CN116470514A - Method for judging stability of offshore wind power alternating current system based on tide algorithm - Google Patents
Method for judging stability of offshore wind power alternating current system based on tide algorithm 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
- H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
- H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
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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
- H02J3/381—Dispersed generators
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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
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/12—Arrangements for reducing harmonics from ac input or output
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/02—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc
- H02M5/04—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters
- H02M5/10—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using 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
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
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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
- H02J2300/28—The renewable source being wind energy
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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
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/76—Power conversion electric or electronic aspects
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Abstract
The invention discloses a stability judging method of an offshore wind power alternating current system based on a tide algorithm. It comprises the following steps: and carrying out power flow iteration according to the reactive power unbalance of the alternating current bus of the diode rectifying unit. The invention fills the blank of research on the aspect of calculation of steady-state power flow of the offshore wind farm based on the networking type fan and the diode rectifying unit at present, provides the method for judging the stability of the alternating current system, and can provide a certain reference for future engineering design; the method is high in universality, suitable for the offshore wind power alternating current systems of various topological structures based on the grid-structured fans and the diode rectification units, and also suitable for different conditions that the operation frequency of the offshore wind power alternating current systems is low frequency, power frequency or medium frequency.
Description
Technical Field
The invention belongs to the technical field of power transmission and distribution of power systems, and particularly relates to a stability judging method of an offshore wind power alternating current system based on a tide algorithm.
Background
The far-sea wind power plant has richer and stable wind energy resources, and is a main trend of wind power development in the future. How to realize the reliable grid connection of the remote large-capacity offshore wind power is a key technology in the current offshore wind power field. The put-into-production open sea wind farm is basically sent out by adopting a high-voltage direct current transmission system based on a modularized multi-level converter. However, this solution requires the construction of large offshore converter station platforms, which is difficult to construct and costly to invest.
In order to improve the economy of the offshore wind power grid-connected system, in recent years, low-cost converters are increasingly receiving attention from academia and industry, wherein the application of diode rectifying units in the offshore wind power grid-connected system gradually becomes a research hot spot. Compared to a thyristor-based grid converter, the diode rectifying unit has smaller power losses, lower investment costs and higher reliability.
Stable ac voltage is a necessary condition for the proper operation of offshore wind farms. The key of implementation of the offshore wind power grid-connected scheme based on the diode rectifying unit is whether the amplitude and the frequency of the offshore alternating current system voltage can be effectively controlled. The diode rectifying unit does not have active control capability and requires a commutation voltage supplied from an external voltage source. One solution is to add additional equipment as a supporting voltage source for the offshore ac system, where the additional equipment may impair the economic benefits of the diode rectifying unit, although the wind turbine may still be operated in a grid-like mode.
The other scheme is that the wind turbine generator is operated in a net-structured mode to control the voltage of the offshore alternating current system. The existing grid-built fan control strategies comprise a grid-built control strategy based on a phase-locked loop, a grid-built control strategy based on a global unified reference coordinate system and a grid-built control strategy based on reactive power-frequency (Q-f) droop control. The application potential of a network construction control strategy based on Q-f droop control is large, the control avoids the problem of system stability caused by lock loss by canceling a phase-locked loop, and the operation reliability of the system is improved by canceling communication.
The tide calculation is a basis for designing a grid-structured fan grid-connected system and analyzing the running stability of the offshore wind power grid-connected system. The existing literature focuses on a control strategy of a grid-structured fan, and no research on a method for judging the stability of an offshore wind power alternating current system based on a tide algorithm exists.
Disclosure of Invention
The invention aims to solve the defects in the background art and provides a method for judging the stability of an offshore wind power alternating current system based on a tide algorithm. The method is simple to implement, has strong applicability and has great use value in engineering design.
