CN104809340A - Method for quickly calculating operating point of multi-end flexible direct-current power transmission system - Google Patents

Abstract

The invention discloses a method for quickly calculating an operating point of a multi-end flexible direct-current power transmission system. Characteristic equations of various current conversion stations under different control modes are built, a building method of an admittance matrix is given according to direct-current network topology of the multi-end flexible direct-current power transmission system, the characteristic equation of each type current conversion station under corresponding control mode is combined to serve as a superaddition equation, and the solution of the equation set is calculated by an iterative method; if the solution does not exist, the control model of the corresponding conversion station is corrected according to a dual-level priority table, so that the characteristic equation of each conversion station is corrected, the group of the equation is re-solved until an effective solution is obtained to serve as the operating point of the flexible direct-current system. The method has the beneficial effects that the operating point of the multi-end flexible direct-current power transmission system can be quickly calculated in real time by few alternating-current grids real time information, and reliable reference to the scheduling and decision of the multi-end flexible direct-current power transmission system is provided.

Description

A kind of quick calculation method of Multi-end flexible direct current transmission system operating point

Technical field

The present invention relates to electric field, particularly relate to a kind of quick calculation method for Multi-end flexible direct current transmission system operating point.

Background technology

Under the multiple pressure that the in short supply and environmental pollution of fossil energy increasingly sharpens, the renewable energy power generations such as wind energy are developed by leaps and bounds, and the exploitation of especially extensive offshore wind farms has become the megatrend of Wind Power Utilization in the world.But because marine wind electric field is away from seashore, and the electrical network on seashore is mostly rack end, and seashore electrical network is comparatively weak, therefore, offshore wind farm is grid-connected creates very large impact to connected grid stability and the quality of power supply etc.Meanwhile, for passive networks such as marine isolated island and drilling platform, because ac cable is by the restriction of excessive capacity current, the remote power-feeding of these passive networks cannot be realized.

Based on above two kinds of factors, Multi-end flexible direct current transmission mode becomes marine wind electric field and the grid-connected best mode of marine passive network, and therefore its correlative study receives and pays close attention to widely.In order to realize real-time, fast dispatch and the control of Multi-end flexible direct current transmission system, a kind of method that can calculate Multi-end flexible direct current transmission system operating point quickly and accurately must be had.

In order to ensure real-time, the fast dispatch of Multi-end flexible direct current transmission system, need the quick calculation method developing a kind of Multi-end flexible direct current transmission system operating point in a hurry.

Summary of the invention

For solving the deficiency that prior art exists, the invention discloses a kind of quick calculation method of Multi-end flexible direct current transmission system operating point, being calculated the operating point of Multi-end flexible direct current transmission system by a small amount of AC network information fast in real time.The invention provides the characteristic equation of dissimilar current conversion station under different control model, propose a kind of quick calculation method of Multi-end flexible direct current transmission system operating point, and give realization flow and the embodiment of these computing method.

For achieving the above object, concrete scheme of the present invention is as follows:

A kind of Multi-end flexible direct current transmission system, comprise management and running central control system, described management and running central control system is by the control system communication of communication network and at least one current conversion station, described management and running central control system comprises advance data server, data server, apps server, SCADA server and at least one workstation, the control system of described current conversion station comprises current conversion station controller, described current conversion station controller by the LAN (Local Area Network) of current conversion station respectively with station gps clock, switching value information acquisition module, AC information acquisition module and a-c cycle information acquisition module.SCADA (Supervisory ControlAnd Data Acquisition) system, i.e. data acquisition and supervisor control.

A quick calculation method for Multi-end flexible direct current transmission system operating point, comprises the following steps:

Step one: set up the characteristic equation of dissimilar current conversion station under different control model;

Step 2: each current conversion station, by its data collection station real-time data collection, stores DC line parameter in the SCADA system database of flexible direct current power transmission system; According to quantity of state information and the DC line parameter of current conversion station Real-time Collection, determine topological structure and the connected mode of current DC network, build the admittance matrix of DC network;

Step 3: the control model of each current conversion station is all initialized as normal control mode;

Step 4: each current conversion station characteristic equation in the normal control mode as additional equation, and in conjunction with the admittance matrix of DC network, constructs the system of equations be with and solved, and utilizes process of iteration to be solved; If separate effectively, then this solution is the current operating point of Multi-end flexible direct current transmission system, if it is invalid to separate, then need to revise control model, after control model correction, reconfigure the characteristic equation of current conversion station, thus build new system of equations, and solve and judge the validity of solution, until find efficient solution, be current operating point.

