CN106786805A - The straight trend section of friendship that a kind of meter and photovoltaic cluster are accessed coordinates method for optimally controlling - Google Patents

Abstract

The straight trend section of friendship that a kind of meter and photovoltaic cluster are accessed coordinates method for optimally controlling：Insertion switch function, the straight trend section Mathematical Modeling of friendship of meter and nonlinear characteristic based on separate unit transverter, dynamic expanding method and coordinate transform, the straight trend section Mathematical Modeling of friendship of meter and nonlinear characteristic that foundation is made up of many transverters；Power coordination optimal controller is built, realizes handing over the reasonable distribution of straight trend section transimission power and the Primary regulation of DC bus-bar voltage；Build voltage and recover optimal controller, recovery control is carried out to DC bus-bar voltage, realize the Secondary Control to DC bus-bar voltage, and improve the dynamic response characteristic of DC bus-bar voltage.The present invention can quickly stabilize power swing, maintain alternating current-direct current mixing microgrid internal power balance；While realizing controlling many coordinations of parallel running transverter, can guarantee that each transverter has optimal dynamic response characteristic again；Both zero dy namics asymptotically stability had been can guarantee that, transverter dynamic characteristic optimum control can have been realized again.

Description

The straight trend section of friendship that a kind of meter and photovoltaic cluster are accessed coordinates method for optimally controlling

Technical field

Straight trend control of section method is handed over the present invention relates to one kind.The friendship that more particularly to a kind of meter and photovoltaic cluster are accessed Straight trend section coordinates method for optimally controlling.

Background technology

With continuing to develop for new-energy grid-connected technology, increasing regenerative resource accesses power network.Photovoltaic, wind-powered electricity generation etc. Will cause that network trend has randomness and uncertainty after intermittent energy is grid-connected, especially when the batch (-type) energy such as photovoltaic Source with cluster form it is grid-connected when, it will so that network trend occur fluctuate in a big way, it will aggravation system load flow control difficulty Degree.

Micro-capacitance sensor has obtained extensive as a kind of effective way for bulk power grid is more efficiently received new energy Concern.Nowadays, the new energy such as photovoltaic accesses the proportion friendship growing day by day, traditional shared by the ratio and DC load of power distribution network Stream micro-capacitance sensor is difficult to preferably adapt to the access of high density distributed energy.Alternating current-direct current mixing micro-capacitance sensor taken into account exchange microgrid and The advantage of direct-current micro-grid, can make up the deficiency of conventional AC microgrid.Alternating current-direct current mixing micro-capacitance sensor can reduce energy multi-level and turn Loss in changing, can more fully consider the output characteristics of the photovoltaic distributed energy, more efficiently balanced to consider direct current The need for electricity of load and AC load, thus preferably realize distributed energy cluster access under " source-net-lotus-storage " it is excellent Change operation and coordinate to control.

Alternating current-direct current mixing micro-capacitance sensor includes the sub- microgrid of exchange and the sub- microgrid of direct current, and AC/DC is passed through between the sub- microgrid of alternating current-direct current Bi-directional inverter is connected, and the transregional transmission of mixing microgrid internal power is realized by AC/DC bi-directional inverters.Many parallel runnings AC/DC bi-directional inverters constitute the straight trend section of friendship.In order to realize real-time, the dynamic of alternating current-direct current mixing microgrid internal power Balance, stabilizes photovoltaic cluster and accesses the power swing for bringing, it is necessary to the power for studying many bi-directional inverters on trend section is soft Property control technology.Controlled by many coordinations of the bi-directional inverter of paired running, realize stable state transmission work(on trend section The reasonable distribution of rate, dynamic response is optimal in transient process.

The content of the invention

The technical problems to be solved by the invention are to provide under a kind of consideration photovoltaic cluster access conditions, realize handing over straight tide The straight trend section of friendship that flow section transmitting active power coordinated allocation, the optimal meter of dynamic response and photovoltaic cluster are accessed is coordinated most Excellent control method.

The technical solution adopted in the present invention is：The straight trend section of friendship that a kind of meter and photovoltaic cluster are accessed coordinates optimal control Method processed, comprises the following steps：

1) insertion switch function, the straight trend section Mathematical Modeling of friendship of meter and nonlinear characteristic based on separate unit transverter, Dynamic expanding method and coordinate transform, the straight trend section mathematics of friendship of meter and nonlinear characteristic that foundation is made up of many transverters Model；

2) power coordination optimal controller is built, realizes handing over the reasonable distribution and dc bus of straight trend section transimission power The Primary regulation of voltage；

3) build voltage and recover optimal controller, recovery control is carried out to DC bus-bar voltage, realize to dc bus electricity The Secondary Control of pressure, and improve the dynamic response characteristic of DC bus-bar voltage.

