CN102983589B - Control method of grid friendly type distributed power source based on hybrid energy storage - Google Patents

Abstract

The invention provides a control method of a grid friendly type distributed power source based on hybrid energy storage. The method comprises the steps of optimally designing a topology structure of the distributed power source, controlling a direct current power supply system in a coordinating mode through a direct current (DC)/DC converter controlling a model normalization model, and self-adaptively controlling a grid of an alternating current (AC) side DC /AC converter. The distributed power source not only can be connected in a large grid to operate so as to reduce the influence of intermittent renewable energy power generation grid connection on the grid and provide support of voltage and frequency for the grid, but also can be connected into a micro-grid to operate as a network unit of the off-network type micro-grid to maintain stability of voltage and frequency of the off-network type micro-grid. When an outer grid breaks down, the distributed power source can realize switch between a grid mode and an island mode so as to improve power supply reliability of important loads in the system. The distributed power source improves technical performance and economic performance of the whole system through matching utilization of an energy type system and a power type energy storage system.

Description

The control method of the friendly type distributed power source of a kind of electrical network based on hybrid energy-storing

Technical field

The present invention relates to distributed power source operation and control, be specifically related to the control method of the friendly type distributed power source of a kind of electrical network based on hybrid energy-storing.

Background technology

The friendly characteristic of electrical network that realizes the distributed power source based on hybrid energy-storing, the control strategy of distributed power source AC converter and effective utilization of hybrid energy-storing are the key technical problems that emphasis need to solve.

(1) distributed power source control strategy

Batch (-type) renewable energy power generation, especially wind power generation and photovoltaic generation, its exert oneself there is intermittence, the feature such as fluctuation and uncontrollability, if be incorporated into the power networks, can bring a series of impact to the safety and stability of electrical network.In order to reduce the impact of renewable energy source power on electrical network, with the renewable energy power generation unit of energy-storage system, can stabilize the power fluctuation of renewable energy power generation, distributed power generation unit is carried out determining power control, can make it according to dispatch command, control its power output.But, outstanding along with environment and energy problem, distributed power source shared ratio in electrical network is increasing, in order to guarantee the safe and reliable operation of electrical network, also more and more higher to distributed power source requirement in grid-connected standard, need distributed power source to possess certain line voltage and frequency supporting role, and adopt the distributed power source of determining power control also not possess this function.

In micro-electrical network, the control method of distributed power source have V ?F control, P ?Q control, Droop controls three types, the distributed power source that adopts Droop to control possesses certain line voltage supporting role, the networking unit that can be used as micro-electrical network moves.But the distributed power source that adopts Droop to control is applied in micro-electrical network, also there is certain problem, as do not considered the impedance model of circuit, can not be applicable to micro-electrical network of various line impedance models, do not possess and conventional unit between power-sharing effect etc., and for adopting the seamless switching of micro-power supply of this kind of control strategy to control also more rare.

(2) hybrid energy-storing control technology

In the Distributed Renewable Energy Power System with energy-storage system, conventionally select storage battery as energy-storage travelling wave tube, but storage battery as the energy-storage travelling wave tube of energy type, have that power density is low, charge and discharge cycles times influence its useful life etc. shortcoming.Super capacitor is as power-type energy-storage travelling wave tube, because its power density is high, have extended cycle life, the advantage such as efficiency for charge-discharge is high, Maintenance free, just receive increasing concern, but because its energy density is lower, be also difficult at present realize jumbo electric power energy storage.Storage battery and ultracapacitor are mixed and are used, be applied to renewable energy system, make the large and super capacitor power density of storage battery energy density greatly, the feature that has extended cycle life combines, and can greatly promote technical performance and the economic performance of whole system.

At present, existing researcher is applied to electric automobile, compact power and renewable energy source domain for hybrid energy-storing and did some researchs, has mainly proposed following several hybrid energy-storing structures:

(1) storage battery and ultracapacitor are directly in parallel.Storage battery, the direct parallel connection of ultracapacitor is the simplest a kind of hybrid energy-storing structure, adopt this structure, can be when there is fluctuation in load, significantly reduce the maximum output current of storage battery during the fluctuation of load, improve the maximum power output ability of mixed energy storage system, but in this structure, because the terminal voltage of batteries and the terminal voltage of bank of super capacitors are forced to equate, cause capacity of super capacitor utilance low, in design, to the connection in series-parallel compound mode of bank of super capacitors, require also comparatively strict, and the course of work of storage battery can not be set flexibly, can not realize the efficient utilization of dissimilar energy storage device.

(2) storage battery is in parallel with super capacitor by DC/DC power inverter.Storage battery is in parallel with super capacitor by DC/DC converter, by the appropriate design to power inverter control strategy, can realize the charge and discharge process of batteries is carried out to flexible management, the advantage of better performance ultracapacitor, improve the performance of hybrid accumulator, extend the useful life of storage battery.But, super capacitor is directly hung on DC bus, ultracapacitor is in charge and discharge process, and terminal voltage can change along with the variation of energy storage capacity, and change in voltage amplitude is larger, and DC bus-bar voltage is unstable.

(3) ultracapacitor is in parallel with storage battery by DC/DC converter.In order to obtain stable DC bus-bar voltage, there is document to propose ultracapacitor by the DC/DC converter hybrid energy-storing structure in parallel with batteries, although during power fluctuation, DC bus-bar voltage is comparatively stable, but adopt this structure, the flexible management of batteries input and output energy can not be realized equally, the effect of all kinds energy storage device can not be given full play to.

