Background technology
Magnet controlled high-voltage shunt reactor is a kind of novel flexible AC transmission system (FACTS) equipment, by regulating reactor, control the magnetic saturation that winding current size changes iron core, regulate the reactance value of major loop iron core winding, thereby reach the function that regulates reactive power.By continuous adjusting, control winding current, can dynamic compensation transmission line capacitive reactive power, suppress capacitive rise effect, power-frequency overvoltage and the secondary arc current of ultra-high/extra-high voltage transmission line, improve the stability of a system.
Ultra-high/extra-high voltage system is to the stability of reactive-load compensation equipment and regulate accuracy to have higher requirement, and the magnet controlled high-voltage shunt reactor automated closed-loop control method that researcher proposes both at home and abroad at present is mainly divided into two classes: the control method that traditional proportional-integral-differential (PID) is controlled and formed with modern control theory.The latter is theoretical novel, but aspect stability, reliability, is needing practical application check; Can look in the ultra-high/extra-high voltage system practical engineering application of seeing the traditional PID control that adopted more.PID controls according to its control target difference and is divided into again: the modes such as line voltage distribution control, Reactive Power Control, reactive factor control.Wherein, it is the most basic that line voltage distribution is controlled, and is also one of conventional control mode, its using the line voltage distribution command value of access point with the difference of actual value as regulating input, maintain stablizing of line voltage distribution.
The problem that the single electric parameters closed-loop control of line voltage distribution exists is: in circuit working conditions change; there is significantly lifting in voltage; reactor absorbs idle excessive; or in the situations such as control unit mistuning joint; only voltage is controlled; may cause reactor overexcitation; being reflected as each electric parameter variation mainly comprises: one time winding overcurrent, the overload of inactivity power and control electric current are high; after reaching the protection threshold values of reactor protection equipment, can there is the tripping operation of reactor gate out switch, off-the-line reactor.When carrying out voltage close loop adjusting, need to limit all the other electric parameters ranges of operation, guarantee before protection action off-the-line; reactor is limited in safe range and is moved; avoid gate out switch action, and then improve reactor operational reliability, maintain the reactive power compensation ability to electrical network.
Summary of the invention
Object of the present invention, be to provide a kind of many electric parameters composite control method of magnet controlled high-voltage shunt reactor, when circuit voltage close loop is controlled, once winding current, reactive power, control electric current are limited to adjusting, make it in safe operation scope, improve reactor operational reliability.
In order to reach above-mentioned purpose, solution of the present invention is:
A kind of magnet controlled many electric parameters of high-voltage shunt reactor composite control method disclosed by the invention, the dynamic property requirement in the time of can adapting to different operating modes, different electric parameters closed-loop adjustment, the stability when meeting reactor and moving under electrical limitations operating mode; Guarantee the instantaneous effective and instantaneous limited characteristic exiting of maximum controlling current restriction, do not affect regulating and controlling quality.The present invention realizes when circuit voltage close loop is controlled, and inhibitory control system overexcitation comprehensively maintains within reactor operates in design allowed band, strengthens reactor reliability of operation.
Embodiment
Below with reference to accompanying drawing, technical scheme of the present invention is elaborated.
In Fig. 1: U
git is line voltage distribution actual value; U
refit is line voltage distribution reference value; E
u, E
ig, E
if, E
q, E
ifmaxrespectively that line voltage distribution, once winding current, control electric current, reactive power and maximum controlling current regulate difference; E
minit is minimal adjustment difference; U
pIDit is closed loop calculated value; V
ifmaxit is maximum controlling current restriction controlling value; U
cfinally to control voltage; PID
u, PID
if, PID
grespectively line voltage distribution closed loop, control current closed-loop and primary current/Reactance Closed Loop operational model; K
mthat top value restriction regulates gain; K
bit is phase shift gain coefficient; LV is low-value gate comparator, exports minimum input value.
As shown in Figure 1, adopt line voltage distribution main ring and winding/control winding overcurrent overheat restriction, reactive power restriction and four restriction secondary rings of the instantaneous restriction of maximum controlling current to carry out compound control, the steps include:
(1) according to winding of reactor, control winding current and reactive power sampling calculated value, whether judgement restriction moves in accordance with the following methods, and calculates adjusting difference:
Restriction adopts the inverse time lag to control to a winding with control winding overcurrent overheat, and winding current is over the long-term running current continuously of its maximum, and thermal accumlation surpasses winding permission thermal capacity, limit movement; Winding current is less than restriction return current set point, limits time delay and returns.Restriction regulates the lowest high-current value that desired value can long-time running according to winding to set, and desired value deducts the adjusted difference E of actual value
ig, E
if.Thermal accumlation calculates according to following formula:
Wherein, C
hbe current accumulation heat, I is current actual value, I
nthat thermal capacitance is calculated electric current base value.
Reactive power is limited in reactor reactive power and exceeds while designing permission capacity, deferred action; Reactive power is less than restriction and returns to reactive power set point, limits time delay and returns.Regulate the absorption maximum reactive power value that desired value can long-time running according to reactor to set, desired value deducts actual value and obtains restriction and regulate difference E
q.
Maximum controlling current is instantaneous when being limited in reactor and controlling winding current and exceed reactor maximum and encourage electric current by force, instantaneous operation; Control electric current is less than restriction and returns to set point, limits time delay and returns.The maximum that regulates desired value to allow according to reactor is encouraged by force current value and is set, for example 1.4 times of specified control electric currents.Desired value deducts actual value and obtains restriction adjusting difference E
ifmax.
(2) line voltage distribution difference E
uwith E
q, E
ig, E
ifthrough low-value gate comparator LV, select minimum value E
min:
(3) E
minthrough corresponding voltage PID or restriction PID model calculation, obtain closed loop calculated value U
pID:
Closed loop operational model is set in accordance with the following methods: voltage-regulation arranges a road PID
u, control electric current adjusting one road PID be set
if, the primary current relevant to winding and reactive power regulate a road PID are set
g, each PID model parameter is adjusted separately.
If restriction is action not, voltage close loop PID
uwith E
mincorrespondence, through PID
ucomputing output closed-loop is controlled voltage U
pID; Restriction regulates secondary ring PID
ifand PID
gmodel following PID
uoperation, by closed-loop control voltage U
pIDinverse obtains secondary ring PID model intermediate computations variate-value.
If limit movement, from voltage close loop PID
u, primary side closed loop PID
gwith control current closed-loop PID
ifin, select and E
mincorresponding PID model calculation, output closed-loop calculated value U
pID; All the other PID model following operations, by closed-loop control voltage U
pIDinverse obtains intermediate computations variate-value.
(4) the instantaneous restriction difference of maximum controlling current E
ifmaxthrough scale operation output controlling value V
ifmax;
(5) U
pIDwith V
ifmaxstack, generates the final voltage U of controlling through amplification, amplitude limit
c.While adopting controllable silicon rectifying bridge to control power supply as reactor, can be according to rectifier bridge AC voltage condition, by U
cbe converted into rectifier bridge trigger angle, control reactor and control winding current size, and then realize the adjusting of line voltage distribution.
Above embodiment only, for explanation technological thought of the present invention, can not limit protection scope of the present invention with this, every technological thought proposing according to the present invention, and any change of doing on technical scheme basis, within all falling into protection range of the present invention.