CN106532743A - Method for obtaining low-frequency oscillation safety control quantity of interconnected system based on oscillation energy - Google Patents

Abstract

The invention provides a method for obtaining a low-frequency oscillation safety control quantity of an interconnected system based on oscillation energy. The method comprises the following steps of calculating a difference value between the oscillation energy corresponding to a current damping ratio of the interconnected system and the oscillation energy corresponding to a target damping ratio; determining a dissipation coefficient KC and calculating removal quantities of the oscillation energy of generators; and carrying out generator tripping priority sorting and estimating the removal quantity of a unit with relatively large oscillation relevance. A reasonable real-time control strategy is provided for low-frequency oscillation of the interconnected system to achieve fast processing of the low-frequency oscillation, and the problem that real-time online adjustment is difficult to implement in engineering is solved.

Description

A kind of interacted system low-frequency oscillation peace control amount acquisition methods based on oscillation energy

Technical field

The present invention relates to control amount acquisition methods are pacified in a kind of low-frequency oscillation, and in particular to a kind of mutual contact based on oscillation energy System low-frequency oscillation peace control amount acquisition methods.

Background technology

With the developing rapidly of China's power industry, the continuous expansion of power system scale, interconnection power system electric power The formation of system, and the application of high-amplification-factor quick response excitation system so that electromotor easily produces rotor under microvariations Between it is relative wave, cause power system underdamping or negative damping low-frequency oscillation.

Negative damping electromotor and the periodic disturbance place element applied outward can all produce energy during low-frequency oscillation. If no catabiotic element in network, the energy for injecting all is consumed in the element legs of place；If also having in network Other catabiotic elements (as other in multi-machine power system have the unit of damping), then apply outward the Implantation Energy of disturbance Except consume on the element of place, can also consume in other units for having damping, disturbance energy will injection network, flow to which He has damping element, forms oscillation energy stream in a network.For interacted system low-frequency oscillation, in network, necessarily there is generation energy Element and catabiotic element, can just propose low-frequency oscillation control strategy using the oscillation energy stream in network.

The global oscillation energy of system is corresponding with amplitude, when under same running status there is low-frequency oscillation in interacted system, vibration Damping ratio is bigger, then corresponding oscillation energy is bigger.It is just, with just to consume contribution of the element of oscillation energy to oscillatory extinction Damping；It is negative to produce contribution of the element of oscillation energy to oscillatory extinction, with negative damping.If total energy expenditure in system More than energy production, then the transient state energy of system constantly can be reduced, it is convergent oscillation；And if energy expenditure is less than energy volume production It is raw, then the transient state energy of system will be continuously increased, and be increasing oscillation；When energy expenditure is equal with energy production, system is Self-sustained oscillation.Oscillation energy stream in network can assess damping characteristic of the element to systematic contributions, and unit is in certain period of time The oscillation energy for sending is bigger, illustrates that the damping of unit is poorer, and the importance degree in low-frequency oscillation is higher, control the unit for Suppress the effect of vibration better.

When interacted system low-frequency oscillation occurs, there are a considerable amount of negative damping units to participate in vibration, using reduction in engineering The method of unit output, often in accordance with the pattern of " off-line setting calculation, real-time matching ", it is difficult to adjusted according to the real-time status of network It is whole, be given relatively reasonable control unit and peace control amount, additionally, this method when the major accidents such as cascading failure occur also without Can be power, and there are problems that cutting, owe, it is poor for the suitability of interacted system dynamic stability real-time control.

The content of the invention

In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a kind of interacted system low frequency based on oscillation energy and shakes Peace control amount acquisition methods are swung, the present invention provides rational Real-Time Control Strategy for interacted system low-frequency oscillation, to realize that low frequency shakes The quick process swung, is difficult to real-time online adjustment in solving the problems, such as engineering.

In order to realize foregoing invention purpose, the present invention is adopted the following technical scheme that：

A kind of interacted system low-frequency oscillation peace control amount acquisition methods based on oscillation energy, methods described include following step Suddenly：

(1) calculate the difference of the current damping ratio of interacted system and oscillation energy corresponding to target damping ratio；

(2) determine dissipation factor K_C, calculate the resection of hunting of generator energy；

(3) cut machine priority ordered, estimation vibration degree of association cuts machine amount compared with large-sized unit.