Summary of the invention

In order to overcome above-mentioned the deficiencies in the prior art, the invention provides the converter control method of the friendly type distributed power source of a kind of electrical network based on hybrid energy-storing, this distributed power source both can be incorporated to large operation of power networks, reduce the impact of intermittent renewable energy source power on electrical network, and provide voltage and frequency to support to electrical network; Also can and electrical network in a subtle way, the networking unit operation as from the micro-electrical network of net type, maintains from voltage and the frequency stabilization of the micro-electrical network of net type; When external electrical network breaks down, this distributed power source can also be realized the double mode switching of grid-connected/isolated island, the power supply reliability of important load in raising system.This distributed power source is coordinated and is utilized by energy type and power-type energy-storage system, has improved whole system technical performance and economic performance.

In order to realize foregoing invention object, the present invention takes following technical scheme:

The control method that the friendly type distributed power source of a kind of electrical network based on hybrid energy-storing is provided, said method comprising the steps of:

Step 1: the topological structure of optimal design distributed power source;

Step 2: coordinate to control DC power-supply system by DC/DC convertor controls pattern normalization model;

Step 3: the electrical network adaptive control of AC DC/AC converter.

In the topological structure of the distributed power source of described step 1, intermittent renewable energy system, lithium battery energy storage battery system and super capacitor energy-storage system are in parallel with DC bus by DC/DC converter A, DC/DC converter B and DC/DC converter C respectively, form the DC power-supply system of distributed power source, this DC power-supply system is connected with AC system by AC DC/AC converter, forms distributed power source.

In described step 2, DC/DC converter comprises DC/DC converter A, DC/DC converter B and DC/DC converter C; The control model of DC/DC converter comprises determines voltage mode control, constant current control model and permanent power control mode; Choosing of power magnitude limit value by the instruction of voltage control loop reference power, current regulator current amplitude limit value and power control loop, determines above-mentioned different control model; Constant current control model comprises constant current charge control model and constant current discharge control model.

In described DC/DC convertor controls pattern normalization model, the difference of the reference value of busbar voltage and its measured value regulates through PI, pass through again current limit link, obtain the reference value of energy-storage system output current, the difference of energy-storage system output current reference value and its output current measured value regulates through PI, and then by power limiting link, obtain the reference value of energy-storage system power output, as the switch triggering signal of DC/DC converter; Described energy-storage system comprises lithium battery energy storage battery system and super capacitor energy-storage system.

Described step 2 comprises the following steps:

Step 2 ?1: tuning controller is measured DC bus-bar voltage U in real time _dC, the state-of-charge of lithium battery and the terminal voltage of super capacitor, and according to Monitoring Data, determine the control model of DC/DC converter;

Step 2 ?2: tuning controller is measured the load power P of the friendly type distributed power source of described electrical network in real time _lpower output P with intermittent renewable energy system _r, calculate the power shortage P of described mixed energy storage system _s, P _s=P _l-P _r, and extract P _sin low frequency component P _{b_ref}, described P _{b_ref}for the value and power reference of permanent power control mode lithium battery energy storage battery system, P _lfor the load power of distributed power source, P _rpower output for intermittent renewable energy system;

Step 2 ?3: when DC bus-bar voltage drops on region 1, i.e. U ₀< U _dC< U ₁time, DC/DC converter A is operated in and determines voltage mode control, and its reference voltage is got U _ref1, the current amplitude limit value of current regulator and the power magnitude limit value of power control loop are got respectively I _max1and P _max1; DC/DC converter B and DC/DC converter C do not work;

Wherein: U ₀the maximum that-DC bus-bar voltage allows;

U _dCthe real-time measurement values of-DC bus-bar voltage;

U _ref1when-DC bus-bar voltage drops on region 1, the fixed voltage-controlled voltage reference value of DC/DC converter A, its choosing value is positioned at region 1, i.e. U ₀< U _ref1< U ₁;

I _max1-DC/DC converter A current regulator allows the current maxima of passing through;

P _max1-DC/DC converter A power control loop allows the maximum power of sending;

Step 2 ?4: when DC bus-bar voltage drops on region 2, i.e. U ₂< U _dC< U ₁time, DC/DC converter A is operated in MPPT control model, and DC/DC converter B is operated in and determines voltage mode control, and its reference voltage is got U _ref2, the current amplitude limit value of current regulator and the power magnitude limit value of power control loop are got respectively I _max2and P _max2; DC/DC converter C is operated in constant current discharge control model, and the reference voltage of its voltage control loop is got U _{ref_ab}, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _{sc_ref}and P _max3; In this process, the terminal voltage U of tuning controller Real-Time Monitoring super capacitor _ucif U detected _min<U _uc<U _max, proceed to step 2 ?5 operation;

Wherein: U _ref2when-DC bus-bar voltage drops on region 2, the fixed voltage-controlled voltage reference value of DC/DC converter B, its choosing value is positioned at region 2, i.e. U ₁< U _ref2< U ₂;

I _max2-DC/DC converter B current regulator allows the current maxima of passing through;

P _max2-DC/DC converter B power control loop allows the maximum power of sending;

U _{ref_ab}the voltage reference value of-DC/DC converter C voltage control loop;

I _{sc_ref}the reference value of the super capacitor charging and discharging currents of-setting;

P _max3-DC/DC converter C power control loop allows the maximum power of sending;

U _ucthe terminal voltage of-super capacitor;

U _minthe smallest end voltage that-super capacitor allows;

