CN102394497B - Microgrid coordination control system and method based on state transition - Google Patents
Microgrid coordination control system and method based on state transition Download PDFInfo
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Abstract
The invention discloses microgrid coordination control system and method based on state transition. The microgrid coordination control system comprises a load measurement and control module, a power distribution network measurement and control module, a distributed power supply measurement and control module and an energy storage device measurement and control module which are respectively in bidirectional connection with a central controller through signal transmit-receive modules; all loads, power distribution networks, distributed power supplies and energy storage devices are connected with a microgrid bus through fling-cut switches (the distributed power supplies and the energy storage devices are provided with corresponding interfaces); all the measurement and control modules are in bidirectional connection with the corresponding fling-cut switches; one output of the distributed power supply measurement and control module is connected with a corresponding power electronic/rotary interface; the outputs of the energy storage device measurement and control module are connected with the power electronic interfaces of the energy storage devices; and the central controller sends operating instructions to all the measurement and control modules according to all acquired information, so as to achieve coordination control of all controlled elements. The system provided by the invention can meet the power quality requirement, has high reliability in power supply for sensitive loads, and achieves continuous supply to significant loads.
Description
Technical field
The present invention relates to little electrical network grid-connected coordination operation control technology, especially a kind of microgrid coordinated control system and method based on the state conversion belong to the power control technology field.
Background technology
Along with constantly increasing of coal, oil, natural gas equal energy source supply growing tension and need for electricity, utilize the generation mode of new forms of energy such as luminous energy, wind energy, biogas to arise at the historic moment, owing to utilize the generating set of this type of energy to be distributed in the primary energy location, so this generation mode is called " distributed power generation " (Distributed Generation) again.Microgrid is integrated various energy resources input (solar energy, wind energy, conventional fossil fuel, biomass energy etc.), multiple product output (hot and cold, electricity etc.), various energy resources converting unit (fuel cell, miniature gas turbine, internal combustion engine, energy-storage system etc.), be the non-same sex complication system that behaviors such as chemistry, thermodynamics, electrodynamics intercouple, have the integrated recycling Inherent advantage that realizes fossil fuel and regenerative resource.
In general, only there is a points of common connection (point of common coupling PCC) between microgrid and the external power grid, therefore, concerning electrical network, microgrid can be regarded controllable electric power or the load in the electrical network as, and it can both can obtain energy from external power grid at the several seconds internal reaction to satisfy the demand of outside transmission and distribution networks, when supply of electric power abundance or external power grid electricity shortage, microgrid also can send electric energy to electrical network in microgrid.Two kinds of operational modes of the general existence of microgrid, under the normal condition, with the external power grid networking operation, the power supply of the load in the microgrid is given in microgrid and external power grid coordinated operation jointly; When monitoring external power grid fault or the quality of power supply can not meet the demands the time, then microgrid changes the islet operation pattern over to, give critical load continuation power supply in the microgrid by the distributed power source in the microgrid, guarantee the uninterrupted supply of electric power of load, keep microgrid self supply and demand energy balance, thereby improved fail safe and the reliability of power supply; When treating that the external power grid fault disappears or the quality of power supply meets the demands, microgrid switches to the networking operation pattern again.The microgrid controller need be realized taking over seamlessly between two kinds of patterns according to the variation of actual motion condition.
The problem that the microgrid hierarchical control need solve mainly contains three: 1, and the reliability service of microgrid: often contain multiple little source in the microgrid, the characteristic difference in little source is subjected to the influence of external condition easily.The capacity of microgrid is generally less, makes that the ability of its disturbance rejection is relatively poor.When little source or load change, may cause the variation of microgrid structure, serious situation can make system shake strongly, even causes the collapse of whole electrical network.For guaranteeing that microgrid can move with security and stability, require hierarchical control can solve microgrid reliability of operation problem.2, the electric energy of high-quality is provided: because little source response speed is slow, inertia is little, and be subjected to primary energy to supply with the influence that changes easily, when load changed, little source load-responsive rapidly changed, and the quality of electric energy is exported in influence.Particularly some sensitive loads require than higher, so require the hierarchical control strategy that the electric energy of high-quality can be provided for load on the basis of microgrid reliability service the quality of power supply.3, the economical operation of microgrid: distributed power generation has great application prospect because of the advantage of its economic environmental protection.After distribution type electric energy inserts big electrical network, little source is cooperated with the conventional electric power system, make it give play to maximum value, be one of hierarchical control problem that need solve.Therefore be necessary to study at the heterarchical architecture microgrid that comprises multiple continuity and intermittent DG, sensitive load and energy storage device, design a kind of energy and satisfy the above coordinated operation control system that requires.