Preferably, step (1) comprises the steps：

Step 1-1, the real time data interconnection active power and bus frequency between interacted system carry out Prony analyses Afterwards, amplitude under respective dominant pattern, damping ratio, frequency of oscillation is extracted, the dominant pattern oscillation equation after extraction is：

In formula：A is amplitude, and ζ is damping ratio, and w is frequency of oscillation,For vibrating initial phase；

Step 1-2, target damping ratio corresponding oscillation mode is regarded as and the control oscillation modes extracted under current failure Unanimously, according to oscillation equation, the oscillation energy under control oscillation modes is calculated, formula is as follows：

Δ W=Δ W_ζ1-ΔW_ζ2

In formula：ΔW_ζ1For the oscillation energy stream on interconnection under current failure；ΔW_ζ2For on interconnection under target damping ratio Oscillation energy stream.

Preferably, step (2) comprise the steps：

Step 2-1, determine dissipation factor K_C；

Step 2-2, calculating t oscillation energy；

Step 2-3, electromotor oscillation energy resection is measured out according to dissipation factor and tieline oscillation energy variation, it is public Formula is：W_P=K_C·ΔW

In formula, Δ W be tieline oscillation energy variation amount, W_PFor hunting of generator energy ablation amount.

Preferably, in step 2-1, the dissipation factor is that the oscillation energy that all units send is flowed out with interconnection 's

The ratio of oscillation energy, formula are as follows：

In formula, Δ W_GFor the oscillation energy sum that all electromotors send；ΔW_SFor shaking that interconnection between interacted system flows out Swing energy.

Preferably, in step 2-2, as PMU data is that temporally point is gathered, and the calculating essence of definite integral

It is exactly the cumulative summation after segmenting to image, therefore the real-time computing formula of the oscillation energy of t is as follows：

In formula, Δ W_ijIt is through branch road L from bus i_ijThe oscillation energy of transmission, Δ P_ijBranch road L_ijActive power change Amount, Δ θ_iThe voltage phase angle variable quantity of bus i, Δ f_iThe frequency variation of bus, s is integration variable, r for definite integral etc. Dosis refracta；P_ij,k、f_i,kCircuit active power and bus frequency of the respectively branch road ij at the kt/r moment.

Preferably, step (3) comprise the steps：

Step 3-1, all electromotors are carried out cutting machine priority ordered according to oscillation energy size, oscillation energy is cut more greatly Machine relative importance value is higher；

Step 3-2, in order and unit capacity arrangement cut machine until resection reach W_P；

If, more than the oscillation energy that unit sends, whole of this unit is cut for step 3-3, the oscillation energy resection of estimation Remove, when estimate resection be not enough to cut off n-th whole unit when, this unit output controlled quentity controlled variable computing formula is：

In formula：P_nActive for n-th electromotor is exerted oneself, W_PiFor the oscillation energy of i-th electromotor, W_GnSend out for n-th The oscillation energy of motor, P_CFor unit output controlled quentity controlled variable.

With immediate prior art ratio, the present invention provide technical scheme there is following excellent effect：

The present invention cuts machine amount according to the oscillation damping ratio of current failure and expected control damping ratio to estimate, improves and cuts Engine efficiency, reduces because cutting off the power shortage problem that unit is excessively likely to result in, while it is less to it also avoid peace control nargin When deficient cut problem.Peace control policy development is present in current engineering complexity, unicity is avoided, it is suitable for various failures Answering property is stronger, and it is higher to cut machine amount estimation degree of accuracy.

The present invention can reflect element to carrying out come cutting machine order the characteristics of the contribution of oscillatory extinction using oscillation energy The method of sequence is more directly perceived effectively to reflect greatly participation factors of the unit in low-frequency oscillation greatly due to sending oscillation energy, The unit is controlled to suppressing interacted system oscillation action to become apparent from, the method implementation result is further lifted.

Description of the drawings

Fig. 1 is a kind of interacted system low-frequency oscillation peace control amount acquisition methods flow process based on oscillation energy that the present invention is provided Figure

Fig. 2 is certain province's 500kV electrical network figure that the present invention is provided

Fig. 3 is line power curve chart after the interconnection C-D N-2 failures that the present invention is provided

Fig. 4 is circuit power under the C-D failures of interconnection after taking measures that the present invention is provided

Specific embodiment

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

The present invention carries out simulating, verifying by taking certain province's electrical network as an example, as shown in figure 1, for a kind of mutual contact based on oscillation energy System low-frequency oscillation peace control amount acquisition methods flow chart, illustrates that the effectiveness of control amount evaluation method is pacified in interacted system low-frequency oscillation, and Relation of the oscillation energy with system oscillation damping ratio is verified, the foundation of evaluation method is illustrated.Province 500kV electrical network figures As shown in Fig. 2 belonging to sending end type electrical network, sending section includes interconnection A-B and interconnection C-D.