U _maxthe maximum terminal voltage that-super capacitor allows;

Step 2 ?5: when DC bus-bar voltage drops on region 3, i.e. U ₃< U _dC< U ₂time, DC/DC converter A is operated in MPPT pattern, and DC/DC converter B is operated in permanent power control mode, and the voltage reference value of its voltage control loop is got U ' _ref-ab, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _max2and P _max2; DC/DC converter C is operated in and determines voltage mode control, and the reference voltage of its voltage control loop is got U _ref3, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _max3and P _max3;

Wherein:

U ' _ref-abthe voltage reference value of-DC/DC converter B voltage control loop;

U _ref3when-DC bus-bar voltage drops on region 3, the fixed voltage-controlled voltage reference value of DC/DC converter C, its choosing value is positioned at region 3, i.e. U ₃<U _ref3<U ₂;

I _max3-DC/DC converter C current regulator allows the current maxima of passing through;

Step 2 ?6: when DC bus-bar voltage drops on region 4, i.e. U ₄< U _dC< U ₃time, DC/DC converter A is operated in MPPT pattern, and the DC/DC converter B of lithium battery system is operated in and determines voltage mode control, and the voltage reference value of its voltage control loop is got U _ref4, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _max2and P _max2; DC/DC converter C is operated in constant current charge control model, and the reference voltage of its voltage control loop is got U _{ref_ab}, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _{sc_ref}and P _max3, in this process, the terminal voltage U of tuning controller Real-Time Monitoring super capacitor _ucif U detected _min<U _uc<U _max, proceed to step 2 ?5 operation;

Wherein:

U ₄the maximum U that-DC bus-bar voltage allows ₀> U ₁> U ₂> U ₃> U ₄;

U _ref4when-DC bus-bar voltage drops on region 4, the fixed voltage-controlled voltage reference value of DC/DC converter B, its choosing value should drop in region 4, i.e. U ₄<U _ref4<U ₃.

In described step 3, AC DC/AC converter adopts motor synchronizing voltage source to control, introduce virtual impedance control and double mode seamless switching controls simultaneously, and the normalized to above-mentioned control model, so that distributed power source is when being incorporated to the micro-electrical network of mesolow, can with inverter type distributed power source or conventional synchronization motor-type distributed power source group net operation in parallel.

During motor synchronizing voltage source is controlled, three-phase voltage and the electric current of the output of Real-time Collection DC/AC converter, according to instantaneous power theory, calculate active-power P and the reactive power Q of the output of DC/AC converter, adopt motor synchronizing voltage source to control, calculate the reference frequency f of the virtual output voltage phasor of DC/AC converter _{vir_ref}with reference amplitude V _{vir_ref}:

$\left\{\begin{array}{c}{f}_{\mathrm{vir}-\mathrm{ref}}=f^{*}-m(P*-P)\\ V_{\mathrm{vir}-\mathrm{ref}}=V^{*}-n(Q*-Q)\end{array}\right.---(2-1)$

Wherein:

F _{vir_ref}the reference frequency of the virtual output voltage phasor of-DC/AC converter;

V _{vir_ref}the reference amplitude of the virtual output voltage phasor of-DC/AC converter;

F ^*the reference frequency of-mixed energy storage system rated voltage;

V ^*the reference amplitude of-mixed energy storage system rated voltage;

The sagging coefficient that m-meritorious/frequency droop is controlled;

The sagging coefficient of n-REACTIVE POWER/VOLTAGE droop control;

P ^*-DC/AC converter is at f ^*the active power reference value of lower output;

Q ^*-DC/AC converter is at V ^*the reactive power reference qref of lower output;

The active power that P-DC/AC converter sends;

The reactive power that Q-DC/AC converter sends;

M and n through type (2 ?2) calculate:

$\left\{\begin{array}{c}m=\frac{f_{\min }-f^{*}}{P_{\max }-P^{*}}\\ n=\frac{V_{\min }-V^{*}}{Q_{\max }-Q^{*}}\end{array}\right.---(2-2)$

Wherein:

F _minthe minimum operation frequency that-mixed energy storage system allows;

V _minthe minimum operation voltage that-mixed energy storage system allows;

P _maxthe maximum active power that-converter can be exported;

Q _maxthe maximum reactive power that-converter can be exported;

During virtual impedance is controlled, according to formula (2 ?3), calculate

$\left\{\begin{array}{c}{V}_{\mathrm{vir}\_\mathrm{ref}}^{\&CenterDot;}=V_{\mathrm{vir}\_\mathrm{ref}}\&angle;{\mathrm{\&theta;}}_{\mathrm{vir}\_\mathrm{ref}}\\ {\mathrm{\&theta;}}_{\mathrm{vir}\_\mathrm{ref}}=2\mathrm{\&pi;}\underset{0}{\overset{t}{\&Integral;}}{f}_{\mathrm{vir}\_\mathrm{ref}}\mathrm{dt}\end{array}\right.---(2-3)$

$V_{\mathrm{ref}}^{\&CenterDot;}=V_{\mathrm{vir}\_\mathrm{ref}}^{\&CenterDot;}-\stackrel{\&CenterDot;}{I}{Z}_{\mathrm{vir}}---(2-4)$

In formula:

the reference phasor of the virtual output voltage phasor of converter;

the reference phasor of converter output voltage phasor;

the electric current phasor that converter sends;

Z _vir-virtual impedance.

