CN104269861A - Electromagnetic looped network reactive power ring current optimal control method based on flexible looped network controller - Google Patents
Electromagnetic looped network reactive power ring current optimal control method based on flexible looped network controller 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
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
- H02J3/1878—Arrangements for adjusting, eliminating or compensating reactive power in networks using tap changing or phase shifting transformers
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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
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
- H02J3/1892—Arrangements for adjusting, eliminating or compensating reactive power in networks the arrangements being an integral part of the load, e.g. a motor, or of its control circuit
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
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Abstract
The invention discloses an electromagnetic looped network reactive power ring current optimal control method based on a flexible looped network controller, and belongs to the technical field of electric power system analysis, operation and control. According to a high-low voltage electromagnetic looped network system, the flexible electric power transmission technology and the optimal load flow calculation method are used for optimally controlling the reactive power distribution electromagnetic looped network reactive power ring current optimal control method based on the flexible looped network controller in an electromagnetic looped network. The method includes the steps that first, the topological structure and the valve level control strategy of the looped network controller are determined; second, the reactive ring current optimized objective function and the constraint condition of the flexible looped network controller are deduced; third, a cataclysmic genetic algorithm is used for optimizing the objective function; fourth, based on an original current converter level control strategy, the current control regulation strategy is added. The electromagnetic looped network reactive power ring current is restrained, and thus the electromagnetic looped network can operate more economically and stably.
Description
Technical field
The invention belongs to power system analysis, run and control technology field.
Background technology
At the initial stage of high voltage order one power network development, the trend that high and low electromagnetic circle net passes through is little, and its existence can improve mains supply reliability, flexibility.Generally speaking, only otherwise affect power network safety operation and do not limit by capacity of short circuit, electromagnetic looped network operation can be maintained.But along with the development of high voltage order one electrical network, transmission load constantly increases, and electromagnetic looped network becomes the serious accident potential of electric power system, brings a lot of problem to operation of power networks.Wherein, the formation of high and low electromagnetic circle net runs the economy of electrical network and causes great impact.In electromagnetic looped network actual motion, because the electric component such as transformer, circuit parameter matching is unreasonable, power circulation can be produced in electromagnetic looped network, and the most general with reactive circular power flow, this power ring fails to be convened for lack of a quorum and the active loss of electrical network is obviously increased, and affects economy operation of power grid.Meanwhile, abroad the research emphasis of electromagnetic looped network is also focusing more on and suppresses in electromagnetic looped network on issuable this theme of power circulation.The main research emphasis of these countries is Flexible Control (FACTS) technology to be applied in electromagnetic looped network, to eliminate circulation or to control power distribution, improves the economy of system cloud gray model; Mainly through taking the Flexible Control means such as THE UPFC (UPFC), phase shifter (phase-shifter), IPC (IPC), controlled series compensation (TCSC) to control power circulation and trend distribution.But because China is to the research of said apparatus and development maturation not enough, device manufacturing process and level also do not reach requirement, are therefore difficult to solve electromagnetic looped network immediately and run the difficulty faced.So the present invention proposes to add present stage comparatively ripe Technology of HVDC based Voltage Source Converter in electromagnetic looped network, solve the Reactive Power Optimazation Problem of electromagnetic looped network.
At present, from the existing flexible DC power transmission engineering that puts into operation and technical characterstic thereof, the field such as Technology of HVDC based Voltage Source Converter is mainly used in wind-electricity integration, urban electricity supply, Power System Interconnection, offshore platform are powered, there is no application in AC network is unlinked.The heap(ed) capacity of the flexible DC power transmission engineering that put into operation reaches 400MW, and highest voltage level reaches ± 200kV; Reach 1000MW at the heap(ed) capacity building flexible DC power transmission engineering, highest voltage level reaches 500kV.In China, State Grid Corporation of China have been put into operation in July, 2011 the first flexible DC power transmission engineering of China by independent research, i.e. Shanghai Nanhui wind-electricity integration flexible DC power transmission demonstration project, engineered capacity reaches 20MW, electric pressure reaches ± 30kV, indicates that China achieves breakthrough from zero in Technology of HVDC based Voltage Source Converter field.At present, in world wide, Technology of HVDC based Voltage Source Converter journey is just rapid in high voltage, Large Copacity future development, engineering quantity gets more and more, application is also more and more extensive, from two ends to the development of multiterminal field, become the important means of extensive open and access and the intelligent grid construction promoting new forms of energy.