(1) checking of oscillation energy and interacted system oscillation damping than relation

Send the N-1D sides failure that section (interconnection A-B, C-D) arranges interconnection C-D to the electrical network outside, emulate duration 40s, Material calculation 0.01s, using oscillation energy formula, try to achieve oscillation energy that all electromotors in 10s～30s electrical networks flow out with And the electrical network sends the oscillation energy of section outflow outside, result of calculation is as shown in the table.

1 oscillation energy stream of table and system damping ratio relation simulation result

The relation of the oscillation energy that simulation results show network flows out and system oscillation damping ratio, system damping are poorer, The oscillation energy of outflow is bigger, therefore can estimate low-frequency oscillation peace control amount according to the changing value of damping ratio.When interacted system occurs During low-frequency oscillation, when the oscillation energy that negative damping unit sends flows in a network, because of via net loss and the energy of positive damping element Amount consumes the oscillation energy for making to send outside section outflow and has reduced relative to the oscillation energy that electromotor sends, therefore dissipation factor Selection is also requisite.

(2) cut machine amount and estimate that simulating, verifying, by taking the electrical network as an example, is carried out under the N-2D sides failure of interconnection C-D, now There is self-sustained oscillation in the electrical network, emulate duration 40s, material calculation 0.01s, and the time for asking for oscillation energy stream is limited to 10s up and down ～30s.When generation is vibrated, the active power curves of interconnection A-B are as shown in Figure 3：

(3) relevant parameter of control oscillation modes under current failure is extracted using prony algorithms, takes line power and bus Frequency plot is identical, extracts result as follows：

2 dominant oscillating mode of table extracts result

	Oscillation amplitude A	Frequency of oscillation f	Dampingratioζ
				A-B line powers	267.24	0.29	0
Node A-bus frequency	0.0243	0.29	0

(4) parameter of oscillation for utilizing oscillation energy formula and prony algorithms to extract, and according to oscillation equationIt is 0.8230 (p.u.) to calculate the oscillation energy that interconnection under current failure sends, target damping The oscillation energy sent than for 0.01, being calculated its corresponding interconnection is 0.8073 (p.u.).Section is sent outside to the electrical network Damping ratio is controlled the tieline oscillation energy value for needing to reduce：Δ W=Δ W_ζ1-ΔW_ζ2=0.0157 (p.u.).

(5) determine dissipation factor, obtain hunting of generator energy ablation amount.Emulation number when being occurred according to self-sustained oscillation According to obtaining the electrical network according to oscillation energy useful calculating method and send the energy that the energy that interconnection sends is sent with all electromotors outside Amount, and calculate dissipation factor：For 1.05, and then according to W_P=K_CΔ W obtains hunting of generator energy ablation amount For 0.0165 (p.u.)

(6) machine priority ordered is cut, that estimates concrete unit cuts machine amount.Data are emulated according to BPA to calculate inside the electrical network The oscillation energy that unit sends, carries out cutting machine priority ordered, takes and sends front ten maximum units of energy, as shown in table 3.By The HXG1 units of excision sequence first completely are not enough in the hunting of generator energy ablation amount of estimation, control is needed according to estimation result The HXG1 unit outputs decrement of system is P_C=(W_P/W_HXG1)·P_{SN HXG1}=278MW.

3 unit oscillation energy of table sorts

(7) the peace control for finally obtaining is cut machine strategy and controls HXG1 unit 278MW and exerts oneself, after taking measures system damping ratio For 0.0093, there is certain difference with target damping ratio.If control HXG1 unit 300MW exert oneself, system damping ratio reaches pre- The 0.01 of phase, cuts machine amount estimation error for 7.3%.As shown in figure 4, for taking interconnection A-B active power after peace control measure to become Change curve.

Finally it should be noted that：Above example is only to illustrate technical scheme rather than a limitation, most Pipe has been described in detail to the present invention with reference to above-described embodiment, and those of ordinary skill in the art should be understood：Still The specific embodiment of the present invention can be modified or equivalent, and without departing from any of spirit and scope of the invention Modification or equivalent, which all should be covered in the middle of scope of the presently claimed invention.