The technical scheme adopted by the invention is as follows: a stability judging method of an offshore wind power alternating current system based on a tide algorithm comprises a grid-structured fan, an alternating current sea cable, a step-up transformer, an alternating current filter, an alternating current bus of a diode rectifying unit and the diode rectifying unit; the grid-structured fan is connected to an alternating current bus of the diode rectifying unit through an alternating current sea cable and a step-up transformer, the alternating current filter is connected to the alternating current bus of the diode rectifying unit, and the alternating current bus of the diode rectifying unit is connected with the diode rectifying unit;
the offshore wind power alternating current system is provided with n nodes, wherein s net-structured fan nodes are PQ nodes, and the numbers of the net-structured fan nodes are n-s+1 to n; the alternating-current bus node of the diode rectifying unit is a PCC node, and the PCC node is numbered 1;
the grid-structured fans are controlled to output reactive power Q under the steady state of all the grid-structured fans wt And controlling the instantaneous frequency of all the net-structured fans in a steady state to be equal to the frequency f of the offshore wind power alternating current system;
the method for judging the stability of the offshore wind power alternating current system based on the tide algorithm comprises the following steps: carrying out tide iteration according to the unbalance amount of the reactive power of the alternating current bus of the diode rectifying unit, and specifically comprising the following steps:
s1: inputting system original data including line parameters and transformer parameters, and inputting rated frequency f of offshore wind power alternating current system (0) Forming an initial node admittance matrix Y (0) ；
S2: initial value P of active power output by given network-structured fan node wtj (0) (j=n-s+1, n-s+2, …, n) to make the active power absorbed by the diode rectifying unit be initial value P r (0) The active power initial value P is output for all net-structured fans wtj (0) The sum of the voltage effective value and the initial value U of the PCC node is calculated 1 (0) The method comprises the steps of carrying out a first treatment on the surface of the N node voltages of offshore wind power alternating current systemThe initial value of the effective value is taken as U i (0) ＝U 1 (0) (i=1, 2, …, n), and the initial values of the voltage phase angles of n nodes of the offshore wind power alternating current system are all theta i (0) ＝0°(i＝1,2,…,n)；
S3: let the grid-structured fan node output reactive power Q wt The value interval of (C) is [ Q ] wtmin ,Q wtmax ]Initial value Q of upper and lower limits of interval wtmin (0) And Q wtmax (0) Taking-1 p.u. and 1p.u., respectively;
s4: let the output reactive power of the grid-structured fan node be Q wtmin (0) Substituted into f (0) 、Y (0) 、U i (0) 、θ i (0) 、P wtj (0) And Q wtmin (0) Carrying out Newton-Laportson method power flow calculation to obtain active power P injected into PCC nodes from offshore wind power alternating current system w And reactive power Q w And the effective voltage value U of PCC node 1 Calculating reactive power Q absorbed by diode rectifying unit r And reactive power Q output by AC filter fil Calculating the surplus of reactive power injected into PCC nodes as Q sur1 (0) The method comprises the steps of carrying out a first treatment on the surface of the Similarly, the output reactive power of the nodes of the net-structured fan is Q wtmax (0) Substituted into f (0) 、Y (0) 、U i (0) 、θ i (0) 、P wtj (0) And Q wtmax (0) Carrying out Newton-Laportson method power flow calculation to obtain reactive power surplus Q injected into PCC nodes sur2 (0) ；
S5: setting the iteration number k=0;
s6: let the grid-structured fan node output reactive power Q wt (k) For taking the average of the upper and lower limits of the interval, i.e. Q wt (k) ＝mean(Q wtmin (k) ，Q wtmax (k) ) (mean () represents taking the average), substituting f (k) 、Y (k) 、U i (k) 、θ i (k) 、P wtj (k) And Q wt (k) Carrying out Newton-Laportson method power flow calculation to obtain active power P injected into PCC nodes from offshore wind power alternating current system w (k+1) And reactive power Q w (k+1) And the effective voltage value U of PCC node 1 (k+1) The method comprises the steps of carrying out a first treatment on the surface of the Calculating reactive power Q absorbed by diode rectifying unit r (k +1) And reactive power Q output by AC filter fil (k+1) Calculating the surplus of reactive power injected into PCC nodes as Q sur (k+1) The method comprises the steps of carrying out a first treatment on the surface of the Calculating frequency f of offshore wind power alternating current system (k+1) And f (k+1) Node admittance matrix Y below (k+1) ；
S7: the error allowable value epsilon is 1 multiplied by 10 -6 If Q sur (k+1) Epsilon or Q wtmax (k) -Q wtmin (k) ) If epsilon is less than or equal to epsilon, outputting a tide calculation result and ending the cycle, otherwise, performing the next step;
s8: if Q sur (k+1) ×Q sur1 (k) Not less than 0, the output reactive power interval of the net-structured fan becomes [ mean (Q) wtmin (k) ,Q wtmax (k) ),Q wtmax (k) ]And Q is sur1 (k+1) ＝Q sur (k+1) The method comprises the steps of carrying out a first treatment on the surface of the If Q sur (k+1) ×Q sur1 (k) <0, the reactive power value interval becomes [ Q ] wtmin (k) ,mean(Q wtmin (k) ,Q wtmax (k) )]And Q is sur2 (k+1) ＝Q sur (k+1) ；
S9: setting k=k+1, and returning to S6 for the next iteration;
s10: and if the circulation is finished, judging iteration convergence, namely stabilizing the offshore wind power alternating current system comprising the grid-structured fan and the diode rectifying unit.