In described step one, the type of current conversion station is divided into constant DC voltage control current conversion station, auxiliary direct current pressure-controlled current conversion station, determines active power controller current conversion station, tape jam controls determines the wind energy turbine set current conversion station that active power controller current conversion station, wind energy turbine set current conversion station and tape jam control.

The control model of described constant DC voltage control current conversion station is divided into: DC voltage control pattern, rectification current-limit mode and inversion current-limit mode, and rectification current-limit mode and inversion current-limit mode are the active current current-limit mode of current conversion station.

The control model of described auxiliary direct current pressure-controlled current conversion station is divided into: voltage drop control model, rectification current-limit mode and inversion current-limit mode.

Described control model of determining active power controller current conversion station is divided into: active power controller pattern, rectification current-limit mode and inversion current-limit mode.

The control model of determining active power controller current conversion station that described tape jam controls is divided into: determine active power controller pattern, rectification decline control model, inversion decline control model, rectification current-limit mode and inversion current-limit mode.

The control model of described wind energy turbine set current conversion station is divided into: meritorious frequency decrease control model and rectification current-limit mode.

The wind energy turbine set current conversion station control model that described tape jam controls is divided into: meritorious frequency decrease control model, voltage drop control model and rectification current-limit mode.

In described step 2, real-time data collection comprises the switching value of current conversion station, AC voltage, the frequency of wind energy turbine set current conversion station and gps time information.

The characteristic equation of described dissimilar current conversion station under different control model is specially: the relational expression providing dissimilar current conversion station DC voltage and DC current under different control model, and gives the scope of two quantity of states under the different control model of dissimilar current conversion station.

In described step 3, the control model of each current conversion station is all initialized as normal control mode, be specially: constant DC voltage control current conversion station, auxiliary direct current pressure-controlled current conversion station adopt DC voltage control pattern, voltage drop control model respectively, the active power controller current conversion station of determining determining active power controller current conversion station and tape jam control is in active power controller pattern, and the wind energy turbine set current conversion station that wind energy turbine set current conversion station and tape jam control is in meritorious frequency decrease control model.

In described step 4, the validity of solution, when differentiating, if the quantity of state of all current conversion stations is all in the scope of corresponding modes, is then separated effectively, is current operating point; If when at least one quantity of state of any one or more current conversion station is not in the scope of the corresponding control model of current conversion station, it is invalid to separate, then need to revise control model, after control model correction, reconfigure the characteristic equation of current conversion station, thus build new system of equations, and solve and judge the validity of solution, until find efficient solution, be current operating point.

In described step 4, when control model is revised, by traveling through current solution of equations, determine the out-of-limit variable of out-of-limit current conversion station, successively by quantity of state priority list and current conversion station priority list determine to wait to revise current conversion station wait revise current conversion station quantity of state, to the out-of-limit situation according to the corresponding control model of current conversion station and positive status amount to be repaired, revise the control model of current conversion station.

In described step 4, the detailed flow process of control model correction is as follows:

A. travel through current solution of equations, judge the DC voltage U of all current conversion stations _dcwith DC current I _dc, find out all out-of-limit U _dcand I _dc; Out-of-limitly refer to the quantity of state scope exceeding this current conversion station and limit under corresponding control model;

B. according to quantity of state priority list and all out-of-limit quantity of states, determine, as the quantity of state type revising foundation, to be positive status amount type to be repaired; Quantity of state priority list is for determining the priority factor of DC voltage and DC current;

C. according to current conversion station priority list and the out-of-limit current conversion station of all positive status amount types to be repaired, current conversion station to be revised is determined; Current conversion station priority list is for determining the priority factor of dissimilar current conversion station;

D. revising the control model of current conversion station and the out-of-limit variable of positive status amount to be repaired according to waiting, revising the control model of this current conversion station.If positive status amount to be repaired exceeds the scope of present control mode, enter the scope of adjacent control model, be then modified to its adjacent control model.

The present invention completes a kind of computing method for calculating Multi-end flexible direct current transmission system operating point fast, to derive the characteristic equation of dissimilar current conversion station under different control model, propose the quick calculation process of steady-state operation point, establish the control model modification method based on control model priority list method, and finally propose the embodiment of this moving calculation method.The present invention is the operating point that can be calculated Multi-end flexible direct current transmission system by a small amount of AC network real-time information fast, in real time, for the scheduling of Multi-end flexible direct current transmission system and decision-making provide reliable reference.

