CN103701140B - Improve the dynamic reactive optimization method for subsequent use of alternating current-direct current electrical network Transient Voltage Stability - Google Patents

Abstract

The invention provides a kind of dynamic reactive optimization method for subsequent use improving alternating current-direct current electrical network Transient Voltage Stability, comprise the following steps: critical failure set and the key node set of determining to affect power system voltage transient stability, and successively node is sorted; Idle the exerting oneself of adjustment dynamic passive compensation equipment, and calculate the trace sensitivity of dynamic passive compensation equipment; M dynamic passive compensation equipment is sorted, and calculates the weight coefficient of dynamic passive compensation equipment interior joint; Calculate dynamic passive compensation place capacity, set up dynamic reactive Optimized model for subsequent use, and solve this dynamic reactive Optimized model for subsequent use.The present invention provides aid decision support for improving multi-feed HVDC electrical network Transient Voltage Stability level, to the extensive alternating current-direct current electrical network Transient Voltage Stability nargin of raising, set up give, power transm ission corridor unimpeded between receiving end, promote AC-HVDC passage conveying capacity, improve economy and the quality of power supply of operation of power networks, be all significant.

Description

Improve the dynamic reactive optimization method for subsequent use of alternating current-direct current electrical network Transient Voltage Stability

Technical field

The present invention relates to a kind of optimization method, specifically relate to a kind of dynamic reactive optimization method for subsequent use improving alternating current-direct current electrical network Transient Voltage Stability.

Background technology

Direct current transportation has at a distance, the advantage of Large Copacity transmission, and regulating and controlling is flexible, is thus used to the interconnected of large scale electric network, one of prevailing transmission passage becoming " transferring electricity from the west to the east ".Along with the advance to perfect order that extra-high voltage grid is built, to 2015, ultra high voltage and transregional, transnational electrical network transmission capacity are 2.61 hundred million kilowatts, ultra high voltage AC and DC assume responsibility for the electric power transfer of more than 80%, extra-high voltage grid ability to transmit electricity comparatively ultrahigh voltage AC and DC improves greatly, and the ability of communication channel being born to power flow transfer is had higher requirement." three China " receiving end electrical network powered ratio from district is powered higher than regular meeting by AC-HVDC path partially by accounting for 32% of regional total load, particularly East China.Spy/super high voltage direct current electricity transmission system concentrates drop point " three China " receiving end electrical network, and the direct current system sum of drop point East China reaches 9 times, forms direct current group.Electrical distance between the direct current drop point of East China Power Grid, between direct current drop point and alternating current interconnection is comparatively near, and the fault in ac transmission system therefore near the catastrophe failure of AC-DC tie line and direct current drop point all can produce larger impact to receiving end electrical network.For the receiving end electrical network of Ac/dc Power Systems, the factor such as grid structure, load level, power distribution, direct current drop point, hvdc control mode of receiving end electrical network all can have an impact to the voltage stability of system.Along with continuous increase and the load center feature increasingly significant of electrical network scale, the Voltage-stabilizing Problems of the receiving end such as East China, Guangdong electrical network becomes increasingly conspicuous in recent years, researcher starts system voltage stabilizes problem to bring in the consideration category of idle work optimization, but still has very large room for development on the depth & wideth of research.In addition, multiple dynamic passive compensation equipment is had in electric power system, as generator, switched capacitors, SVC, on-load tap-changing transformer etc.A lot of research about Dynamic reactive power optimization at present only lays particular emphasis on a certain equipment wherein, and have ignored the cooperation between equipment.The algorithm of current most of electrical power system dynamic reactive power optimization only demonstrates its correctness in mini system, also there is no practical bulk power grid Dynamic reactive power optimization algorithm, be therefore necessary to carry out the research about the dynamic reactive power optimization method that can be applicable to large-scale electrical power system.In for subsequent use, reserve is the emphasis paid close attention to always, and the research specially for Reactive Power Reserve is also more rare, and the dynamic reactive especially for multi-infeed HVDC receiving end electrical network is for subsequent use, lacks especially.Reactive Power Reserve optimization and voltage stabilization belong to system realm problem, and each dynamic passive compensation device distribution is local at each of system, meet regulation requirement and system transient modelling voltage stabilization to maintain each Area Node transient voltage of system.Just because of this, the contribution of these dynamic passive compensation equipment to raising system transient modelling voltage stabilization is different.These dynamic passive compensation equipment contributions to system transient modelling voltage stabilization of how to evaluate are keys of computing system reactive power reserve.The present invention proposes a kind of dynamic reactive optimization method for subsequent use improving alternating current-direct current electrical network Transient Voltage Stability.Research shows the dynamic reactive optimization method for subsequent use adopting the present invention to propose, and effectively can improve alternating current-direct current electrical network Transient Voltage Stability.