In the step S2, the effective value U of the voltage of the PCC node is solved by the following equation 1 ：
Wherein P is r Active power absorbed by the diode rectifying unit; f is the frequency of an offshore wind power alternating current system; r is R dc The direct current resistor is arranged between the rectifying station and the inverting station; u (U) dc The direct current voltage of the inversion station; x is X t Commutating the reactance of the transformer for the diode rectifying unit; t is the transformation ratio of the diode rectifying unit converter transformer.
The reactive power Q absorbed by the diode rectifying unit is solved in the step S4 and the step S6 through the following formula r And reactive power Q output by AC filter fil ：
Q fil ＝2πfC 0 U 1 2
Wherein P is w Injecting active power of PCC nodes into the offshore wind power alternating current system; t is the transformation ratio of a diode rectifying unit converter transformer; u (U) dc For inverting the DC voltage of the station, U 1 The voltage effective value of the PCC node; f is the frequency of an offshore wind power alternating current system; c (C) 0 Is the fundamental wave equivalent capacitance of the alternating current filter.
In the steps S4 and S6, the reactive power surplus Q of the PCC node is injected sur Reactive power Q for injecting PCC nodes from offshore wind power alternating current system w Adding reactive power Q output by AC filter fil Subtracting the reactive power Q absorbed by the diode rectifying unit r 。
In the step S6, the frequency f of the offshore wind power alternating current system is solved through the following formula:
f＝K p Q wt +f (0)
wherein K is p The proportional coefficient of the reactive power controller of the net-structured fan; q (Q) wt Outputting reactive power for the grid-formed fan nodes; f (f) (0) The frequency is rated for the offshore wind power alternating current system.
The beneficial effects of the invention are as follows:
1. for the offshore wind power alternating current system based on the grid-structured fan and the diode rectification unit, the invention fills the blank of research in the aspect of steady state power flow calculation, provides the alternating current system stability judging method, and can provide a certain reference for future engineering design.
2. The invention has strong universality, is suitable for the offshore wind power alternating current system based on the grid-structured fans and the diode rectification units with various topological structures, and is also suitable for different conditions that the operation frequency of the offshore wind power alternating current system is low frequency, power frequency or medium frequency.
Drawings
FIG. 1 is a schematic diagram of a marine wind power grid-connected system based on a grid-structured fan and a diode rectification unit in an embodiment;
fig. 2 is a flowchart of the steady-state power flow calculation method of the present invention.
Detailed Description
The invention will now be described in further detail with reference to the drawings and specific examples, which are given for clarity of understanding and are not to be construed as limiting the invention.