Beneficial effect of the present invention:

1. for calculating Multi-end flexible direct current transmission system operating point fast, in real time.

2. for providing reliable reference for the Real-Time Scheduling of Multi-end flexible direct current transmission system.

3. for determining the control model of each current conversion station of Multi-end flexible direct current transmission system under different grid conditions.

4. for calculating the voltage of Multi-end flexible direct current transmission system under different grid conditions, electric current and power.

5. for calculating and the planning of the Multi-end flexible direct current transmission system method of operation.

Accompanying drawing explanation

Fig. 1 is the flow process of operating point quick calculation method;

Fig. 2 is the control model modification method based on twin-stage priority list;

Fig. 3 is the constructing plan of operation control system.

Embodiment:

Below in conjunction with accompanying drawing, the present invention is described in detail:

The application sets up the characteristic equation of dissimilar current conversion station under different control model, the method for building up of its admittance matrix is provided according to the DC network topology of Multi-end flexible direct current transmission system, in conjunction with the characteristic equation of each current conversion station under its corresponding control model as additional equation, process of iteration is utilized to calculate this solution of equations.Exist if separate, then this solution is the operating point of Multi-end flexible direct current transmission system; If solution does not exist, then according to the corresponding current conversion station control model of twin-stage priority list correction, thus revise the characteristic equation of each current conversion station, again solve the group of this equation, so repeat, terminate until calculate.

(1) type of current conversion station can be divided into constant DC voltage control current conversion station, auxiliary direct current pressure-controlled current conversion station, determines active power controller current conversion station, tape jam controls determines the wind energy turbine set current conversion station that active power controller current conversion station, wind energy turbine set current conversion station and tape jam control.Below according to current conversion station type, provide the characteristic equation under its corresponding control model respectively.

A. the control model of constant DC voltage control current conversion station can be divided into two kinds: DC voltage control pattern, rectification current-limit mode and inversion current-limit mode.Rectification current-limit mode and inversion current-limit mode are the active current current-limit mode of current conversion station, and its difference is that the former enters current-limit mode because the active current that flows to DC network is excessive, the latter because of the active current flowed out from DC network excessive.The characteristic equation of this current conversion station is:

Rectification current-limit mode: $I_{\mathrm{dc}}=\frac{u_{\mathrm{ac}}\mathrm{\α}{P}_N}{U_{\mathrm{dc}}},I_{\mathrm{dc}}\≥I_{\mathrm{dcH}}$

DC voltage control pattern: U _dc=U _dc*, I _dcL< I _dc< I _dcH

Inversion current-limit mode: $I_{\mathrm{dc}}=-\frac{u_{\mathrm{ac}}\mathrm{\&alpha;}{P}_N}{U_{\mathrm{dc}}},I_{\mathrm{dc}}\&le;I_{\mathrm{dcL}}$

Wherein: U _dc, I _dcbe respectively the DC voltage of current conversion station, electric current, U _dc*for direct voltage reference value, u _acfor the AC voltage of current conversion station, α is the Overflow RateHT of active current, P _nfor the specified meritorious capacity of transverter, I _dcH, I _dcLbe respectively DC current threshold value when current conversion station is cut into rectification current-limit mode, inversion current-limit mode.

B. the control model of auxiliary direct current pressure-controlled current conversion station can be divided into two kinds: voltage drop control model, rectification current-limit mode and inversion current-limit mode.The control strategy of the type current conversion station is that voltage drop controls under normal circumstances, coordinates, jointly realize the Control of Voltage of DC network with constant DC voltage control current conversion station.The characteristic equation of this current conversion station is:

Rectification current-limit mode: $I_{\mathrm{dc}}=\frac{u_{\mathrm{ac}}\mathrm{\&alpha;}{P}_N}{U_{\mathrm{dc}}},I_{\mathrm{dc}}\&GreaterEqual;I_{\mathrm{dcH}}$

Voltage drop control model: U _dc=k _ass(U _dc-U _dc*), I _dcL< I _dc< I _dcH

Inversion current-limit mode: $I_{\mathrm{dc}}=-\frac{u_{\mathrm{ac}}\mathrm{\&alpha;}{P}_N}{U_{\mathrm{dc}}},I_{\mathrm{dc}}\&le;I_{\mathrm{dcL}}$

Wherein: k _assfor the Slope Parameters of auxiliary direct current pressure-controlled, other parameters are the same.