Step 1) specifically include：

(1) under x coordinate space, the straight trend section Mathematical Modeling of friendship to the meter and nonlinear characteristic of separate unit transverter is entered Mobile state is expanded, and the straight trend section Mathematical Modeling of friendship for obtaining the meter and nonlinear characteristic of transverter is as follows, and subscript k is represented in formula Kth platform transverter：

Wherein：

Wherein, each symbol definition is as follows：i_d(k)、i_q(k)Represent the dq axle components of kth platform transverter ac-side current； i_{d_ref(k)}、i_{q_ref(k)}Represent the reference value of kth platform transverter ac-side current dq axle components；e_d、e_qRepresent alternating current net side three-phase The dq axle components of voltage, ξ_1(k)、ξ_2(k)It is the dynamic state variables for introducing, L_(k)Kth platform transverter AC filter inductance is represented, ω is the angular frequency of power network, u_d(k)、u_q(k)Represent the dq axle components of kth platform transverter AC voltage；

(2) coordinate transform is chosen, by the straight trend section number of the friendship of the meter of the transverter after dynamic expanding and nonlinear characteristic Learn model to be mapped under new coordinate system z spaces, obtain under z coordinate space through the new transverter after state feedback linearization The straight trend section Mathematical Modeling of friendship of meter and nonlinear characteristic；Specifically：

Based on differential geometric theory, following dynamic expanding coordinate transform is chosen：

z_(k)=Φ_(k)(x) be from x coordinate space to z coordinate space under coordinate mapping, wherein Φ_(k)X () is local micro- Divide homeomorphism,

The Bu Lunuofu that the straight trend section Mathematical Modeling of the friendship of the meter of separate unit transverter and nonlinear characteristic is written as This base master pattern, constitutes the straight trend section Mathematical Modeling of friendship of the meter and nonlinear characteristic of new separate unit transverter：

Wherein：

V is the straight trend section Mathematical Modeling of the friendship of meter and nonlinear characteristic of separate unit transverter new under z coordinate space Input variable, i.e. pre-control variable；

(3) the straight trend section Mathematical Modeling of the friendship of the meter and nonlinear characteristic being made up of n platform transverters, specific as follows：

Wherein：

A_(k)And B_(k)It is the square in the straight trend section Mathematical Modeling of the friendship of meter and nonlinear characteristic of new separate unit transverter Battle array.

Step 2) include：

(1) self adaptation for setting up active power and DC bus-bar voltage coordinates droop control rule, specific as follows：

△P_(k)=m_(k)×△u_dc (5)

Wherein, each symbol definition is as follows：△u_dc=u_{dc_ref}-u_dcRepresent DC bus-bar voltage departure, u_dcRepresent direct current The measuring value of busbar voltage；u_{dc_ref}Represent the reference value of DC bus-bar voltage, △ P_(k)Represent the difference power that each transverter undertakes Volume, m_(k)It is the sagging coefficient of each transverter；

The sagging coefficient of each transverter is defined as follows：

Wherein：

△P_(k)max=2P_N(k) (8)

Each symbol definition is as follows：P_N(k)Represent the rated power of transverter transmission, P_re(k)Represent the dynamic power of transverter Allowance, P_(k)It is the active power of the transverter transmission of actual measurement, it is stipulated that from exchanging area to DC area transmission be the u for just_dcmax、 u_dcminRespectively DC bus-bar voltage higher limit and lower limit, △ u_dcmax、△P_(k)maxDC bus-bar voltage and kth are represented respectively The maximum deviation of platform transverter transimission power；

(2) using feedback linearization method improve transimission power dynamic response characteristic, be according to feedback linearization method, To step 1) in the straight trend section Mathematical Modeling of friendship of the meter and nonlinear characteristic of new separate unit transverter that obtains ask for inner ring Feedback Control Laws, obtain：

v_(k)Represent pre-control variable, u_(k)Represent input variable.

Wherein：

Pre-control variable v is asked for by quadratic performance index linear optimal contro8 method for designing_(k)：

Wherein P* is the solution of following Riccati equation：

R and Q are respectively the weight matrix of input variable and state variable, A_(k)And B_(k)For step 1) in the new separate unit that obtains Matrix in the straight trend section Mathematical Modeling of the friendship of meter and nonlinear characteristic of transverter.

Step 3) described in structure voltage recover optimal controller, including：

According to step 1) in after the dynamic expanding that obtains the meter and nonlinear characteristic of transverter the straight trend section mathematics of friendship Model, output vector is chosen again is：

Choose following coordinate transform：

Wherein ξ is the expansion dynamic variable introduced to eliminate steady-state error, ξ_(k)=∫ z '_4(k)dt；

To step 1) in the straight trend section Mathematical Modeling of friendship of the meter and nonlinear characteristic of new separate unit transverter that obtains, Inner loop feedback control law is asked for, control variables u ' is obtained_(k)

Wherein：

Wherein, each symbol definition is as follows：C represents dc bus equivalent capacitance, i_d(k)、i_q(k)Represent the exchange of kth platform transverter The dq axle components of side electric current；i_{q_ref(k)}Represent the reference value of kth platform transverter ac-side current q axle components, u_{dc_ref(k)}Represent The reference value of k platform transverter DC bus-bar voltages,；e_d、e_qRepresent the dq axle components of alternating current net side three-phase voltage, L_(k)Represent kth Platform transverter AC filter inductance, ω is the angular frequency of power network, I_LRepresent kth platform Converter DC-side output current value.

