CN104993489B - Island network in emergency circumstances optimum cutting load method for determination of amount - Google Patents

Abstract

The invention belongs to POWER SYSTEM EMERGENCY CONTROL measure technical field, disclose one kind and be applied to island network in emergency circumstances optimum cutting load method for determination of amount.It is characterized in that：Governor characteristic according to electromotor and part throttle characteristics obtain the mathematic(al) representation of the frequency characteristic of island network, can obtain the mathematic(al) representation of the maximum frequency deviation of island network further；According to maximum frequency deviation formula and the anti-pushing system of frequency normal operation range be subject to initial time after disturbance should unbalanced power amount size；Then according to the initial time that calculates should unbalanced power amount size determine the size of optimum cutting load.The inventive method is set up on strict mathematical formulae theoretical derivation basis, and quantitative obtains optimal cutting load amount, and not only principle is simple for the method, convenience of calculation, and can more accurately determine the minimum cutting load amount of island network.

Description

Island network in emergency circumstances optimum cutting load method for determination of amount

Technical field

The invention belongs to POWER SYSTEM EMERGENCY CONTROL measure technical field, more particularly, to one kind to be applied to island network urgent In the case of optimum cutting load method for determination of amount.

Background technology

Island network refers to the low capacity electrical network departing from bulk power grid, and its maximum single-machine capacity is typically no less than net capacity 8%.Due to many factors such as economy and history, China still suffers from the weak electrical network of multiple isolated operations, and its net internal loading accounts for Proportion, spare capacity is few, and unit quantity is few, and single-machine capacity accounting is big, therefore the single power source trip fault of generation will be to electrical network Cause great impact, or even collapse of frequency can be caused.Therefore, cutting load must be taken to arrange after isolated network hinders for some reason and loses power supply Apply the frequency stable to keep electrical network.

At present, the research of the determination with regard to optimum cutting load for the domestic and international Research Literature is main in the following areas：1. using examination The empirical method gathered；2. the problem of optimum cutting load is converted into general mathematical problem；3. adopt the transient emulation of time domain.And And it is mainly based upon bulk power grid with regard to optimum cutting load quantifier elimination, less to the correlational study of island network；On the other hand this A little methods lack degree of accuracy or need complicated mathematical calculation.The present invention proposes a kind of island network in emergency circumstances Excellent cutting load method for determination of amount.

Content of the invention

In order to overcome the shortcomings of prior art presence, the present invention proposes a kind of island network in emergency circumstances optimum cutting load Method for determination of amount, including：

A kind of island network in emergency circumstances optimum cutting load method for determination of amount it is characterised in that：

Step 1, the operational factor of acquisition island network, including：The frequency mediating effect+6 coefficient of electromotorIts Middle R is the static difference coefficient of speed regulator, Load Regulation COEFFICIENT K_L, in system, the capacity of participation primary frequency modulation unit accounts for operation machine The ratio beta of group total capacity, electromotor inertia time constant T_J, time constant T of speed regulator_G, above each time constant arrives for reduction System always specified generated output P_GNUnder famous value, unit is the second, and remaining variables are system always specified generated output P_GNBe System rated frequency f_NUnder perunit value；

Step 2, the governor characteristic according to electromotor and part throttle characteristics set up the mathematical table of the frequency characteristic of island network Reach formula；

Step 3, obtain further island network maximum frequency deviation mathematic(al) representation；

Counter to push away island network disturbed for step 4, the mathematic(al) representation according to maximum frequency deviation and frequency normal operation range After dynamic initial time should unbalanced power amount size；

Step 5, according to the initial time that calculates should unbalanced power amount size determine the big of optimum cutting load amount Little, make the system failure occur after unbalanced power amount be equal to calculate should unbalanced power amount.

Described island network in emergency circumstances optimum cutting load method for determination of amount it is characterised in that：In described step 2 The mathematic(al) representation of frequency characteristic Δ f (t) of island network is

Intermediate variable K in formula_S=K_L+βK_G, intermediate variableIntermediate variableIn Between variableT is the time, and unit is the second, the system before imbalance with power total Rated generation power P_GNOn the basis of power initial unbalance, Δ P=P_G-P_L0, wherein P_GIt is subject to total after disturbance for island network Generated output, P_L0It is subject to total loading after disturbance for island network.