As shown in fig. 1, the offshore wind power ac system in the present embodiment includes a mesh fan a, an ac sea cable E, a step-up transformer F, an ac filter D, a diode rectifying unit ac bus C, and a diode rectifying unit B; the net-structured fan A is connected to the diode rectifying unit alternating current bus C through the alternating current sea cable E and the step-up transformer F, the alternating current filter D is connected to the diode rectifying unit alternating current bus C, and the diode rectifying unit alternating current bus C is connected with the diode rectifying unit B;
as shown in fig. 1, the offshore wind power alternating current system in this embodiment has 33 nodes, wherein there are 30 grid-formed fan nodes, the grid-formed fan nodes are PQ nodes, and the grid-formed fan nodes are numbered 4 to 33; the alternating-current bus node of the diode rectifying unit is also called as a PCC node, the PCC node is a balance node, and the PCC node is numbered 1;
controlling all the net-structured fans to output reactive power Q under steady state wt And controlling the instantaneous frequency of all the net-structured fans in the steady state to be equal to the frequency of the offshore wind power alternating current systemA rate f;
as shown in fig. 2, the method for judging the stability of the offshore wind power alternating current system based on the tide algorithm comprises the following steps:
(1) Inputting system original data including line parameters and transformer parameters, and inputting rated frequency f of offshore wind power alternating current system (0) Forming an initial node admittance matrix Y (0) ；
(2) Initial value P of active power output by given network-structured fan node wtj (0) (j=n-s+1, n-s+2, …, n) to make the active power absorbed by the diode rectifying unit be initial value P r (0) The active power initial value P is output for all net-structured fans wtj (0) The sum of the voltage effective value and the initial value U of the PCC node is calculated 1 (0) The method comprises the steps of carrying out a first treatment on the surface of the The initial values of the voltage effective values of n nodes of the offshore wind power alternating current system are all taken as U i (0) ＝U 1 (0) (i=1, 2, …, n), and the initial values of the voltage phase angles of n nodes of the offshore wind power alternating current system are all theta i (0) ＝0°(i＝1,2,…,n)；
(3) Let the grid-structured fan node output reactive power Q wt The value interval of (C) is [ Q ] wtmin ,Q wtmax ]Initial value Q of upper and lower limits of interval wtmin (0) And Q wtmax (0) Taking-1 p.u. and 1p.u., respectively;
(4) Let the output reactive power of the grid-structured fan node be Q wtmin (0) Substituted into f (0) 、Y (0) 、U i (0) 、θ i (0) 、P wtj (0) And Q wtmin (0) Carrying out Newton-Laportson method power flow calculation to obtain active power P injected into PCC nodes from offshore wind power alternating current system w And reactive power Q w And the effective voltage value U of PCC node 1 Calculating reactive power Q absorbed by diode rectifying unit r And reactive power Q output by AC filter fil Calculating the surplus of reactive power injected into PCC nodes as Q sur1 (0) . Similarly, the output reactive power of the nodes of the net-structured fan is Q wtmax (0) Substituted intof (0) 、Y (0) 、U i (0) 、θ i (0) 、P wtj (0) And Q wtmax (0) Carrying out Newton-Laportson method power flow calculation to obtain reactive power surplus Q injected into PCC nodes sur2 (0) ；
(5) Setting the iteration number k=0;
(6) Let the grid-structured fan node output reactive power Q wt (k) For taking the average of the upper and lower limits of the interval, i.e. Q wt (k) ＝mean(Q wtmin (k) ，Q wtmax (k) ) (mean () represents taking the average), substituting f (k) 、Y (k) 、U i (k) 、θ i (k) 、P wtj (k) And Q wt (k) Carrying out Newton-Laportson method power flow calculation to obtain active power P injected into PCC nodes from offshore wind power alternating current system w (k+1) And reactive power Q w (k+1) And the effective voltage value U of PCC node 1 (k+1) The method comprises the steps of carrying out a first treatment on the surface of the Calculating reactive power Q absorbed by diode rectifying unit r (k +1) And reactive power Q output by AC filter fil (k+1) Calculating the surplus of reactive power injected into PCC nodes as Q sur (k+1) The method comprises the steps of carrying out a first treatment on the surface of the Calculating frequency f of offshore wind power alternating current system (k+1) And f (k+1) Node admittance matrix Y below (k+1) ；
(7) The error allowable value epsilon is 1 multiplied by 10 -6 If Q sur (k+1) Epsilon or Q wtmax (k) -Q wtmin (k) ) If epsilon is less than or equal to epsilon, outputting a tide calculation result and ending the cycle, otherwise, performing the next step;
(8) If Q sur (k+1) ×Q sur1 (k) Not less than 0, the output reactive power interval of the net-structured fan becomes [ mean (Q) wtmin (k) ,Q wtmax (k) ),Q wtmax (k) ]And Q is sur1 (k+1) ＝Q sur (k+1) The method comprises the steps of carrying out a first treatment on the surface of the If Q sur (k+1) ×Q sur1 (k) <0, the reactive power value interval becomes [ Q ] wtmin (k) ,mean(Q wtmin (k) ,Q wtmax (k) )]And Q is sur2 (k+1) ＝Q sur (k+1 ；
(9) Setting k=k+1, and returning to the step (6) for the next iteration;
(10) And if the circulation is finished, judging iteration convergence, namely stabilizing the offshore wind power alternating current system comprising the grid-structured fan and the diode rectifying unit.