Summary of the invention
At the prior art above shortcomings, the purpose of this invention is to provide and a kind ofly can satisfy quality of power supply requirement, again to the negative power supply reliability height of sensitivity, realize the microgrid operation coordinated control system to the important load uninterrupted power supply.
To achieve these goals, the technical solution used in the present invention is such:
A kind of microgrid coordinated control system based on the state conversion, it comprise central controller, to each load carry out observing and controlling the load control module, to power distribution network carry out observing and controlling the power distribution network control module, each distributed power source is carried out the distributed power source control module of observing and controlling and the energy storage device control module that energy storage device is carried out observing and controlling, load control module, power distribution network control module, distributed power source control module and energy storage device control module believe that by transmitting-receiving module is connected with central controller is two-way respectively; Each load is connected with the microgrid bus by fling-cut switch respectively with power distribution network, each distributed power source is connected with the microgrid bus with fling-cut switch by power electronics/rotatable interface successively, and energy storage device is connected with the microgrid bus with fling-cut switch by the power electronics interface successively; Point of common coupling place between microgrid and power distribution network is provided with the measurement mechanism for amplitude, frequency and the phase place of measuring point of common coupling both sides voltage, and measurement mechanism is connected with central controller; Each control module and the two-way connection of corresponding fling-cut switch; Wherein one tunnel output of each distributed power source control module connects corresponding power electronics/rotatable interface, and wherein one tunnel output of energy storage device control module connects the power electronics interface of energy storage device correspondence; Central controller sends operational order according to each road information of gathering to each control module, to realize the coordination control between each controlled member.
Described load is divided into interruptible load and sensitive load; Distributed power source is divided into intermittence power supply and continuity power supply.
The microgrid control method for coordinating, this method earlier with the intermittence power supply in the microgrid, energy storage device, continuity power supply, power distribution network and interruptible load by at net or move back two kinds of situation permutation and combination of net and go out all possible running statuses, totally 32 kinds, the sensitive load in the microgrid connects at net all the time; Then with the situation that does not allow in 32 kinds of possible running statuses to occur and the situation removal that does not meet actual conditions, do not consider, simplify to obtain 12 kinds of effective running statuses, every kind of state is to control mode such as the following table of intermittence power supply, energy storage device, continuity power supply, power distribution network and interruptible load:
Wherein, " MPPT " control refers to that intermittent power supply adopts the maximal power tracing control mode, and " PQ " control instigates inverter by active power and the reactive power of reference power output output; " Droop " control refers to the control mode of inverter simulation conventional synchronization generator; " V/f " control refers to no matter how how little source power output changes, and the frequency of its output voltage and amplitude frequency maintain set point always; " 0 " representative disconnects; " 1 " representative connects; "-" representative does not have the little source of this class to be in running status.
The trigger event that may cause microgrid state conversion simultaneously is divided into 11 kinds, and corresponding is numbered: numbering 1-energy storage device electric energy exhausts or fault and out of service; Numbering 2-energy-storage units resumes operation; Numbering 3-continuity power supply is all out of service; Numbering 4-continuity power unit resumes operation; The intermittent power supply of numbering 5-is all out of service; The intermittent power unit of numbering 6-resumes operation; The reserve capacity of numbering 7-continuity power supply can satisfy maximum sensitive load; The output of numbering 8-continuity power reaches maximum; The reserve capacity of numbering 9-continuity power supply can satisfy maximum interruptible load; Numbering 10-distribution network failure or power failure; Numbering 11-power distribution network recovers normal; When trigger event took place, microgrid was transformed into transformational relation such as the following table of next state by current running status:
Compared with prior art, the present invention has the following advantages:
1, the network that comprises multiple continuity and intermittent DG, sensitive load and energy storage device in the microgrid, what propose is a kind of coordinated operation control strategy based on the state conversion, set the control mode of each element of microgrid under the different conditions, determine on the basis of transduction pathway between effective running status, to corresponding trigger event, realized the level and smooth conversion of each state of microgrid, guaranteed the uninterrupted power supply of local sensitive load.