The control model of c. determining active power controller current conversion station can be divided into two kinds: active power controller pattern, rectification current-limit mode and inversion current-limit mode.The characteristic equation of this current conversion station is:

Rectification current-limit mode: $I_{\mathrm{dc}}=\frac{u_{\mathrm{ac}}\mathrm{\&alpha;}{P}_N}{U_{\mathrm{dc}}},I_{\mathrm{dc}}\&GreaterEqual;I_{\mathrm{dcH}}$

Active power controller pattern: $I_{\mathrm{dc}}=\frac{P_{*}}{U_{\mathrm{dc}}},I_{\mathrm{dcL}}<I_{\mathrm{dc}}<I_{\mathrm{dcH}}$

Inversion current-limit mode: $I_{\mathrm{dc}}=-\frac{u_{\mathrm{ac}}\mathrm{\&alpha;}{P}_N}{U_{\mathrm{dc}}},I_{\mathrm{dc}}{\&le;I}_{\mathrm{dcL}}$

Wherein: P _*for the active power reference value of active power controller, other parameters are the same.

D. the control model of determining active power controller current conversion station that tape jam controls can be divided into two kinds: determine active power controller pattern, rectification decline control model, inversion decline control model, rectification current-limit mode and inversion current-limit mode.Wherein, rectification decline control model and inversion decline control model are the fail-safe control strategy of the type current conversion station under damage.The characteristic equation of this current conversion station is:

Rectification current-limit mode: $I_{\mathrm{dc}}=\frac{u_{\mathrm{ac}}\mathrm{\&alpha;}{P}_N}{U_{\mathrm{dc}}},I_{\mathrm{dc}}\&GreaterEqual;I_{\mathrm{dcH}}$

Rectification decline control model: $I_{\mathrm{dc}}=k_{\mathrm{apc}}(U_{\mathrm{dc}}-U_{\mathrm{dcL}})+\frac{P_{*}}{U_{\mathrm{dcL}}},U_{\mathrm{dc}}<U_{\mathrm{dcL}},\frac{p_{*}}{U_{\mathrm{dcL}}}\&le;I_{\mathrm{dc}}<I_{\mathrm{dcH}}$

Active power controller pattern: $I_{\mathrm{dc}}=\frac{P_{*}}{U_{\mathrm{dc}}},U_{\mathrm{dcL}}\&le;U_{\mathrm{dc}}<U_{\mathrm{dcH}},\frac{P_{*}}{U_{\mathrm{dcH}}}\&le;I_{\mathrm{dc}}<\frac{P_{*}}{U_{\mathrm{dcL}}}$

Inversion decline control model: $I_{\mathrm{dc}}=k_{\mathrm{apc}}(U_{\mathrm{dc}}-U_{\mathrm{dcH}})+\frac{P_{*}}{U_{\mathrm{dcH}}},U_{\mathrm{dc}}\&GreaterEqual;U_{\mathrm{dcH}},I_{\mathrm{dcL}}<I_{\mathrm{dc}}<\frac{p_{*}}{U_{\mathrm{dcH}}}$

Inversion current-limit mode: $I_{\mathrm{dc}}=-\frac{u_{\mathrm{ac}}\mathrm{\&alpha;}{P}_N}{U_{\mathrm{dc}}},I_{\mathrm{dc}}\&le;I_{\mathrm{dcH}}$

Wherein: k _apcfor determining the Slope Parameters of active power controller current conversion station fail-safe control, U _dcH, U _dcLbe respectively DC current threshold value when current conversion station is cut into inversion decline control model, rectification decline control model by active power controller pattern, other parameters are the same.

