CN102856924B - Microgrid smooth switch control method based on composite energy storage - Google Patents

Microgrid smooth switch control method based on composite energy storage Download PDF

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CN102856924B
CN102856924B CN201210312921.2A CN201210312921A CN102856924B CN 102856924 B CN102856924 B CN 102856924B CN 201210312921 A CN201210312921 A CN 201210312921A CN 102856924 B CN102856924 B CN 102856924B
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micro
capacitance sensor
energy storage
composite energy
voltage
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CN201210312921.2A
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CN102856924A (en
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刘志文
夏文波
刘明波
陈志刚
孙浩
张磊
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中国能源建设集团广东省电力设计研究院
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Abstract

The invention relates to a microgrid smooth switch control method and strategy based on composite energy storage. According to the invention, a low voltage microgrid containing a plurality kinds of distributed power supplies is arranged, a public connecting point PCC in the low voltage microgrid, the distributed power supplies and the switches of all branches are monitored by a microgrid energy management system EMS, and the microgrid energy management system EMS detects the on/off state of the public connecting point PCC of the microgrid to judge whether the low voltage microgrid is located at an isolated island operation state or a grid-connected operation state. The microgrid smooth switch control method is characterized in that a composite energy storage unit composed of a supercapacitor and a storage battery is arranged in the low voltage microgrid containing the plurality kinds of distributed power supplies, and the composite energy storage unit is used for performing microgrid smooth switch control on the basis of the monitoring of the microgrid energy management system EMS on the low voltage microgrid. According to the invention, the composite energy storage characteristics are fully utilized to greatly improve the power supply reliability and power supply quality of the microgrid under a switch emergency state to facilitate the generalization and application of the microgrid.

Description

A kind of micro-capacitance sensor based on composite energy storage takes over seamlessly control method
Technical field
The present invention relates to micro-capacitance sensor and take over seamlessly control method, especially a kind of micro-capacitance sensor based on composite energy storage takes over seamlessly control method and strategy.Belong to electric power system power transmission and distribution technical field.
Background technology
Micro-capacitance sensor has grid-connected and isolated island two kinds of operational modes, micro-capacitance sensor and public power distribution network are incorporated into the power networks under normal circumstances, its voltage and frequency stability are all supported by public power distribution network, when breaking down in power distribution network or micro-capacitance sensor inside, the points of common connection (PCC) of micro-capacitance sensor and power distribution network will disconnect immediately, and micro-capacitance sensor transfers island operation state to by the state of being incorporated into the power networks.For most of micro-capacitance sensor, the distributed power source utilizing renewable resource to generate electricity in micro-capacitance sensor is exerted oneself and can not be met workload demand completely, when micro-capacitance sensor by grid-connected proceed to unplanned islet operation time often emergent power vacancy, cause micro-capacitance sensor cannot keep voltage and frequency stabilization, distributed power source will be caused time serious out of service, load power-off, whole micro-capacitance sensor is absorbed in collapse.Therefore studying micro-grid connection runs to unplanned isolated island switching and islet operation to the control method of grid-connected switching and strategy, guarantee the smooth transition under different operational mode of micro-capacitance sensor, significant to the quality of power supply and power supply reliability improving micro-capacitance sensor.
The research switched operational mode at present mainly concentrates on the switching between source and net, namely the load-carrying distributed power source of separate unit and public power distribution network are incorporated into the power networks and switching between off-grid islet operation, and internet with public power distribution network to whole micro-capacitance sensor between operational mode switch study relative less.Current existing micro-capacitance sensor operational mode smooth-switching method mainly contains two kinds:
One, main power source adopt V/F control switch mode: micro-capacitance sensor by grid-connected switch to islet operation time, distributed power source as islet operation main power source controls to transfer V/F to by grid-connected PQ and controls, and changes inverter control parameter simultaneously and takes over seamlessly to realize micro-capacitance sensor operational mode.The subject matter that this changing method exists is: (1) actual micro-capacitance sensor is when islet operation; main power source General Requirements possesses stability and larger capacity well; often only can select diesel engine generator or energy storage device; and do not select distributed power source; but diesel engine generator is in stopped status time grid-connected; energy storage device is also often in floating charge state, and therefore actual micro-capacitance sensor is comparatively rare by the grid-connected situation that main power source can be controlled to transfer to V/F control by PQ in unplanned isolated island handoff procedure.(2) situation of power shortage when the method does not consider grid-connected turn of unplanned isolated island, only consider that islet operation after switching can reach power-balance or the little situation of vacancy, if not still after plan switching, isolated island power shortage is larger, as the distributed power source finite capacity of main power source, microgrid power vacancy cannot be filled up, then take over seamlessly and cannot realize.