Pre-control variable v ' is asked for by quadratic performance index linear optimal contro8 method for designing_(k)：

Wherein P* is the solution of following Riccati equation：

R and Q are respectively the weight matrix of input variable and state variable, A_(k)And B_(k)For step 1) in the new separate unit that obtains Matrix in the straight trend section Mathematical Modeling of the friendship of meter and nonlinear characteristic of transverter.

It is of the invention it is a kind of count and the straight trend section of friendship that photovoltaic cluster is accessed coordinates method for optimally controlling, with having as follows Beneficial effect：

(1) present invention puies forward control method and can take into full account that photovoltaic cluster accesses the shadow brought to micro-capacitance sensor power flowcontrol Ring, can quickly stabilize power swing, maintain alternating current-direct current mixing microgrid internal power balance, improve DC bus-bar voltage quality；

(2) present invention carries dual excellent optimal with dynamic response of the distribution of power coordination when control method can take into account stable state Change target, while realizing controlling many coordinations of parallel running transverter, can guarantee that each transverter has again optimal Dynamic response characteristic；

(3) present invention takes into full account the nonlinear characteristic of trend section, using the method for dynamic expanding to system zero dy namics It is designed.Theoretical and case verification result shows that institute's extracting method both can guarantee that zero dy namics asymptotically stability, and transverter can be realized again Dynamic characteristic optimum control.

Brief description of the drawings

Fig. 1 is the flow chart that the straight trend section of friendship that present invention meter and photovoltaic cluster are accessed coordinates method for optimally controlling；

Fig. 2 is that photovoltaic cluster accesses mixing microgrid exemplary topology diagram；

Fig. 3 is system entirety control block diagram；

Fig. 4 is NONLINEAR OPTIMAL CONTROL block diagram；

Fig. 5 is that self adaptation coordinates sagging rule curve map；

Fig. 6 is DC bus-bar voltage oscillogram；

Fig. 7 is trend section transimission power oscillogram；

Fig. 8 is DC bus-bar voltage oscillogram in voltage recovery process；

Fig. 9 is transimission power oscillogram under Traditional control in voltage recovery process；

Figure 10 is transimission power oscillogram under NONLINEAR OPTIMAL CONTROL in voltage recovery process.

Specific embodiment

The straight trend section of friendship that a kind of meter of the invention and photovoltaic cluster are accessed is coordinated with reference to embodiment and accompanying drawing Method for optimally controlling is described in detail.

As shown in figure 1, the straight trend section of friendship that a kind of meter of the invention and photovoltaic cluster are accessed coordinates method for optimally controlling, Comprise the following steps：

1) characteristic of the switch non-linearity of transverter, insertion switch function, meter and non-thread based on separate unit transverter are considered Property the straight trend section Mathematical Modeling of friendship of characteristic, dynamic expanding method and coordinate transform, the meter that foundation is made up of many transverters And the straight trend section Mathematical Modeling of friendship of nonlinear characteristic；Specifically include：

(1) under x coordinate space, the straight trend section Mathematical Modeling of friendship to the meter and nonlinear characteristic of separate unit transverter is entered Mobile state is expanded, and the straight trend section Mathematical Modeling of friendship for obtaining the meter and nonlinear characteristic of transverter is as follows, and subscript k is represented in formula Kth platform transverter：

Wherein：

Wherein, each symbol definition is as follows：i_d(k)、i_q(k)Represent the dq axle components of kth platform transverter ac-side current； i_{d_ref(k)}、i_{q_ref(k)}Represent the reference value of kth platform transverter ac-side current dq axle components；e_d、e_qRepresent alternating current net side three-phase The dq axle components of voltage, ξ_1(k)、ξ_2(k)It is the dynamic state variables for introducing, L_(k)Kth platform transverter AC filter inductance is represented, ω is the angular frequency of power network, u_d(k)、u_q(k)Represent the dq axle components of kth platform transverter AC voltage；

(2) coordinate transform is chosen, by the straight trend section number of the friendship of the meter of the transverter after dynamic expanding and nonlinear characteristic Learn model to be mapped under new coordinate system z spaces, obtain under z coordinate space through the new transverter after state feedback linearization The straight trend section Mathematical Modeling of friendship of meter and nonlinear characteristic；Specifically：

Based on differential geometric theory, following dynamic expanding coordinate transform is chosen：

z_(k)=Φ_(k)(x) be from x coordinate space to z coordinate space under coordinate mapping, wherein Φ_(k)X () is local micro- Divide homeomorphism,

The Bu Lunuofu that the straight trend section Mathematical Modeling of the friendship of the meter of separate unit transverter and nonlinear characteristic is written as This base master pattern, constitutes the straight trend section Mathematical Modeling of friendship of the meter and nonlinear characteristic of new separate unit transverter：

Wherein：

v_(k)It is the straight trend section Mathematical Modeling of the friendship of the meter and nonlinear characteristic of separate unit transverter new under z coordinate space Input variable, i.e. pre-control variable；

(3) the straight trend section Mathematical Modeling of the friendship of the meter and nonlinear characteristic being made up of n platform transverters, specific as follows：

Wherein：

A_(k)And B_(k)It is the square in the straight trend section Mathematical Modeling of the friendship of meter and nonlinear characteristic of new separate unit transverter Battle array.