2, provide methods such as voltage support, continuity power supply frequency modulation frequency modulation to realize regulating in the indifference of all running status frequencies by power distribution network, energy storage device, improved the power supply quality of sensitive load.
3, consider the capacity limit of energy storage device by the setting of frequency modulation frequency modulation and trigger condition, to prolong its service time as far as possible, improve the microgrid operational reliability.
Description of drawings
Fig. 1 is control principle figure of the present invention.
Fig. 2 is microgrid state transition graph of the present invention.
Embodiment
Below in conjunction with the drawings and specific embodiments the present invention is described in further detail.
In the microgrid system, relate to interruptible load, sensitive load, power distribution network, the intermittence energy, the continuity energy and energy storage device six major parts, every part relates to corresponding control element: line-breaker, power electronics interface or rotatable interface, on-load switch.Thinking of the present invention is exactly this six most information of gathering earlier, comprises each little source power output, system busbar electric voltage frequency amplitude, power distribution network electric voltage frequency amplitude, on-load switch state, interconnection on off state etc.Central controller calculates the running status of decision system and the control of each element of microgrid according to the microgrid system information, and microgrid can be moved with security and stability, passes through the power output in each little source of optimization computation decision-making simultaneously, makes microgrid reach the requirement of economical operation.Last central controller sends concrete control command to each local controller spare of microgrid, to realize the control target of central controller.Central controller simultaneously can judge that it is in the sort of running status after to above-mentioned informix, in case go out the present condition trigger event, namely be transformed into next state according to the transformational relation that pre-establishes, thereby realize to satisfy quality of power supply requirement, to the negative power supply reliability height of sensitivity, realize the purpose to the important load uninterrupted power supply again.Specific implementation is described in detail as follows.
Referring to Fig. 1, the present invention is based on the microgrid coordinated control system of state conversion, it comprises central controller MGCC, interruptible load is carried out the interruptible load control module of observing and controlling, sensitive load is carried out the sensitive load control module of observing and controlling, power distribution network is carried out the power distribution network control module of observing and controlling, the intermittence energy is carried out the intermittence energy control module of observing and controlling, the continuity energy is carried out the continuity energy control module of observing and controlling and the energy storage device control module that energy storage device carries out observing and controlling (is simplified in order to make figure, above-mentioned each control module all is expressed as control module), the interruptible load control module, the sensitive load control module, the power distribution network control module, intermittence energy control module, continuity energy control module is connected with central controller is two-way by transmitting-receiving letter module respectively with the energy storage device control module.Interruptible load, sensitive load and power distribution network directly are connected with the microgrid bus by fling-cut switch, the intermittence energy is connected with the microgrid bus with fling-cut switch by power electronics/rotatable interface (being power electronics interface or rotatable interface) successively with the continuity energy, and energy storage device is connected with the microgrid bus with fling-cut switch by the power electronics interface successively.The intermittence energy, the continuity energy and energy storage device are connected with corresponding control module, gathered the energy storage information of the intermittence energy, the continuity energy and energy storage device by control module, between microgrid and power distribution network, point of common coupling is set, the point of common coupling place is provided with the measurement mechanism for the amplitude of measuring point of common coupling both sides voltage, frequency, phase place, and measurement mechanism is connected with central controller.All control modules and the two-way connection of corresponding fling-cut switch, the break-make information that both had been used for gathering fling-cut switch also is used for sending control signal and makes fling-cut switch be transformed into another kind of state by a kind of state.Wherein one tunnel output of intermittence energy control module and continuity energy control module connects corresponding power electronics/rotatable interface, wherein one tunnel output of energy storage device control module connects the power electronics interface of energy storage device correspondence, switching and the operation control method of control energy storage device.
The information on load that the central controller utilization is gathered and distributed power source DG and energy storage device fuel situation and running status are sent operational order according to established coordination control strategy to each bottom controller; Bottom controller comprise little source controller (Microsource Controller, MC) and load governor (Load Controller, LC), they are for carrying out the local control unit of central controller MGCC concrete operations instruction.Power distribution network control module, intermittence energy control module, continuity energy control module and energy storage device control module belong to little source controller, and interruptible load control module and sensitive load control module belong to load governor.Little source controller MC finishes the control to distributed power source, and the running status of measuring distributed power source.Load governor is used for detection load and the quality of power supply, controls the switching of on-load switch simultaneously.