During double mode seamless switching is controlled,

When distributed power source detects large electric network fault, grid-connected switch disconnects, f ^*and V ^*set-point by frequency and the amplitude of line voltage, change into the set point under independent operation mode;

When the fault clearance of large electrical network, distributed power source is converted to while being incorporated into the power networks pattern by independent operation mode, and the motor synchronizing that starts distributed power source is controlled, when meeting grid-connected condition, closed grid-connected switch, is incorporated into the power networks distributed power source, to reduce the grid-connected impact to electrical network of distributed power source.

During motor synchronizing is controlled, the frequency adjusted value of DC/AC converter output voltage phasor and range-adjusting value through type (2 ?5) calculate:

$\left\{\begin{array}{c}\mathrm{\&Delta;f}=(K_{p1}+\frac{K_{i1}}{s})(f_g-f_i)\\ \mathrm{\&Delta;U}=(K_{p2}+\frac{K_{i2}}{s})(U_g-U_i)\end{array}\right.---(2-5)$

Wherein:

The frequency adjusted value of Δ f-DC/AC converter output voltage phasor;

The range-adjusting value of Δ U-DC/AC converter output voltage phasor;

K _p1the proportional control factor of-DC/AC frequency inverter Synchronization Control;

K _i1the integral adjustment coefficient of-DC/AC frequency inverter Synchronization Control;

K _p2-DC/AC converter voltage magnitude is followed the tracks of the proportional control factor in controlling;

K _i2-DC/AC converter voltage magnitude is followed the tracks of the integral adjustment coefficient in controlling;

U _gthe amplitude of-line voltage phasor;

U _ithe amplitude of the voltage phasor that-DC/AC converter sends.

Compared with prior art, beneficial effect of the present invention is:

1. can be applicable to the grid-connected operation of distributed power source and control, reduce the impact of batch (-type) renewable energy source power on electrical network, make distributed power source according to higher level's dispatch command with scheduling Power operation, and can automatically participate in frequency, the voltage-regulation of electrical network, improve the receiving ability of electrical network to distribution type renewable energy generating, realized energy conservation and environmental protection benefit;

2. can be applicable to from operation and the control of distributed power source in the micro-electrical network of net type, make distributed power source can be used as the networking unit of micro-electrical network, with the common all load powers of subsystem of conventional electric generators, other inverter type distributed power sources, maintain the stable of frequency in electrical network and voltage;

3. can be applicable to the dual mode operated micro-electrical network of grid-connected/isolated island, realize two kinds of seamless switchings under pattern, improve the power supply reliability of load;

4. the operation that can be applicable to mixed energy storage system is controlled, can optimum management storage battery and the charge and discharge process of super capacitor, improve the course of work of storage battery, and reduce its charge and discharge cycles number of times and maximum depth of discharge, extend the useful life of energy-storage system;

5. operation and the control of the DC power-supply system that can be applicable to comprise renewable energy power generation and energy-storage system, can stable DC busbar voltage, maintains the stable operation of system.

Accompanying drawing explanation

Fig. 1 coordinates the control flow chart of control between DC power-supply system each several part in the embodiment of the present invention;

Fig. 2 is the topology diagram of the friendly type distributed power source of the electrical network based on hybrid energy-storing in the embodiment of the present invention;

Fig. 3 is DC/DC converter plurality of operating modes normalization control chart in the embodiment of the present invention;

Fig. 4 is distributed power source DC bus-bar voltage traffic coverage schematic diagram in the embodiment of the present invention;

Fig. 5 is the electrical network adaptive control flow chart of AC DC/DC converter in the embodiment of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail.

As Fig. 1, the control method of the friendly type distributed power source of a kind of electrical network based on hybrid energy-storing is provided, said method comprising the steps of:

Step 1: the topological structure of optimal design distributed power source;

Step 2: coordinate to control DC power-supply system by DC/DC convertor controls pattern normalization model;

Step 3: the electrical network adaptive control of AC DC/AC converter.

As Fig. 2, in the topological structure of distributed power source, intermittent renewable energy system, lithium battery energy storage battery system and super capacitor energy-storage system are in parallel with DC bus by DC/DC converter A, DC/DC converter B and DC/DC converter C respectively, form the DC power-supply system of distributed power source, this DC power-supply system is connected with AC system by AC DC/AC converter, forms distributed power source.

In described step 2, DC/DC converter comprises DC/DC converter A, DC/DC converter B and DC/DC converter C; DC/DC converter A is unidirectional DC/DC converter, and DC/DC converter B and DC/DC converter C are two-way DC/DC converter.The control model of DC/DC converter comprises determines voltage mode control, constant current control model and permanent power control mode; Choosing of power magnitude limit value by the instruction of voltage control loop reference power, current regulator current amplitude limit value and power control loop, determines above-mentioned different control model; Constant current control model comprises constant current charge control model and constant current discharge control model.

As Fig. 3, in described DC/DC convertor controls pattern normalization model, the difference of the reference value of busbar voltage and its measured value regulates through PI, pass through again current limit link, obtain the reference value of energy-storage system output current, the difference of energy-storage system output current reference value and its output current measured value regulates through PI, and then by power limiting link, obtain the reference value of energy-storage system power output, as the switch triggering signal of DC/DC converter; Described energy-storage system comprises lithium battery energy storage battery system and super capacitor energy-storage system.

