Summary of the invention
The invention provides a kind of for can be grid-connected and from the micro-grid system of network operation and energy control method, ensure the operation that micro-grid system is flexible, controlled.
For achieving the above object, the technical solution adopted in the present invention is as follows:
Can be grid-connected and from the micro-grid system of network operation, comprise distributed energy electricity generation system: be connected to ac bus, for generation of electric energy by inverter or controller; Energy-storage system: be connected to ac bus by PCS, for storing and providing energy; PCC switch: the connection and the disconnection that realize micro-grid system and outer net, detection of grid state realizes grid-connected and from the seamless switching of net action; Central controller: realize information interaction by CAN and distributed energy electricity generation system, energy-storage system and load governor; Energy control apparatus: realize information interaction by Ethernet and distributed energy electricity generation system, energy-storage system and central controller; Load controller: detection load power, by load power condition feedback to energy control apparatus, the switching load instruction of received energy control device; And load: be connected to ac bus by load governor.
As the preferred embodiments of the present invention, described distributed energy electricity generation system comprises photovoltaic generating system, wind generator system, and diesel power generation system, photovoltaic generating system is connected to ac bus by DC/AC inverter, for micro-capacitance sensor provides regenerative resource; Wind generator system is connected to ac bus by AC-DC-AC converter, for micro-capacitance sensor provides regenerative resource; Diesel engine generator, as synchronous generator unit, provides energy to micro-capacitance sensor, stablizes controlled energy source as microgrid.
As the preferred embodiments of the present invention, described energy-storage system comprises storage battery and super capacitor, described storage battery is connected to ac bus by two-way DC/AC converter, for stabilizing microgrid energy fluctuation, support micro-capacitance sensor at short notice to run, described super capacitor is connected to ac bus by two-way DC/AC converter, for stabilizing microgrid power fluctuation.
Based on above-mentioned for can the energy control method of grid-connected and micro-grid system from network operation, the operation phase comprises the following steps:
(1); Gather the output/absorbed power P of storage battery
li-PCS, ultracapacitor output/absorbed power P
sC-PCS, distributed energy electricity generation system power output P
pV, whole micro-capacitance sensor load power P
load, whole micro-capacitance sensor line loss power P
loss, storage battery remaining capacity SOC
li-PCS, ultracapacitor remaining capacity SOC
sC-PCS;
(2) output/absorbed power P of energy-storage system is calculated
hESS, then according to the output/absorbed power P of given Δ Pref by energy-storage system
hESSbe divided into N grade, given as the output of lithium battery using N* Δ Pref, remainder is compensated by ultracapacitor;
(3) generate strategy
(3.1) if the remaining capacity SOC of storage battery
li-PCSbe less than 70%, judge N value size, if N<0, then utilize super capacitor to revise N value, then to lithium cell charging until the dump energy of lithium battery returns to the minimum electricity of start up system, return islet operation pattern; If N>=0, then according to the off-load load of switching order until N<0, then utilize super capacitor to N value revise then to lithium cell charging until the dump energy of lithium battery returns to the minimum electricity of start up system, return islet operation pattern;
(3.2) if the dump energy of lithium battery is between 70% to 100%, then super capacitor is utilized to revise N value;
(3.3) if the remaining capacity SOC of storage battery
li-PCSequal 100%, judge N value size, if N>0, super capacitor is then utilized to revise N value, if N<0, then according to switching order offered load, until N>0, and then utilize super capacitor to revise N value, then make lithium battery delivered power until the dump energy of lithium battery reaches the minimum electricity of start up system.
As the preferred embodiments of the present invention, the compensation method of described ultracapacitor is: if the dump energy of ultracapacitor is between 60 ~ 65%, then 1 is added to N, ultracapacitor is made to be in charged state, if the dump energy of ultracapacitor is between 95 ~ 100%, then 1 is subtracted to N, make ultracapacitor be in discharge condition.
In step (3.1), if according to the off-load load of switching order time, only remaining critical loads, then close super capacitor, enters the grid-connected charged state of lithium battery.