Because element is more and each element distances is nearer in the microgrid, little source controller MC links to each other with central controller MGCC is two-way by transmitting-receiving letter module with load governor LC, adopt the layered mode networking, utilize central controller to focus on relevant information to realize each interelement coordinated operation control.
Central controller is mainly finished three kinds of functions-----power management, control, the running status management of being incorporated into the power networks synchronously, is made of three unit accordingly, and they are respectively: power management block, lock unit, running status administrative unit.
Power management block.Power management block mainly is made up of two parts: a part is the power output basic point according to each distributed power source of information calculations, and microgrid is moved by economic way, realizes the economic dispatch of microgrid; Another part is to calculate power outside the plan according to system frequency deviation, gives each little source this part power division outside the plan then, makes system frequency return to rated value, realizes the adjusting of system frequency indifference, improves the load power supply quality.Comprise many continuity power supplys in the microgrid, central controller MGCC can distribute meritorious and reactive power (such as according to indexs such as operation fuel cost and network loss rates) by certain principle, specifies in the optimized operation point that each continuity power supply is exerted oneself under the various running statuses; Simultaneously also must real-time acquisition system frequency and voltage magnitude, the frequency departure that produces according to the microgrid primary frequency modulation under Ding Yi some running status calculates meritorious increment in the present invention, and will gain merit according to predefined distribution coefficient and to regulate increment and distribute to each continuity power supply, implement the control of secondary frequency adjustment, regulate to realize the frequency indifference.
Lock unit.Microgrid and power distribution network are incorporated into the power networks, and an important operating process is arranged---the control of being incorporated into the power networks synchronously.Not only there is difference in magnitude in the voltage phasor that point of common coupling between microgrid and power distribution network (Point of common coupling is called for short PCC) is located both sides, also has difference on the frequency, and the phase angle difference that constantly changes.Therefore, the decision condition that is incorporated into the power networks synchronously of microgrid must comprise difference in magnitude, difference on the frequency and phase angle difference, only satisfies when being incorporated into the power networks condition in point of common coupling PCC both sides voltage and frequency, just can finish being incorporated into the power networks of microgrid and power distribution network.
The basic principle that should follow when microgrid is incorporated power distribution network into is:
1. during point of common coupling PCC breaker closing, enough little to the impulse current of microgrid;
2. after microgrid is incorporated utility network into, can enough promptly enter the synchronous operation state.
The primary condition that must satisfy between mentioned above principle requirement microgrid voltage and the power distribution network voltage is that difference in magnitude, difference on the frequency and the phase difference of both sides voltage is enough little.In the microgrid system of invention, utilize energy storage device to realize being incorporated into the power networks synchronously of microgrid and power distribution network as main control unit.At the measurement mechanism at point of common coupling PCC place with the amplitude of the point of common coupling PCC both sides voltage that measures, frequency, transmission of phase to central controller MGCC.Central controller MGCC is the voltage difference delta U of point of common coupling PCC both sides, the phase difference δ input as isochronous controller, regulate the voltage control loop that is input to the energy storage device inverter through proportional integral PI then, control the control of finishing inverter by this locality, make the voltage of the voltage-tracing power distribution network of microgrid.When difference in magnitude, difference on the frequency, phase difference satisfy when being incorporated into the power networks condition, send reclosing command by central controller MGCC to the circuit breaker at point of common coupling PCC place, being incorporated into the power networks synchronously of realization microgrid and power distribution network.After finishing synchronously, need to close immediately synchronous governor, in order to avoid influence grid-connected system to the operation control of energy storage device.
The running status administrative unit is the central controller most important component, is the important channel that microgrid realizes coordinating control.MGCC monitors the running status of microgrid in real time, after the trigger event that the conversion of microgrid state occurs, the corresponding change takes place according to the element in control method (state transition graph) the control microgrid of formulating in advance in MGCC, and microgrid is adjusted in real time by conversion plan.In ensuing explanation, will describe the microgrid control method for coordinating based on the state conversion in detail.