Described island network in emergency circumstances optimum cutting load method for determination of amount it is characterised in that：In described step 3 The maximum frequency deviation Δ f of island network_maxFor

Intermediate variable in formulaIntermediate variable

Described island network in emergency circumstances optimum cutting load method for determination of amount it is characterised in that：Described step 4 obtains Island network be subject to disturbance after initial time should unbalanced power amount Δ P^*For

The normal frequency range run of island network is (f_min,f_max).

Beneficial effects of the present invention：

The inventive method passes through the theoretical derivation of strict mathematical formula, determines the optimum cutting load of quantifier elimination island network Amount, method is simple, and calculating speed is fast, and effect is good, overcomes existing method to calculate numerous and diverse, the slow problem of convergence rate, is more favorable for Actual engineer applied.

Brief description

Fig. 1 is island network in emergency circumstances optimum cutting load method for determination of amount flow chart.

Fig. 2 is the geographical wiring diagram of certain island network that embodiment provides.

Fig. 3 is certain island network of embodiment offer in emergency circumstances by frequency before and after the cutting load amount of context of methods determination Response curve.

Specific embodiment

Below in conjunction with the accompanying drawings, preferred embodiment is elaborated.

Embodiment 1

Fig. 1 is meter island network in emergency circumstances optimum cutting load method for determination of amount flow chart.

Step 1：Obtain the operational factor of island network

Island network operational factor includes：The frequency mediating effect+6 coefficient of electromotorWherein R is speed regulator Static difference coefficient, Load Regulation COEFFICIENT K_L, in system, the capacity of participation primary frequency modulation unit accounts for the ratio of operating unit total capacity Value β, electromotor inertia time constant T_J, time constant T of speed regulator_G, above each time constant is always specified of reduction to system Electrical power P_GNUnder famous value, unit is the second, and remaining variables are P_GN, system nominal frequency f_NUnder perunit value；

Step 2：Ask for the frequency characteristic mathematic(al) representation of island network

According to the frequency characteristic mathematic(al) representation of the gain of parameter island network in step 1 it is：

In formula：Intermediate variable K_S=K_L+βK_G, intermediate variableIntermediate variableMiddle VariableT is the time, and unit is the second, the system before imbalance with power always specified Generated output P_GNOn the basis of power initial unbalance, Δ P=P_G-P_L0, wherein P_GIt is subject to total generating electricity after disturbance for island network Power, P_L0It is subject to total loading after disturbance for island network；

Step 3：Try to achieve island network maximum frequency deviation

Show that maximum frequency deviation is according to the frequency characteristic mathematics in step 2：

Intermediate variable in formulaIntermediate variable

Step 4：Try to achieve island network be subject to disturbance after initial time should unbalanced power amount size

The normal frequency range run of island network is (f_min,f_max), thus can obtain island network by when after disturbance initially Quarter should unbalanced power amount be：

Step 5：It is determined that the loading of excision

According to the initial time calculating should unbalanced power amount it is determined that excision loading, make the system failure Unbalanced power amount after generation be equal to calculate should unbalanced power amount.

Embodiment 2

Tu2Wei Mou city regional power grid geographical wiring diagram.This regional power grid is by five aluminium electrolysis enterprises having power plant for self-supply Networking isolated power grid, 10, total electromotor, wherein 350MW unit 2,150MW unit 2,155MW unit 3,135MW Unit 3.This regional power grid operating unit 9 at present, wherein 350MW unit 2,150MW unit 2,155MW unit 3, 135MW unit 2, load total amount is 1300MW.

First, obtain the operational factor of island network.The frequency mediating effect+6 COEFFICIENT K of electromotor_G=20；Total with system Load Regulation COEFFICIENT K on the basis of rated power_L=1.5；Participating in the capacity of primary frequency modulation unit in system, to account for operating unit total Ratio beta=100% of capacity；Electromotor inertia time constant_TJ=10s；Time constant T of speed regulator_G=3s.