Startup stage control method comprise the following steps:
A: image data: the output/absorbed power P of lithium battery
li-PCS, ultracapacitor output/absorbed power P
sC-PCS, photovoltaic generation and wind power generation power output P
pV, whole micro-capacitance sensor load power P
load, whole micro-capacitance sensor line loss power P
loss, lithium battery remaining capacity SOC
li-PCS, ultracapacitor remaining capacity SOC
sC-PCS;
B: if the remaining capacity SOC of lithium battery
li-PCSbe less than the minimum electricity of start up system, then grid-connectedly charge to lithium battery, until reach the minimum electricity of start up system, then isolated island charges to ultracapacitor;
C: the remaining capacity SOC of checking ultracapacitor
sC-PCSif, SOC
sC-PCSbe less than the minimum electricity that maintenance system is normally run, then (7.1)-(7.3) of circulating are until SOC
sC-PCSthe minimum electricity that the system that reaches normally is run, carries out voltage stabilizing with ultracapacitor, islet operation.
Compared with prior art, the present invention is a kind of for can be grid-connected and at least have the following advantages from the micro-grid system of network operation and energy control method: the present invention includes the distributed energy electricity generation system for generation of electric energy, for storing and provide the energy-storage system of energy, realize connection and the disconnection of micro-grid system and outer net, detection of grid state realizes PCC switch that is grid-connected and seamless switching from net action, central controller, energy control apparatus, load controller, and load, the present invention passes through central controller, energy control apparatus, and load controller controls energy and regulates, thus ensure that micro-grid system is flexible, controlled operation.
Embodiment
1, micro-grid system
Refer to shown in Fig. 1; the invention provides a kind of for can be grid-connected and from the micro-grid system of network operation and energy control method, described micro-grid system be primarily of the solar panel for photovoltaic generation, the blower fan for wind power generation, energy-storage system and grid-connected solid-state switch (i.e. PCC switch) and corresponding Control protection device and control device composition.Whole micro-grid system is based on ac bus, and DC bus, wouldn't bringing onto load as reserved.And build the communication network of internal system.
This micro-grid system, chief component comprises: distributed energy electricity generation system, for generation of electric energy; Energy-storage system, for storing and providing energy; PCC switch, realizes micro-capacitance sensor grid-connected with bulk power grid and be separated; Load governor, controls load; Central controller, fast to distributed energy electricity generation system and energy-storage system sending controling instruction; Energy control apparatus, receives micro-capacitance sensor information, formulates energy control strategy; Charging pile is used for electric motor car discharge and recharge; SVG/APF is for improving the quality of power supply; And common power load.
Described distributed energy electricity generation system comprises: the solar panel for photovoltaic generation, the blower fan for wind power generation, and diesel power generation system.Wherein, photovoltaic battery panel is connected to ac bus by DC/AC inverter, for micro-capacitance sensor provides regenerative resource; Blower fan is connected to ac bus by AC-DC-AC converter, for micro-capacitance sensor provides regenerative resource; Diesel engine generator, as synchronous generator unit, provides energy to micro-capacitance sensor, and what can be used as microgrid stablizes controlled energy source.
Described energy-storage system comprises: batteries to store energy device and super capacitor energy storage device.Described batteries to store energy device is connected to ac bus by two-way DC/AC converter, for stabilizing microgrid energy fluctuation, supporting micro-capacitance sensor at short notice and running.Described super capacitor is connected to ac bus by two-way DC/AC converter, for stabilizing microgrid power fluctuation.
Described PCC switch is the tie point of micro-capacitance sensor and bulk power grid, and detection of grid state realizes grid-connected and from the seamless switching of net action; Load governor is the equipment managed a region load, and needing can the function of detection load power, can be real-time by load power condition feedback to energy management center.Simultaneously can the switching load instruction of received energy administrative center; Described central controller, according to the real time status of micro-capacitance sensor, sends instruction to distributed energy electricity generation system, load governor, and receives their feedback information, control in real time micro-capacitance sensor.The information that energy control apparatus reception central controller and distributed energy electricity generation system, load governor are fed to and information on load, meeting under the constraintss such as system capacity balance and micro battery start and stop restriction, the electric energy scheduling of overall arrangement the best.Energy control apparatus Ethernet interface and lower floor's controller carry out communication, and realize regenerative resource prediction, load power is predicted, the calculation functions such as optimisation strategy computing.
Described SVG realizes reactive power compensation, and APF realizes micro-capacitance sensor active power filtering, and charging pile carries out discharge and recharge to electric motor car.Described common power load comprises: illumination and desktop computer.