Four kinds of little source controllers are arranged in the microgrid, comprise power distribution network, energy storage device, intermittent power supply and continuity power supply, every kind of power supply comprises the switching two states, can constitute 16 kinds of power supply assembled state.Also comprise two kinds of loads---sensitive load and interruptible load in addition, except the microgrid entire system is stopped transport, must remain the uninterrupted power supply of sensitive load, have only interruptible load that two states is arranged, therefore can obtain 32 kinds of possible running statuses of microgrid, wherein power supply drops into or loads and represent with " 1 " when connecting, and represents that with " 0 " possible running status is as shown in table 1 when withdrawing from.Because some running status does not meet actual conditions, do not consider, perhaps be set to not allow present condition, microgrid will directly change other state over to this moment, represent with "-", non-existent running status, remaining every kind state be corresponding a kind of Status Name all, and these titles are Status Names that the present invention defines voluntarily.
Because continuity output power of power supply governing speed is slower; power shortage in the time of must cooperating the quick load-responsive variation of energy storage device ability and state conversion; and consider the random fluctuation of intermittent output power of power supply; also must utilize energy storage device to suppress fast power changes; can see Table the reliable power supply that state 3,4,9,10 in 1,11 and 12 all can not guarantee local load; set aforementioned six kinds of states for not allowing out present condition, this moment, microgrid directly changed stopped status over to.Be microgrid and power distribution network is incorporated into the power networks and energy storage device does not insert state for state 18,20,26,28; in case microgrid and power distribution network disconnect operation; owing to there is not storage battery to carry out the fast power compensation; microgrid will change stopped status over to, therefore state 18,20,26,28 together will be set at no energy storage connection status.
It is that the state that local load is powered is the state of emergency that the setting microgrid only has energy storage device, and it is that the state that system powers is intermittent stable state that intermittent power supply and energy storage device are only arranged.This two states must energy storage device variations of exerting oneself of compensation load or intermittent power supply, and energy storage device finite capacity can specify under the aforementioned two states microgrid and only power for local sensitive load, namely state 6 and 14 is not considered in the table 1.And when microgrid access power distribution network was incorporated into the power networks, the microgrid system can satisfy local sensitive load and interruptible load power supply simultaneously, and state 17,19,21,23,25,27,29 and 31 does not meet actual conditions in the table 1 as can be known, does not consider.After state reduction, 12 kinds of effective statuses that can get the microgrid system are as shown in table 2.
The rule of state name is in the table 1: in the microgrid continuity power supply or intermittent power supply are only arranged under " continuity ", this state of " intermittence " representative in the Status Name; " comprehensively " represents and contains continuity power supply and intermittent power supply in the microgrid simultaneously; " stablize " to represent in the microgrid and only power to sensitive load; " support " represents microgrid and is sensitive load and interruptible load power supply simultaneously." connection " represents microgrid and is connected with power distribution network, otherwise expression disconnects.Because " connection " itself just shows that the microgrid system gives the power supply of local sensitive load and interruptible load simultaneously, so in name, do not embody " support " especially.
Known that by the last running state analysis that may exist microgrid satisfied uninterrupted load (being sensitive load) is provided under the prerequisite of reliable power supply, having only 12 kinds of running statuses is effective running statuses, i.e. the effective Running Status Table of table 2 microgrid.Distributed power source, energy storage device, switch all are controlled elements in the microgrid, by setting the control mode of each element under the different running statuses, power supply reliability and the quality of power supply thereby load in guarantee this locality.Provided the control mode that each element adopts in the microgrid under 12 kinds of effective running statuses in the table 2." MPPT " control refers to that intermittent power supply adopts the maximal power tracing control mode, and " PQ " control instigates inverter by reference power active power of output and reactive power; " Droop " control refers to the sagging control mode of inverter simulation conventional synchronization generator; " V/f " control refers to no matter how how little source power output changes, and the frequency of its output voltage and amplitude frequency maintain set point always; " 0 " representative disconnects; " 1 " representative connects; "-" expression does not have the little source of this class to be in running status, so need not consider the control mode in this type of little source.
In all states of the normal operation of intermittent power supply (in the table 2, state 4,5,6,8,10,12), because the dynamic change of wind speed, intensity of illumination and temperature, the power output of intermittent power supply such as wind-force and photovoltaic generation exists than great fluctuation process, in order to guarantee the peak use rate of regenerative resource, intermittent power supply adopts the maximal power tracing control mode, i.e. and " MPPT ", the active power that does not participate in the microgrid system is regulated.