Summary of the invention
The object of the invention is for high and low electromagnetic circle net system, utilize flexible transmission technology and most sorrow tidal current computing method come reactive power distribution in optimal control electromagnetic looped network based on flexible ring net controller electromagnetic looped network reactive power circulation optimal control method.
Step of the present invention is:
(1) topological structure and the valve level control strategy of loop network control device is determined: add flexible ring net controller in the low-pressure side of electromagnetic looped network, namely originally the electromagnetic looped network two ends of open loop operation were being needed to adopt flexible direct current converter station to be back-to-back connected, form soft loop-net operation thus, wherein flexible ring net controller adopts modular multi-level converter topological structure; The control strategy of flexible ring net controller is divided into system-level control and converter level to control, system-level control command comprises meritorious class instruction and idle class instruction: meritorious class instruction is that active power controller strategy is determined in current conversion station I employing, current conversion station II adopts constant DC voltage control strategy, and idle class instruction is that two current conversion stations all adopt and determine Reactive Power Control strategy; Converter level modulation strategy adopts: vector control, is also called Direct Current Control;
(2), under three-phase grid balance condition, there is following equation group in reactive power circulation optimization object function and constraints: the general principle of flexible DC power transmission steady operation:
(1)
(2)
(3)
(4)
(5)
(6)
(7)
In formula, i represents that converter is numbered; U
acifor converter AC voltage; μ is direct voltage usage factor; M is modulation ratio; U
dcifor the converter direct voltage of i Nodes; δ is phase shifting angle; P
iref, Q
irefbe respectively input active power and the reactive power reference instruction at converter place; I
acifor converter ac bus side alternating current; I
di_ref, I
qi_refbe respectively the dq axle component of alternating current, get alternating voltage U here
acidirection vector is d direction of principal axis;
(8)
(9)
The minimum optimization object function of reactive power circulation can be expressed as:
（10）
In formula, U
nHfor the on high-tension side rated voltage of electromagnetic looped network; k
1, k
2for the no-load voltage ratio of transformer T1 and T2; U
ci, U
c2represent the ac bus voltage of flexible ring net controller;
,
for the total resistance of electromagnetic looped network;
Power flow equation is as follows:
（11）
In formula: n is system node number; P
gi, Q
gifor the meritorious and idle of system generator node is exerted oneself; P
aci, Q
acifor load active power and the reactive power of node; P
iref, Q
ireffor direct current system access node active power and reactive power, when converter absorbs idle from node, Q
irefget on the occasion of, when converter to AC system input idle time, Q
irefget negative value; Q
cifor the reactive compensation capacity of node; G
ij, B
ijfor conductance and the susceptance of node admittance matrix ranks element; U
ij, θ
ijfor the voltage magnitude between node i, j and phase angle;
Variable bound comprises state variable constrain and control variables constraint, and control variables comprises generator terminal voltage U
g, reactive power compensation point compensation capacity Q
c, transformer tapping gear T, converter active power reference value P
refwith reactive power reference qref Q
ref; State variable mainly considers each node voltage U and flexible draping controller both sides Injection Current Iac;
AC system variations per hour is constrained to:
(12)
In formula: i refers to exchange node; Min subscript represents the lower limit to dependent variable; Max subscript represents the higher limit to dependent variable;
During the variable bound of direct current system:
(13)
I in formula refers to DC node;
(3) the electromagnetic looped network optimal load flow containing flexible ring net controller solves implementation procedure, and step is as follows:
1) given catastrophe number of times C
a, algebraically N when catastrophe occurs
c, maximum evolutionary generation N
max;
2) according to basic genetic algorithmic optimizing;
3) as genetic algebra N
genreach N
cshi Jinhang catastrophe process, retain optimum individual, other individual initialization generate new colony, return step 2), until reach maximum catastrophe number of times C
a;
4) repeatedly above-mentioned steps 2 is performed) and 3), until reach maximum evolutionary generation N
max;
(4) regulating strategy of current limit is taken into account:
From formula 1,2, active power and reactive power reference qref use I indirectly
acithe d axle of (i=1,2) and q axle representation in components; Value and power reference generate strategy into:
When active current is preferential, the active power amount needing conveying be ensured, therefore I
dcan directly as reference value I
d_refbe input to controller; In conjunction with restriction of current I
ac_max, obtain the allowable upper limit value of reactive current component, it compares with optimal value I-q_opt, selects smaller as reference value I
q_refbe input to controller;
When reactive current is preferential, optimizing the I-q_opt calculated can directly as reference value I
q_refbe input to controller; In conjunction with restriction of current I
ac_max, obtain I
q_optactive current corresponding in situation, it can be used as reference value I
d_refbe input to controller.