Summary of the invention

In order to overcome above-mentioned the deficiencies in the prior art, the invention provides a kind of dynamic reactive optimization method for subsequent use improving alternating current-direct current electrical network Transient Voltage Stability, aid decision support is provided for improving multi-feed HVDC electrical network Transient Voltage Stability level, to the extensive alternating current-direct current electrical network Transient Voltage Stability nargin of raising, set up give, power transm ission corridor unimpeded between receiving end, promote AC-HVDC passage conveying capacity, improve economy and the quality of power supply of operation of power networks, be all significant.

In order to realize foregoing invention object, the present invention takes following technical scheme:

The invention provides a kind of dynamic reactive optimization method for subsequent use improving alternating current-direct current electrical network Transient Voltage Stability, said method comprising the steps of:

Step 1: determine the critical failure set and the key node set that affect Transient Voltage Stability in Electric Power System, and successively node is sorted;

Step 2: idle the exerting oneself of adjustment dynamic passive compensation equipment, and calculate the trace sensitivity of dynamic passive compensation equipment;

Step 3: m dynamic passive compensation equipment is sorted, and calculates the weight coefficient of dynamic passive compensation equipment;

Step 4: calculate dynamic passive compensation equipment sparing capacity, set up dynamic reactive Optimized model for subsequent use, and solve this dynamic reactive Optimized model for subsequent use.

Described step 1 comprises the following steps:

Step 1-1: carry out fault scanning to electric power system, determines according to fault serious conditions the critical failure set affecting Transient Voltage Stability in Electric Power System, and according to node voltage level determination key node set each between age at failure;

Step 1-2: successively node is sorted according to fault serious conditions;

The node of prioritization generation voltage transient unstability, according to node minimum voltage and the sequence of unstability speed; For recovering stable fault, the voltage resume of more each node, to the time of more than 0.8pu, descendingly to sort;

Step 1-3: the ordering values of each node under different faults is added, more ascending arrangement, thus obtain node sequencing, the node come above is defined as key node.

Dynamic passive compensation equipment in described step 2 comprises generator, Static Var Compensator SVC and STATCOM STATCOM.

Described step 2 specifically comprises the following steps:

Step 2-1: adjust each the idle of dynamic passive compensation equipment respectively and exert oneself, and again time-domain-simulation is carried out to critical failure;

Step 2-2: for certain fault F _l, single key node i, calculates the trace sensitivity TSI of dynamic passive compensation equipment j _{l, i, j};

Step 2-3: for certain fault F _l, multiple key node, calculates the trace sensitivity TSI of dynamic passive compensation equipment j _l,j;

Step 2-4: for multiple fault, multiple node, calculates the trace sensitivity TSI of dynamic passive compensation equipment j _j.

In step 2-2 described in dynamic passive compensation equipment dynamic passive compensation equipment dynamic passive compensation equipment, TSI _{l, i, j}be expressed as:

${\mathrm{TSI}}_{l,i,j}=\underset{k=1}{\overset{N_k}{\mathrm{\Σ}}}\left(\frac{V_{i,l}(t_k,Q_{j0}+\mathrm{\Δ}{Q}_j)-V_{i,l}(t_k,Q_{j0})}{\mathrm{\Δ}{Q}_{\mathrm{Rj}}}\right)---\left(1\right)$

Wherein, j=1,2 ..., m; N _kfor total number of sample points; t _kfor the sampling time; Q _j0for the initially idle of dynamic passive compensation equipment j is exerted oneself; Δ Q _jfor the idle variable quantity of exerting oneself of adjustment dynamic passive compensation equipment j; Δ Q _rjfor the Reactive Power Reserve variable quantity of dynamic passive compensation equipment j; V _i,l(t _k, Q _j0+ Δ Q _j) for after adjustment dynamic passive compensation equipment j idle exert oneself, at fault F _lunder, the voltage of node i is at sampling instant t _ktime value; Before adjustment dynamic passive compensation equipment j idle exert oneself, at fault F _lunder, the voltage of node i is at sampling instant t _ktime value.

In described step 2-3, TSI _l,jbe expressed as:

${\mathrm{TSI}}_{l,j}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{TSI}}_{l,i,j}---\left(2\right)$

Wherein, n is key node sum.

