CN117081177B - Micro-grid operation power control method for hydroelectric main dispatching unit in island mode - Google Patents
Micro-grid operation power control method for hydroelectric main dispatching unit in island mode Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
- H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
- H02J3/241—The oscillation concerning frequency
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/50—Controlling the sharing of the out-of-phase component
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
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Abstract
The invention relates to the technical field of micro-grids, in particular to a method for controlling running power of a micro-grid of a hydroelectric main regulator group in an island mode. Firstly, analyzing load characteristics, secondly, analyzing new energy characteristics, energy storage devices and small hydropower characteristics, constructing corresponding models, then performing active power balance and frequency control, further performing characteristic analysis of a reactive voltage regulating device, performing reactive power balance and voltage control of a micro-grid by matching with the result of the load characteristic analysis, and synchronously considering power balance under uncertainty of each regulation image in the regulation process. After the island operation of the micro-grid, the active power and the frequency are regulated by the cooperation of the hydroelectric generating set, the energy storage device and the new energy, and the reactive power and the voltage are regulated mainly by the reactive voltage regulating device.
Description
Technical Field
The invention relates to the technical field of micro-grids.
Background
As the proportion of distributed generation increases, micro-grids have received widespread attention. The micro-grid is a small power generation system formed by converging distributed power supplies, energy storage equipment, an energy conversion device, related loads, a monitoring device and a protection device, and is an autonomous system capable of realizing self-control, protection and management, wherein the energy storage equipment comprises a plurality of energy storage units, and each energy storage unit comprises an energy storage element and a PCS (namely an energy storage DC/DC converter).
The micro-grid has two operation modes of grid connection and island, wherein the island mode refers to that the micro-grid is not in parallel operation with the large power grid, and at the moment, if the power provided by the distributed power supply can not meet the power requirement of a load, the energy storage equipment discharges to provide power for the load; the energy storage unit is charged if the power provided by the distributed power supply is greater than the power demand of the load. In actual operation, when the large power grid breaks down to force the micro power grid to operate in an island mode, the micro power grid system is seriously unbalanced due to the fact that the support of the large power grid is lost, and the instability of the micro power grid operation is further aggravated due to the fact that the island mode suddenly causes the fluctuation and the intermittence of the distributed power supply output.
At present, the frequency adjustment method in the traditional micro-grid island mode comprises master-slave control, peer-to-peer control and the like, and the control modes of the master-slave control and the peer-to-peer control on the distributed power supply are different, so that the frequency and the voltage can be adjusted. However, the master-slave control needs to select one or more micro power supplies as a master control unit, and when the micro power grid is changed from the grid-connected mode to the island mode, voltage and frequency support is provided for the micro power grid system, and the method has the problems of strong dependence on the master control unit and a communication line and easy failure of mode switching; all micro power supplies in the peer-to-peer control method are in the same place and do not depend on a certain main control unit and a communication line, and the method is favorable for plug and play of the micro power supplies and expansion of a micro power grid system, but does not consider the recovery problem of frequency and voltage and is poor in frequency modulation.
Disclosure of Invention
In order to improve the running stability of the micro-grid, the invention provides a method for controlling the running power of the micro-grid of a hydroelectric main regulator group in an island mode.
The technical scheme adopted by the invention for achieving the purpose is as follows:
a micro-grid operation power control method of a hydroelectric main regulator group in an island mode comprises the following steps:
s1, analyzing load characteristics of a micro-grid system, constructing a load characteristic prediction model, analyzing characteristics of a hydroelectric generating set and constructing a future output operation model of the hydroelectric generating set;
s2, after a load characteristic analysis result of the micro-grid system is obtained, new energy characteristic analysis and energy storage device characteristic analysis are carried out, and a future operation model of the new energy and the energy storage device is constructed;
s3, formulating an adjustment strategy according to the load characteristic analysis result, the new energy characteristic analysis result and the energy storage device characteristic analysis result to realize active power balance and frequency control of the micro-grid system;
s4, after a load characteristic analysis result of the micro-grid system is obtained, carrying out reactive voltage regulation device characteristic analysis;
and S5, formulating an adjustment strategy according to the load characteristic analysis result and the reactive voltage adjustment device characteristic analysis result to realize reactive power balance and voltage control of the micro-grid system.