The invention discloses a kind of optimal power flow control method based on flexible ring net controller, be intended to suppress electromagnetic looped network reactive power circulation.First, propose and install flexible ring net controller on the circuit of electromagnetic looped network low-pressure side, the topological structure of this flexible ring net controller converter valve is modularization multi-level converter (MMC), and converter valve system type of attachment is back-to-back type.Secondly, by pushing over electromagnetic looped network Mathematical Modeling, the target function of reactive circular power flow producing cause and optimal power flow control in electromagnetic looped network is obtained; Meanwhile, in conjunction with under MMC-HVDC systematic steady state service conditions to the independent uneoupled control characteristic of active power (P) and reactive power (Q), obtain the power flowcontrol scope of flexible ring net controller.Finally, the controlled quentity controlled variable of flexible ring net controller is included in optimal power flow control variable, pass through global optimization, under considering system safety constraints, flexible ring net controller is to the optimal control effect of reactive power circulation in electromagnetic looped network, and the optimal power flow control problem of flexible ring net controller is converted into a tide optimization problem.This method to overcome in traditional electromagnetic looped network only by changing line parameter circuit value to suppress the power flowcontrol existed in reactive power circulation to be limited in scope and optimal power flow control such as can not follow load variations and carry out timely at the problems; While suppression reactive circular power flow, flexible ring net controller also can provide voltage support for both sides ac bus, enable electromagnetic looped network more economically, stable operation.
Accompanying drawing explanation
Fig. 1 is the electric 500/220kV magnetic loop network topology structure adding flexible ring net controller;
Fig. 2 is modular multi-level converter topological structure;
Fig. 3 is converter level direct voltage control schematic diagram;
Fig. 4 to unlink schematic diagram containing flexible ring net controller electromagnetic looped network;
Fig. 5 is catastrophic genetic algorithm flow chart;
Fig. 6 takes into account current limit principle of adjustment and control figure;
Fig. 7 does not add trend distribution in flexible ring net controller electromagnetic looped network;
Fig. 8 is that after adding flexible ring net controller, in electromagnetic looped network, trend distributes.
Embodiment
In electromagnetic looped network, flexible ring net controller is utilized to suppress reactive power circulation:
1. topological structure and the valve level control strategy of loop network control device is determined.
2. in conjunction with reactive circular power flow Mathematical Modeling in MMC-HVDC stable state transmission of electricity Mathematical Modeling and electromagnetic looped network, reactive circular power flow optimization object function and the constraints of flexible ring net controller is derived.
3. owing to containing more discrete variable in bound for objective function, in order to improve the global convergence effect of Algorithm for Solving, catastrophic genetic algorithm is adopted to carry out optimizing to target function here.
4. line current restriction will be subject in flexible ring net controller power delivery process, and the current limit mode different according to it, the idle fan-out capability that flexible ring net controller can carry out regulating and controlling voltage is also variant, therefore on original converter level control strategy, with the addition of the regulating strategy taking into account Current Control.
