out discretization, can obtain

$\left\{\begin{array}{c}L\frac{i_{\mathrm{\α}}(k+1)-i_{\mathrm{\α}}\left(k\right)}{T_S}=u_{\mathrm{\α}}\left(k\right)-e_{\mathrm{\α}}\left(k\right)-{\mathrm{Ri}}_{\mathrm{\α}}\left(k\right)\\ L\frac{i_{\mathrm{\β}}(k+1)-i_{\mathrm{\β}}\left(k\right)}{T_S}=u_{\mathrm{\β}}\left(k\right)-e_{\mathrm{\β}}\left(k\right)-{\mathrm{Ri}}_{\mathrm{\β}}\left(k\right)\end{array}\right.---\left(4\right)$

In formula, R represents that resistance, L represent inductance, i_α(k+1)、i_β(k+1) represent that three-phase inverter is defeated respectively The α component in k+1 moment that goes out electric current under α β coordinate system and β component；i_α(k)、i_βK () represents three contraries respectively Become α component and the β component in device output electric current k moment under α β coordinate system；u_α(k)、u_βK () represents three respectively Phase inverter output voltage is k moment α component and β component under α β coordinate system；e_α(k)、e_βK () represents respectively System common point voltage is k moment α component and β component under α β coordinate system；T_SFor the sampling period.

Can be obtained by formula (4):

$\left\{\begin{array}{c}{i}_{\mathrm{\α}}(k+1)=(1-\frac{{\mathrm{RT}}_S}{L})i_{\mathrm{\α}}\left(k\right)+\frac{T_S}{L}\[u_{\mathrm{\α}}\left(k\right)-e_{\mathrm{\α}}\left(k\right)\]\\ i_{\mathrm{\β}}(k+1)=(1-\frac{{\mathrm{RT}}_S}{L})i_{\mathrm{\β}}\left(k\right)+\frac{T_S}{L}\[u_{\mathrm{\β}}\left(k\right)-e_{\mathrm{\β}}\left(k\right)\]\end{array}\right.---\left(5\right)$

Then

$\left\{\begin{array}{c}{i}_d(k+1)=i_{\mathrm{\α}}(k+1)\cos \mathrm{\θ}+i_{\mathrm{\β}}(k+1)\sin \mathrm{\θ}\\ i_q(k+1)=-i_{\mathrm{\α}}(k+1)\sin \mathrm{\θ}+i_{\mathrm{\β}}(k+1)\cos \mathrm{\θ}\end{array}\right.---\left(6\right)$

In formula, θ is system space angle；i_d(k+1)、i_q(k+1) it is illustrated respectively in what the K+1 moment doped Inverter output current d axle and q axle component.

Second step: set up target value function,

Use current error quadratic power and as value goal function:

$g={\[i_d^{*}-i_d(k+1)\]}^2+{\[i_q^{*}-i_q(k+1)\]}^2---\left(7\right)$

In formula, i^* _dAnd i^* _qRepresent currently practical sampled current value；G represents current flow sampled value and prediction electricity The difference of flow valuve.

The form calculus using traversal goes out the three-phase inversion under all 8 switch functions combination effects respectively Device controlled volume predictive value, the minimum switch function compound action of the system function optimization functional value that selects to make structure in Three-phase inverter, the switch making target error electric current minimum is output switch control.Model current PREDICTIVE CONTROL is calculated The flow chart of method.

3rd step: build phantom, carry out simulating, verifying

This algorithm applies in super capacitor system, and experimental system includes photovoltaic module, accumulator battery, super electricity Container, load and corresponding changer, as it is shown on figure 3, wherein photovoltaic array is by DC transformer (DC/DC) Control be incorporated to dc bus, to photovoltaic use maximal power tracing technology (MPPT), then by DC/AC inverse Become device incoming transport bus, use meritorious, idle control (P/Q)；Batteries to store energy, uses bidirectional, dc to become Stream device (DC/DC), by DC/AC inverter incoming transport bus, uses constant voltage, constant frequency (V/f) to control； Super capacitor energy-storage, uses two-way DC converter (DC/DC), by DC/AC inverter incoming transport bus, Use meritorious, idle control (P/Q).Under islet operation pattern, photovoltaic generation unit, energy-storage system of accumulator And super capacitor energy-storage system is load supplying by respective three-phase inverter and wave filter in AC parallel connection.

Utilize super capacitor that the watt current in threephase asynchronous start-up course and reactive current are carried out soon Speed is followed the tracks of, and its simulation result as shown in Figure 4, increases over time, and the change of system voltage amplitude tends to balance.

These are only embodiments of the invention, be not limited to the present invention, all spirit in the present invention and Within principle, any modification, equivalent substitution and improvement etc. done, the present invention's being all contained in applying for awaiting the reply Within right.

Claims (9)

1. a hybrid energy-storing stabilizes the control method of impact load, it is characterised in that described method includes:

I, set up inverter control model；

II, set up value goal function；

III, structure phantom.