In the step S1:
the calculation formula of the load characteristic analysis is as follows:
，
wherein:the fluctuation degree of the total load in the micro-grid system in one day in the island mode is adopted; />Is the power of the j-th load point at the i-th moment; m is the number of load points and is the number of all running electric equipment in the island micro-grid; n is the number of hours per day, 24; l (L) x Is the accumulated value of all load fluctuation amounts; l (L) si Is the accumulated value of the fluctuation amount of the daily load;
according to the obtained load characteristic analysis result, a prediction model is constructed, and the calculation formula is as follows:
，
wherein:αis a prediction coefficient, and is the ratio of the historical load fluctuation amount to the future load fluctuation amount;Fis the load in island mode; l (L) i The fluctuation degree of the total load in the micro-grid system in one day in the island mode is adopted;
the future output operation model of the hydroelectric generating set comprises the following steps:
historical theoretical output model:
historical theoretical output = hydrologic resource quantity x installed capacity x historical average utilization;
future output model:
future force = historical theoretical force x scheduling coefficient.
The new energy future operation model in step S2 includes:
wind power future operation model:
future wind power output = wind power installed capacity x wind speed exponential function;
photovoltaic future operation model:
photovoltaic future output = photovoltaic installed capacity x solar radiation index function;
regional resource future utilization model:
utilization = future predicted/theoretical output;
the future operation model of the energy storage device comprises the following steps:
run-time model:
run time = actual run capacity/average power;
and (3) a charge and discharge frequency model:
charge-discharge times = actual operating capacity/single charge-discharge capacity;
capacity model:
actual operating capacity = capacity x cycle life coefficient.
The active power balance and frequency control of the micro-grid system in the step S3 include the following steps:
s3-1, dividing the active power load and the reactive power load of the micro-grid into two grades, namely a large change and a small change, wherein the adjustment time of the large change is longer than that of the small change, the primary frequency modulation of the hydroelectric generating set responds to the small change of the active load, the secondary frequency modulation of the hydroelectric generating set responds to the large change of the active load, the primary voltage control of the hydroelectric generating set responds to the small change of the reactive load, and the secondary voltage control of the hydroelectric generating set responds to the large change of the reactive load;
s3-2, recording power adjustment step sizes required to be tracked by load characteristic analysis, new energy characteristic analysis and energy storage device characteristic analysis, and adding the power adjustment step sizes to obtain a final total power step size required to be adjusted;
s3-3, according to small change of load and combination of uncertainty of new energy output, performing primary frequency adjustment, and automatically tracking to achieve real-time frequency balance, wherein the calculation formula is as follows:
，
wherein: the PFR is the power that the hydroelectric generating set frequency primary regulator needs to provide or absorb; k is the gain factor; Δp is the power offset;
according to the large change of the load, the uncertainty of the new energy output and the capacity of the energy storage device are combined to carry out secondary frequency adjustment, and the calculation formula is as follows:
，
wherein: PFCR is the power that the hydroelectric generating set frequency secondary regulator needs to provide or absorb; kp is the proportional gain; Δf is the frequency offset; ki is integral gain of a pid controller of a parameter on-site hydroelectric generating set adjusting system, and the value range is 0.01-10; and ∈ (Δf) dt is the integral of the frequency offset.
In the step S5, the reactive power balance and the voltage control are performed by dividing the reactive voltage control into two stages according to the reactive power load characteristic and the reactive voltage adjusting device characteristic, wherein the reactive voltage adjusting device comprises a capacitor bank, an on-load voltage adjusting tap, a static reactive generator SVG and a static reactive compensator SVC, and the primary voltage control is performed by the automatic voltage regulator AVR of the hydroelectric generating set to respond to the small change of the reactive load, so as to realize the real-time balance and the voltage stabilization of the reactive power; the secondary voltage control is mainly regulated by a capacitor bank, an on-load voltage regulating transformer tap, a static var generator SVG and a static var compensator SVC, and responds to larger change of reactive power load to realize basic balance of reactive power and basic stability of voltage.