In described step 2-4, TSI _jbe expressed as:

${\mathrm{TSI}}_j=\underset{l=1}{\overset{N_l}{\mathrm{\Σ}}}{\mathrm{TSI}}_{l,j}---\left(3\right)$

Wherein, N _lfor critical failure sum.

Described step 3 comprises the following steps:

Step 3-1: according to trace sensitivity index TSI _jm dynamic passive compensation equipment is sorted, TSI _jit is maximum that maximum characterizes the percentage contribution of this dynamic passive compensation equipment to Transient Voltage Stability, and the dynamic passive compensation equipment that percentage contribution is large reserves more Reactive Power Reserve amount;

Step 3-2: with TSI _jmaximum of T SI _maxfor benchmark, normalized TSI _j, calculate the weight coefficient p of dynamic passive compensation equipment _j, have:

p _j＝TSI _j/TSI _max（4）。

Described step 4 comprises the following steps:

Step 4-1: calculate dynamic passive compensation equipment sparing capacity;

Dynamic passive compensation equipment sparing capacity Q _rTrepresent, its expression formula is:

$Q_{\mathrm{RT}}=\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{p}_j(Q_{\mathrm{gj}\max }-Q_{\mathrm{gj}})---\left(5\right)$

Wherein, Q _gjmaxfor the idle upper limit of exerting oneself of dynamic passive compensation equipment j, Q _gjfor the current idle of dynamic passive compensation equipment j is exerted oneself;

Step 4-2: to improve dynamic passive compensation equipment sparing capacity Q _rTas dynamic reactive optimization aim for subsequent use, set up dynamic reactive Optimized model for subsequent use;

Step 4-3: adopt this dynamic reactive of genetic algorithm for solving Optimized model for subsequent use.

The target function of described dynamic reactive Optimized model for subsequent use is;

$\max Q_{\mathrm{RT}}=\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{p}_j(Q_{\mathrm{gj}\max }-Q_{\mathrm{gj}})---\left(6\right);$

The constraints of described dynamic reactive Optimized model for subsequent use comprises power flow equation constraint and variable bound; Described variable bound is control variables constraint and state variable constrain;

In dynamic reactive Optimized model for subsequent use, each node meritorious is exerted oneself and idle exerting oneself all meets following power flow equation, has:

$\left\{\begin{array}{c}{P}_{\mathrm{Gi}}-P_{\mathrm{Li}}-P_{\mathrm{ti}\left(\mathrm{dc}\right)}-V_i\underset{r=1}{\overset{n}{\mathrm{\Σ}}}{V}_r(G_{\mathrm{ir}}\cos {\mathrm{\δ}}_{\mathrm{ir}}+B_{\mathrm{ir}}\sin {\mathrm{\δ}}_{\mathrm{ir}})=0\\ Q_{\mathrm{Gi}}+Q_{\mathrm{Ci}}-Q_{\mathrm{Li}}-Q_{\mathrm{ti}\left(\mathrm{dc}\right)}-V_i\underset{r=1}{\overset{n}{\mathrm{\Σ}}}{V}_r(G_{\mathrm{ir}}\sin {\mathrm{\δ}}_{\mathrm{ir}}-B_{\mathrm{ir}}\cos {\mathrm{\δ}}_{\mathrm{ir}})=0\end{array}\right.---\left(7\right)$

Wherein, P _giand Q _giwhat be respectively generators in power systems node meritoriously exerts oneself and idlely to exert oneself; P _liand Q _liwhat be respectively load bus meritoriously exerts oneself and idlely to exert oneself; Q _cifor the reactive compensation capacity of node; P _{ti (dc)}and Q _{ti (dc)}be respectively the meritorious input of DC node and idle input; G _ijand B _ijbe respectively the conductance between node i, r and susceptance; V _iand V _rbe respectively the voltage of node i, r; δ _irfor the phase difference of voltage between node i, r;

1) node i is on rectification side change of current bus, P _{ti (dc)}and Q _{ti (dc)}be expressed as:

$\left\{\begin{array}{c}{P}_{\mathrm{ti}\left(\mathrm{dc}\right)}=k_p{U}_{\mathrm{dR}}{I}_d\\ Q_{\mathrm{ti}\left(\mathrm{dc}\right)}=k_p{I}_d\sqrt{{\left(\frac{3\sqrt{2}}{\mathrm{\π}{K}_{\mathrm{dR}}}b{V}_R\right)}^2-U_{\mathrm{dR}}^2}\end{array}\right.---\left(8\right)$