Step of the present invention is:
(1) loop network control device is added in the low-pressure side of electromagnetic looped network as shown in Figure 1.The cardinal principle of the flexible ring net controller based on Technology of HVDC based Voltage Source Converter is originally needing the electromagnetic looped network two ends of open loop operation to adopt flexible direct current converter station to be back-to-back connected, and forming soft loop-net operation thus.Therefore, flexible ring net controller can not only through-put power, realizes loop-net operation, can also participate in line voltage simultaneously and regulate, provide dynamic reactive to support and suppress reactive power circulation.Flexible ring net controller adopts modularization multi-level converter (MMC) topological structure.The more traditional two level topological structures of modular multilevel circulator topological structure have more advantage, and increasing flexible DC power transmission engineering adopts modular multi-level converter topological structure at present.MMC is a kind of multilevel converter utilizing series half-bridge technological maheup, and its external loop diagnostic is voltage source converter characteristic, can accomplish four quadrant running.Due to its half-bridge cells modularized design, it is made to expand flexibly, easy to maintenance; Adopt many level change of current direct current transportation, have the advantages that loss is less, and output harmonic wave is little, without the need to filter.Three-phase MMC main circuit topological structure refers to Fig. 2.The control strategy of flexible ring net controller is divided into system-level control and converter level to control.Its system-level control command comprises meritorious class instruction and idle class instruction: meritorious class instruction is that active power controller strategy is determined in current conversion station I employing, current conversion station II adopts constant DC voltage control strategy, and idle class instruction is that two current conversion stations all adopt and determine Reactive Power Control strategy.The converter level modulation strategy of flexible ring net controller adopts: vector control, is also called Direct Current Control.Further, in traditional VSC Direct Current Control, with the addition of again the re-set target that current limit control strategy is optimized to reach reactive circular power flow.The converter level of flexible ring net controller controls to see Fig. 3.
(2) in conjunction with reactive circular power flow Mathematical Modeling in MMC-HVDC stable state transmission of electricity Mathematical Modeling and electromagnetic looped network, reactive circular power flow optimization object function and the constraints of flexible ring net controller is derived.The impact of flexible ring net controller on electromagnetic looped network operational objective is studied from the angle of control effects.Include in optimal control variable by the controlled quentity controlled variable of flexible ring net controller under study for action, by global optimization, the flexible ring net controller under consideration system safety constraints is to the optimal control effect of reactive power.If specify the control objectives of flexible ring net controller, can be just an optimization problem by the power flowcontrol question variation of flexible ring net controller.
As shown in Figure 3, the converter level of flexible ring net controller controls to be adopt Direct Current Control; Its outer ring controller is according to active power reference value P
refwith reactive power reference qref Q
refand direct voltage reference value U
dcalculate inner ring current reference value i
dand i
q, inner ring current controller follow current reference value d, q axle component desired value u-of output voltage
drefand u
qref, the instantaneous value u of modulating wave is generated thereafter by dq inverse transformation
st (), approaches modulation strategy finally by nearest level and generates its sinusoidal voltage waveform U
c(t).According to the general principle of flexible DC power transmission steady operation, under three-phase grid balance condition, there is following equation group:
(1)
(2)
(3)
(4)
(5)
(6)
(7)
In formula, i represents that converter is numbered; U
acifor converter AC voltage; μ is direct voltage usage factor; M is modulation ratio; U
dcifor the converter direct voltage of i Nodes; δ is phase shifting angle; P
iref, Q
irefbe respectively input active power and the reactive power reference instruction at converter place; I
acifor converter ac bus side alternating current; I
di_ref, I
qi_refbe respectively the dq axle component of alternating current, get alternating voltage U here
acidirection vector is d direction of principal axis;
As shown in Figure 4, electromagnetic looped network is unlinked in bus 1 position in FIG, becomes both end power supplying network and analyzes.Then have:
(8)
(9)
To sum up analyze, containing the electromagnetic looped network wattles power economic equivalent of flexible ring net controller, the minimum optimization object function of its reactive power circulation can be expressed as:
（10）
In formula, U
nHfor the on high-tension side rated voltage of electromagnetic looped network; k
1, k
2for the no-load voltage ratio of transformer T1 and T2; U
ci, U
c2represent the ac bus voltage of flexible ring net controller;
,
for the total resistance of electromagnetic looped network;
In the optimal load flow carrying out ac and dc systems solves, the item considering that direct current system trend is corresponding should be increased in regular alternating current system load flow equation.Therefore its power flow equation is as follows:
（11）
In formula: n is system node number; P
gi, Q
gifor the meritorious and idle of system generator node is exerted oneself; P
aci, Q
acifor load active power and the reactive power of node; P
iref, Q
ireffor direct current system access node active power and reactive power, when converter absorbs idle from node, Q
irefget on the occasion of, when converter to AC system input idle time, Q
irefget negative value; Q
cifor the reactive compensation capacity of node; G
ij, B
ijfor conductance and the susceptance of node admittance matrix ranks element; U
ij, θ
ijfor the voltage magnitude between node i, j and phase angle;
Variable bound comprises state variable constrain and control variables constraint, and in the electromagnetic looped network system containing flexible ring net controller, control variables comprises generator terminal voltage U
g, reactive power compensation point compensation capacity Q
c, transformer tapping gear T, converter active power reference value P
refwith reactive power reference qref Q
ref; State variable mainly considers each node voltage U and flexible draping controller both sides Injection Current Iac;
AC system variations per hour is constrained to:
(12)
In formula: i refers to exchange node; Min subscript represents the lower limit to dependent variable; Max subscript represents the higher limit to dependent variable;
During the variable bound of direct current system, due in flexible DC power transmission, its active power and reactive power can realize decoupling zero and independently control, but still will meet the equilibrium relationships of formula (5), also will meet following restriction relation simultaneously:
(13)
I in formula refers to DC node.