Two, distributed power source all adopts the switch mode of droop control: the distributed power source in micro-capacitance sensor all adopts PQ to control when grid-connected, all droop control is transferred to during islet operation, in basic droop control device, increase sinking crown fixed point adjustable ring during switching, realize level and smooth conversion that is grid-connected and isolated island control model by the switching of this loop.The method does not take into full account the impact of power shortage in unplanned handoff procedure equally, if isolated island power shortage is larger after unplanned switching, adopt droop control to require higher to distributed power source variable capacity, take over seamlessly in the micro-capacitance sensor that permeability is lower and realize being difficult to.
Summary of the invention
Object of the present invention, cause quality of power supply degradation by grid-connected to emergent power vacancy during unplanned isolated island switching in order to solve micro-capacitance sensor in prior art, and micro-capacitance sensor and public power distribution network exist nonsynchronous problem during micro-grid connection, a kind of micro-capacitance sensor based on composite energy storage is provided to take over seamlessly control method and strategy.
Object of the present invention can reach by the following technical programs:
A kind of micro-capacitance sensor based on composite energy storage takes over seamlessly control method and strategy, low pressure micro-capacitance sensor containing multiple distributed power source is set, points of common connection PCC in described low pressure microgrid, the switch of each distributed power source and all branch roads is monitored by energy management system of micro-grid EMS, by the open/close status detecting micro-capacitance sensor points of common connection PCC, energy management system of micro-grid EMS judges that low pressure micro-capacitance sensor is in island operation state or the state that is incorporated into the power networks, it is characterized in that: in described containing in the low pressure micro-capacitance sensor of multiple distributed power source, the composite energy storage unit be made up of ultracapacitor and storage battery is set, the basis that energy management system of micro-grid EMS monitors low pressure micro-capacitance sensor utilize composite energy storage unit to take over seamlessly control to micro-capacitance sensor, concrete grammar and strategy as follows:
1) unplanned isolated island switching controls is turned by being incorporated into the power networks
When detecting that micro-capacitance sensor points of common connection PCC is in off-state, low pressure micro-capacitance sensor switches by being incorporated into the power networks to unplanned isolated island, do not changing under distributed power source operation control model prerequisite, composite energy storing device ultracapacitor and storage battery formed is as main power source during micro-capacitance sensor islet operation, on the basis of composite energy storing device structure reasonable in design and charge/discharge control method, turning unplanned isolated island switching control strategy by formulating suitable micro-grid connection, guaranteeing that before and after switching, important load normal power supply and distributed power source normally run;
2) grid-connected switching controls is turned by islet operation
When detecting that public distribution network restoration is powered, micro-capacitance sensor is switched to by island operation state and is incorporated into the power networks, before grid-connected, presynchronization control is carried out to the composite energy storage as main power source, by the voltage of low pressure micro-capacitance sensor and phase adjust to basically identical with public power distribution network, thus effectively reduce isolated island to the impact of being incorporated into the power networks when switching and vibration, guarantee the smooth transition in operational mode handoff procedure.
Further, when turning unplanned isolated island switching controls by being incorporated into the power networks, according to ultracapacitor port voltage u capsize controls the switching of ultracapacitor and storage battery, with DC bus-bar voltage u in stable composite energy storage unit cfor target regulates exerting oneself, if ultracapacitor operational voltage upper limit is u in composite energy storage unit of ultracapacitor combination storage battery cap-up, working voltage lower limit is u cap-low, port voltage surplus coefficient is α (0< α <1), then the switching control strategy of grid-connected turn of unplanned isolated island is as follows:
1) microgrid EMS system obtains PCC point by optical fiber communication and cut-offs information to judge micro-capacitance sensor whether islet operation, immediately ultracapacitor being switched to discharge condition by floating charge state when monitoring micro-capacitance sensor islet operation, composite energy storage unit being switched to V/F controlled discharge pattern by charge mode simultaneously; For reducing the shock effect of composite energy storing device input to micro-capacitance sensor to greatest extent, the reference voltage that composite energy storage V/F controls and reference frequency/phase angle get voltage and the frequency/angle values that PCC point disconnects moment public power distribution network;
2) because micro-capacitance sensor exists power shortage, composite energy storage unit controls power output by V/F and holds micro-capacitance sensor voltage and frequency, composite energy storage DC bus-bar voltage u cdecline, ultracapacitor transient response is exerted oneself, and fills up rapidly microgrid power vacancy, meanwhile ultracapacitor port voltage u capdecline gradually;
3) u is worked as cap-up>u cap> α u cap-uptime, the secondary load in excision low pressure micro-capacitance sensor, if be P by the peak power output of the batteries in composite energy storage unit bat-up, now all the other distributed electrical source power sums are S dg-whole, the load gross power before excision is S load-whole, after excision, remaining load power is S load-res, then the secondary load power S excised is needed load-cutmust following formula be met:
S load - res = S load - whole - S load - cut &beta; P bat - up + | S | dg - | S | load - res &GreaterEqual; 0 - - - ( 1 )
In expression formula (1), β (0< β <1) is power headroom coefficient, its effect is when storage battery works as main power source separately, guarantee to there is certain meritorious and idle variable capacity after inversion, the power fluctuation brought with the change of stabilizing other distributed power source or important load;
4) u is worked as cap=α u cap-uptime, the batteries in composite energy storage unit switches to discharge mode by floating charge state, and now storage battery and ultracapacitor are powered to micro-capacitance sensor as main power source simultaneously;
5) u is worked as cap-low<u cap< α u cap-uptime, bank of super capacitors is discharged to terminal voltage u capdecline gradually, batteries is powered and is promoted to stable state gradually; Work as u cap=u cap-lowtime, excision bank of super capacitors, is powered to micro-capacitance sensor important load as main power source separately by batteries.