Solving the effective value U of the PCC node voltage in the step (2) by the following equation 1 ：
Wherein P is r Active power absorbed by the diode rectifying unit; f is the frequency of an offshore wind power alternating current system; r is R dc The direct current resistor is arranged between the rectifying station and the inverting station; u (U) dc The direct current voltage of the inversion station; x is X t Commutating the reactance of the transformer for the diode rectifying unit; t is the transformation ratio of the diode rectifying unit converter transformer.
The reactive power Q absorbed by the diode rectifying unit is solved in the step (4) and the step (6) through the following formula r And reactive power Q output by AC filter fil ：
Q fil ＝2πfC 0 U 1 2
Wherein P is w Injecting active power of PCC nodes into the offshore wind power alternating current system; t is the transformation ratio of a diode rectifying unit converter transformer; u (U) dc For inverting the DC voltage of the station, U 1 The voltage effective value of the PCC node; f is the frequency of an offshore wind power alternating current system; c (C) 0 Is the fundamental wave equivalent capacitance of the alternating current filter.
The step (4) and the step(6) In, injection of reactive power surplus Q into PCC node sur Reactive power Q for injecting PCC nodes from offshore wind power alternating current system w Adding reactive power Q output by AC filter fil Subtracting the reactive power Q absorbed by the diode rectifying unit r 。
In the step (6), the frequency f of the offshore wind power alternating current system is solved through the following formula:
f＝K p Q wt +f (0)
wherein K is p The proportional coefficient of the reactive power controller of the net-structured fan; q (Q) wt Outputting reactive power for the grid-formed fan nodes; f (f) (0) The frequency is rated for the offshore wind power alternating current system.
The system parameters in this embodiment are shown in table 1:
TABLE 1
And calculating steady-state power flow of the offshore wind power alternating current system based on the grid-structured fans and the diode rectification units in MATLAB. The voltage calculation results of all nodes of the offshore wind power alternating current system are given in table 2, the injection power calculation results of all nodes of the offshore wind power alternating current system are given in table 3, the frequency calculation results of the offshore wind power alternating current system are given in table 4, and the effectiveness of the invention is demonstrated by the tide calculation results.
TABLE 2 voltage at each node of offshore wind power alternating current system
TABLE 3 injection power for each node of offshore wind A.C. system
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TABLE 4 offshore wind energy AC system frequency
What is not described in detail in this specification is prior art known to those skilled in the art.
Claims (5)
1. A stability judging method of an offshore wind power alternating current system based on a tide algorithm is characterized by comprising the following steps of: the offshore wind power alternating current system comprises a net-structured fan (A), an alternating current sea cable (E), a step-up transformer (F), an alternating current filter (D), a diode rectifying unit alternating current bus (C) and a diode rectifying unit (B); the net-structured fan (A) is connected to the diode rectifying unit alternating current bus (C) through an alternating current sea cable (E) and a step-up transformer (F), the alternating current filter (D) is connected to the diode rectifying unit alternating current bus (C), and the diode rectifying unit alternating current bus (C) is connected with the diode rectifying unit (B);
the offshore wind power alternating current system is provided with n nodes, wherein s net-structured fan nodes are PQ nodes, and the numbers of the net-structured fan nodes are n-s+1 to n; the alternating-current bus node of the diode rectifying unit is a PCC node, and the PCC node is numbered 1;
the grid-structured fans are controlled to output reactive power Q under the steady state of all the grid-structured fans wt And controlling the instantaneous frequency of all the net-structured fans in a steady state to be equal to the frequency f of the offshore wind power alternating current system;