Wherein, k _pfor the number of poles of converter; U _dRfor rectification side direct voltage; I _dfor DC line electric current; K _dRfor rectification side converter transformer no-load voltage ratio; B is 6 pulse wave cascaded bridges numbers of every pole; V _rfor the ac bus voltage magnitude of rectification side;

2) node i is on inverter side change of current bus, P _{ti (dc)}and Q _{ti (dc)}be expressed as:

$\left\{\begin{array}{c}{P}_{\mathrm{ti}\left(\mathrm{dc}\right)}={-k}_p{U}_{\mathrm{dI}}{I}_d\\ Q_{\mathrm{ti}\left(\mathrm{dc}\right)}=k_p{I}_d\sqrt{{\left(\frac{3\sqrt{2}}{\mathrm{\π}{K}_{\mathrm{dI}}}b{V}_I\right)}^2-U_{\mathrm{dI}}^2}\end{array}\right.---\left(9\right)$

Wherein, U _dIfor inverter side direct voltage; K _dIfor inverter side converter transformer no-load voltage ratio; V _ifor the ac bus voltage magnitude of inverter side;

Control variables constraint is as follows:

$\left\{\begin{array}{c}{V}_{\mathrm{Gi}\min }\≤V_{\mathrm{Gi}}\≤V_{\mathrm{Gi}\max },i=\mathrm{1,2},...,N_G\\ V_{\mathrm{SVCg}\min \≤}{V}_{\mathrm{SVCg}}\≤V_{\mathrm{SVCg}\max },g=\mathrm{1,2},...,N_{\mathrm{SVC}}\\ V_{\mathrm{SVGh}\min \≤}{V}_{\mathrm{SVGh}}\≤V_{\mathrm{SVGh}\max },h=\mathrm{1,2},...,N_{\mathrm{SVG}}\\ Q_{\mathrm{Cj}\min \≤}{Q}_{\mathrm{Cj}}\≤Q_{\mathrm{Cj}\max },j=\mathrm{1,2},...,N_C\\ T_{k\min }\≤T_k\≤T_{k\max },k=\mathrm{1,2},...,N_T\\ U_{\mathrm{dl}\min }\≤U_{\mathrm{dl}}\≤U_{\mathrm{dl}\max },l=\mathrm{1,2},...,N_{\mathrm{dc}}\\ I_{\mathrm{dm}\min }\≤I_{\mathrm{dm}}\≤I_{\mathrm{dm}\max },m=\mathrm{1,2},...,N_{\mathrm{dc}}\\ P_{\mathrm{dn}\min }\≤P_{\mathrm{dn}}\≤P_{\mathrm{dn}\max },n=\mathrm{1,2},...,N_{\mathrm{dc}}\\ {\mathrm{\θ}}_{\mathrm{dr}\min }\≤{\mathrm{\θ}}_{\mathrm{dr}}\≤{\mathrm{\θ}}_{\mathrm{dr}\max },r=\mathrm{1,2},...,N_{\mathrm{dc}}\end{array}\right.$

Wherein, N _g, N _sVC, N _sVG, N _c, N _tand N _dcbe respectively generator nodes, SVG nodes, STATCOM nodes, shunt capacitor nodes, transformer application of adjustable tap number and DC network nodes; V _gifor the terminal voltage of generator node, V _giminand V _gimaxbe respectively V _gilower limit and higher limit; V _sVCgfor the terminal voltage of SVC node, V _sVCgminand V _sVCgmaxbe respectively V _sVCglower limit and higher limit; V _sVGhfor the terminal voltage of STATCOM node, V _sVGhminand V _sVGhmaxbe respectively V _sVGhlower limit and higher limit; Q _cjfor the compensation capacity of Shunt Capacitor Unit, Q _cjminand Q _cjmaxbe respectively Q _cjlower limit and higher limit; T _kfor transformer application of adjustable tap, T _kminand T _kmaxbe respectively T _klower limit and higher limit; U _dl, I _dm, P _dnand θ _drbe respectively converter control voltage, control electric current, control power and pilot angle, U _dlminand U _dlmax, I _dmminand I _dmmax, P _dnminand P _dnmax, θ _drminand θ _drmaxrepresent corresponding lower limit and higher limit respectively;

State variable constrain is as follows:

$\left\{\begin{array}{c}{Q}_{\mathrm{Gi}\min }\≤Q_{\mathrm{Gi}}\≤Q_{\mathrm{Gi}\max },i=\mathrm{1,2},...,N_G\\ B_{\mathrm{SVCg}\min }\≤B_{\mathrm{SVCg}}\≤B_{\mathrm{SVCg}\max },g=\mathrm{1,2},...,N_{\mathrm{SVC}}\\ I_{\mathrm{SVGh}\min }\≤I_{\mathrm{SVGh}}\≤I_{\mathrm{SVGh}\max },h=\mathrm{1,2},...,N_{\mathrm{SVG}}\\ V_{\mathrm{Lp}\min }\≤V_{\mathrm{Lp}}\≤V_{\mathrm{Lp}\max },p=\mathrm{1,2},...,N_L\end{array}\right.---\left(11\right)$

Wherein, N _lfor load bus number; Q _giexert oneself for generator node is idle, B _sVCgfor SVC susceptance, I _sVGhfor STATCOM current amplitude, Q _giminand Q _gimaxbe respectively Q _gilower limit and higher limit; B _sVCgminand B _sVCgmaxbe respectively B _sVCglower limit and higher limit; I _sVGhminand I _sVGhmaxbe respectively I _sVGhlower limit and higher limit; V _lpfor load bus voltage magnitude, V _lpminand V _lpmaxbe respectively V _lplower limit and higher limit.

Compared with prior art, beneficial effect of the present invention is:

1. for the feature of multi-feed HVDC system, the invention provides a kind of dynamic reactive optimization method for subsequent use improving alternating current-direct current electrical network Transient Voltage Stability, the configuration of reasonable arrangement dynamic reactive reserve capacity, effectively can improve direct current commutation lsafety level, meets the requirement of electrical network transient voltage security;

2. compared with the traditional Reactive Power Reserve optimization method based on static state, this method considers the dynamic characteristic of system in detail, can determine dynamic passive compensation equipment sparing capacity more exactly, and the optimizing operation for electrical network provides basis;

This method is analyzed by time-domain-simulation, the weight coefficient of each dynamic passive compensation equipment can be determined quick and easy, exactly, can be applicable to the dynamic reactive optimization for subsequent use of large-scale electrical power system, the algorithm overcoming the optimization of conventional electric power system dynamic reactive-load can only be applied to the shortcoming of mini system;

The present invention provides aid decision support for improving multi-feed HVDC electrical network Transient Voltage Stability level, to the extensive alternating current-direct current electrical network Transient Voltage Stability nargin of raising, set up give, power transm ission corridor unimpeded between receiving end, promote AC-HVDC passage conveying capacity, improve economy and the quality of power supply of operation of power networks, be all significant.

Accompanying drawing explanation

Fig. 1 is the dynamic reactive optimization method flow chart for subsequent use improving alternating current-direct current electrical network Transient Voltage Stability;

Fig. 2 adopts genetic algorithm for solving dynamic reactive Optimized model flow chart for subsequent use;

Fig. 3 is 3 machine 10 node regulation test ac and dc systems schematic diagrames in the invention process;

Fig. 4 is the voltage curve of node 1, node 2, node 4 and node 5 in 3 machine 10 node regulation test ac and dc systemses;

Fig. 5 be 3 machine 10 node regulations test ac and dc systemses in node 3, node 6 ~ node 10 voltage curve;

Fig. 6 is the set end voltage changing generator G3, investigates the voltage change curve figure of fault lower node 3;

Fig. 7 is the set end voltage changing generator G3, investigates the voltage change curve figure of fault lower node 6;

Fig. 8 is the set end voltage changing generator G3, investigates the voltage change curve figure of fault lower node 7;

Fig. 9 is the set end voltage changing generator G3, investigates the voltage change curve figure of fault lower node 8;

Figure 10 is the set end voltage changing generator G3, investigates the voltage change curve figure of fault lower node 9;

Figure 11 is the set end voltage changing generator G3, investigates the voltage change curve figure of fault lower node 10;

Figure 12 is the set end voltage changing generator G3, the idle change curve that under investigation fault, generator G3 sends;

Figure 13 be investigate SVC under fault initially idle exert oneself change before and after the voltage change curve figure of node 3;

Figure 14 be investigate SVC under fault initially idle exert oneself change before and after the voltage change curve figure of node 6;

Figure 15 be investigate SVC under fault initially idle exert oneself change before and after the voltage change curve figure of node 7;

Figure 16 be investigate SVC under fault initially idle exert oneself change before and after the voltage change curve figure of node 8;

Figure 17 be investigate SVC under fault initially idle exert oneself change before and after the voltage change curve figure of node 9;

Figure 18 be investigate SVC under fault initially idle exert oneself change before and after the voltage change curve figure of node 10;

Figure 19 be investigate SVC under fault initially idle exert oneself change before and after the idle change curve of exerting oneself of SVC;

Figure 20 is node 3(Generator end before and after optimizing) voltage curve;

Figure 21 is node 6 voltage curve before and after optimizing.