Further, when turning grid-connected switching controls by islet operation, when detecting that public distribution network restoration is powered, be again incorporated in power distribution network after low pressure micro-capacitance sensor is adjusted to proper states, to be switched to by island operation state by micro-capacitance sensor and to be incorporated into the power networks, its switching control strategy is as follows:
1) in order to reduce impact during grid-connected combined floodgate, control voltage and phase angle to be transferred to public power distribution network basically identical before grid-connected by presynchronization, the mode of the reference voltage that the present invention adopts directly adjustment main power source V/F to control and reference frequency carries out presynchronization control;
2), when carrying out presynchronization control adjustment, the dq axle component v of inverter output end mouth voltage in composite energy storage unit is measured d, v q, low pressure micro-capacitance sensor angle values θ, the voltage dq axle component v of public power distribution network d-gridand v q-grid, public power distribution network phase angle theta grid, when the voltage of micro-capacitance sensor and public power distribution network and phase angle meet following expression (2), implement and net operation;
In above formula | U| gridwith | U| is respectively public power distribution network and micro-capacitance sensor voltage magnitude, | U| nfor rated voltage amplitude, θ is micro-capacitance sensor angle values, θ gridpublic power distribution network phase angle;
3) grid-connected complete after, immediately by composite energy storage unit by V/F control mode switch to charge mode, bank of super capacitors and batteries proceed to charged state, then recover the power supply to secondary load.
Further, involved low pressure micro-capacitance sensor electric pressure is 380V, can comprise photovoltaic, wind-driven generator, important load A, secondary load B and secondary load C; Described photovoltaic, wind-driven generator and composite energy storing device are by inverter access low pressure micro-capacitance sensor; The switch that described photovoltaic, wind-force send out machine, composite energy storing device and all branch roads is monitored by energy management system of micro-grid EMS.
Further, low pressure micro-capacitance sensor is when being incorporated into the power networks, and photovoltaic generation loop and wind power generation loop adopt PQ to control, and the batteries in composite energy storage unit is in floating charge state, and bank of super capacitors is in floating charge state.
Further, when entering island operation state, photovoltaic generation loop and wind power generation loop still adopt PQ to control, and composite energy storage unit, as main power source, adopts V/F to control to maintain micro-capacitance sensor voltage and frequency stabilization.
The present invention has following outstanding beneficial effect:
1, by making full use of composite energy storage feature, do not changing under distributed power source operation control model prerequisite, a turn unplanned isolated island switching control strategy is run by formulating suitable micro-grid connection, guarantee that before and after switching, important load normal power supply and distributed power source normally run, this, by increasing substantially micro-capacitance sensor at the power supply reliability switched under the state of emergency and power supply quality, is conducive to micro-capacitance sensor promotion and application.
2, when micro-capacitance sensor is switched to being incorporated into the power networks by islet operation, by carrying out presynchronization control to composite energy storage unit, by the voltage of low pressure micro-capacitance sensor and phase adjust to basically identical with public power distribution network, effectively reduce grid-connected switch time impact and vibration, realize micro-capacitance sensor and taken over seamlessly to grid-connected by islet operation.
3, the present invention arranges the composite energy storage unit be made up of ultracapacitor and storage battery in low pressure micro-capacitance sensor, can play that super capacitor power density is large, fast response time feature, the high advantage of storage battery energy density can being taken into account again, effectively can solving the problem of unbalanced power when micro-capacitance sensor switches to unplanned isolated island by being incorporated into the power networks.