E. the control model of wind energy turbine set current conversion station can be divided into two kinds: meritorious frequency decrease control model and rectification current-limit mode.Meritorious frequency decrease control model is namely according to the real-time frequency f of wind energy turbine set _wfthe active power command value of wind energy turbine set current conversion station is controlled with decline control characteristic.The characteristic equation of this current conversion station is:

Rectification current-limit mode: $I_{\mathrm{dc}}=\frac{u_{\mathrm{ac}}\mathrm{\&alpha;}{P}_N}{U_{\mathrm{dc}}},I_{\mathrm{dc}}\&GreaterEqual;I_{\mathrm{dcH}}$

Meritorious frequency decrease control model: $I_{\mathrm{dc}}=\frac{f_{\mathrm{wf}}-f_N+k_{f1}{P}_N}{k_{f1}{U}_{\mathrm{dc}}},I_{\mathrm{dc}}<I_{\mathrm{dcH}}$

Wherein, k _f1for wind energy turbine set current conversion station gain merit frequency decrease control Slope Parameters, f _nfor the rated frequency of wind farm network, other parameters are the same.

F. the wind energy turbine set current conversion station control model that tape jam controls can be divided into three kinds: meritorious frequency decrease control model, voltage drop control model and rectification current-limit mode.Voltage drop control model is the fail-safe control pattern of wind energy turbine set current conversion station, for flowing into the performance number of DC network when straight-flow system overtension limit wind energy turbine set, prevents the deterioration of overvoltage of direct current situation.The characteristic equation of this current conversion station is:

Rectification current-limit mode: $I_{\mathrm{dc}}=\frac{u_{\mathrm{ac}}\mathrm{\&alpha;}{P}_N}{U_{\mathrm{dc}}},I_{\mathrm{dc}}\&GreaterEqual;I_{\mathrm{dcH}}$

Meritorious frequency decrease control model: $I_{\mathrm{dc}}=\frac{f_{\mathrm{wf}}-f_N+k_{f1}{P}_N}{k_{f1}{U}_{\mathrm{dc}}},U_{\mathrm{dc}}<U_{\mathrm{dcH}},I_{\mathrm{dch}}\&le;I_{\mathrm{dc}}<I_{\mathrm{dcH}}$

Voltage drop control model: I _dc=k _f2(U _dc-U _dcH)+I _dch, U _dc>=U _dcH, I _dc< I _dch

Wherein, k _f2for the Slope Parameters of wind energy turbine set current conversion station voltage drop control model, I _dchfor wind energy turbine set current conversion station is U in DC voltage _dcHtime corresponding DC current values.

(2) as shown in figures 1 and 3, propose the flow process that Multi-end flexible direct current transmission system operating point calculates fast, and this flow process be divided into following step:

One. the Real-time Collection of data message.Need the quantity of information gathered to comprise the frequency of the switching value of current conversion station, AC voltage and wind energy turbine set current conversion station, meanwhile, for ensureing that account form is a certain correct time section, the information of Real-time Collection also should comprise the gps time information of current conversion station.The quantity of information gathered is that each current conversion station is gathered by its data collection station, gps time information one piece packing is also sent to the advance data server at flexible direct current power transmission system management and running center by the information of Real-time Collection by telecommunications network, carry out preliminary examination and verification to data.Meanwhile, realize program that operating point calculates fast or module and transmit DC line parameter to the SCADA system request at flexible direct current power transmission system management and running center, and then get data from data server.

Two. the foundation of DC network admittance matrix.According to the topological structure of DC network and the switching value information of current conversion station, set up the admittance matrix of DC network.The parameter of each bar DC line is depended in the foundation of this matrix on the one hand, and another aspect also depends on the situation that puts into operation of each current conversion station.DC line parameter can directly read from the SCADA system database of flexible direct current power transmission system, and the situation that puts into operation of each current conversion station then depends on the Real-Time Switch amount information of current conversion station.

Three. the selection of initial calculation running status.The control model of each current conversion station is all initialized as normal control mode.Because Multi-end flexible direct current transmission system most of time is in normal operating condition, and under normal operating condition, the computing method of Multi-end flexible direct current transmission system are determined, therefore, select normal operating condition to be initial calculation running status.In this condition, constant DC voltage control current conversion station, auxiliary direct current pressure-controlled current conversion station adopt DC voltage control pattern, voltage drop control model respectively, the active power controller current conversion station of determining determining active power controller current conversion station and tape jam control is in active power controller pattern, and the wind energy turbine set current conversion station that wind energy turbine set current conversion station and tape jam control is in meritorious frequency decrease control model.

Four. form system of equations in conjunction with admittance matrix and each current conversion station characteristic equation in the normal control mode, utilize this solution of equations of solution by iterative method.The most high reps of this system of equations is secondary, therefore, it is possible to meet the rapidity and requirement of real-time that calculate.