the method for judging the stability of the offshore wind power alternating current system based on the tide algorithm comprises the following steps: carrying out tide iteration according to the unbalance amount of the reactive power of the alternating current bus of the diode rectifying unit, and specifically comprising the following steps:
s1: inputting system original data including line parameters and transformer parameters, and inputting rated frequency f of offshore wind power alternating current system (0) Forming an initial node admittance matrix Y (0) ；
S2: initial value P of active power output by given network-structured fan node wtj (0) (j=n-s+1, n-s+2, …, n) to make the active power absorbed by the diode rectifying unit be initial value P r (0) The active power initial value P is output for all net-structured fans wtj (0) The sum of the voltage effective value and the initial value U of the PCC node is calculated 1 (0) The method comprises the steps of carrying out a first treatment on the surface of the The initial values of the voltage effective values of n nodes of the offshore wind power alternating current system are all taken as U i (0) ＝U 1 (0) (i=1, 2, …, n), and the initial values of the voltage phase angles of n nodes of the offshore wind power alternating current system are all theta i (0) ＝0°(i＝1,2,…,n)；
S3: let the grid-structured fan node output reactive power Q wt The value interval of (C) is [ Q ] wtmin ,Q wtmax ]Initial value Q of upper and lower limits of interval wtmin (0) And Q wtmax (0) Taking-1 p.u. and 1p.u., respectively;
s4: let the output reactive power of the grid-structured fan node be Q wtmin (0) Substituted into f (0) 、Y (0) 、U i (0) 、θ i (0) 、P wtj (0) And Q wtmin (0) Carrying out Newton-Laporthelson method tide calculation to obtain offshore wind powerActive power P injected into PCC node by AC system w And reactive power Q w And the effective voltage value U of PCC node 1 Calculating reactive power Q absorbed by diode rectifying unit r And reactive power Q output by AC filter fil Calculating the surplus of reactive power injected into PCC nodes as Q sur1 (0) The method comprises the steps of carrying out a first treatment on the surface of the Similarly, the output reactive power of the nodes of the net-structured fan is Q wtmax (0) Substituted into f (0) 、Y (0) 、U i (0) 、θ i (0) 、P wtj (0) And Q wtmax (0) Carrying out Newton-Laportson method power flow calculation to obtain reactive power surplus Q injected into PCC nodes sur2 (0) ；
S5: setting the iteration number k=0;
s6: let the grid-structured fan node output reactive power Q wt (k) For taking the average of the upper and lower limits of the interval, i.e. Q wt (k) ＝mean(Q wtmin (k) ，Q wtmax (k) ) Substituted into f (k) 、Y (k) 、U i (k) 、θ i (k) 、P wtj (k) And Q wt (k) Carrying out Newton-Laportson method power flow calculation to obtain active power P injected into PCC nodes from offshore wind power alternating current system w (k+1) And reactive power Q w (k+1) And the effective voltage value U of PCC node 1 (k+1) The method comprises the steps of carrying out a first treatment on the surface of the Calculating reactive power Q absorbed by diode rectifying unit r (k+1) And reactive power Q output by AC filter fil (k+1) Calculating the surplus of reactive power injected into PCC nodes as Q sur (k+1) The method comprises the steps of carrying out a first treatment on the surface of the Calculating frequency f of offshore wind power alternating current system (k+1) And f (k+1) Node admittance matrix Y below (k+1) ；
S7: the error allowable value epsilon is 1 multiplied by 10 -6 If Q sur (k+1) Epsilon or Q wtmax (k) -Q wtmin (k) ) If epsilon is less than or equal to epsilon, outputting a tide calculation result and ending the cycle, otherwise, performing the next step;
s8: if Q sur (k+1) ×Q sur1 (k) Not less than 0, the output reactive power interval of the net-structured fan becomes [ mean (Q) wtmin (k) ,Q wtmax (k) ),Q wtmax (k) ]And Q is sur1 (k+1) ＝Q sur (k+1) The method comprises the steps of carrying out a first treatment on the surface of the If Q sur (k+1) ×Q sur1 (k) <0, the reactive power value interval becomes [ Q ] wtmin (k) ,mean(Q wtmin (k) ,Q wtmax (k) )]And Q is sur2 (k+1) ＝Q sur (k+1) ；
S9: setting k=k+1, and returning to S6 for the next iteration;
s10: and if the circulation is finished, judging iteration convergence, namely stabilizing the offshore wind power alternating current system comprising the grid-structured fan and the diode rectifying unit.