4, in micro-capacitance sensor handoff procedure, by the two close cycles charge/discharge control method of design capacitance outer voltage and inductive current inner ring, can respond rapidly at composite energy storing device and exert oneself simultaneously in a large number, maintain DC bus-bar voltage and stablize, guarantee that whole composite energy storing device keeps stable operation.
Accompanying drawing explanation
Fig. 1 is the structural representation of the low pressure micro-capacitance sensor that the present invention's specific embodiment relates to.
Fig. 2 is the composite energy storage cellular construction schematic diagram that the present invention's specific embodiment relates to.
Fig. 3 is the composite energy storage unit charge/discharge principle schematic that the present invention relates to.
Fig. 4 is the composite energy storage unit charge/discharge controller double-loop control block diagram that the present invention relates to.
Fig. 5 is the presynchronization control principle drawing that the present invention's specific embodiment relates to.
Embodiment
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in detail:
The micro-capacitance sensor based on composite energy storage that the present embodiment relates to takes over seamlessly control method and strategy, low pressure micro-capacitance sensor containing multiple distributed power source is set, points of common connection PCC in described low pressure microgrid, the switch of each distributed power source and all branch roads is monitored by energy management system of micro-grid EMS, by the open/close status detecting micro-capacitance sensor points of common connection PCC, energy management system of micro-grid EMS judges that low pressure micro-capacitance sensor is in island operation state or the state that is incorporated into the power networks, it is characterized in that: in described containing in the low pressure micro-capacitance sensor of multiple distributed power source, composite energy storage unit is set, the basis that energy management system of micro-grid EMS monitors low pressure micro-capacitance sensor utilize composite energy storage unit to take over seamlessly control to micro-capacitance sensor, concrete grammar and strategy as follows:
1) be incorporated into the power networks a turn unplanned isolated island switching controls: when detecting that micro-capacitance sensor points of common connection PCC is in off-state, low pressure micro-capacitance sensor switches by being incorporated into the power networks to unplanned isolated island, do not changing under distributed power source operation control model prerequisite, composite energy storing device ultracapacitor and storage battery formed is as main power source during micro-capacitance sensor islet operation, on the basis of composite energy storing device structure reasonable in design and charge/discharge control method, unplanned isolated island switching control strategy is turned by formulating suitable micro-grid connection, guarantee that before and after switching, important load normal power supply and distributed power source normally run,
2) islet operation turns grid-connected switching controls: when detecting that public distribution network restoration is powered, micro-capacitance sensor is switched to by island operation state and is incorporated into the power networks, before grid-connected, presynchronization control is carried out to the composite energy storage as main power source, by the voltage of low pressure micro-capacitance sensor and phase adjust to basically identical with public power distribution network, thus effectively reduce isolated island to the impact of being incorporated into the power networks when switching and vibration, guarantee the smooth transition in operational mode handoff procedure.
Turn unplanned isolated island switching controls and islet operation to being incorporated into the power networks of relating in the present embodiment below to turn grid-connected switching controls and be described in detail:
Be incorporated into the power networks turn unplanned isolated island switching controls time, according to ultracapacitor port voltage u capsize controls the switching of ultracapacitor and storage battery, with DC bus-bar voltage u in stable composite energy storage unit cfor target regulates exerting oneself, if ultracapacitor operational voltage upper limit is u in composite energy storage unit of ultracapacitor combination storage battery cap-up, working voltage lower limit is u cap-low, port voltage surplus coefficient is α (0< α <1), then the switching control strategy of grid-connected turn of unplanned isolated island is as follows:
1) microgrid EMS system obtains PCC point by optical fiber communication and cut-offs information to judge micro-capacitance sensor whether islet operation, immediately ultracapacitor being switched to discharge condition by floating charge state when monitoring micro-capacitance sensor islet operation, composite energy storage unit being switched to V/F controlled discharge pattern by charge mode simultaneously; For reducing the shock effect of composite energy storing device input to micro-capacitance sensor to greatest extent, the reference voltage that composite energy storage V/F controls and reference frequency/phase angle get voltage and the frequency/angle values that PCC point disconnects moment public power distribution network;