As Fig. 4, described step 2 comprises the following steps:

Step 2 ?1: tuning controller is measured DC bus-bar voltage U in real time _dC, the state-of-charge of lithium battery and the terminal voltage of super capacitor, and according to Monitoring Data, determine the control model of DC/DC converter;

Step 2 ?2: tuning controller is measured the load power P of the friendly type distributed power source of described electrical network in real time _lpower output P with intermittent renewable energy system _r, calculate the power shortage P of described mixed energy storage system _s, P _s=P _l-P _r, and extract P _sin low frequency component P _{b_ref}, described P _{b_ref}for the value and power reference of permanent power control mode lithium battery energy storage battery system, P _lfor the load power of distributed power source, P _rpower output for intermittent renewable energy system;

Step 2 ?3: when DC bus-bar voltage drops on region 1, i.e. U ₀< U _dC< U ₁time, DC/DC converter A is operated in and determines voltage mode control, and its reference voltage is got U _ref1, the current amplitude limit value of current regulator and the power magnitude limit value of power control loop are got respectively I _max1and P _max1; DC/DC converter B and DC/DC converter C do not work;

Wherein: U ₀the maximum that-DC bus-bar voltage allows;

U _dCthe real-time measurement values of-DC bus-bar voltage;

U _ref1when-DC bus-bar voltage drops on region 1, the fixed voltage-controlled voltage reference value of DC/DC converter A, its choosing value is positioned at region 1, i.e. U ₀< U _ref1< U ₁;

I _max1-DC/DC converter A current regulator allows the current maxima of passing through;

P _max1-DC/DC converter A power control loop allows the maximum power of sending;

Step 2 ?4: when DC bus-bar voltage drops on region 2, i.e. U ₂< U _dC< U ₁time, DC/DC converter A is operated in MPPT control model, and DC/DC converter B is operated in and determines voltage mode control, and its reference voltage is got U _ref2, the current amplitude limit value of current regulator and the power magnitude limit value of power control loop are got respectively I _max2and P _max2; DC/DC converter C is operated in constant current discharge control model, and the reference voltage of its voltage control loop is got U _{ref_ab}, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _{sc_ref}and P _max3; In this process, the terminal voltage U of tuning controller Real-Time Monitoring super capacitor _ucif U detected _min<U _uc<U _max, proceed to step 2 ?5 operation;

Wherein: U _ref2when-DC bus-bar voltage drops on region 2, the fixed voltage-controlled voltage reference value of DC/DC converter B, its choosing value is positioned at region 2, i.e. U ₁< U _ref2< U ₂;

I _max2-DC/DC converter B current regulator allows the current maxima of passing through;

P _max2-DC/DC converter B power control loop allows the maximum power of sending;

U _{ref_ab}the voltage reference value of-DC/DC converter C voltage control loop;

I _{sc_ref}the reference value of the super capacitor charging and discharging currents of-setting;

P _max3-DC/DC converter C power control loop allows the maximum power of sending;

U _ucthe terminal voltage of-super capacitor;

U _minthe smallest end voltage that-super capacitor allows;

U _maxthe maximum terminal voltage that-super capacitor allows;

Step 2 ?5: when DC bus-bar voltage drops on region 3, i.e. U ₃< U _dC< U ₂time, DC/DC converter A is operated in MPPT pattern, and DC/DC converter B is operated in permanent power control mode, and the voltage reference value of its voltage control loop is got U ' _ref-ab, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _max2and P _max2; DC/DC converter C is operated in and determines voltage mode control, and the reference voltage of its voltage control loop is got U _ref3, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _max3and P _max3;

Wherein:

U ' _ref-abthe voltage reference value of-DC/DC converter B voltage control loop;

U _ref3when-DC bus-bar voltage drops on region 3, the fixed voltage-controlled voltage reference value of DC/DC converter C, its choosing value is positioned at region 3, i.e. U ₃<U _ref3<U ₂;

I _max3-DC/DC converter C current regulator allows the current maxima of passing through;

Step 2 ?6: when DC bus-bar voltage drops on region 4, i.e. U ₄< U _dC< U ₃time, DC/DC converter A is operated in MPPT pattern, and the DC/DC converter B of lithium battery system is operated in and determines voltage mode control, and the voltage reference value of its voltage control loop is got U _ref4, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _max2and P _max2; DC/DC converter C is operated in constant current charge control model, and the reference voltage of its voltage control loop is got U _{ref_ab}, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _{sc_ref}and P _max3, in this process, the terminal voltage U of tuning controller Real-Time Monitoring super capacitor _ucif U detected _min<U _uc<U _max, proceed to step 2 ?5 operation;

Wherein:

U ₄the maximum U that-DC bus-bar voltage allows ₀> U ₁> U ₂> U ₃> U ₄;

U _ref4when-DC bus-bar voltage drops on region 4, the fixed voltage-controlled voltage reference value of DC/DC converter B, its choosing value should drop in region 4, i.e. U ₄<U _ref4<U ₃.

As Fig. 5, AC DC/AC converter adopts motor synchronizing voltage source to control, introduce virtual impedance control and double mode seamless switching controls simultaneously, and the normalized to above-mentioned control model, so that distributed power source is when being incorporated to the micro-electrical network of mesolow, can with inverter type distributed power source or conventional synchronization motor-type distributed power source group net operation in parallel.