Claims (6)

1. control amount acquisition methods are pacified in a kind of interacted system low-frequency oscillation based on oscillation energy, it is characterised in that methods described bag Include following steps：

(1) calculate the difference of the current damping ratio of interacted system and oscillation energy corresponding to target damping ratio；

(2) determine dissipation factor K_C, calculate the resection of hunting of generator energy；

(3) cut machine priority ordered, estimation vibration degree of association cuts machine amount compared with large-sized unit.

2. method according to claim 1, it is characterised in that step (1) comprises the steps：

Step 1-1, the real time data interconnection active power and bus frequency between interacted system carry out, after Prony analyses, carrying Amplitude under respective dominant pattern, damping ratio, frequency of oscillation is taken, the dominant pattern oscillation equation after extraction is：

In formula：A is amplitude, and ζ is damping ratio, and w is frequency of oscillation,For vibrating initial phase；

Step 1-2, target damping ratio corresponding oscillation mode is regarded as it is consistent with the control oscillation modes extracted under current failure, According to oscillation equation, the oscillation energy under control oscillation modes is calculated, formula is as follows：

Δ W=Δ W_ζ1-ΔW_ζ2

In formula：ΔW_ζ1For the oscillation energy stream on interconnection under current failure；ΔW_ζ2For shaking on interconnection under target damping ratio Swing energy stream.

3. method according to claim 1, it is characterised in that step (2) comprise the steps：

Step 2-1, determine dissipation factor K_C；

Step 2-2, calculating t oscillation energy；

Step 2-3, electromotor oscillation energy resection, formula are measured out according to dissipation factor and tieline oscillation energy variation For：W_P=K_C·ΔW

In formula, Δ W be tieline oscillation energy variation amount, W_PFor hunting of generator energy ablation amount.

4. method according to claim 3, it is characterised in that in step 2-1, the dissipation factor is that all units are sent out The ratio of the oscillation energy that the oscillation energy for going out and interconnection flow out, formula are as follows：

$K_C=\frac{{\mathrm{\ΔW}}_G}{{\mathrm{\ΔW}}_S},(K_C>1)$

In formula, Δ W_GFor the oscillation energy sum that all electromotors send；ΔW_SFor the oscillation energy that interconnection between interacted system flows out Amount.

5. method according to claim 3, it is characterised in that in step 2-2, as PMU data is that temporally point is adopted Collection, and the calculating essence of definite integral is exactly the cumulative summation after segmenting to image, therefore the oscillation energy of t calculates public affairs in real time Formula is as follows：

$\begin{array}{c}{\mathrm{\ΔW}}_{ij}\≈{\∫}_0^t{\mathrm{\ΔP}}_{ij}{\mathrm{d\Δ\θ}}_i={\∫}_0^t{\mathrm{\ΔP}}_{ij}2{\mathrm{\π\Δf}}_{i}ds\≈\\ 2\mathrm{\π}\underset{r\→\mathrm{\∞}}{\lim }\underset{k=1}{\overset{r}{\mathrm{\Σ}}}\frac{t}{r}\left(P_{ij,k}-P_{ij,a}\right)\left(f_{i,k}-f_{i,a}\right)\end{array}$

In formula, Δ W_ijIt is through branch road L from bus i_ijThe oscillation energy of transmission, Δ P_ijBranch road L_ijActive power variable quantity, Δ θ_iThe voltage phase angle variable quantity of bus i, Δ f_iIt is the frequency variation of bus, s is integration variable, and r is the isodisperse of definite integral Amount；P_ij,k、f_i,kCircuit active power and bus frequency of the respectively branch road ij at the kt/r moment.

6. method according to claim 1, it is characterised in that step (3) comprise the steps：

Step 3-1, all electromotors are carried out cutting machine priority ordered according to oscillation energy size, it is excellent that oscillation energy cuts more greatly machine First spend higher；

Step 3-2, in order and unit capacity arrangement cut machine until resection reach W_P；

If step 3-3, the oscillation energy resection of estimation are more than the oscillation energy that unit sends, the whole excision of this unit, When estimate resection be not enough to cut off n-th whole unit when, this unit output controlled quentity controlled variable computing formula is：

$P_C=\frac{W_P-\underset{i=1}{\overset{n-1}{\mathrm{\Σ}}}{W}_{Pi}}{W_{Gn}}{P}_n$

In formula：P_nActive for n-th electromotor is exerted oneself, W_PiFor the oscillation energy of i-th electromotor, W_GnFor n-th electromotor Oscillation energy, P_CFor unit output controlled quentity controlled variable.