Step S3, an adjustment strategy is formulated, when the power adjustment of the hydroelectric generating set and the energy storage device cannot meet the change of loads and new energy, a scheme strategy for cutting loads and new energy is set, strategic selection is carried out according to the priority and bearable capacity of the loads, the loads with lower priority are temporarily removed, so that the continuity of power supply and the stable operation of the system are ensured, or the new energy is adjusted, and the active power balance and the stability of frequency are ensured;
the step S5 is an adjustment strategy, when the adjustment of the reactive voltage device cannot meet the change of reactive load, a load shedding scheme strategy is set, strategic selection is carried out according to the load priority and the bearable capacity, and the load with lower priority is temporarily removed, so that the reactive power balance and the voltage stability are ensured;
further comprising step S6: judging whether the power of the hydroelectric generating set is out of limit, if not, ending the regulation, if so, making a regulation strategy again, and carrying out coordination control of active-frequency and reactive-voltage to realize the rebalancing of the active and reactive power.
Compared with the prior art, the invention has the advantages that:
according to the invention, firstly, load characteristics are analyzed, secondly, new energy characteristics, energy storage devices and small hydropower characteristics are analyzed, a corresponding model is constructed, then active power balance and frequency control are performed, then characteristic analysis of a reactive voltage regulating device is performed, reactive power balance and voltage control of a micro-grid are performed in cooperation with the result of the load characteristic analysis, and the power balance under the condition of uncertainty of each regulation image is synchronously considered in the regulation process. After the island operation of the micro-grid, the active power and the frequency are regulated by the cooperation of the hydroelectric generating set, the energy storage device and the new energy, and the reactive power and the voltage are regulated mainly by the reactive voltage regulating device.
Drawings
Fig. 1 is a schematic diagram of the present invention.
Fig. 2 is a flow chart of the present invention.
Detailed Description
The invention provides a method for controlling the running power of a micro-grid of a hydroelectric main-control unit in an island mode, which is shown in fig. 1-2, and comprises the following steps:
s1, analyzing load characteristics of a micro-grid system, constructing a load characteristic prediction model, analyzing characteristics of a hydroelectric generating set and constructing a future output operation model of the hydroelectric generating set;
the load characteristics comprise load fluctuation and distribution characteristics of the total demand in a time domain, and the calculation formula of the load characteristic analysis is as follows:
，
wherein:the fluctuation degree of the total load in the micro-grid system in one day in the island mode is adopted; />Is the power of the j-th load point at the i-th moment; m is the number of load points and is the number of all running electric equipment in the island micro-grid; n is the number of hours per day, 24; l (L) x Is the accumulated value of all load fluctuation amounts; l (L) si Is the accumulated value of the fluctuation amount of the daily load;
according to the obtained load characteristic analysis result, a prediction model is constructed, and the calculation formula is as follows:
，
wherein: alpha is a prediction coefficient, and is the ratio of the historical load fluctuation amount to the future load fluctuation amount; f is the load in island mode; li is the fluctuation degree of the total load in the micro-grid system in one day in the island mode;
the characteristic analysis of the hydroelectric generating set comprises the relation among hydrologic resources, installed capacity and historical theoretical output, and the construction of the future output operation model of the hydroelectric generating set according to the analysis result comprises the following steps:
historical theoretical output model:
historical theoretical output = hydrologic resource quantity x installed capacity x historical average utilization;
the hydrologic resource amount represents hydrologic resources of the region where the hydropower station is located, such as annual average rainfall or runoff; the installed capacity is the capacity of a generator set installed or installable by a hydropower station; the historical average utilization rate is the average utilization rate of the hydropower station calculated according to the historical data, namely the ratio of the actual power generation amount to the installed capacity.
Future output model:
future force = historical theoretical force x scheduling coefficient.
The dispatching coefficient is determined according to actual operation conditions of reservoir dispatching and hydropower stations and is used for considering the influence of factors such as actual water level dispatching, reservoir management, operation states of power generation equipment and the like on the power generation output.
S2, after a load characteristic analysis result of the micro-grid system is obtained, new energy characteristic analysis and energy storage device characteristic analysis are carried out, wherein the new energy characteristic analysis comprises the relations among regional resources, installed capacity, wind power and photovoltaic output, a future operation model of the new energy and the energy storage device is constructed, and the calculation formula is as follows:
wind power future operation model:
future wind power output = wind power installed capacity x wind speed exponential function;
the wind speed index function may be modeled based on measured wind speed data and characteristics of the wind turbine, for example using a weber wind speed distribution model or a specific power curve model.
Photovoltaic future operation model:
photovoltaic future output = photovoltaic installed capacity x solar radiation index function;
the solar radiation index function can be modeled according to the actually measured solar radiation data and the characteristics of the photovoltaic system, and factors such as the efficiency, the temperature and the like of the photovoltaic panel can be considered.