2) because micro-capacitance sensor exists power shortage, composite energy storage unit controls power output by V/F and holds micro-capacitance sensor voltage and frequency, composite energy storage DC bus-bar voltage u cdecline, the ultracapacitor transient response of composite energy storage unit is exerted oneself, and fills up rapidly microgrid power vacancy, meanwhile described ultracapacitor port voltage u capdecline gradually;
3) u is worked as cap-up>u cap> α u cap-uptime, the secondary load in excision low pressure micro-capacitance sensor, if be P by the peak power output of the batteries in composite energy storage unit bat-up, now all the other distributed electrical source power sums are S dg-whole, the load gross power before excision is S load-whole, after excision, remaining load power is S load-res, then the secondary load power S excised is needed load-cutmust following formula be met:
S load - res = S load - whole - S load - cut &beta; P bat - up + | S | dg - | S | load - res &GreaterEqual; 0 - - - ( 1 )
In expression formula (1), β (0< β <1) is power headroom coefficient, its effect is when storage battery works as main power source separately, guarantee to there is certain meritorious and idle variable capacity after inversion, the power fluctuation brought with the change of stabilizing other distributed power source or important load;
4) u is worked as cap=α u cap-uptime, the batteries in composite energy storage unit switches to discharge mode by floating charge state, and now storage battery and ultracapacitor are powered to micro-capacitance sensor as main power source simultaneously;
5) u is worked as cap-low<u cap< α u cap-uptime, bank of super capacitors is discharged to terminal voltage u capdecline gradually, batteries is powered and is promoted to stable state gradually; Work as u cap=u cap-lowtime, excision bank of super capacitors, is powered to micro-capacitance sensor important load as main power source separately by batteries;
When entering island operation state, composite energy storage unit is as main power source, and adopt V/F to control to maintain micro-capacitance sensor voltage and frequency stabilization, other distributed power source still adopts PQ to control.
Turn in grid-connected switching controls process carrying out islet operation, when detecting that public distribution network restoration is powered, again be incorporated in power distribution network after low pressure micro-capacitance sensor is adjusted to proper states, to be switched to by island operation state by micro-capacitance sensor and to be incorporated into the power networks, its switching control strategy is as follows:
1) in order to reduce impact during grid-connected combined floodgate, control voltage and phase angle to be transferred to public power distribution network basically identical before grid-connected by presynchronization, the mode of the reference voltage that the present invention adopts directly adjustment main power source V/F to control and reference frequency carries out presynchronization control;
2), when carrying out presynchronization control adjustment, the dq axle component v of inverter output end mouth voltage in composite energy storage unit is measured d, v q, low pressure micro-capacitance sensor angle values θ, the voltage dq axle component v of public power distribution network d-gridand v q-grid, public power distribution network phase angle theta grid, when the voltage of micro-capacitance sensor and public power distribution network and phase angle meet following expression (2), implement and net operation;
In above formula | U| gridwith | U| is respectively public power distribution network and micro-capacitance sensor voltage magnitude, | U| nfor rated voltage amplitude, θ is micro-capacitance sensor angle values, θ gridpublic power distribution network phase angle;
With reference to Fig. 2-Fig. 5, v in figure d, v qbe respectively the dq axle component of composite energy storage inverter output end mouth voltage, θ is micro-capacitance sensor angle values, v d-gridand v q-gridbe respectively the voltage dq axle component of public power distribution network, θ gridpublic power distribution network phase angle, v d-refand v q-reffor voltage dq axle reference component during micro-capacitance sensor islet operation, f reffor frequency reference during micro-capacitance sensor islet operation, v ' d-ref, v ' q-refwith f ' refit is then the reference value of the voltage after being adjusted by presynchronization and frequency;
3) grid-connected complete after, immediately by composite energy storage unit by V/F control mode switch to charge mode, bank of super capacitors and batteries proceed to charged state, then recover the power supply to secondary load.
It should be noted that:
Low pressure micro-capacitance sensor is when being incorporated into the power networks, and photovoltaic generation loop and wind power generation loop adopt PQ to control.Consider from reducing discharge and recharge number of times and improving the angle in useful life, the storage battery in composite energy storage unit is in floating charge state, and ultracapacitor is in floating charge state or play a part to stabilize power fluctuation according to the needs of micro-electric low voltage network utility power quality control.
Below the structure and working principle of the composite energy storage unit that the present embodiment relates to is described:
See figures.1.and.2, the composite energy storage unit that the present invention relates to forms primarily of bank of super capacitors, batteries, dc-link capacitance, Buck-Boost reversible transducer, biphase rectification/inverter and relevant control thereof.The control input end of the biphase rectification/inverter of described composite energy storage unit connects the EMS system signal output of low pressure micro-capacitance sensor.