Embodiment

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

Embodiment

For 3 machine 10 node systems, the embodiment of the present invention makes 5 times alternating current interconnections between bus 5 and 6 into 2 times alternating current interconnections and 1 time bipolar direct current transmission line, because the direction of the active power of former alternating current circuit flows to node 6 from node 5, so set node 5 as rectification side, 6 is inverter side, as shown in Figure 3.The reactive power absorbed due to direct current system is comparatively large, so the capacity that is configured with respectively on node 6 SVC that is ± 180MVar and capacity are the Capacitor banks of 1000MVar, the every pool-size of this Capacitor banks is 100MVar, totally 10 groups.In addition, the unit of original system, load and electric network data is retained constant.Form the correction test macro of alternating current-direct current series-parallel connection transmission of electricity thus.

Fault scanning is carried out to this system, determines the critical failure set threatening system voltage stabilizes.In order to the validity of TSI index is described easily, this example only investigates the most serious N-1 fault, the permanent short trouble of three-phase is there is in alternating current interconnection when failure mode is t=1s between node 5 ~ node 6 in node 6 side, 0.09s tripping faulty line node 6 side switch after fault, 0.1s tripping faulty line node 5 side switch.Fig. 4 and Fig. 5 be each node voltage curve under fault for this reason, and as can be seen from the figure, after failure removal, the Voltage Drop amplitude of node 3, node 6, node 7, node 8, node 9 and node 10 is maximum and recover the slowest, therefore selects these 6 nodes to be key node.

For this fault, the generator reactive of computing node 3 is exerted oneself and the idle trace sensitivity TSI exerted oneself of node 6SVC respectively.

The set end voltage initial value of setting generator G3 is respectively 1.011p.u. and 1.021p.u., and the idle change curve that the voltage change curve of simulation calculation investigation fault lower node 3, node 6, node 7, node 8, node 9 and node 10 and generator G3 send is respectively as shown in Fig. 6 ~ Figure 12.Calculate according to formula (3) that to investigate the idle trace sensitivity index TSI exerting oneself change of generator G3 under fault be 0.017.

Setting SVC initially idle exerting oneself is respectively 0 and 120MVar capacitive reactive power, and the idle change curve that the voltage change curve of simulation calculation investigation fault lower node 3, node 6, node 7, node 8, node 9 and node 10 and SVC send is respectively as shown in Figure 13 ~ Figure 19.Calculate according to formula (3) that to investigate the idle trace sensitivity index TSI exerting oneself change of SVC under fault be 0.701.

Before and after dynamic reactive optimization for subsequent use, control variables contrast is as shown in table 1.Before and after dynamic reactive optimization for subsequent use, reactive power reserve contrast is as shown in table 2.As seen from Table 1, the reactive power reserve after optimization improves (422.4-230.4)/230.4*100%=83.3% than optimizing precontract.

Table 1

Control variables	Before optimization	After optimization
			V g3（p.u.)	1.01	1.04
The group number (group) that node 6 shunt capacitor drops into	10	7
			SVC is idle to exert oneself (capacitive is just, MVar)	0	-180

Table 2

Investigate the most serious N-1 fault, the permanent short trouble of three-phase is there is in alternating current interconnection when failure mode is t=0.1s between node 5 ~ node 6 in node 6 side, 0.09s tripping faulty line node 6 side switch after fault, 0.1s tripping faulty line node 5 side switch.Figure 20 and Figure 21 is respectively generator G3 set end voltage and node 6 voltage curve, as can be seen from the figure, after optimizing, the transient voltage of system recovers than fast before optimization, and this illustrates that the optimized algorithm adopting this problem to propose effectively can improve the Enhancement of Transient Voltage Stability of electrical network.

Finally should be noted that: above embodiment is only in order to illustrate that technical scheme of the present invention is not intended to limit, although with reference to above-described embodiment to invention has been detailed description, those of ordinary skill in the field are to be understood that: still can modify to the specific embodiment of the present invention or equivalent replacement, and not departing from any amendment of spirit and scope of the invention or equivalent replacement, it all should be encompassed in the middle of right of the present invention.