During motor synchronizing voltage source is controlled, three-phase voltage and the electric current of the output of Real-time Collection DC/AC converter, according to instantaneous power theory, calculate active-power P and the reactive power Q of the output of DC/AC converter, adopt motor synchronizing voltage source to control, calculate the reference frequency f of the virtual output voltage phasor of DC/AC converter _{vir_ref}with reference amplitude V _{vir_ref}:

$\left\{\begin{array}{c}{f}_{\mathrm{vir}-\mathrm{ref}}=f^{*}-m(P*-P)\\ V_{\mathrm{vir}-\mathrm{ref}}=V^{*}-n(Q*-Q)\end{array}\right.---(2-1)$

Wherein:

F _{vir_ref}the reference frequency of the virtual output voltage phasor of-DC/AC converter;

V _{vir_ref}the reference amplitude of the virtual output voltage phasor of-DC/AC converter;

F ^*the reference frequency of-mixed energy storage system rated voltage;

V ^*the reference amplitude of-mixed energy storage system rated voltage;

The sagging coefficient that m-meritorious/frequency droop is controlled;

The sagging coefficient of n-REACTIVE POWER/VOLTAGE droop control;

P ^*-DC/AC converter is at f ^*the active power reference value of lower output;

Q ^*-DC/AC converter is at V ^*the reactive power reference qref of lower output;

The active power that P-DC/AC converter sends;

The reactive power that Q-DC/AC converter sends;

When distributed power source is when being incorporated into the power networks pattern, f ^*, V ^*for frequency and the magnitude of voltage of electrical network, when distributed power source is during in independent operation mode, f ^*, V ^*for the reference value of setting, in the system of 380V, generally get 50Hz, 380V.

M and n through type (2 ?2) calculate:

$\left\{\begin{array}{c}m=\frac{f_{\min }-f^{*}}{P_{\max }-P^{*}}\\ n=\frac{V_{\min }-V^{*}}{Q_{\max }-Q^{*}}\end{array}\right.---(2-2)$

Wherein:

F _minthe minimum operation frequency that-mixed energy storage system allows;

V _minthe minimum operation voltage that-mixed energy storage system allows;

P _maxthe maximum active power that-converter can be exported;

Q _maxthe maximum reactive power that-converter can be exported;

During virtual impedance is controlled, according to formula (2 ?3), calculate

$\left\{\begin{array}{c}{V}_{\mathrm{vir}\_\mathrm{ref}}^{\&CenterDot;}=V_{\mathrm{vir}\_\mathrm{ref}}\&angle;{\mathrm{\&theta;}}_{\mathrm{vir}\_\mathrm{ref}}\\ {\mathrm{\&theta;}}_{\mathrm{vir}\_\mathrm{ref}}=2\mathrm{\&pi;}\underset{0}{\overset{t}{\&Integral;}}{f}_{\mathrm{vir}\_\mathrm{ref}}\mathrm{dt}\end{array}\right.---(2-3)$

$V_{\mathrm{ref}}^{\&CenterDot;}=V_{\mathrm{vir}\_\mathrm{ref}}^{\&CenterDot;}-\stackrel{\&CenterDot;}{I}{Z}_{\mathrm{vir}}---(2-4)$

In formula:

the reference phasor of the virtual output voltage phasor of converter;

the reference phasor of converter output voltage phasor;

the electric current phasor that converter sends;

Z _vir-virtual impedance.

During double mode seamless switching is controlled,

When distributed power source detects large electric network fault, grid-connected switch disconnects, f ^*and V ^*set-point by frequency and the amplitude of line voltage, change into the set point under independent operation mode;

Fault clearance when large electrical network, distributed power source is converted to while being incorporated into the power networks pattern by independent operation mode, switch L1 and L2 in closed Fig. 5, the motor synchronizing that starts distributed power source is controlled, when meeting grid-connected condition, closed grid-connected switch, is incorporated into the power networks distributed power source, to reduce the grid-connected impact to electrical network of distributed power source.

During motor synchronizing is controlled, the frequency adjusted value of DC/AC converter output voltage phasor and range-adjusting value through type (2 ?5) calculate:

$\left\{\begin{array}{c}\mathrm{\&Delta;f}=(K_{p1}+\frac{K_{i1}}{s})(f_g-f_i)\\ \mathrm{\&Delta;U}=(K_{p2}+\frac{K_{i2}}{s})(U_g-U_i)\end{array}\right.---(2-5)$

Wherein:

The frequency adjusted value of Δ f-DC/AC converter output voltage phasor;

The range-adjusting value of Δ U-DC/AC converter output voltage phasor;

K _p1the proportional control factor of-DC/AC frequency inverter Synchronization Control;

K _i1the integral adjustment coefficient of-DC/AC frequency inverter Synchronization Control;

K _p2-DC/AC converter voltage magnitude is followed the tracks of the proportional control factor in controlling;

K _i2-DC/AC converter voltage magnitude is followed the tracks of the integral adjustment coefficient in controlling;

U _gthe amplitude of-line voltage phasor;

U _ithe amplitude of the voltage phasor that-DC/AC converter sends.

Finally should be noted that: above embodiment is only in order to illustrate that technical scheme of the present invention is not intended to limit, although the present invention is had been described in detail with reference to above-described embodiment, those of ordinary skill in the field are to be understood that: still can modify or be equal to replacement the specific embodiment of the present invention, and do not depart from any modification of spirit and scope of the invention or be equal to replacement, it all should be encompassed in the middle of claim scope of the present invention.

Claims (8)

1. a control method for the friendly type distributed power source of the electrical network based on hybrid energy-storing, is characterized in that: said method comprising the steps of:

Step 1: the topological structure of optimal design distributed power source;

Step 2: coordinate to control DC power-supply system by DC/DC convertor controls pattern normalization model;

Step 3: the electrical network adaptive control of AC DC/AC converter;

In described DC/DC convertor controls pattern normalization model, the difference of the reference value of busbar voltage and its measured value regulates through PI, pass through again current limit link, obtain the reference value of energy-storage system output current, the difference of energy-storage system output current reference value and its output current measured value regulates through PI, and then by power limiting link, obtain the reference value of energy-storage system power output, as the switch triggering signal of DC/DC converter; Described energy-storage system comprises lithium battery energy storage battery system and super capacitor energy-storage system.