2, energy management strategies
In micro-grid system, no matter isolated island or grid-connected situation, under photovoltaic DC-to-AC converter and wind-force frequency converter always work in maximal power tracing (MPPT) pattern, its real-time power output is mainly by illumination, and the impact of temperature, presents uncontrollable characteristic.Special during micro-capacitance sensor islet operation, need energy storage device and carry out power adjustments, micro-capacitance sensor could be maintained and reliablely and stablely run.
(1), under normal operation, two PCS equipment all can be used as the main inverter supporting micro-capacitance sensor voltage, therefore the present invention proposes two cover voltage stabilizing schemes.
A, Li-PCS(lithium battery PCS) voltage stabilizing scheme
Because lithium ion battery energy density is high, micro-capacitance sensor voltage can be supported the long period as source of stable pressure.Now, SC-PCS(ultracapacitor PCS) will power mode be operated in, the high fdrequency component of process micro-capacitance sensor internal power sudden change.
B, SC-PCS(ultracapacitor PCS) voltage stabilizing scheme
Super capacitor has the feature of high power density, but its energy density is lower, is not suitable for running under nominal power for a long time, general 10s ~ 20s.Under SC-PCS is operated in potentiostatic mode, automatically can reacts chugging, greatly reduce the requirement to Realtime Capability of Communication, improve communication system redundancy.
Adopt Li-PCS voltage stabilizing scheme when isolated island starts in the present invention, during grid-connected normal operation, adopt SC-PCS voltage stabilizing scheme.
(2) energy management strategies principle
A, prime power management strategy
For SC-PCS voltage stabilizing scheme, using the power given of the difference of workload demand and new forms of energy as whole mixed energy storage system.
P
load+P
loss-P
PV=P
Li-PCS+P
SC-PCS=P
HESS(1)
P
load: system loading power;
P
loss: line loss power;
P
pV: new forms of energy power output;
P
li-PCS: lithium battery output/absorbed power;
P
sC-PCS: ultracapacitor output/absorbed power;
P
hESS: mixed energy storage system output/absorbed power.
If P
hESSfor just, then mixed energy storage system should export deficit power; If P
hESSbe negative, show that hybrid system should absorb surplus power.By power given classification, such as power given scope is-20kw ~ 20kw, is classified into each grade of N by certain power Δ Pref.And given as the output of Li-PCS using N* Δ Pref, remainder is compensated by SC-PCS automatically.
P
sC-PCSfor just, showing that now SC-PCS is in power stage state; P
sC-PCSbe negative, show that SC-PCS is in power absorption state.No matter for which kind of state, exchange the Δ Pref that power is all less than 0.5 times.
B, correction strategy
A, first to revise according to Li-PCS
According to the SOC state of Li-PCS, energy management strategies is divided into three parts:
①Di energy storage district strategy;
2. normal district strategy;
3. saturation region strategy.
Wherein normal district's strategy maintenance elementary tactics is constant.When the SOC of Li-PCS enters low energy storage district, 1., restriction N value is less than zero to system Access strategy, and namely Li-PCS can only absorbed power, until SOC
li-PCSthe SOC state returning to 95%(lithium battery can choose suitable reference value according to battery parameter and system configuration).Work as SOC
li-PCSwhen returning to 95%, return islet operation pattern.
When the SOC of Li-PCS enters saturation region, 3., restriction N value is greater than zero to system Access strategy, and namely Li-PCS can only delivered power, until SOC
li-PCSreturn to during 95%., can suitably load, to meet power-balance.
B, again to revise according to SC-PCS
When the SOC of SC-PCS enters low energy storage district, 1 process is added to gained N value above, makes SC-PCS be in charged state all the time; When the SOC of SC-PCS enters saturation region, 1 process is subtracted to the N value of gained above, makes SC-PCS be in discharge condition all the time.The SOC relation of the energy management strategies finally obtained and two PCS as shown in Figure 2.
The present invention has following beneficial effect: the invention provides a kind of micro-grid system and energy management strategies thereof, and the micro-capacitance sensor management strategy in the present invention is mainly a kind of according to system mode, rapid-action integrated control strategy.Consider from the several aspect of energy-storage system, grid-connected power generation system and load, a set of control strategy flexibly of customization, ensure that the operation that micro-capacitance sensor can be safe, controlled.