Claims (9)

1. improve a dynamic reactive optimization method for subsequent use for alternating current-direct current electrical network Transient Voltage Stability, it is characterized in that: said method comprising the steps of:

Step 1: determine the critical failure set and the key node set that affect Transient Voltage Stability in Electric Power System, and successively node is sorted;

Step 2: idle the exerting oneself of adjustment dynamic passive compensation equipment, and calculate the trace sensitivity of dynamic passive compensation equipment;

Step 3: m dynamic passive compensation equipment is sorted, and calculates the weight coefficient of dynamic passive compensation equipment;

Step 4: calculate dynamic passive compensation equipment sparing capacity, set up dynamic reactive Optimized model for subsequent use, and solve this dynamic reactive Optimized model for subsequent use;

Described step 3 comprises the following steps:

Step 3 ?1: according to trace sensitivity index TSI _jm dynamic passive compensation equipment is sorted, TSI _jit is maximum that maximum characterizes the percentage contribution of this dynamic passive compensation equipment to Transient Voltage Stability, and the dynamic passive compensation equipment that percentage contribution is large reserves Reactive Power Reserve amount;

Step 3 ?2: with TSI _jmaximum of T SI _maxfor benchmark, normalized TSI _j, calculate the weight coefficient p of dynamic passive compensation equipment _j, have:

p _j＝TSI _j/TSI _max(4)。

2. the dynamic reactive optimization method for subsequent use of raising alternating current-direct current electrical network Transient Voltage Stability according to claim 1, is characterized in that: described step 1 comprises the following steps:

Step 1 ?1: fault scanning is carried out to electric power system, determines according to fault serious conditions the critical failure set affecting Transient Voltage Stability in Electric Power System, and according to node voltage level determination key node set each between age at failure;

Step 1 ?2: successively node is sorted according to fault serious conditions;

The node of prioritization generation voltage transient unstability, according to node minimum voltage and the sequence of unstability speed; For recovering stable fault, the voltage resume of more each node, to the time of more than 0.8pu, descendingly to sort;

Step 1 ?3: the ordering values of each node under different faults to be added, more ascending arrangement, thus to obtain node sequencing, the node come above is defined as key node.

3. the dynamic reactive optimization method for subsequent use of raising alternating current-direct current electrical network Transient Voltage Stability according to claim 1, is characterized in that: the dynamic passive compensation equipment in described step 2 comprises generator, Static Var Compensator SVC and STATCOM STATCOM.

4. the dynamic reactive optimization method for subsequent use of raising alternating current-direct current electrical network Transient Voltage Stability according to claim 3, is characterized in that: described step 2 specifically comprises the following steps:

Step 2 ?1: adjust each the idle of dynamic passive compensation equipment respectively and exert oneself, and again time-domain-simulation is carried out to critical failure;

Step 2 ?2: for certain fault F _l, single key node i, calculates the trace sensitivity TSI of dynamic passive compensation equipment j _{l, i, j};

Step 2 ?3: for certain fault F _l, multiple key node, calculates the trace sensitivity TSI of dynamic passive compensation equipment j _l,j;

Step 2 ?4: for multiple fault, multiple node, calculates the trace sensitivity TSI of dynamic passive compensation equipment j _j.

5. the dynamic reactive optimization method for subsequent use of raising alternating current-direct current electrical network Transient Voltage Stability according to claim 4, is characterized in that: in described step 2 ?2, TSI _{l, i, j}be expressed as:

Wherein, j=1,2 ..., m; N _kfor total number of sample points; t _kfor the sampling time; Q _j0for the initially idle of dynamic passive compensation equipment j is exerted oneself; Δ Q _jfor the idle variable quantity of exerting oneself of adjustment dynamic passive compensation equipment j; Δ Q _rjfor the Reactive Power Reserve variable quantity of dynamic passive compensation equipment j; V _i,l(t _k, Q _j0+ Δ Q _j) for after adjustment dynamic passive compensation equipment j idle exert oneself, at fault F _lunder, the voltage of node i is at sampling instant t _ktime value; V _i,l(t _k, Q _j0) for before adjustment dynamic passive compensation equipment j idle exert oneself, at fault F _lunder, the voltage of node i is at sampling instant t _ktime value.

6. the dynamic reactive optimization method for subsequent use of raising alternating current-direct current electrical network Transient Voltage Stability according to claim 4, is characterized in that: in described step 2 ?3, TSI _l,jbe expressed as:

Wherein, n is key node sum.

7. the dynamic reactive optimization method for subsequent use of raising alternating current-direct current electrical network Transient Voltage Stability according to claim 4, is characterized in that: in described step 2 ?4, TSI _jbe expressed as:

Wherein, N _lfor critical failure sum.