(3) the electromagnetic looped network optimal load flow containing flexible ring net controller solves implementation procedure, owing to containing more discrete variable in bound for objective function, in order to improve the global convergence effect of Algorithm for Solving, catastrophic genetic algorithm is adopted to carry out optimizing to target function here.Algorithm for Solving basic step is described below:
1) given catastrophe number of times C
a, algebraically N when catastrophe occurs
c, maximum evolutionary generation N
max;
2) according to basic genetic algorithmic (GA) optimizing;
3) as genetic algebra N
genreach N
cshi Jinhang catastrophe process, retain optimum individual, other individual initialization generate new colony, return step 2), until reach maximum catastrophe number of times C
a.
4) repeatedly above-mentioned steps 2 is performed) and 3), until reach maximum evolutionary generation N
max;
It specifically solves flow chart as shown in Figure 5.
(4) regulating strategy of current limit is taken into account:
Line current restriction will be subject in flexible ring net controller power delivery process, and the current limit mode different according to it, the idle fan-out capability that flexible ring net controller can carry out regulating and controlling voltage is also variant, because being employed herein the regulating strategy taking into account Current Control.
From formula 1,2, active power and reactive power reference qref use I indirectly
acithe d axle of (i=1,2) and q axle representation in components; As in Fig. 6, use I
drepresent the active current that flexible direct current power transmission system needs the active power of conveying corresponding; I
q_optthe reactive current component that the idle reference value optimal value that expression utilizes optimized algorithm to try to achieve is corresponding; I
ac_maxfor electric current I
acmaximum; I
d_ref, I
q_refrepresent the current component that the ideal reference of active power and Reactive Power Control is corresponding respectively.Value and power reference after improvement generate strategy into:
When active current is preferential, the active power amount needing conveying be ensured, therefore I
dcan directly as reference value I
d_refbe input to controller; In conjunction with restriction of current I
ac_max, obtain the allowable upper limit value of reactive current component, it compares with optimal value I-q_opt, selects smaller as reference value I
q_refbe input to controller;
When reactive current is preferential, optimizing the I-q_opt calculated can directly as reference value I
q_refbe input to controller; In conjunction with restriction of current I
ac_max, obtain I
q_optactive current corresponding in situation, it can be used as reference value I
d_refbe input to controller.
sample calculation analysis
For verifying validity and the correctness of proposed method, the typical 220/300kV of certain electrical network is adopted to carry out the validity of method and correctness grinds card.Do not add the electromagnetic looped network trend distribution of flexible ring net controller as shown in Figure 6.In node 3 electric pressure be 220kV circuit on add loop network control device after trend distribution as shown in Figure 7.