2. The method for judging the stability of the offshore wind power communication system based on the tide algorithm according to claim 1, wherein the method is characterized by comprising the following steps of: in the step S2, the effective value U of the voltage of the PCC node is solved by the following equation 1 ：
Wherein P is r Active power absorbed by the diode rectifying unit; f is the frequency of an offshore wind power alternating current system; r is R dc The direct current resistor is arranged between the rectifying station and the inverting station; u (U) dc The direct current voltage of the inversion station; x is X t Commutating the reactance of the transformer for the diode rectifying unit; t is the transformation ratio of the diode rectifying unit converter transformer.
3. The method for judging the stability of the offshore wind power communication system based on the tide algorithm according to claim 1, wherein the method is characterized by comprising the following steps of: the reactive power Q absorbed by the diode rectifying unit is solved in the step S4 and the step S6 through the following formula r And exchange withReactive power Q output by filter fil ：
Wherein P is w Injecting active power of PCC nodes into the offshore wind power alternating current system; t is the transformation ratio of a diode rectifying unit converter transformer; u (U) dc For inverting the DC voltage of the station, U 1 The voltage effective value of the PCC node; f is the frequency of an offshore wind power alternating current system; c (C) 0 Is the fundamental wave equivalent capacitance of the alternating current filter.
4. The method for judging the stability of the offshore wind power communication system based on the tide algorithm according to claim 1, wherein the method is characterized by comprising the following steps of: in the steps S4 and S6, the reactive power surplus Q of the PCC node is injected sur Reactive power Q for injecting PCC nodes from offshore wind power alternating current system w Adding reactive power Q output by AC filter fil Subtracting the reactive power Q absorbed by the diode rectifying unit r 。
5. The method for judging the stability of the offshore wind power communication system based on the tide algorithm according to claim 1, wherein the method is characterized by comprising the following steps of: in the step S6, the frequency f of the offshore wind power alternating current system is solved through the following formula:
f＝K p Q wt +f (0)
wherein K is p The proportional coefficient of the reactive power controller of the net-structured fan; q (Q) wt Outputting reactive power for the grid-formed fan nodes; f (f) (0) The frequency is rated for the offshore wind power alternating current system.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109787239A (en) * | 2019-02-27 | 2019-05-21 | 西安交通大学 | Tide model exchanges the alternating iteration tidal current computing method and system of combined hybrid system with multi-frequency |
| CN113162048A (en) * | 2021-01-12 | 2021-07-23 | 河南理工大学 | Load flow calculation method of multi-terminal flexible direct current grid-connected offshore wind power system |
| CN114640141A (en) * | 2022-05-17 | 2022-06-17 | 浙江大学 | Network-building type fan control method for offshore wind power diode rectification unit sending-out system |
| CN114914955A (en) * | 2022-07-11 | 2022-08-16 | 广东电网有限责任公司佛山供电局 | Active and reactive joint optimization scheduling method and system for microgrid |
| US20220393473A1 (en) * | 2019-10-30 | 2022-12-08 | Zhejiang University | Offshore wind farm low-frequency alternating-current uncontrolled rectification electric power transmission system |
| US20230028397A1 (en) * | 2022-05-17 | 2023-01-26 | Zhejiang University | Grid-forming wind turbine control method for diode rectifier unit-based offshore wind power transmission system |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109787239A (en) * | 2019-02-27 | 2019-05-21 | 西安交通大学 | Tide model exchanges the alternating iteration tidal current computing method and system of combined hybrid system with multi-frequency |
| US20220393473A1 (en) * | 2019-10-30 | 2022-12-08 | Zhejiang University | Offshore wind farm low-frequency alternating-current uncontrolled rectification electric power transmission system |
| CN113162048A (en) * | 2021-01-12 | 2021-07-23 | 河南理工大学 | Load flow calculation method of multi-terminal flexible direct current grid-connected offshore wind power system |
| CN114640141A (en) * | 2022-05-17 | 2022-06-17 | 浙江大学 | Network-building type fan control method for offshore wind power diode rectification unit sending-out system |
| US20230028397A1 (en) * | 2022-05-17 | 2023-01-26 | Zhejiang University | Grid-forming wind turbine control method for diode rectifier unit-based offshore wind power transmission system |
| CN114914955A (en) * | 2022-07-11 | 2022-08-16 | 广东电网有限责任公司佛山供电局 | Active and reactive joint optimization scheduling method and system for microgrid |
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