In fig. 2, V/F controls as to determine voltage and to determine FREQUENCY CONTROL; PCC point is points of common connection; PWM is pulse width modulation; SPWM is sinusoidal pulse width modulation; PI controls as proportional plus integral control.DC/DC (A) and DC/DC (B) is Buck-Boost reversible transducer, realizes the charging and discharging of bank of super capacitors and batteries respectively; C is dc-link capacitance; i l (A)and i l (B)be respectively the electric current flowing through inductance in DC/DC (A) and DC/DC (B), u capfor bank of super capacitors port voltage, u cfor DC bus-bar voltage; Controlling unit A and controlling unit B is respectively according to input variable u cap, i l (A), i l (B)and u csize and export corresponding analog control signal in conjunction with charge/discharge control method and switching control strategy; PWM is pulse width modulation, and the analog signal provided according to controlling unit A and controlling unit B generates corresponding pulse signal and directly controls DC/DC (A) and DC/DC (B); V/F controls, for the control model of composite energy storing device when micro-capacitance sensor islet operation, by regulating exerting oneself of composite energy storing device, micro-capacitance sensor voltage and frequency to be maintained set point; SPWM is sinusoidal pulse width modulation, and the analog signal controlling to provide according to V/F generates the output of corresponding pulse signal control inverter.
Ultracapacitor is connected with micro-capacitance sensor through biphase rectification/inverter after being connected to DC bus respectively by Buck-Boost reversible transducer DC/DC (A) with DC/DC (B) with storage battery again, wherein the low-pressure side of DC/DC (A) and DC/DC (B) connects ultracapacitor and storage battery respectively, and high pressure side joint DC bus.
DC bus is the passage that ultracapacitor and storage battery and microgrid energy exchange, when micro-capacitance sensor by grid-connected in unplanned islet operation handoff procedure, the power exported sharply changes, this must cause DC bus-bar voltage to change, and the output voltage of biphase rectification/inverter and DC voltage closely related, biphase rectification/inverter output voltage is also fluctuated, make the composite energy storage unit as main power source cannot maintain micro-capacitance sensor rated voltage, when DC bus-bar voltage is fallen serious, two way convertor even will be caused to work, cause micro-capacitance sensor to lose main power source to support, therefore guarantee that DC bus-bar voltage is stable to take over seamlessly realizing micro-capacitance sensor there is important function.Generally speaking, increasing dc-link capacitance is the most direct mode suppressing voltage fluctuation, but will system response time be reduced like this, therefore the present invention is designed to ultracapacitor and storage battery arranges charge controller DC/DC (A) and DC/DC (B) respectively, this not only can need according to switching controls the charging and discharging controlling ultracapacitor and storage battery respectively, and on high-tension side output voltage can be controlled when discharging, thus DC bus-bar voltage is kept to stablize.
Due to micro-capacitance sensor be switched to islet operation from being incorporated into the power networks time, general need ensure micro-capacitance sensor important load normal power supply, therefore the capacity amount that in Fig. 2, storage battery needs configure only need meet important load and power, and ultracapacitor is in order to ensure seamlessly transitting of switching, the capacity configured must meet the power requirement of all loads in micro-capacitance sensor;
The capacity amount of the batteries of described composite energy storage unit is at least match with the power of important load A, and in the capacity of Capacitor banks and low pressure micro-capacitance sensor, all the power of load matches.Namely the capacity amount of the batteries of described composite energy storage unit is at least to meet important load A power reguirements, and Capacitor banks is in order to ensure seamlessly transitting of switching, and the capacity configured meets the power requirement of whole load in low pressure micro-capacitance sensor.
The control circui of described composite energy storage unit mainly controls biphase rectification/inverter, Buck-Boost reversible transducer DC/DC (A) and DC/DC (B), and wherein biphase rectification/inverter is assigned instruction according to micro-capacitance sensor EMS system and carried out switching and controlling; DC/DC (A) and DC/DC (B) carries out switching and controlling according to ultracapacitor port voltage and DC bus-bar voltage.
Be described below in conjunction with the operation principle of accompanying drawing to the present embodiment:
With reference to Fig. 2-Fig. 4, the composite energy storage charge/discharge control procedure of the present embodiment is as follows:
As shown in figs 2-4, u in Fig. 3 sfor storage battery or bank of super capacitors port voltage, r sfor energy storage equivalent internal resistance, i lfor flowing through the electric current of inductance L, G 1and G 2for switching tube, u cfor DC bus-bar voltage, i invfor two way convertor the input or output current.