In all running statuses that power distribution network is connected with microgrid (in the table 2, state 8,9,10,11,12), supported for microgrid provides voltage by power distribution network, energy storage device all adopts charging control mode (except the state 12), after energy is full of, change floating charge state over to, under other states, have enough energy to come load-responsive power to change to guarantee energy storage device.Because the continuity power supply has sufficient primary energy and meritorious regulating power, so adopt the PQ control based on central control command, PQ control is to instigate inverter by active power and the reactive power of reference power output output, does not participate in voltage and frequency adjustment (state 9,10,12).
In continuity stable state, comprehensive stability state, comprehensive status of support and continuity status of support (state 3,5,6,7 in the table 2), owing to there is not power distribution network that Voltage Reference is provided, energy storage device takes the Droop control mode to provide Voltage Reference for system, and regulate power output with the underpower of compensating coefficient conversion transient process, participation system primary frequency modulation.Inverter Droop control mainly refers to the control characteristic of inverter simulation traditional analog conventional synchronization generator.This control mode utilizes inverter output frequency and active power linear and principle that voltage magnitude and reactive power are linear realizes control.The continuity power supply adopts based on the PQ control of central controller MGCC power instruction or Droop control, participation system frequency modulation frequency modulation.The power instruction active power of output of central controller MGCC, reactive power can be directly pressed in PQ control.Droop control can not directly be sent active power by central controller MGCC power instruction, but finishes by the translation droop characteristic, and when frequency retrieval arrived rated frequency, active power of output was the set-point of central controller MGCC.Adopt the continuity power supply of Droop control to participate in primary frequency modulation simultaneously, but its meritorious governing speed is slower, also must compensates quick load changes in demand and the fluctuation of intermittent output power of power supply by energy storage device.
Because the energy storage device finite capacity, arranging and adopting energy storage device meritorious value of exerting oneself under rated frequency of Droop control is 0, if the frequency of microgrid is below or above rated frequency (f0=50Hz), energy storage device injects or absorb active power to microgrid.The continuity power supply participates in the secondary FREQUENCY CONTROL and makes that system frequency returns to rated value after the microgrid stable operation, and the active power of output of energy storage device also is back to 0.When a plurality of continuity power supplys participate in the microgrid frequency modulation frequency modulation, if adopting distributed control mode is that a plurality of continuity power supplys in parallel adopt the control of frequency indifference simultaneously, adjustment process is easy to generate vibration and overshoot, it is stable that the microgrid system is difficult for, and therefore adopts the secondary frequency adjustment that is realized microgrid by the central controlled mode of central controller MGCC in the invention.
In intermittent stable state and the state of emergency (in the table 2, state 4,2), power distribution network is not connected with microgrid, and the continuity power supply microgrid that makes out of service loses the frequency modulation frequency modulation ability, only energy storage device possesses the power adjustments ability, so energy storage device adopts V/f control.The V/f control mode refers to no matter how how little source power output changes, and the frequency of its output voltage and amplitude frequency maintain set point always, adopts little source of V/f control mode can regard a controllable voltage source as.V/F is controlled to be system provides rated frequency and rated voltage to support.The limited time of microgrid stable operation this moment, when the energy storage device depleted of energy, system will change stopped status over to.
When microgrid of the present invention moves with certain state in 12 kinds of states, meeting some requirements (trigger event namely occurring) down, running status can change, and is converted to another kind of state by a kind of state.Table 3 is microgrid state transition trigger event table, has listed 11 trigger events altogether, and Fig. 2 is the microgrid state transition graph of this microgrid coordinated operation control system, according to characteristics of the present invention, always has 44 kinds of possible state conversions.Digitized representation among Fig. 2 corresponding trigger event sequence number in the table 3.
As previously mentioned, microgrid one has 12 kinds of effective running statuses, and every kind of state can only be transformed into the another kind of state that is associated from a kind of state.Each state conversion all is caused by a trigger event.Fig. 2 has provided the transduction pathway of microgrid effective status, table 3 is the corresponding trigger event table of numeral number among Fig. 2, the separate unit continuity power supply maximum output of PGimax for putting into operation in the table 3, the continuity power supply number of m for putting into operation, PGi is current the exerting oneself of the separate unit continuity power supply that puts into operation, PSLmax is maximum sensitive load, and PILmax is maximum interruptible load.