2) power coordination optimal controller is built, realizes handing over the reasonable distribution and dc bus of straight trend section transimission power The Primary regulation of voltage, specific control block diagram is as shown in Figure 3 and Figure 4；Including：

(1) self adaptation for setting up active power and DC bus-bar voltage coordinates droop control rule, be according to each transverter Dynamic margin adaptively change sagging coefficient, and then ensure that power difference coordinates optimum allocation between many transverters. It is specific as follows：

△P_(k)=m_(k)×△u_dc (5)

Wherein, each symbol definition is as follows：△u_dc=u_{dc_ref}-u_dcRepresent DC bus-bar voltage departure, u_dcRepresent direct current The measuring value of busbar voltage；u_{dc_ref}Represent the reference value of DC bus-bar voltage, △ P_(k)Represent the difference power that each transverter undertakes Volume, m_(k)It is the sagging coefficient of each transverter；

The sagging coefficient of each transverter is defined as follows：

Wherein：

△P_(k)max=2P_N(k) (8)

Each symbol definition is as follows：P_N(k)Represent the rated power of transverter transmission, P_re(k)Represent the dynamic power of transverter Allowance, P_(k)It is the active power of the transverter transmission of actual measurement, it is stipulated that from exchanging area to DC area transmission be the u for just_dcmax、 u_dcminRespectively DC bus-bar voltage higher limit and lower limit, △ u_dcmax、△P_(k)maxDC bus-bar voltage and kth are represented respectively The maximum deviation of platform transverter transimission power；

It is as shown in Figure 5 that the self adaptation of active power and DC bus-bar voltage coordinates droop control rule curve.Wherein,

a)△u_dc>0, DC bus-bar voltage is less than rated voltage, illustrates for DC area, the wattful power that system sends Less than the active power of Systemic absorption, it is △ P that now exchanging area should convey power by bi-directional inverter to DC area to rate_(k)> 0；

b)△u_dc<0, DC bus-bar voltage is higher than rated voltage, is illustrated for DC area, the wattful power that system sends Rate is more than the active power of Systemic absorption, and now DC area should be to the power that exchanging area conveys surplus by bi-directional inverter △P_(k)<0。

(2) improve the dynamic response characteristic of transimission power using feedback linearization method, be that it exists as controller inner ring Realize it is quick to outer shroud reference instruction, while accurately track, devise explicit state feedback optimal control, reduce transimission power and surpass Adjust, vibration is decayed as early as possible, improve the dynamic response of transimission power.

According to feedback linearization method, to step 1) in the friendship of the meter and nonlinear characteristic of new separate unit transverter that obtains Straight trend section Mathematical Modeling asks for inner loop feedback control law, obtains：

v_(k)Represent pre-control variable, u_(k)Represent input variable,

Wherein：

Pre-control variable v is asked for by quadratic performance index linear optimal contro8 method for designing_(k)：

Wherein P* is the solution of following Riccati equation：

R and Q are respectively the weight matrix of input variable and state variable, A_(k)And B_(k)For step 1) in the new separate unit that obtains Matrix in the straight trend section Mathematical Modeling of the friendship of meter and nonlinear characteristic of transverter.

3) build voltage and recover optimal controller, recovery control is carried out to DC bus-bar voltage, realize to dc bus electricity The Secondary Control of pressure, and improve the dynamic response characteristic of DC bus-bar voltage.Specific control block diagram is as shown in Figure 3 and Figure 4.Its In, described structure voltage recovers optimal controller, including：

According to step 1) in after the dynamic expanding that obtains the meter and nonlinear characteristic of transverter the straight trend section mathematics of friendship Model, output vector is chosen again is：

Choose following coordinate transform：

Wherein ξ is the expansion dynamic variable introduced to eliminate steady-state error, ξ_(k)=∫ z '_4(k)dt；

To step 1) in the straight trend section Mathematical Modeling of friendship of the meter and nonlinear characteristic of new separate unit transverter that obtains, Inner loop feedback control law is asked for, control variables u ' is obtained_(k)

Wherein：

Wherein, each symbol definition is as follows：C represents dc bus equivalent capacitance, i_d(k)、i_q(k)Represent the exchange of kth platform transverter The dq axle components of side electric current；i_{q_ref(k)}Represent the reference value of kth platform transverter ac-side current q axle components, u_{dc_ref(k)}Represent The reference value of k platform transverter DC bus-bar voltages,；e_d、e_qRepresent the dq axle components of alternating current net side three-phase voltage, L_(k)Represent kth Platform transverter AC filter inductance, ω is the angular frequency of power network, I_LRepresent kth platform Converter DC-side output current value.