Five. the distinguishing validity of solution.According to solution of equations, i.e. the DC voltage U of each current conversion station _dcwith DC side electric current I _dcin corresponding scope, whether judge the validity of this solution.Separating effective adequate condition is all DC voltage U _dcwith DC current I _dcin scope all under its corresponding control model.

Six. if separate effectively, then this solution is the current operating point of Multi-end flexible direct current transmission system.If it is invalid to separate, then revise the control model of corresponding current conversion station, repeat step 4, five, until obtain efficient solution.

(3), in control model modification method as shown in Figure 2, detailed flow process is as follows:

1. travel through current solution of equations, judge the DC voltage U of all current conversion stations _dcwith DC current I _dc, find out all out-of-limit U _dcand I _dc.

2., according to quantity of state priority list and all out-of-limit quantity of states, determine, as the quantity of state type revising foundation, to be positive status amount type to be repaired.

3., according to current conversion station priority list and the out-of-limit current conversion station of all positive status amount types to be repaired, determine current conversion station to be revised.

4. revising the control model of current conversion station and the out-of-limit situation of positive status amount to be repaired according to waiting, revising the control model of this current conversion station.

(4) as shown in Figure 2 based in the current conversion station control model modification method of twin-stage priority list, quantity of state priority list is as shown in table 1, and current conversion station priority list is as shown in table 2.Priority factor is lower, represents that priority is higher.

Table 1 quantity of state priority list

Quantity of state type	Priority factor	Quantity of state type	Priority factor
				DC current	1	DC voltage	2

Table 2 current conversion station priority list

Current conversion station type	Priority factor	Current conversion station type	Priority factor
				Constant DC voltage control current conversion station	1	What tape jam controlled determines active power controller current conversion station	4
Auxiliary direct current pressure-controlled current conversion station	2	Wind energy turbine set current conversion station	5
				Determine active power controller current conversion station	3	With the wind energy turbine set current conversion station that tape jam controls	6

(5) constructing plan of operation control system as shown in Figure 3.Multi-end flexible direct current transmission system decision center is management and running central control system, the calculating of primary responsibility straight-flow system operating point; Implementation unit is the controller of current conversion station, the control of the interior unit of real-time information collection and station in primary responsibility station.In management and running central control system, the pre-service of advance data network in charge real-time information and screening; Data server is responsible for storing SCADA data and other significant datas; Apps server is mainly used to the storage and the operation that realize the aid decision making program such as system software and operating point calculation procedure; SCADA server is mainly used to realize SCADA system; Workstation is mainly the man-machine interface of management and running personnel and data base administrator.Functionally, switching value information acquisition module mainly gathers the information of AC and DC side Switch equipment to the Real-time Collection of current conversion station controller; AC information acquisition module mainly gathers transverter exit potential or AC busbar voltage information; A-c cycle information acquisition module mainly gathers transverter AC bus frequency information; Gps clock module of standing is used for for station provides precise time to be decided to be entirely.For communication network aspect, adopt local area network communication mode in current conversion station, between management and running center and current conversion station, adopt the network communication mode based on ICP/IP protocol.

By reference to the accompanying drawings the specific embodiment of the present invention is described although above-mentioned; but not limiting the scope of the invention; one of ordinary skill in the art should be understood that; on the basis of technical scheme of the present invention, those skilled in the art do not need to pay various amendment or distortion that creative work can make still within protection scope of the present invention.

Claims (9)

1. a quick calculation method for Multi-end flexible direct current transmission system operating point, is characterized in that, comprises the following steps:

Step one: set up the characteristic equation of dissimilar current conversion station under different control model;

Step 2: each current conversion station, by its data collection station real-time data collection, stores DC line parameter in the SCADA system database of flexible direct current power transmission system; According to quantity of state information and the DC line parameter of current conversion station Real-time Collection, determine topological structure and the connected mode of current DC network, build the admittance matrix of DC network;

Step 3: the control model of each current conversion station is all initialized as normal control mode;

Step 4: each current conversion station characteristic equation in the normal control mode as additional equation, and in conjunction with the admittance matrix of DC network, constructs the system of equations be with and solved, and utilizes process of iteration to be solved; If separate effectively, then this solution is the current operating point of Multi-end flexible direct current transmission system, if it is invalid to separate, then need to revise control model, after control model correction, reconfigure the characteristic equation of current conversion station, thus build new system of equations, and solve and judge the validity of solution, until find efficient solution, be current operating point.