Regional resource future utilization model:
utilization = future predicted/theoretical output;
the theoretical output can be calculated according to the resource condition and the installed capacity of the region, and the wind speed and the solar radiation quantity of the region are considered.
The future operation model of the energy storage device comprises the following steps:
run-time model:
run time (hours) =actual run capacity (kWh)/average power (kW);
this model assumes that the energy storage system has a stable and constant power output during operation. By dividing the actual operating capacity by the average power, the time that the energy storage system can operate continuously can be obtained.
And (3) a charge and discharge frequency model:
charge-discharge times = actual operating capacity (kWh)/single charge-discharge capacity (kWh);
the single charge-discharge capacity represents the capacity of the energy storage system that can be supplied with power in a single charge-discharge cycle. By dividing the actual operating capacity by the single charge-discharge capacity, it is possible to obtain how many times the energy storage system needs to be charged and discharged in actual operation.
Capacity model:
actual operating capacity (kWh) =capacity (kWh) ×cycle life coefficient;
the cycle life factor is a factor that measures the cycle life of the energy storage system, indicating how many complete charge and discharge cycles the energy storage system is capable of. By multiplying the capacity by the cycle life coefficient, the actual operating capacity of the energy storage system may be obtained.
S3, formulating an adjustment strategy according to the load characteristic analysis result, the new energy characteristic analysis result and the energy storage device characteristic analysis result to realize active power balance and frequency control of the micro-grid system;
s3-1, dividing the active power load and the reactive power load of the micro-grid into two grades, namely a large change and a small change, wherein the large change and the small change are distinguished according to the adjustment capability of primary frequency modulation and secondary frequency modulation of the field device, the adjustment time of the large change is longer than that of the small change, namely if the primary frequency modulation is the adjustment of an hour level, the secondary frequency modulation is the adjustment of a second level, the primary frequency modulation of the hydroelectric generating set responds to the small change of the active load, the secondary frequency modulation of the hydroelectric generating set responds to the large change of the active load, the primary voltage control of the hydroelectric generating set responds to the small change of the reactive load, and the secondary voltage control of the hydroelectric generating set responds to the large change of the reactive load;
s3-2, recording power adjustment step sizes required to be tracked by load characteristic analysis, new energy characteristic analysis and energy storage device characteristic analysis, and adding the power adjustment step sizes to obtain a final total power step size required to be adjusted; new energy characteristic analysis, further comprising: the distributed energy sources in the micro-grid, such as main energy forms of photovoltaic, wind power and the like, are regarded as generalized loads, namely "-" loads due to strong uncertainty and poor controllability;
s3-3, according to small change of load and combination of uncertainty of new energy output, frequency is adjusted once by setting a control reference value PFR of a speed regulator of the hydroelectric generating set, and automatic tracking is carried out to achieve real-time balance of the frequency, wherein the calculation formula is as follows:
，
wherein: the PFR is the power that the hydroelectric generating set frequency primary regulator needs to provide or absorb; k is a gain coefficient for measuring the influence of frequency offset on the primary frequency adjustment power; Δp is the power offset, representing the difference between the actual load and the balanced load of the power system;
all power frequency control is divided into two times, according to the large change of load, the uncertainty of new energy output and the capacity of an energy storage device are combined, the frequency is secondarily adjusted by setting a reference value PFCR of a hydroelectric generating set frequency modulator, and the basic power balance calculation formula is as follows:
，
wherein: PFCR is the power that the hydroelectric generating set frequency secondary regulator needs to provide or absorb; kp is a proportional gain for measuring the effect of frequency offset on the frequency secondary adjustment power; Δf is a frequency offset representing the difference between the actual frequency and the nominal frequency; ki is integral gain, the value range is 0.01-10, and parameters are manually set for a pid controller of a field hydroelectric generating set adjusting system before use and are used for measuring the influence of frequency offset integral on frequency secondary adjusting power; where ∈ (Δf) dt is the integral of the frequency offset and represents the accumulation over time.