Pre-control variable v ' is asked for by quadratic performance index linear optimal contro8 method for designing_(k)：

Wherein P* is the solution of following Riccati equation：

R and Q are respectively the weight matrix of input variable and state variable, A_(k)And B_(k)For step 1) in the new separate unit that obtains Matrix in the straight trend section Mathematical Modeling of the friendship of meter and nonlinear characteristic of transverter.

Embodiment is given below.

Under the alternating current-direct current mixing microgrid structure shown in Fig. 2, related embodiment is given.Wherein, parameters are as follows：Exchange Line voltage 10kV, transformer voltage ratio 10kV/220V, ac filter inductance 81.136mH, dc bus rated voltage 560V, change Stream device switching frequency 3000Hz.

Embodiment 1：Systematic steady state is run during to 0.6s, direct-current micro-grid sudden load increase 280kW, is run during to 0.8s, direct current Microgrid load is die-offed 480kW.DC bus-bar voltage waveform and trend section transimission power waveform difference are as shown in Figure 6 and Figure 7.

As seen from Figure 6, when DC load occurs step disturbance, carry control strategy and be able to maintain that dc bus electricity Pressure stabilization, and cause that DC bus-bar voltage has linear dynamic response, the dynamic regulation time is short, dead-beat.

As seen from Figure 7, after load occurs step disturbance, each transverter transmitting active power changes therewith Become, to make up power difference, realize the dynamic equilibrium of power.During 0.6s sudden load increases, lateral DC side transmission wattful power is exchanged Rate increases, and the active power allowance of three transverters successively decreases successively, thus the power difference for undertaking also is sequentially reduced, wherein No. 1 Transverter undertakes 110kW, and No. 2 transverters undertake 92.5kW, and No. 3 transverters undertake 70kW；When 0.8s loads are die-offed, direct current is lateral AC transmitting active power increases, and the active power allowance of three transverters is incremented by successively, thus the power difference for undertaking Increase successively, wherein No. 1 transverter undertakes 147.5kW, No. 2 transverters undertake 157.5kW, and No. 3 transverters undertake 170kW. In transient process, each transverter transimission power non-overshoot, dead-beat, regulating time are short, embody good dynamic response characteristic.

Embodiment 2：When system stable operation is to 0.7s, DC load is uprushed 500kW, and MEMS sends instruction during 0.8s, opens Dynamic voltage recovers control.This paper voltages are recovered into optimum control and tradition is determined voltage control strategy and contrasted, under two kinds of strategies DC bus-bar voltage waveform is as shown in figure 8, hand over straight trend section transmitting active power difference as shown in Figure 9 and Figure 10.

As seen from Figure 8, voltage recovery optimum control is proposed herein can effectively improve dynamic voltage characteristics so that There is no overshoot in voltage recovery process, with shorter regulating time, thus it determines voltage control with more excellent compared to tradition Dynamic response characteristic.

Comparison diagram 9 and Figure 10 can be seen that because No. 1 margin of power maximum of transverter after 0.7s, thus MEMS are cut Change No. 1 transverter and undertake the task that voltage recovers control.During using this paper control strategies, in transient process, transverter transmission work( Rate is small without impact, overshoot, and vibration can comparatively fast calm down, and regulating time is short, with more excellent power dynamic response characteristic.

Claims (4)

1. the straight trend section of friendship that a kind of meter and photovoltaic cluster are accessed coordinates method for optimally controlling, it is characterised in that including as follows Step：

1) insertion switch function, the straight trend section Mathematical Modeling of friendship of meter and nonlinear characteristic based on separate unit transverter, dynamic Expansion method and coordinate transform, the straight trend section mathematical modulo of friendship of meter and nonlinear characteristic that foundation is made up of many transverters Type；

2) power coordination optimal controller is built, realizes handing over the reasonable distribution and DC bus-bar voltage of straight trend section transimission power Primary regulation；

3) build voltage and recover optimal controller, recovery control is carried out to DC bus-bar voltage, realize to DC bus-bar voltage Secondary Control, and improve the dynamic response characteristic of DC bus-bar voltage.

2. the straight trend section of friendship that a kind of meter according to claim 1 and photovoltaic cluster are accessed coordinates method for optimally controlling, Characterized in that, step 1) specifically include：

(1) under x coordinate space, the straight trend section Mathematical Modeling of friendship to the meter and nonlinear characteristic of separate unit transverter enters action State is expanded, and the straight trend section Mathematical Modeling of friendship for obtaining the meter and nonlinear characteristic of transverter is as follows, and subscript k represents kth in formula Platform transverter：

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{x}}_{\left(k\right)}=f_{\left(k\right)}\left(x_{\left(k\right)}\right)+g_{\left(k\right)}\left(x_{\left(k\right)}\right)u_{\left(k\right)}\\ y_{\left(k\right)}=H_{\left(k\right)}\left(x_{\left(k\right)}\right)\end{array}\right.---\left(1\right)$