Below in conjunction with Fig. 3, energy control method of the present invention is described in detail:
(1) energy management center starts, and makes system mode identify State=1.
(2) image data: the output/absorbed power P of lithium battery
li-PCS, ultracapacitor output/absorbed power P
sC-PCS, photovoltaic generation and wind power generation power output P
pV, whole micro-capacitance sensor load power P
load, whole micro-capacitance sensor line loss power P
loss, lithium battery remaining capacity SOC
li-PCS, ultracapacitor remaining capacity SOC
sC-PCS;
(3) if the remaining capacity SOC of lithium battery
li-PCSbe greater than the minimum electricity of start up system, then isolated island charges with given power 20kw to ultracapacitor, and now State=1b goes to (5);
(4) if the remaining capacity SOC of lithium battery
li-PCSbe less than the minimum electricity of start up system, then grid-connectedly charge with given power 20kw to lithium battery, now State=1a, circulatory monitoring, until the minimum electricity reaching start up system, then isolated island charges to ultracapacitor.
(5) remaining capacity SOC of ultracapacitor is checked
sC-PCSif, SOC
sC-PCSbe less than the minimum electricity that maintenance system is normally run, then the process of (2)-(4) of circulating is until SOC
sC-PCSreach the minimum electricity that maintenance system is normally run, carry out voltage stabilizing with ultracapacitor, islet operation, now State=2.
(6) image data: the output/absorbed power P of lithium battery
li-PCS, ultracapacitor output/absorbed power P
sC-PCS, photovoltaic generation and wind power generation power output P
pV, whole micro-capacitance sensor load power P
load, whole micro-capacitance sensor line loss power P
loss, lithium battery remaining capacity SOC
li-PCS, ultracapacitor remaining capacity SOC
sC-PCS;
(7) according to the output/absorbed power P of following formulae discovery energy-storage system
hESS:
P
load+P
loss-P
PV=P
Li-PCS+P
SC-PCS=P
HESS,
Wherein, P
load: system loading power; P
loss: line loss power; P
pV: new forms of energy power output; P
li-PCS: lithium battery output/absorbed power; P
sC-PCS: ultracapacitor output/absorbed power;
According to the output/absorbed power P of energy-storage system that given power Δ Pref will obtain
hESSbe divided into N grade, given as the output of lithium battery using N* Δ Pref, remainder is revised by ultracapacitor.
(8) strategy is determined:
(8.1) if the remaining capacity SOC of storage battery
li-PCSbe less than 70%, judge N value size, if N<0, then utilize super capacitor to revise N value, then to lithium cell charging until the dump energy of lithium battery returns to the minimum electricity of start up system, return islet operation pattern; If N>=0, then according to the off-load load of switching order until N<0, then utilize super capacitor to N value revise then to lithium cell charging until the dump energy of lithium battery returns to the minimum electricity of start up system, return islet operation pattern; If only remaining critical loads, then close super capacitor, enter the grid-connected charged state of lithium battery, otherwise supplement according to the super capacitor compensation process described in step (8.1); The described method utilizing super capacitor to carry out revising is: if the dump energy of ultracapacitor is between 60 ~ 65%, 1 is added to N, makes ultracapacitor be in charged state, if the dump energy of ultracapacitor is between 95 ~ 100%, 1 is subtracted to N, makes ultracapacitor be in discharge condition;
(8.2) if the dump energy of lithium battery is between 70% to 100%, then according to the super capacitor modification method described in step (8.1), N value is revised;
(8.3) remaining capacity SOC of storage battery
li-PCSequal 100%, judge N value size, if N>0, super capacitor is then utilized to revise N value, if N<0, then according to switching order offered load, until N>0, and then utilize super capacitor to revise N value, then make lithium battery delivered power until the dump energy of lithium battery reaches the minimum electricity of start up system.
In whole control method, if receive the situation of pseudoinstruction or only remaining critical load, then close super capacitor, enter the grid-connected charged state of lithium battery; If excision lithium battery or appointment lithium battery are in holding state, then lithium battery and super capacitor are all closed.
The above embodiment only have expressed one of the present invention and implements, and be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.