Setting a regulating strategy, when the power regulation of the hydroelectric generating set and the energy storage device can not meet the load and the change of new energy, setting a scheme strategy for cutting the load and the new energy, carrying out strategic selection according to the priority and bearable capacity of the load, temporarily eliminating the load with lower priority so as to ensure the continuity of power supply and the stable operation of the system, or regulating the new energy so as to ensure the balance of active power and the stability of frequency;
s4, after a load characteristic analysis result of the micro-grid system is obtained, carrying out reactive voltage regulation device characteristic analysis;
and S5, formulating an adjustment strategy according to the load characteristic analysis result and the reactive voltage adjustment device characteristic analysis result to realize reactive power balance and voltage control of the micro-grid system.
The reactive power balance and voltage control are characterized in that reactive voltage control is divided into two stages according to reactive power load characteristics and reactive voltage regulating device characteristics, wherein the reactive voltage regulating device comprises a capacitor bank and an on-load voltage regulating tap, a static reactive generator SVG and a static reactive compensator SVC, and the primary voltage control responds to small changes of reactive loads through an automatic voltage regulator AVR of a hydroelectric generating set to realize real-time balance and voltage stabilization of reactive power; the secondary voltage control is mainly regulated by a capacitor bank, an on-load voltage regulating transformer tap, a static var generator SVG and a static var compensator SVC, and responds to larger change of reactive power load to realize basic balance of reactive power and basic stability of voltage.
The regulation strategy comprises the steps of setting a load shedding scheme strategy when the regulation of the reactive voltage device cannot meet the change of reactive load, carrying out strategic selection according to the priority and bearable capacity of the load, and temporarily rejecting the load with lower priority so as to ensure the reactive power balance and the voltage stability;
policy adjustment, further comprising: load reduction regulation, new energy regulation, energy storage regulation and small hydropower regulation, and medium and small hydropower is mainly based on dam type regulation.
S6, judging whether the power of the hydroelectric generating set is out of limit, if not, finishing regulation, if so, making a regulation strategy again, carrying out coordination control of active-frequency and reactive-voltage, and adopting a proper load cutting mode in the steps according to the actual working condition of the generating set to realize the rebalancing of the active and reactive power.
The present invention has been described in terms of embodiments, and it will be appreciated by those of skill in the art that various changes can be made to the features and embodiments, or equivalents can be substituted, without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (5)
1. The method for controlling the running power of the micro-grid of the hydroelectric main regulating unit in the island mode is characterized by comprising the following steps of:
s1, analyzing load characteristics of a micro-grid system, constructing a load characteristic prediction model, and carrying out characteristic analysis on a hydroelectric generating set
Analyzing and constructing a future output operation model of the hydroelectric generating set;
s2, after a load characteristic analysis result of the micro-grid system is obtained, new energy characteristic analysis and energy storage device characteristic classification are carried out
Analyzing and constructing a future operation model of the new energy source and the energy storage device;
s3, formulating an adjustment strategy according to the load characteristic analysis result, the new energy characteristic analysis result and the energy storage device characteristic analysis result
Active power balance and frequency control of the micro-grid system are slightly realized;
s4, after a load characteristic analysis result of the micro-grid system is obtained, carrying out reactive voltage regulation device characteristic analysis;
s5, formulating a regulating strategy according to the load characteristic analysis result and the reactive voltage regulating device characteristic analysis result to realize micro-electricity
Reactive power balance and voltage control of the network system;
in the step S1:
the calculation formula of the load characteristic analysis is as follows:
，
wherein:the fluctuation degree of the total load in the micro-grid system in one day in the island mode is adopted; />Is the power of the j-th load point at the i-th moment; m is the number of load points, which is all the running electricity utilization devices in the island micro-grid
The number of preparations; n is the number of hours per day; lx is the accumulated value of all load fluctuation amounts; lsi is the accumulated value of the current daily load fluctuation amount;
according to the obtained load characteristic analysis result, a prediction model is constructed, and the calculation formula is as follows:
wherein: alpha is a prediction coefficient, and is the ratio of the historical load fluctuation amount to the future load fluctuation amount; f is the load in island mode; li is the fluctuation degree of the total load in the micro-grid system in one day in the island mode;
the future output operation model of the hydroelectric generating set comprises the following steps:
historical theoretical output model:
historical theoretical output = hydrologic resource quantity x installed capacity x historical average utilization;
future output model:
future output = historical theoretical output x scheduling coefficient;
the active power balance and frequency control of the micro-grid system in the step S3 include the following steps:
s3-1, dividing the active power load and the reactive power load of the micro-grid into two grades of large change and small change, wherein the adjustment time of the large change is longer than that of the small change, and the primary frequency modulation of the hydroelectric generating set responds to the small change of the active load and the hydroelectric generating set responds to the hydroelectric generating set
The secondary frequency modulation of the group responds to large changes in the active load, the primary voltage control of the hydroelectric generating set responds to small changes in the reactive load, and the secondary voltage control of the hydroelectric generating set responds to large changes in the reactive load;
s3-2, recording power adjustment step sizes required to be tracked by load characteristic analysis, new energy characteristic analysis and energy storage device characteristic analysis, and adding the power adjustment step sizes to obtain a final total power step size required to be adjusted;
s3-3, according to small change of load and combination of uncertainty of new energy output, performing primary frequency adjustment, and automatically tracking to achieve real-time frequency balance, wherein the calculation formula is as follows:
，
wherein: the PFR is the power that the hydroelectric generating set frequency primary regulator needs to provide or absorb; k is the gain factor; Δp is the power offset;
according to the large change of the load, the uncertainty of the new energy output and the capacity of the energy storage device are combined to carry out secondary frequency adjustment, and the calculation formula is as follows:
，
wherein: PFCR is the power that the hydroelectric generating set frequency secondary regulator needs to provide or absorb; kp is the proportional gain; Δf is the frequency offset; ki is integral gain of a pid controller of a parameter on-site hydroelectric generating set adjusting system, and the value range is 0.01-10; and ∈ (Δf) dt is the integral of the frequency offset.
2. The method for controlling the operating power of the micro-grid of the hydroelectric main-generator set in the island mode according to claim 1, wherein the future operation model of the new energy in step S2 comprises:
wind power future operation model:
future wind power output = wind power installed capacity x wind speed exponential function;
photovoltaic future operation model:
photovoltaic future output = photovoltaic installed capacity x solar radiation index function;
regional resource future utilization model:
utilization = future predicted/theoretical output;
the future operation model of the energy storage device comprises the following steps:
run-time model:
run time = actual run capacity/average power;
and (3) a charge and discharge frequency model:
charge-discharge times = actual operating capacity/single charge-discharge capacity;
capacity model:
actual operating capacity = capacity x cycle life coefficient.
3. The method for controlling the running power of the micro-grid of the hydroelectric main regulating set in the island mode according to claim 1, wherein in the step S5, the reactive power balance and the voltage control are divided into two stages according to the reactive power load characteristic and the reactive voltage regulating device characteristic, wherein the reactive voltage regulating device comprises a capacitor bank, an on-load voltage regulating tap, a static var generator SVG and a static var compensator SVC, and the one-stage voltage control is used for realizing the real-time balance and the voltage stabilization of the reactive power by the automatic voltage regulator AVR of the hydroelectric main regulating set in response to the small change of the reactive power load; the secondary voltage control is mainly regulated by a capacitor bank, an on-load voltage regulating transformer tap, a static var generator SVG and a static var compensator SVC, and responds to larger change of reactive power load to realize basic balance of reactive power and basic stability of voltage.
4. The method for controlling the running power of the micro-grid of the hydroelectric generating main regulating set in the island mode according to claim 1, wherein the step S3 is characterized in that an adjusting strategy is formulated, when the power adjustment of the hydroelectric generating set and the energy storage device cannot meet the requirement of load and new energy change, a scheme strategy for cutting the load and the new energy is set, the strategic selection is carried out according to the priority and the bearable capacity of the load, the load with lower priority is temporarily removed, so as to ensure the continuity of power supply and the stable running of the system, or the new energy is adjusted, so as to ensure the active power balance and the stability of frequency;
and step S5, adjusting a strategy, setting a load shedding scheme strategy when the adjustment of the reactive voltage device cannot meet the change of reactive load, and performing strategic selection according to the load priority and the bearable capacity, so as to temporarily reject the load with lower priority, thereby guaranteeing the reactive power balance and the voltage stability.
5. The method for controlling the running power of the micro-grid of the hydroelectric main-generator set in the island mode according to claim 1, further comprising the step of S6: judging whether the power of the hydroelectric generating set is out of limit, if not, ending the regulation, if so, making a regulation strategy again, and carrying out coordination control of active-frequency and reactive-voltage to realize the rebalancing of the active and reactive power.
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