8. the dynamic reactive optimization method for subsequent use of raising alternating current-direct current electrical network Transient Voltage Stability according to claim 1, is characterized in that: described step 4 comprises the following steps:

Step 4 ?1: calculate dynamic passive compensation equipment sparing capacity;

Dynamic passive compensation equipment sparing capacity Q _rTrepresent, its expression formula is:

Wherein, Q _gjmaxfor the idle upper limit of exerting oneself of dynamic passive compensation equipment j, Q _gjfor the current idle of dynamic passive compensation equipment j is exerted oneself;

Step 4 ?2: to improve dynamic passive compensation equipment sparing capacity Q _rTas dynamic reactive optimization aim for subsequent use, set up dynamic reactive Optimized model for subsequent use;

Step 4 ?3: adopt this dynamic reactive of genetic algorithm for solving Optimized model for subsequent use.

9. the dynamic reactive optimization method for subsequent use of raising alternating current-direct current electrical network Transient Voltage Stability according to claim 8, is characterized in that: the target function of described dynamic reactive Optimized model for subsequent use is:

The constraints of described dynamic reactive Optimized model for subsequent use comprises power flow equation constraint and variable bound; Described variable bound is control variables constraint and state variable constrain;

In dynamic reactive Optimized model for subsequent use, each node meritorious is exerted oneself and idle exerting oneself all meets following power flow equation, has:

Wherein, P _giand Q _giwhat be respectively generators in power systems node meritoriously exerts oneself and idlely to exert oneself; P _liand Q _liwhat be respectively load bus meritoriously exerts oneself and idlely to exert oneself; Q _cifor the reactive compensation capacity of node; P _{ti (dc)}and Q _{ti (dc)}be respectively the meritorious input of DC node and idle input; G _ijand B _ijbe respectively the conductance between node i, r and susceptance; V _iand V _rbe respectively the voltage of node i, r; δ _irfor the phase difference of voltage between node i, r;

1) node i is on rectification side change of current bus, P _{ti (dc)}and Q _{ti (dc)}be expressed as:

Wherein, k _pfor the number of poles of converter; U _dRfor rectification side direct voltage; I _dfor DC line electric current; K _dRfor rectification side converter transformer no-load voltage ratio; B is 6 pulse wave cascaded bridges numbers of every pole; V _rfor the ac bus voltage magnitude of rectification side;

2) node i is on inverter side change of current bus, P _{ti (dc)}and Q _{ti (dc)}be expressed as:

Wherein, U _dIfor inverter side direct voltage; K _dIfor inverter side converter transformer no-load voltage ratio; V _ifor the ac bus voltage magnitude of inverter side;

Control variables constraint is as follows:

Wherein, N _g, N _sVC, N _sVG, N _c, N _tand N _dcbe respectively generator nodes, SVG nodes, STATCOM nodes, shunt capacitor nodes, transformer application of adjustable tap number and DC network nodes; V _gifor the terminal voltage of generator node, V _giminand V _gimaxbe respectively V _gilower limit and higher limit; V _sVCgfor the terminal voltage of SVC node, V _sVCgminand V _sVCgmaxbe respectively V _sVCglower limit and higher limit; V _sVGhfor the terminal voltage of STATCOM node, V _sVGhminand V _sVGhmaxbe respectively V _sVGhlower limit and higher limit; Q _cjfor the compensation capacity of Shunt Capacitor Unit, Q _cjminand Q _cjmaxbe respectively Q _cjlower limit and higher limit; T _kfor transformer application of adjustable tap, T _kminand T _kmaxbe respectively T _klower limit and higher limit; U _dl, I _dm, P _dnand θ _drbe respectively converter control voltage, control electric current, control power and pilot angle, U _dlminand U _dlmax, I _dmminand I _dmmax, P _dnminand P _dnmax, θ _drminand θ _drmaxrepresent corresponding lower limit and higher limit respectively;

State variable constrain is as follows:

Wherein, N _lfor load bus number; Q _giexert oneself for generator node is idle, B _sVCgfor SVC susceptance, I _sVGhfor STATCOM current amplitude, Q _giminand Q _gimaxbe respectively Q _gilower limit and higher limit; B _sVCgminand B _sVCgmaxbe respectively B _sVCglower limit and higher limit; I _sVGhminand I _sVGhmaxbe respectively I _sVGhlower limit and higher limit; V _lpfor load bus voltage magnitude, V _lpminand V _lpmaxbe respectively V _lplower limit and higher limit.