When distribution is broken down or have a power failure (trigger event 10), measurement module monitoring distribution side voltage, size of current and the frequency change at point of common coupling PCC place, if detected value surpasses limit value, then central controller MGCC disconnects point of common coupling PCC place switch rapidly, when the cut-out microgrid provides short circuit current to the fault point, guarantee that microgrid continues safe and stable operation.The control mode (shown in Figure 2) of each element of microgrid under the corresponding state is set in central controller MGCC condition managing unit then, makes microgrid carry out the transition to new running status smoothly, and it is stable to keep microgrid frequency and voltage.
Many continuity power supplys may be arranged in the microgrid, but because fault or maintenance have only part of generating units to put into operation, so the peak power output of continuity power supply changes.When microgrid is in comprehensive status of support and continuity status of support, if exerting oneself, the continuity power supply reaches (trigger event 8) after the maximum, local load continues to increase, and it is additional meritorious not enough that energy storage device will be controlled droop characteristic according to Droop, and system frequency will descend and underfrequency.In order to save the energy of energy storage device, be the sensitive load power supply to guarantee that microgrid has sufficient energy when the state of emergency occurring, energy storage device is only born the compensation that quick load changes under aforementioned two states.Exerting oneself when the continuity power supply disconnects interruptible load after reaching maximum immediately, aforementioned two states respectively the conversion operation state to comprehensive stability state and continuity stable state.
The maximum of sensitive load and interruptible load can obtain according to the historical load data prediction; when microgrid is in stopped status; if continuity power backup capacity can satisfy maximum sensitive load (trigger event 7), then microgrid can restart and be the sensitive load power supply.When microgrid was in continuity stable state and comprehensive stability state, if the reserve capacity of continuity power supply energy can satisfy maximum interruptible load (trigger event 9), then the microgrid state was converted to continuity status of support and comprehensive status of support respectively.After the distribution fault clearance restores electricity (trigger event 11), microgrid will be connected operation again with power distribution network.Central controller MGCC can utilize the measurement module at point of common coupling PCC place to calculate phase difference and the difference in magnitude of microgrid point of common coupling PCC both sides voltage, send synchronic command again to energy storage device, realize reconnecting synchronously of microgrid and power distribution network by regulating energy storage device set end voltage frequency and amplitude.
Referring to table 4, a kind of running status admin table of the microgrid coordinated operation control system based on state conversion.Central controller MGCC condition managing unit detects input variable and changes (being trigger event), and system namely according to the state transduction pathway that pre-establishes, is transformed into designated state with microgrid from current running status.Table 4 has been listed path and the trigger event for every kind of state conversion, and the variation of input variable is as the generation of trigger event, thus the variation of the control variables that causes.The state conversion of whole microgrid is carried out according to listed scheme in the table 4.The distributed power source DG, energy storage device and the interruptible load that comprise the different capacity regulating characteristics in the microgrid, frequency indifference adjusting under all running statuses of microgrid and the capacity limit of energy storage device adopt a kind of microgrid coordinated operation control algolithm based on the state conversion.Algorithm is with the current running status of microgrid and the trigger event input variable as central controller MGCC, and output variable then is the control mode of each element, adjusts in real time by the conversion plan that pre-establishes to realize the microgrid running status.
Table 1: microgrid of the present invention may Running Status Table.
Table 2: effective running status of the present invention and each element control mode table.
Table 3: the state transition trigger event table that the present invention proposes.
Table 4: microgrid running status admin table of the present invention.