As shown in Figure 3, by control switch pipe G 1and G 2make-and-break time can realize energy two-way transmission and control, simultaneously can regulate DC bus-bar voltage u csize.Take over seamlessly for guaranteeing that DC bus-bar voltage is stable have important function to realizing micro-capacitance sensor, the present invention controls ultracapacitor and storage battery output voltage respectively by Buck-Boost reversible transducer fluctuates to suppress DC bus-bar voltage.Because the voltage transfering function of Buck-Boost reversible transducer when the constant voltage output state of boost mode exists the zero point of RHP in S territory, then system belongs to non minimum phase system, open-loop unstable.In order to stable DC busbar voltage, the present invention's employing capacitance voltage outer shroud as shown in Figure 4 and the double-closed-loop control pattern of inductive current inner ring.
U in Fig. 4 c_reffor DC bus-bar voltage reference value, i l_reffor flowing through the current reference value of inductance L.In figure, outer voltage mainly maintains output voltage stabilization, and current inner loop, by fast dynamic response, produces suitable offset current and strengthens output voltage stability.In order to strengthen the stability of the DC bus-bar voltage when output-power fluctuation, adopt power feedforward method will current i closely-related with power output invparticipate in current inner loop control as Front Feed Compensation, this will improve current inner loop to the response speed of power output, thus improve DC bus-bar voltage stability further, guarantee two way convertor steady operation.
Current i closely-related with power output invparticipate in current inner loop control as Front Feed Compensation, this will improve current inner loop to the response speed of power output, thus improve DC bus-bar voltage stability further, guarantee two way convertor steady operation.
The above; be only the specific embodiment of the best of the present invention; but protection scope of the present invention is not limited thereto; anyly be familiar with those skilled in the art in the scope that the present invention discloses; be equal to according to technical scheme of the present invention and inventive concept thereof and replace or change, all belonged to protection scope of the present invention.

Claims (5)

1. the micro-capacitance sensor based on composite energy storage takes over seamlessly a control method, arranges containing the low pressure micro-capacitance sensor of multiple distributed power source, the switch of the points of common connection PCC in described low pressure micro-capacitance sensor, each distributed power source and all branch roads by micro-energy management system EMS monitors, by the open/close status detecting micro-capacitance sensor points of common connection PCC, microgrid energy management system EMS judges that low pressure micro-capacitance sensor is in island operation state or the state that is incorporated into the power networks, it is characterized in that: in described containing in the low pressure micro-capacitance sensor of multiple distributed power source, the composite energy storage unit be made up of ultracapacitor and storage battery is set, the basis that microgrid energy management system EMS monitors low pressure micro-capacitance sensor utilizes composite energy storage unit to take over seamlessly control to micro-capacitance sensor, and concrete grammar is as follows:
1) unplanned isolated island switching controls is turned by being incorporated into the power networks
When detecting that micro-capacitance sensor points of common connection PCC is in off-state, low pressure micro-capacitance sensor switches by being incorporated into the power networks to unplanned isolated island, unbalanced problem is there is by the power in unplanned isolated island handoff procedure that is incorporated into the power networks for micro-capacitance sensor, do not changing under distributed power source operation control model prerequisite, main power source during composite energy storage unit islet operation unplanned as micro-capacitance sensor using ultracapacitor and storage battery composition, unplanned isolated island switching control strategy is turned by formulating micro-grid connection, guarantee that before and after switching, important load normal power supply and distributed power source normally run,
2) grid-connected switching controls is turned by unplanned islet operation
When detecting that public distribution network restoration is powered, micro-capacitance sensor is switched to by unplanned island operation state and is incorporated into the power networks, before grid-connected, presynchronization control is carried out to the composite energy storage unit as main power source, by the voltage of low pressure micro-capacitance sensor and phase adjust to basically identical with public power distribution network, thus effectively reduce unplanned isolated island to the impact of being incorporated into the power networks when switching and vibration, guarantee the smooth transition in operational mode handoff procedure;
3) when turning unplanned isolated island switching controls by being incorporated into the power networks, according to ultracapacitor port voltage u capsize controls the switching of ultracapacitor and storage battery, with DC bus-bar voltage u in stable composite energy storage unit cfor target regulates exerting oneself, if ultracapacitor operational voltage upper limit is u in composite energy storage unit of ultracapacitor and storage battery cap-up, working voltage lower limit is u cap-low, port voltage surplus coefficient is α, 0< α <1, then the grid-connected switching control strategy turning isolated island is as follows:
3-1) micro-capacitance sensor EMS system obtains PCC point by optical fiber communication and cut-offs information to judge micro-capacitance sensor whether islet operation, immediately ultracapacitor being switched to discharge condition by floating charge state when monitoring micro-capacitance sensor islet operation, composite energy storage unit being switched to V/F controlled discharge pattern by charge mode simultaneously; For reducing the shock effect of composite energy storage unit input to micro-capacitance sensor to greatest extent, the reference voltage that composite energy storage V/F controls and reference frequency/phase angle get voltage and the frequency/angle values that PCC point disconnects moment public power distribution network;
3-2) because micro-capacitance sensor exists power shortage, composite energy storage unit controls power output by V/F and holds micro-capacitance sensor voltage and frequency, composite energy storage DC bus-bar voltage u cdecline, ultracapacitor transient response is exerted oneself, and fills up rapidly microgrid power vacancy, meanwhile ultracapacitor port voltage u capdecline gradually;
3-3) work as u cap-up> u cap> α u cap-uptime, the secondary load in excision low pressure micro-capacitance sensor, if be P by the peak power output of the storage battery in composite energy storage unit bat-up, now all the other distributed electrical source power sums are S dg, the load gross power before excision is S load-whole, after excision, remaining load power is S load-res, then the secondary load power S excised is needed load-cutmust following formula be met:
S load - res = S load - whole - S load - cut &beta; P bat - up + | S | dg - | S | load - res &GreaterEqual; 0 - - - ( 1 )
0< β <1 in expression formula (1), β is power headroom coefficient, its effect is when storage battery works as main power source separately, guarantee to there is certain meritorious and idle variable capacity after inversion, the power fluctuation brought with the change of stabilizing other distributed power source or important load;
3-4) work as u cap=α u cap-uptime, the storage battery in composite energy storage unit switches to discharge mode by floating charge state, and now storage battery and ultracapacitor are powered to micro-capacitance sensor as main power source simultaneously;
3-5) work as u cap-low< u cap< α u cap-uptime, ultracapacitor is discharged to terminal voltage u capdecline gradually, storage battery power supply is promoted to stable state gradually; Work as u cap=u cap-lowtime, excision ultracapacitor, is powered to micro-capacitance sensor important load as main power source separately by storage battery.
2. a kind of micro-capacitance sensor based on composite energy storage takes over seamlessly control method as claimed in claim 1, it is characterized in that: when turning grid-connected switching controls by unplanned islet operation, when detecting that public distribution network restoration is powered, again be incorporated in power distribution network after low pressure micro-capacitance sensor is adjusted to proper states, to be switched to by unplanned island operation state by micro-capacitance sensor and to be incorporated into the power networks, its switching control strategy is as follows:
1) in order to reduce impact during grid-connected combined floodgate, control voltage and phase angle to be transferred to public power distribution network basically identical before grid-connected by presynchronization, the reference voltage adopting directly adjustment main power source V/F to control and the mode of reference frequency carry out presynchronization control;
2), when carrying out presynchronization control adjustment, the dq axle component v of inverter output end mouth voltage in composite energy storage unit is measured d, v q, low pressure micro-capacitance sensor angle values θ, the voltage dq axle component v of public power distribution network d-gridand v q-grid, public power distribution network phase angle theta grid, when the voltage of micro-capacitance sensor and public power distribution network and phase angle meet following expression (2), implement and net operation;
In above formula | U| gridwith | U| is respectively public power distribution network and micro-capacitance sensor voltage magnitude, | U| nfor rated voltage amplitude, θ is micro-capacitance sensor angle values, θ gridpublic power distribution network phase angle;
3) grid-connected complete after, immediately by composite energy storage unit by V/F control mode switch to charge mode, ultracapacitor and storage battery proceed to charged state, then recover the power supply to secondary load.
3. a kind of micro-capacitance sensor based on composite energy storage takes over seamlessly control method as claimed in claim 1 or 2, it is characterized in that: involved low pressure micro-capacitance sensor electric pressure is 380V, comprise photovoltaic, wind-driven generator, important load A, secondary load B and secondary load C; Described photovoltaic, wind-driven generator and composite energy storage unit are by inverter access low pressure micro-capacitance sensor; The switch of described photovoltaic, wind-driven generator, composite energy storage unit and all branch roads is monitored by microgrid energy management system EMS.
4. a kind of micro-capacitance sensor based on composite energy storage takes over seamlessly control method as claimed in claim 1 or 2, it is characterized in that: low pressure micro-capacitance sensor is when being incorporated into the power networks, photovoltaic generation loop and wind power generation loop adopt PQ to control, storage battery in composite energy storage unit is in floating charge state, and ultracapacitor is in floating charge state.
5. a kind of micro-capacitance sensor based on composite energy storage takes over seamlessly control method as claimed in claim 1 or 2, it is characterized in that: when entering island operation state, photovoltaic generation loop and wind power generation loop adopt PQ to control, composite energy storage unit, as main power source, adopts V/F to control to maintain micro-capacitance sensor voltage and frequency stabilization.
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