Secondly, according to the mathematic(al) representation that above parameter can ask for island network frequency characteristic it is：

Island network maximum frequency deviation can be tried to achieve again according to above formula derivation is：

Again, according to island network normal operating frequency scope be 49.5～50.5Hz, try to achieve island network be subject to disturbance after Should initial power amount of unbalance size be

ΔP^*=0.5 × 1735/6.116=141.8MW

If 350MW unit breaks down mediation in power plant for self-supply 3 in island network, exert oneself as 324MW, now before stop jumping Power shortage is 324MW, and the load that need to excise to not affect normal frequency is 324MW-141.8MW=182.2MW.

Excise above-mentioned load finally by PSASP power system transient simulation software verification.

As shown in figure 3, island network 350MW unit fault does not take cutting load measure system by frequency unstability after mediating, Take the optimum cutting load amount that the inventive method calculates, excise load 182.2MW, low-limit frequency is 49.5Hz, just returns to Within the scope of often.

Above-described embodiment is only the present invention preferably specific embodiment, but protection scope of the present invention is not limited to This, any those familiar with the art the invention discloses technical scope in, the change that can readily occur in or replace Change, all should be included within the scope of the present invention.Therefore, protection scope of the present invention should be with the protection model of claim Enclose and be defined.

Claims (4)

1. a kind of island network in emergency circumstances optimum cutting load method for determination of amount it is characterised in that：

Step 1, the operational factor of acquisition island network, including：The frequency mediating effect+6 coefficient of electromotorWherein R is The static difference coefficient of speed regulator, Load Regulation COEFFICIENT K_L, participating in the capacity of primary frequency modulation unit in system, to account for operating unit total The ratio beta of capacity, electromotor inertia time constant T_J, time constant T of speed regulator_G, above each time constant is for reduction to system Always specified generated output P_GNUnder famous value, unit is the second, and remaining variables are system always specified generated output P_GNWith system volume Determine frequency f_NUnder perunit value；

Step 2, the governor characteristic according to electromotor and part throttle characteristics set up the mathematic(al) representation of the frequency characteristic of island network；

Step 3, obtain further island network maximum frequency deviation mathematic(al) representation；

Step 4, the mathematic(al) representation according to maximum frequency deviation and the anti-island network that pushes away of frequency normal operation range are by after disturbance Initial time should unbalanced power amount size；

Step 5, according to the initial time that calculates should unbalanced power amount size determine the size of optimum cutting load amount, make The system failure occur after unbalanced power amount be equal to calculate should unbalanced power amount.

2. according to claim 1 method it is characterised in that：Frequency characteristic Δ f (t) of the island network in described step 2 Mathematic(al) representation be

$\mathrm{\Δ}f\left(t\right)=\frac{50\mathrm{\Δ}P}{K_s}\[1-(\cos bt-\frac{a+c}{b}\sin bt)e^{-at}\]$

Intermediate variable K in formula_S=K_L+βK_G, intermediate variableIntermediate variableMiddle anaplasia AmountT is the time, and unit is the second, the system before imbalance with power always specified Generated output P_GNOn the basis of power initial unbalance, Δ P=P_G-P_L0, wherein P_GIt is subject to total generating electricity after disturbance for island network Power, P_L0It is subject to total loading after disturbance for island network.

3. according to claim 2 method it is characterised in that：The maximum frequency deviation Δ of the island network in described step 3 f_maxFor

${\mathrm{\Δf}}_{max}=\left|\frac{50\mathrm{\Δ}P}{K_S}(1+A_m{e}^{-{\mathrm{at}}_m})\right|$

Intermediate variable in formula $A_m=\sqrt{\frac{{\mathrm{\βK}}_G{T}_G}{T_J}},$ Intermediate variable $t_m=\frac{1}{b}{\tan }^{-1}\[\left(\frac{2T_J{T}_{G}b}{K_L{T}_G-T_J}\right)\].$

4. according to claim 3 method it is characterised in that：Described step 4 obtains island network and is subject to initial time after disturbance Should unbalanced power amount Δ P^*For

${\mathrm{\ΔP}}^{*}=P_{GN}\left|\mathrm{\Δ}P\right|=\frac{P_{GN}(f_N-f_{min})K_S}{50(1+A_m{e}^{-{\mathrm{at}}_m})}$

The normal frequency range run of island network is (f_min,f_max).