Comparative analysis tidal current chart 7 and Fig. 8 visible, the load factor of circuit and transformer is reduced after eliminating reactive circular power flow, improve the transfer capability of circuit, transformer etc., the voltage of 330 kV buses improves 3 kV respectively, if this electromagnetic looped network heavy service, eliminate reactive circular power flow and will significantly improve voltage operation level.And obviously can reduce active power loss after elimination reactive circular power flow.When there is reactive circular power flow, in this electromagnetic looped network 1, between 2 nodes, between circuit and 3,4 nodes, double loop loss amounts to 1.363 MW+4.935 Mvar, 2, between 3 nodes, between system interconnection transformer and 1,4 nodes, transformer loss amounts to 0.078 MW+75.616 Mvar, adds up to 1.441 MW+ 80.551 Mvar.And after reactive circular power flow elimination, line loss amounts to 1.156 MW+4.594 Mvar, and transformer loss amounts to 0.078 MW+ 75.616 Mvar, adds up to 1.223 MW+69.284 Mvar.Visible active loss reduces about 0.22 MW, if annual utilization hours calculates by 8 760 h, rate for incorporation into the power network calculates by average about 0.25 yuan/kWh, then the annual economic benefit that can obtain about 48.2 ten thousand yuan in reduction active loss.This example effectively demonstrates the optimal control effect of flexible ring net controller to reactive power in electromagnetic looped network.
Claims (1)
1., based on a flexible ring net controller electromagnetic looped network reactive power circulation optimal control method, it is characterized in that:
(1) topological structure and the valve level control strategy of loop network control device is determined: add flexible ring net controller in the low-pressure side of electromagnetic looped network, namely originally the electromagnetic looped network two ends of open loop operation were being needed to adopt flexible direct current converter station to be back-to-back connected, form soft loop-net operation thus, wherein flexible ring net controller adopts modular multi-level converter topological structure; The control strategy of flexible ring net controller is divided into system-level control and converter level to control, system-level control command comprises meritorious class instruction and idle class instruction: meritorious class instruction is that active power controller strategy is determined in current conversion station I employing, current conversion station II adopts constant DC voltage control strategy, and idle class instruction is that two current conversion stations all adopt and determine Reactive Power Control strategy; Converter level modulation strategy adopts: vector control, is also called Direct Current Control;
(2), under three-phase grid balance condition, there is following equation group in reactive power circulation optimization object function and constraints: the general principle of flexible DC power transmission steady operation:
(1)
(2)
(3)
(4)
(5)
(6)
(7)
In formula, i represents that converter is numbered; U
acifor converter AC voltage; μ is direct voltage usage factor; M is modulation ratio; U
dcifor the converter direct voltage of i Nodes; δ is phase shifting angle; P
iref, Q
irefbe respectively input active power and the reactive power reference instruction at converter place; I
acifor converter ac bus side alternating current; I
di_ref, I
qi_refbe respectively the dq axle component of alternating current, get alternating voltage U here
acidirection vector is d direction of principal axis;
(8)
(9)
The minimum optimization object function of reactive power circulation can be expressed as:
（10）
In formula, U
nHfor the on high-tension side rated voltage of electromagnetic looped network; k
1, k
2for the no-load voltage ratio of transformer T1 and T2; U
ci, U
c2represent the ac bus voltage of flexible ring net controller;
,
for the total resistance of electromagnetic looped network;
Power flow equation is as follows:
（11）
In formula: n is system node number; P
gi, Q
gifor the meritorious and idle of system generator node is exerted oneself; P
aci, Q
acifor load active power and the reactive power of node; P
iref, Q
ireffor direct current system access node active power and reactive power, when converter absorbs idle from node, Q
irefget on the occasion of, when converter to AC system input idle time, Q
irefget negative value; Q
cifor the reactive compensation capacity of node; G
ij, B
ijfor conductance and the susceptance of node admittance matrix ranks element; U
ij, θ
ijfor the voltage magnitude between node i, j and phase angle;
Variable bound comprises state variable constrain and control variables constraint, and control variables comprises generator terminal voltage U
g, reactive power compensation point compensation capacity Q
c, transformer tapping gear T, converter active power reference value P
refwith reactive power reference qref Q
ref; State variable mainly considers each node voltage U and flexible draping controller both sides Injection Current Iac;
AC system variations per hour is constrained to:
(12)
In formula: i refers to exchange node; Min subscript represents the lower limit to dependent variable; Max subscript represents the higher limit to dependent variable;
During the variable bound of direct current system:
(13)
I in formula refers to DC node;
(3) the electromagnetic looped network optimal load flow containing flexible ring net controller solves implementation procedure, and step is as follows:
1) given catastrophe number of times C
a, algebraically N when catastrophe occurs
c, maximum evolutionary generation N
max;
2) according to basic genetic algorithmic optimizing;
3) as genetic algebra N
genreach N
cshi Jinhang catastrophe process, retain optimum individual, other individual initialization generate new colony, return step 2), until reach maximum catastrophe number of times C
a;
4) repeatedly above-mentioned steps 2 is performed) and 3), until reach maximum evolutionary generation N
max;
(4) regulating strategy of current limit is taken into account:
From formula 1,2, active power and reactive power reference qref use I indirectly
acithe d axle of (i=1,2) and q axle representation in components; Value and power reference generate strategy into:
When active current is preferential, the active power amount needing conveying be ensured, therefore I
dcan directly as reference value I
d_refbe input to controller; In conjunction with restriction of current I
ac_max, obtain the allowable upper limit value of reactive current component, it compares with optimal value I-q_opt, selects smaller as reference value I
q_refbe input to controller;
When reactive current is preferential, optimizing the I-q_opt calculated can directly as reference value I
q_refbe input to controller; In conjunction with restriction of current I
ac_max, obtain I
q_optactive current corresponding in situation, it can be used as reference value I
d_refbe input to controller.