2. the control method of the friendly type distributed power source of electrical network based on hybrid energy-storing according to claim 1, it is characterized in that: in the topological structure of the distributed power source of described step 1, intermittent renewable energy system, lithium battery energy storage battery system and super capacitor energy-storage system are in parallel with DC bus by DC/DC converter A, DC/DC converter B and DC/DC converter C respectively, form the DC power-supply system of distributed power source, this DC power-supply system is connected with AC system by AC DC/AC converter, forms distributed power source.

3. the control method of the friendly type distributed power source of the electrical network based on hybrid energy-storing according to claim 1, is characterized in that: in described step 2, DC/DC converter comprises DC/DC converter A, DC/DC converter B and DC/DC converter C; The control model of DC/DC converter comprises determines voltage mode control, constant current control model and permanent power control mode; Choosing of power magnitude limit value by voltage control loop voltage reference value, current regulator current amplitude limit value and power control loop, determines above-mentioned different control model; Constant current control model comprises constant current charge control model and constant current discharge control model.

4. the control method of the friendly type distributed power source of electrical network based on hybrid energy-storing according to claim 1, is characterized in that: described step 2 comprises the following steps:

Step 2 ?1: tuning controller is measured DC bus-bar voltage U in real time _dC, the state-of-charge of lithium battery and the terminal voltage of super capacitor, and according to Monitoring Data, determine the control model of DC/DC converter;

Step 2 ?2: tuning controller is measured the load power P of the friendly type distributed power source of described electrical network in real time _lpower output P with intermittent renewable energy system _r, the power shortage P of calculating mixed energy storage system _s, P _s=P _l-P _r, and extract P _sin low frequency component P _{b_ref}; Described P _{b_ref}for the value and power reference of permanent power control mode lithium battery energy storage battery system, P _lfor the load power of distributed power source, P _rpower output for intermittent renewable energy system;

Step 2 ?3: when DC bus-bar voltage drops on region 1, i.e. U ₀< U _dC< U ₁time, DC/DC converter A is operated in and determines voltage mode control, and its reference voltage is got U _ref1, the current amplitude limit value of current regulator and the power magnitude limit value of power control loop are got respectively I _max1and P _max1; DC/DC converter B and DC/DC converter C do not work;

Wherein: U ₀the maximum that-DC bus-bar voltage allows;

U _dCthe real-time measurement values of-DC bus-bar voltage;

U _ref1when-DC bus-bar voltage drops on region 1, the fixed voltage-controlled voltage reference value of DC/DC converter A, its choosing value is positioned at region 1, i.e. U ₀< U _ref1< U ₁;

I _max1-DC/DC converter A current regulator allows the current maxima of passing through;

P _max1-DC/DC converter A power control loop allows the maximum power of sending;

Step 2 ?4: when DC bus-bar voltage drops on region 2, i.e. U ₂< U _dC< U ₁time, DC/DC converter A is operated in MPPT control model, and DC/DC converter B is operated in and determines voltage mode control, and its reference voltage is got U _ref2, the current amplitude limit value of current regulator and the power magnitude limit value of power control loop are got respectively I _max2and P _max2; DC/DC converter C is operated in constant current discharge control model, and the reference voltage of its voltage control loop is got U _{ref_ab}, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _{sc_ref}and P _max3; In this process, the terminal voltage Uuc of tuning controller Real-Time Monitoring super capacitor, if detect U _min<U _uc<U _max, proceed to step 2 ?5 operation;

Wherein: U _ref2when-DC bus-bar voltage drops on region 2, the fixed voltage-controlled voltage reference value of DC/DC converter B, its choosing value is positioned at region 2, i.e. U ₁< U _ref2< U ₂;

I _max2-DC/DC converter B current regulator allows the current maxima of passing through;

P _max2-DC/DC converter B power control loop allows the maximum power of sending;

U _{ref_ab}the voltage reference value of-DC/DC converter C voltage control loop;

I _{sc_ref}the reference value of the super capacitor charging and discharging currents of-setting;

P _max3-DC/DC converter C power control loop allows the maximum power of sending;

U _ucthe terminal voltage of-super capacitor;

U _minthe smallest end voltage that-super capacitor allows;

U _maxthe maximum terminal voltage that-super capacitor allows;

Step 2 ?5: when DC bus-bar voltage drops on region 3, i.e. U ₃< U _dC< U ₂time, DC/DC converter A is operated in MPPT pattern, and DC/DC converter B is operated in permanent power control mode, and the voltage reference value of its voltage control loop is got U ' _ref-ab, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _max2and P _max2; DC/DC converter C is operated in and determines voltage mode control, and the reference voltage of its voltage control loop is got U _ref3, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _max3and P _max3;

Wherein:

U ' _ref-abthe voltage reference value of-DC/DC converter B voltage control loop;

U _ref3when-DC bus-bar voltage drops on region 3, the fixed voltage-controlled voltage reference value of DC/DC converter C, its choosing value is positioned at region 3, i.e. U ₃<U _ref3<U ₂;

I _max3-DC/DC converter C current regulator allows the current maxima of passing through;