Claims (3)
1. microgrid coordinated control system based on state conversion, it is characterized in that: it comprise central controller, to each load carry out observing and controlling the load control module, to power distribution network carry out observing and controlling the power distribution network control module, each distributed power source is carried out the distributed power source control module of observing and controlling and the energy storage device control module that energy storage device is carried out observing and controlling, load control module, power distribution network control module, distributed power source control module and energy storage device control module believe that by transmitting-receiving module is connected with central controller is two-way respectively; Each load is connected with the microgrid bus by fling-cut switch respectively with power distribution network, each distributed power source is connected with the microgrid bus with fling-cut switch by power electronics/rotatable interface successively, and energy storage device is connected with the microgrid bus with fling-cut switch by the power electronics interface successively; Point of common coupling place between microgrid and power distribution network is provided with the measurement mechanism for amplitude, frequency and the phase place of measuring point of common coupling both sides voltage, and measurement mechanism is connected with central controller; Each control module and the two-way connection of corresponding fling-cut switch; Wherein one tunnel output of each distributed power source control module connects corresponding power electronics/rotatable interface, and wherein one tunnel output of energy storage device control module connects the power electronics interface of energy storage device correspondence; Central controller sends operational order according to each road information of gathering to each control module, to realize the coordination control between each controlled member;
Described load is divided into interruptible load and sensitive load; Distributed power source is divided into intermittence power supply and continuity power supply;
Described central controller is defined as 12 kinds with the effective running status of microgrid, and every kind of state is to control mode such as the following table of intermittence power supply, energy storage device, continuity power supply, power distribution network and interruptible load:
Wherein, " MPPT " control refers to that intermittent power supply adopts the maximal power tracing control mode, and " PQ " control instigates inverter by active power and the reactive power of reference power output; " Droop " control refers to the sagging control mode of inverter simulation conventional synchronization generator; " V/f " control refers to no matter how how little source power output changes, and the frequency of its output voltage and amplitude frequency maintain set point always; " 0 " representative disconnects; " 1 " representative connects; "-" representative does not have the little source of this class to be in running status.
2. microgrid coordinated control system according to claim 1 is characterized in that: described central controller may cause that the trigger event of microgrid state conversion is divided into 11 kinds, and corresponding is numbered: numbering 1-energy storage device electric energy exhausts or fault and out of service; Numbering 2-energy-storage units resumes operation; Numbering 3-continuity power supply is all out of service; Numbering 4-continuity power unit resumes operation; The intermittent power supply of numbering 5-is all out of service; The intermittent power unit of numbering 6-resumes operation; The reserve capacity of numbering 7-continuity power supply can satisfy maximum sensitive load; The output of numbering 8-continuity power reaches maximum; The reserve capacity of numbering 9-continuity power supply can satisfy maximum interruptible load; Numbering 10-distribution network failure or power failure; Numbering 11-power distribution network recovers normal; When trigger event took place, microgrid was transformed into transformational relation such as the following table of next state by current running status:
。
3. microgrid control method for coordinating, it is characterized in that: this method earlier with the intermittence power supply in the microgrid, energy storage device, continuity power supply, power distribution network and interruptible load by at net or move back two kinds of situation permutation and combination of net and go out all possible running statuses, totally 32 kinds, the sensitive load in the microgrid connects at net all the time; Then with the situation that does not allow in 32 kinds of possible running statuses to occur and the situation removal that does not meet actual conditions, do not consider, simplify to obtain 12 kinds of effective running statuses, every kind of state is to control mode such as the following table of intermittence power supply, energy storage device, continuity power supply, power distribution network and interruptible load:
Wherein, " MPPT " control refers to that intermittent power supply adopts the maximal power tracing control mode, and " PQ " control instigates inverter by active power and the reactive power of reference power output; " Droop " control refers to the control mode of inverter simulation conventional synchronization generator; " V/f " control refers to no matter how how little source power output changes, and the frequency of its output voltage and amplitude frequency maintain set point always; " 0 " representative disconnects; " 1 " representative connects; "-" representative does not have the little source of this class to be in running status;
The trigger event that may cause microgrid state conversion simultaneously is divided into 11 kinds, and corresponding is numbered: numbering 1-energy storage device electric energy exhausts or fault and out of service; Numbering 2-energy-storage units resumes operation; Numbering 3-continuity power supply is all out of service; Numbering 4-continuity power unit resumes operation; The intermittent power supply of numbering 5-is all out of service; The intermittent power unit of numbering 6-resumes operation; The reserve capacity of numbering 7-continuity power supply can satisfy maximum sensitive load; The output of numbering 8-continuity power reaches maximum; The reserve capacity of numbering 9-continuity power supply can satisfy maximum interruptible load; Numbering 10-distribution network failure or power failure; Numbering 11-power distribution network recovers normal; When trigger event took place, microgrid was transformed into transformational relation such as the following table of next state by current running status:
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