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| CN104967116A (en) * | 2015-06-03 | 2015-10-07 | 山东电力研究院 | Electromagnetic ring network ring opening method for multi-DC infeed receiving-end grid |
| CN105515036A (en) * | 2015-12-21 | 2016-04-20 | 中国电力科学研究院 | Flexible ring network controller capacity design method |
| CN105552915A (en) * | 2016-02-25 | 2016-05-04 | 国网福建省电力有限公司 | Optimal load flow calculation method of MMC (Modular Multilevel Converter)-HVDC (High Voltage Direct Current) contained alternating current and direct current hybrid power grid taking static security constraint into consideration |
| CN105552946A (en) * | 2015-12-30 | 2016-05-04 | 国网辽宁省电力有限公司电力科学研究院 | DC voltage control method of flexible ring network controller and control system thereof |
| CN106451421A (en) * | 2016-09-27 | 2017-02-22 | 南方电网科学研究院有限责任公司 | Modeling and unlinking method of AC/DC power grid containing electromagnetic loop network |
| CN106803679A (en) * | 2015-11-26 | 2017-06-06 | 国网智能电网研究院 | A kind of flexible ring net controller and control method for electromagnetic looped network solution inscription of loop |
| CN106921172A (en) * | 2015-12-28 | 2017-07-04 | 国网智能电网研究院 | A kind of topological structure of flexible ring net controller |
| CN106998074A (en) * | 2017-03-15 | 2017-08-01 | 全球能源互联网研究院 | A kind of control method and system for modular multi-level flexible direct current current conversion station |
| CN107026476A (en) * | 2017-05-16 | 2017-08-08 | 中国电力科学研究院 | A kind of method and apparatus for suppressing electromagnetic looped network power circulation |
| CN105576716B (en) * | 2016-01-08 | 2018-02-23 | 国网北京市电力公司 | The acquisition methods and device of the control parameter of voltage source converter |
| CN107749635A (en) * | 2017-11-15 | 2018-03-02 | 江苏方天电力技术有限公司 | A kind of closed loop network running optimizatin method |
| CN107809118A (en) * | 2016-09-09 | 2018-03-16 | 贵州电网有限责任公司电力调度控制中心 | A kind of design method of electromagnetic looped network uncoupling loop scheme |
| CN109861202A (en) * | 2018-11-15 | 2019-06-07 | 国网江苏省电力有限公司电力科学研究院 | A kind of flexible interconnection distribution networks dynamic optimization dispatching method and system |
| CN110350570A (en) * | 2019-07-11 | 2019-10-18 | 中国能源建设集团江苏省电力设计院有限公司 | A kind of full rank TSM control method based on back-to-back VSC-HVDC |
| CN111193273A (en) * | 2020-04-14 | 2020-05-22 | 中国电力科学研究院有限公司 | Phase modulator control method, phase modulator control device, phase modulator system and storage medium |
| CN112398135A (en) * | 2020-11-30 | 2021-02-23 | 国网冀北电力有限公司电力科学研究院 | Control method and device of multi-port power electronic transformer of anti-electromagnetic looped network |
| CN112736957A (en) * | 2020-12-24 | 2021-04-30 | 华中科技大学 | Harmonic compensation type flexible direct current converter and control method |
| CN113972666A (en) * | 2021-11-16 | 2022-01-25 | 贵州电网有限责任公司 | Loop closing reactive circulation restraining method for power distribution network |
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| CN104732302A (en) * | 2015-04-09 | 2015-06-24 | 中国电力科学研究院 | Multistage electromagnetic loop circuit optimized loop-opening method based on immunity algorithm |