Step 2 ?6: when DC bus-bar voltage drops on region 4, i.e. U ₄< U _dC< U ₃time, DC/DC converter A is operated in MPPT pattern, and the DC/DC converter B of lithium battery system is operated in and determines voltage mode control, and the voltage reference value of its voltage control loop is got U _ref4, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _max2and P _max2; DC/DC converter C is operated in constant current charge control model, and the reference voltage of its voltage control loop is got U _{ref_ab}, the amplitude limit value of current regulator and the amplitude limit value of power control loop are got respectively I _{sc_ref}and P _max3, in this process, the terminal voltage U of tuning controller Real-Time Monitoring super capacitor _ucif U detected _min<U _uc<U _max, proceed to step 2 ?5 operation;

Wherein:

U ₄the maximum U that-DC bus-bar voltage allows ₀> U ₁> U ₂> U ₃> U ₄;

U _ref4when-DC bus-bar voltage drops on region 4, the fixed voltage-controlled voltage reference value of DC/DC converter B, its choosing value should drop in region 4, i.e. U ₄<U _ref4<U ₃.

5. the control method of the friendly type distributed power source of electrical network based on hybrid energy-storing according to claim 1, it is characterized in that: in described step 3, AC DC/AC converter adopts motor synchronizing voltage source to control, introduce virtual impedance control and double mode seamless switching controls simultaneously, and the normalized to above-mentioned control model, so that distributed power source is when being incorporated to the micro-electrical network of mesolow, can with inverter type distributed power source or conventional synchronization motor-type distributed power source group net operation in parallel.

6. the control method of the friendly type distributed power source of electrical network based on hybrid energy-storing according to claim 5, it is characterized in that: during motor synchronizing voltage source is controlled, three-phase voltage and the electric current of the output of Real-time Collection DC/AC converter, according to instantaneous power theory, calculate active-power P and the reactive power Q of the output of DC/AC converter, adopt motor synchronizing voltage source to control, calculate the reference frequency f of the virtual output voltage phasor of DC/AC converter _{vir_ref}with reference amplitude V _{vir_ref}:

$\left\{\begin{array}{c}{f}_{\mathrm{vir}-\mathrm{ref}}=f^{*}-m(P*-P)\\ V_{\mathrm{vir}-\mathrm{ref}}=V^{*}-n(Q*-Q)\end{array}\right.---(2-1)$

Wherein:

F _{vir_ref}the reference frequency of the virtual output voltage phasor of-DC/AC converter;

V _{vir_ref}the reference amplitude of the virtual output voltage phasor of-DC/AC converter;

F ^*the reference frequency of-mixed energy storage system rated voltage;

V ^*the reference amplitude of-mixed energy storage system rated voltage;

The sagging coefficient that m-meritorious/frequency droop is controlled;

The sagging coefficient of n-REACTIVE POWER/VOLTAGE droop control;

P ^*-DC/AC converter is at f ^*the active power reference value of lower output;

Q ^*-DC/AC converter is at V ^*the reactive power reference qref of lower output;

The active power that P-DC/AC converter sends;

The reactive power that Q-DC/AC converter sends;

M and n through type (2 ?2) calculate:

$\left\{\begin{array}{c}m=\frac{f_{\min }-f^{*}}{P_{\max }-P^{*}}\\ n=\frac{V_{\min }-V^{*}}{Q_{\max }-Q^{*}}\end{array}\right.---(2-2)$

Wherein:

F _minthe minimum operation frequency that-mixed energy storage system allows;

V _minthe minimum operation voltage that-mixed energy storage system allows;

P _maxthe maximum active power that-converter can be exported;

Q _maxthe maximum reactive power that-converter can be exported.

7. the control method of the friendly type distributed power source of electrical network based on hybrid energy-storing according to claim 5, is characterized in that: during virtual impedance is controlled, according to formula (2 ?3), calculate

$\left\{\begin{array}{c}{V}_{\mathrm{vir}\_\mathrm{ref}}^{\&CenterDot;}=V_{\mathrm{vir}\_\mathrm{ref}}\&angle;{\mathrm{\&theta;}}_{\mathrm{vir}\_\mathrm{ref}}\\ {\mathrm{\&theta;}}_{\mathrm{vir}\_\mathrm{ref}}=2\mathrm{\&pi;}\underset{0}{\overset{t}{\&Integral;}}{f}_{\mathrm{vir}\_\mathrm{ref}}\mathrm{dt}\end{array}\right.---(2-3)$

$V_{\mathrm{ref}}^{\&CenterDot;}=V_{\mathrm{vir}\_\mathrm{ref}}^{\&CenterDot;}-\stackrel{\&CenterDot;}{I}{Z}_{\mathrm{vir}}---(2-4)$

In formula:

the reference phasor of the virtual output voltage phasor of converter;

the reference phasor of converter output voltage phasor;

the electric current phasor that converter sends;

Z _vir-virtual impedance.

8. the control method of the friendly type distributed power source of electrical network based on hybrid energy-storing according to claim 5, is characterized in that: during double mode seamless switching is controlled,

When distributed power source detects large electric network fault, grid-connected switch disconnects, f ^*and V ^*set-point by frequency and the amplitude of line voltage, change into the set point under independent operation mode;

When the fault clearance of large electrical network, distributed power source is converted to while being incorporated into the power networks pattern by independent operation mode, and the motor synchronizing that starts distributed power source is controlled, when meeting grid-connected condition, closed grid-connected switch, is incorporated into the power networks distributed power source, to reduce the grid-connected impact to electrical network of distributed power source.