Wherein：

$\begin{array}{cc}{f}_{\left(k\right)}\left(x\right)=\left(\begin{array}{c}{i}_{d\left(k\right)}-i_{d\_ref\left(k\right)}\\ {\mathrm{\&omega;i}}_{q\left(k\right)}+e_d/L_{\left(k\right)}\\ i_{q\left(k\right)}-i_{q\_ref\left(k\right)}\\ -{\mathrm{\&omega;i}}_{d\left(k\right)}+e_q/L_{\left(k\right)}\end{array}\right)& g_{\left(k\right)}\left(x\right)=\left(\begin{array}{cc}0& 0\\ -\frac{1}{L_{\left(k\right)}}& 0\\ 0& 0\\ 0& -\frac{1}{L_{\left(k\right)}}\end{array}\right)\end{array}$

$\left\{\begin{array}{c}{x}_{\left(k\right)}={\left(\begin{array}{cccc}{\mathrm{\&xi;}}_{1\left(k\right)}& i_{d\left(k\right)}& {\mathrm{\&xi;}}_{2\left(k\right)}& i_{q\left(k\right)}\end{array}\right)}^T\\ u_{\left(k\right)}^T=\left(\begin{array}{cc}{u}_{d\left(k\right)}& u_{q\left(k\right)}\end{array}\right)\\ H_{\left(k\right)}\left(x_{\left(k\right)}\right)={\left(\begin{array}{cc}{h}_{1\left(k\right)}\left(x_{\left(k\right)}\right)& h_{2\left(k\right)}\left(x_{\left(k\right)}\right)\end{array}\right)}^T\\ ={\left(\begin{array}{cc}{\mathrm{\&xi;}}_{1\left(k\right)}& {\mathrm{\&xi;}}_{2\left(k\right)}\end{array}\right)}^T\end{array}\right.$

$\left\{\begin{array}{c}{\mathrm{\&xi;}}_{1\left(k\right)}=\&Integral;(i_{d\left(k\right)}-i_{d\_ref\left(k\right)})dt\\ {\mathrm{\&xi;}}_{2\left(k\right)}=\&Integral;(i_{q\left(k\right)}-i_{q\_ref\left(k\right)})dt\end{array}\right.$

Wherein, each symbol definition is as follows：i_d(k)、i_q(k)Represent the dq axle components of kth platform transverter ac-side current；i_{d_ref(k)}、 i_{q_ref(k)}Represent the reference value of kth platform transverter ac-side current dq axle components；e_d、e_qRepresent the dq of alternating current net side three-phase voltage Axle component, ξ_1(k)、ξ_2(k)It is the dynamic state variables for introducing, L_(k)Kth platform transverter AC filter inductance is represented, ω is power network Angular frequency, u_d(k)、u_q(k)Represent the dq axle components of kth platform transverter AC voltage；

(2) coordinate transform is chosen, by the straight trend section mathematical modulo of the friendship of the meter of the transverter after dynamic expanding and nonlinear characteristic Type is mapped under new coordinate system z spaces, obtain under z coordinate space through the new transverter after state feedback linearization meter and The straight trend section Mathematical Modeling of friendship of nonlinear characteristic；Specifically：

Based on differential geometric theory, following dynamic expanding coordinate transform is chosen：

${\mathrm{\&Phi;}}_{\left(k\right)}\left(x\right)=z_{\left(k\right)}=\left\{\begin{array}{c}{z}_{1\left(k\right)}=h_{1\left(k\right)}\left(x\right)={\mathrm{\&xi;}}_{1\left(k\right)}\\ z_{2\left(k\right)}=L_{f\left(k\right)}{h}_{1\left(k\right)}\left(x\right)\\ z_{3\left(k\right)}=h_{2\left(k\right)}\left(x\right)={\mathrm{\&xi;}}_{2\left(k\right)}\\ z_{4\left(k\right)}=L_{f\left(k\right)}{h}_{2\left(k\right)}\left(x\right)\end{array}\right.---\left(2\right)$

z_(k)=Φ_(k)(x) be from x coordinate space to z coordinate space under coordinate mapping, wherein Φ_(k)X () is that infinitesimal is same Embryo,

The Bu Lunuo Paderewskis that the straight trend section Mathematical Modeling of the friendship of the meter of separate unit transverter and nonlinear characteristic is written as Master pattern, constitutes the straight trend section Mathematical Modeling of friendship of the meter and nonlinear characteristic of new separate unit transverter：

${\stackrel{\&CenterDot;}{z}}_{\left(k\right)}=A_{\left(k\right)}{z}_{\left(k\right)}+B_{\left(k\right)}{v}_{\left(k\right)}---\left(3\right)$

Wherein：

V is the input of the straight trend section Mathematical Modeling of the friendship of meter and nonlinear characteristic of separate unit transverter new under z coordinate space Variable, i.e. pre-control variable；

(3) the straight trend section Mathematical Modeling of the friendship of the meter and nonlinear characteristic being made up of n platform transverters, specific as follows：

$\stackrel{\&CenterDot;}{z}=Az+Bv---\left(4\right)$

Wherein：

A_(k)And B_(k)It is the matrix in the straight trend section Mathematical Modeling of the friendship of meter and nonlinear characteristic of new separate unit transverter.