2. the quick calculation method of a kind of Multi-end flexible direct current transmission system operating point as claimed in claim 1, it is characterized in that, in described step one, the type of current conversion station is divided into constant DC voltage control current conversion station, auxiliary direct current pressure-controlled current conversion station, determines active power controller current conversion station, tape jam controls determines the wind energy turbine set current conversion station that active power controller current conversion station, wind energy turbine set current conversion station and tape jam control.

3. the quick calculation method of a kind of Multi-end flexible direct current transmission system operating point as claimed in claim 2, it is characterized in that, the control model of described constant DC voltage control current conversion station is divided into: DC voltage control pattern, rectification current-limit mode and inversion current-limit mode, and rectification current-limit mode and inversion current-limit mode are the active current current-limit mode of current conversion station;

The control model of described auxiliary direct current pressure-controlled current conversion station is divided into: voltage drop control model, rectification current-limit mode and inversion current-limit mode;

Described control model of determining active power controller current conversion station is divided into: active power controller pattern, rectification current-limit mode and inversion current-limit mode.

4. the quick calculation method of a kind of Multi-end flexible direct current transmission system operating point as claimed in claim 2, is characterized in that, the control model of described wind energy turbine set current conversion station is divided into: meritorious frequency decrease control model and rectification current-limit mode;

The control model of determining active power controller current conversion station that described tape jam controls is divided into: determine active power controller pattern, rectification decline control model, inversion decline control model, rectification current-limit mode and inversion current-limit mode;

The wind energy turbine set current conversion station control model that described tape jam controls is divided into: meritorious frequency decrease control model, voltage drop control model and rectification current-limit mode.

5. the quick calculation method of a kind of Multi-end flexible direct current transmission system operating point as claimed in claim 1, it is characterized in that, in described step 2, real-time data collection comprises the switching value of current conversion station, AC voltage, the frequency of wind energy turbine set current conversion station and gps time information.

6. the quick calculation method of a kind of Multi-end flexible direct current transmission system operating point as claimed in claim 1, it is characterized in that, the characteristic equation of described dissimilar current conversion station under different control model is specially: the relational expression providing dissimilar current conversion station DC voltage and DC current under different control model, and gives the scope of two quantity of states under the different control model of dissimilar current conversion station.

7. the quick calculation method of a kind of Multi-end flexible direct current transmission system operating point as claimed in claim 1, it is characterized in that, in described step 3, the control model of each current conversion station is all initialized as normal control mode, be specially: constant DC voltage control current conversion station, auxiliary direct current pressure-controlled current conversion station adopts DC voltage control pattern respectively, voltage drop control model, the active power controller current conversion station of determining determining active power controller current conversion station and tape jam control is in active power controller pattern, the wind energy turbine set current conversion station that wind energy turbine set current conversion station and tape jam control is in meritorious frequency decrease control model.

8. the quick calculation method of a kind of Multi-end flexible direct current transmission system operating point as claimed in claim 1, is characterized in that, in described step 4, the validity of separating is when differentiating, if the quantity of state of all current conversion stations is all in the scope of corresponding modes, then separates effectively, be current operating point; If when at least one quantity of state of any one or more current conversion station is not in the scope of the corresponding control model of current conversion station, it is invalid to separate, then need to revise control model, after control model correction, reconfigure the characteristic equation of current conversion station, thus build new system of equations, and solve and judge the validity of solution, until find efficient solution, be current operating point.

9. the quick calculation method of a kind of Multi-end flexible direct current transmission system operating point as described in claim 1 or 8, is characterized in that, in described step 4, the detailed flow process of control model correction is as follows:

A. travel through current solution of equations, judge the DC voltage U of all current conversion stations _dcwith DC current I _dc, find out all out-of-limit U _dcand I _dc;

B. according to quantity of state priority list and all out-of-limit quantity of states, determine, as the quantity of state type revising foundation, to be positive status amount type to be repaired; Quantity of state priority list is for determining the priority factor of DC voltage and DC current;

C. according to current conversion station priority list and the out-of-limit current conversion station of all positive status amount types to be repaired, current conversion station to be revised is determined; Current conversion station priority list is for determining the priority factor of dissimilar current conversion station;

D. revising the control model of current conversion station and the out-of-limit variable of positive status amount to be repaired according to waiting, revising the control model of this current conversion station.