2. control method as claimed in claim 1, it is characterised in that described step I inverter is sat at static α β The lower output electric current of mark system is shown below:

$\left\{\begin{array}{c}L\frac{{\mathrm{di}}_{\mathrm{\α}}}{dt}=u_{\mathrm{\α}}-e_{\mathrm{\α}}-{\mathrm{Ri}}_{\mathrm{\α}}\\ L\frac{{\mathrm{di}}_{\mathrm{\β}}}{dt}=u_{\mathrm{\β}}-e_{\mathrm{\β}}-{\mathrm{Ri}}_{\mathrm{\β}}\end{array}\right.---\left(1\right)$

In formula, R: resistance, L: inductance, i_α、i_βRepresent that three-phase inverter output electric current is in α β coordinate system respectively Lower α component and β component；u_α、u_βRespectively represent three-phase inverter output voltage under α β coordinate system α component and β component；e_α、e_βRepresent system common point voltage α component and β component under α β coordinate system respectively.

3. control method as claimed in claim 1, it is characterised in that the on off state S of described step I inverter_i It is shown below:

In formula, i represents a, b, c；

Described inverter output voltage component u under α β coordinate system_α、u_βIt is calculated as follows respectively:

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

In formula, DC bus-bar voltage U_dc。

4. control method as claimed in claim 2, it is characterised in that output current equation is carried out at discretization Reason is shown below:

$\left\{\begin{array}{c}L\frac{i_{\mathrm{\α}}\left(k+1\right)-i_{\mathrm{\α}}\left(k\right)}{T_S}=u_{\mathrm{\α}}\left(k\right)-e_{\mathrm{\α}}\left(k\right)-{\mathrm{Ri}}_{\mathrm{\α}}\left(k\right)\\ L\frac{i_{\mathrm{\β}}\left(k+1\right)-i_{\mathrm{\β}}\left(k\right)}{T_S}=u_{\mathrm{\β}}\left(k\right)-e_{\mathrm{\β}}\left(k\right)-{\mathrm{Ri}}_{\mathrm{\β}}\left(k\right)\end{array}\right.---\left(4\right)$

In formula, T_S: sampling period, R: resistance, L: inductance, i_α(k+1)、i_β(k+1) three-phase is represented respectively The α component in inverter output current k+1 moment under α β coordinate system and β component；i_α(k)、i_βK () represents respectively The α component in three-phase inverter output electric current k moment under α β coordinate system and β component；u_α(k)、u_β(k) difference Represent three-phase inverter output voltage k moment α component and β component under α β coordinate system；e_α(k)、e_β(k) point Biao Shi system common point voltage k moment α component and β component under α β coordinate system；

The inverter output current d axle and the q axle component that dope are shown below:

$\left\{\begin{array}{c}{i}_d\left(k+1\right)=i_{\mathrm{\α}}\left(k+1\right)\cos \mathrm{\θ}+i_{\mathrm{\β}}\left(k+1\right)\sin \mathrm{\θ}\\ i_q\left(k+1\right)=-i_{\mathrm{\α}}\left(k+1\right)\sin \mathrm{\θ}+i_{\mathrm{\β}}\left(k+1\right)\cos \mathrm{\θ}\end{array}\right.---\left(5\right)$

In formula, θ: system space angle, R: resistance, L: inductance, i_α(k+1)、i_β(k+1) represent respectively The α component in three-phase inverter output electric current k+1 moment under α β coordinate system and β component.

5. control method as claimed in claim 1, it is characterised in that shown step II value goal function is as follows Shown in formula:

$g={\[i_d^{*}-i_d(k+1)\]}^2+{\[i_q^{*}-i_q(k+1)\]}^2---\left(6\right)$

In formula, i^* _dAnd i^* _qRepresent currently practical sample rate current d axle under dq coordinate system and q axle component respectively； G: current flow sampled value and the difference of predicted current value.

6. control method as claimed in claim 1, it is characterised in that described step III applies to super capacitor The phantom of system；

Described super capacitor system includes: photovoltaic array, batteries to store energy, super capacitor energy-storage, load and phase The changer answered；

Described photovoltaic array, batteries to store energy and super capacitor energy-storage are existed by respective three-phase inverter and wave filter AC parallel connection is load supplying.

7. control method as claimed in claim 6, it is characterised in that described photovoltaic array is by DC transformer (DC/DC) control is incorporated to dc bus, to photovoltaic employing maximal power tracing technology (MPPT), then by DC/AC inverter incoming transport bus, uses meritorious, idle control (P/Q)；

Described batteries to store energy, uses bidirectional, dc current transformer (DC/DC), by DC/AC inverter incoming transport Bus, uses constant voltage, constant frequency (V/f) to control；

Described super capacitor energy-storage, uses two-way DC converter (DC/DC), DC/AC inverter access and hand over Stream bus, uses meritorious, idle control (P/Q).

8. control method as claimed in claim 6, it is characterised in that use surpassing in described super capacitor system Watt current in threephase asynchronous start-up course and reactive current are quickly followed the tracks of by level electric capacity.

9. control method as claimed in claim 1, it is characterised in that described step I inverter includes two level Three-phase voltage-type inverter；

Both ends of power is arranged in parallel switch, and described switch includes brachium pontis and lower brachium pontis, on described brachium pontis and under Arranging a little between brachium pontis, described point is provided with inductance and the resistance of series connection with load between being connected.