3. the straight trend section of friendship that a kind of meter according to claim 1 and photovoltaic cluster are accessed coordinates method for optimally controlling, Characterized in that, step 2) include：

(1) self adaptation for setting up active power and DC bus-bar voltage coordinates droop control rule, specific as follows：

△P_(k)=m_(k)×△u_dc (5)

Wherein, each symbol definition is as follows：△u_dc=u_{dc_ref}-u_dcRepresent DC bus-bar voltage departure, u_dcRepresent dc bus The measuring value of voltage；u_{dc_ref}Represent the reference value of DC bus-bar voltage, △ P_(k)The power difference that each transverter undertakes is represented, m_(k)It is the sagging coefficient of each transverter；

The sagging coefficient of each transverter is defined as follows：

$m_{\left(k\right)}=\frac{{\mathrm{\&Delta;P}}_{\left(k\right)max}}{{\mathrm{\&Delta;u}}_{dcmax}}\&times;\frac{P_{re\left(k\right)}}{\underset{i=1}{\overset{n}{\&Sigma;}}{P}_{re\left(k\right)}}---\left(6\right)$

Wherein：

$\begin{array}{c}{P}_{re\left(k\right)}=\left\{\begin{array}{c}{P}_{N\left(k\right)}+P_{\left(k\right)},{\mathrm{\&Delta;u}}_{dc}<0\\ P_{N\left(k\right)}-P_{\left(k\right)},{\mathrm{\&Delta;u}}_{dc}>0\end{array}\right.\\ {\mathrm{\&Delta;u}}_{dc\max }=u_{dc\max }-u_{dc}=u_{dc}-u_{dc\min }\end{array}---\left(7\right)$

△P_(k)max=2P_N(k) (8)

Each symbol definition is as follows：P_N(k)Represent the rated power of transverter transmission, P_re(k)The dynamic power allowance of transverter is represented, P_(k)It is the active power of the transverter transmission of actual measurement, it is stipulated that from exchanging area to DC area transmission be the u for just_dcmax、u_dcminRespectively It is DC bus-bar voltage higher limit and lower limit, △ u_dcmax、△P_(k)maxDC bus-bar voltage and kth platform transverter are represented respectively The maximum deviation of transimission power；

(2) improve the dynamic response characteristic of transimission power using feedback linearization method, be according to feedback linearization method, to step It is rapid 1) in the straight trend section Mathematical Modeling of friendship of the meter and nonlinear characteristic of new separate unit transverter that obtains ask for inner loop feedback Control law, obtains：

$u_{\left(k\right)}=E_{\left(k\right)}^{-1}\left(x\right)\&lsqb;v_{\left(k\right)}-{\mathrm{\&alpha;}}_{\left(k\right)}\left(x\right)\&rsqb;---\left(9\right)$

v_(k)Represent pre-control variable, u_(k)Represent input variable.

Wherein：

${\mathrm{\&alpha;}}_{\left(k\right)}\left(x\right)=\left[\begin{array}{c}{L}_{f\left(k\right)}^{{\mathrm{\&gamma;}}_1^{\&prime;}}{h}_{1\left(k\right)}\left(x\right)\\ L_{f\left(k\right)}^{{\mathrm{\&gamma;}}_2^{\&prime;}}{h}_{2\left(k\right)}\left(x\right)\end{array}\right]=\left[\begin{array}{c}{\mathrm{\&omega;i}}_{q\left(k\right)}+e_d/L_{\left(k\right)}\\ -{\mathrm{\&omega;i}}_{d\left(k\right)}+e_q/L_{\left(k\right)}\end{array}\right]---\left(10\right)$

$\begin{array}{c}{E}_{\left(k\right)}\left(x\right)=\left(\begin{array}{cc}{L}_{g_{1\left(k\right)}}{L}_{f\left(k\right)}{h}_{1\left(k\right)}\left(x\right)& L_{g_{2\left(k\right)}}{L}_{f\left(k\right)}{h}_{1\left(k\right)}\left(x\right)\\ L_{g_{1\left(k\right)}}{L}_{f\left(k\right)}{h}_{2\left(k\right)}\left(x\right)& L_{g_{2\left(k\right)}}{L}_{f\left(k\right)}{h}_{2\left(k\right)}\left(x\right)\end{array}\right)\\ =\left(\begin{array}{cc}-\frac{1}{L_{\left(k\right)}}& 0\\ 0& -\frac{1}{L_{\left(k\right)}}\end{array}\right)\end{array}---\left(11\right)$

Pre-control variable v is asked for by quadratic performance index linear optimal contro8 method for designing_(k)：

$v_{\left(k\right)}=-R^{-1}{B}_{\left(k\right)}^T{P}^{*}{z}_{\left(k\right)}---\left(12\right)$

Wherein P* is the solution of following Riccati equation：

$A_{\left(k\right)}^{T}P+{\mathrm{PA}}_{\left(k\right)}-{\mathrm{PB}}_{\left(k\right)}{R}^{-1}{B}_{\left(k\right)}^{T}P+Q=0---\left(13\right)$

R and Q are respectively the weight matrix of input variable and state variable, A_(k)And B_(k)For step 1) in the new separate unit change of current that obtains Matrix in the straight trend section Mathematical Modeling of the friendship of meter and nonlinear characteristic of device.