| CN104967116A (en) * | 2015-06-03 | 2015-10-07 | 山东电力研究院 | Electromagnetic ring network ring opening method for multi-DC infeed receiving-end grid |
| CN106803679A (en) * | 2015-11-26 | 2017-06-06 | 国网智能电网研究院 | A kind of flexible ring net controller and control method for electromagnetic looped network solution inscription of loop |
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| CN105576716B (en) * | 2016-01-08 | 2018-02-23 | 国网北京市电力公司 | The acquisition methods and device of the control parameter of voltage source converter |
| CN105552915A (en) * | 2016-02-25 | 2016-05-04 | 国网福建省电力有限公司 | Optimal load flow calculation method of MMC (Modular Multilevel Converter)-HVDC (High Voltage Direct Current) contained alternating current and direct current hybrid power grid taking static security constraint into consideration |
| CN105552915B (en) * | 2016-02-25 | 2018-02-06 | 国网福建省电力有限公司 | A kind of alternating current-direct current mixing network optimization tidal current computing methods of HVDC containing MMC for considering Static Security Constraints |
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| CN106451421B (en) * | 2016-09-27 | 2019-01-04 | 南方电网科学研究院有限责任公司 | A kind of modeling of the power grid of alternating current-direct current containing electromagnetic looped network and method of unlinking |
| CN106451421A (en) * | 2016-09-27 | 2017-02-22 | 南方电网科学研究院有限责任公司 | Modeling and unlinking method of AC/DC power grid containing electromagnetic loop network |
| CN106998074A (en) * | 2017-03-15 | 2017-08-01 | 全球能源互联网研究院 | A kind of control method and system for modular multi-level flexible direct current current conversion station |
| CN107026476B (en) * | 2017-05-16 | 2021-03-16 | 中国电力科学研究院 | Method and device for restraining power circulation of electromagnetic looped network |
| CN107026476A (en) * | 2017-05-16 | 2017-08-08 | 中国电力科学研究院 | A kind of method and apparatus for suppressing electromagnetic looped network power circulation |
| CN107749635A (en) * | 2017-11-15 | 2018-03-02 | 江苏方天电力技术有限公司 | A kind of closed loop network running optimizatin method |
| CN109861202A (en) * | 2018-11-15 | 2019-06-07 | 国网江苏省电力有限公司电力科学研究院 | A kind of flexible interconnection distribution networks dynamic optimization dispatching method and system |
| CN110350570A (en) * | 2019-07-11 | 2019-10-18 | 中国能源建设集团江苏省电力设计院有限公司 | A kind of full rank TSM control method based on back-to-back VSC-HVDC |
| CN110350570B (en) * | 2019-07-11 | 2022-06-03 | 中国能源建设集团江苏省电力设计院有限公司 | Full-order terminal sliding mode control method based on back-to-back VSC-HVDC |
| CN111193273A (en) * | 2020-04-14 | 2020-05-22 | 中国电力科学研究院有限公司 | Phase modulator control method, phase modulator control device, phase modulator system and storage medium |
| CN112398135A (en) * | 2020-11-30 | 2021-02-23 | 国网冀北电力有限公司电力科学研究院 | Control method and device of multi-port power electronic transformer of anti-electromagnetic looped network |
| CN112398135B (en) * | 2020-11-30 | 2023-12-05 | 国网冀北电力有限公司电力科学研究院 | Control method and device for multi-port power electronic transformer of anti-electromagnetic ring network |
| CN112736957A (en) * | 2020-12-24 | 2021-04-30 | 华中科技大学 | Harmonic compensation type flexible direct current converter and control method |
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