4. the straight trend section of friendship that a kind of meter according to claim 1 and photovoltaic cluster are accessed coordinates method for optimally controlling, Characterized in that, step 3) described in structure voltage recover optimal controller, including：

According to step 1) in after the dynamic expanding that obtains the meter and nonlinear characteristic of transverter the straight trend section Mathematical Modeling of friendship, Again choosing output vector is：

$\left\{\begin{array}{c}{y}_{1\left(k\right)}=h_{1\left(k\right)}\left(x\right)=u_{dc\left(k\right)}-u_{dc\_ref\left(k\right)}\\ y_{2\left(k\right)}=h_{2\left(k\right)}\left(x\right)=i_{q\left(k\right)}-i_{q\_ref\left(k\right)}\end{array}\right.---\left(14\right)$

Choose following coordinate transform：

$z_{\left(k\right)}^{\&prime;}=\left\{\begin{array}{c}{z}_{1\left(k\right)}^{\&prime;}=h_{1\left(k\right)}\left(x\right)\\ z_{2\left(k\right)}^{\&prime;}=L_{f\left(k\right)}{h}_{1\left(k\right)}\left(x\right)\\ z_{3\left(k\right)}^{\&prime;}={\mathrm{\&xi;}}_{\left(k\right)}\\ z_{4\left(k\right)}^{\&prime;}=h_{2\left(k\right)}\left(x\right)\end{array}\right.---\left(15\right)$

Wherein ξ is the expansion dynamic variable introduced to eliminate steady-state error, ξ_(k)=∫ z '_4(k)dt；

To step 1) in the straight trend section Mathematical Modeling of friendship of the meter and nonlinear characteristic of new separate unit transverter that obtains, ask for Inner loop feedback control law, obtains control variables u '_(k)

$u_{\left(k\right)}^{\&prime;}=E_{\left(k\right)}^{\&prime;-1}\left(x\right)\&lsqb;v_{\left(k\right)}^{\&prime;}-{\mathrm{\&alpha;}}_{\left(k\right)}^{\&prime;}\left(x\right)\&rsqb;---\left(16\right)$

Wherein：

${\mathrm{\&alpha;}}_{\left(k\right)}^{\&prime;}\left(x\right)=\left[\begin{array}{c}\frac{3}{2}\frac{e_d}{{\mathrm{Cu}}_{dc}}({\mathrm{\&omega;i}}_{q\left(k\right)}+e_d/L_{\left(k\right)})-\frac{3}{2}\frac{e_d{i}_{d\left(k\right)}}{{\mathrm{Cu}}_{dc}^2}(\frac{e_d{i}_{d\left(k\right)}}{{\mathrm{Cu}}_{dc}}-\frac{I_L}{C})\\ -{\mathrm{\&omega;i}}_{d\left(k\right)}+e_q/L_{\left(k\right)}\end{array}\right]---\left(17\right)$

$E_{\left(k\right)}^{\&prime;}\left(x\right)=\left(\begin{array}{cc}\frac{3}{2}\frac{e_d}{L_{\left(k\right)}{\mathrm{Cu}}_{dc}}& 0\\ 0& -\frac{1}{L_{\left(k\right)}}\end{array}\right)---\left(18\right)$

Wherein, each symbol definition is as follows：C represents dc bus equivalent capacitance, i_d(k)、i_q(k)Represent kth platform transverter AC electricity The dq axle components of stream；i_{q_ref(k)}Represent the reference value of kth platform transverter ac-side current q axle components, u_{dc_ref(k)}Represent kth platform The reference value of transverter DC bus-bar voltage,；e_d、e_qRepresent the dq axle components of alternating current net side three-phase voltage, L_(k)Kth platform is represented to change Stream device AC filter inductance, ω is the angular frequency of power network, I_LRepresent kth platform Converter DC-side output current value.

Pre-control variable v ' is asked for by quadratic performance index linear optimal contro8 method for designing_(k)：

$v_{\left(k\right)}^{\&prime;}=-R^{-1}{B}_{\left(k\right)}^T{P}^{*}{z}_{\left(k\right)}^{\&prime;}---\left(19\right)$

Wherein P* is the solution of following Riccati equation：

$A_{\left(k\right)}^{T}P+{\mathrm{PA}}_{\left(k\right)}-{\mathrm{PB}}_{\left(k\right)}{R}^{-1}{B}_{\left(k\right)}^{T}P+Q=0---\left(20\right)$

R and Q are respectively the weight matrix of input variable and state variable, A_(k)And B_(k)For step 1) in the new separate unit change of current that obtains Matrix in the straight trend section Mathematical Modeling of the friendship of meter and nonlinear characteristic of device.