CN103107536B - State estimation method for offshore oilfield group power grid - Google Patents

Abstract

The invention relates to a state estimation method for an offshore oilfield group power grid. The method includes the following steps: network parameters of an offshore oilfield group power grid system are acquired from an energy management system (EMS) and input into a public information model; measurement data is read from a supervisory control and data acquisition (SCADA) system of the EMS, and the measurement data comprises remote measuring measurement and remote signaling measurement; weight of the measurement data is assigned to be 1; nodal injection current is introduced to be used as a state variable, relay protection measurement is introduced to be used as a measurement quantity, and the state variable is initialized; each oilfield platform power grid is used as an area, and a state variable of the initialized state variable is solved; if the maximum measurement residual is smaller than a threshold value 1, and then a state estimation result is stored and output; if the maximum measurement residual is larger than the threshold value 1, then the data with the maximum residual is marked as bad data, if a bad data proportion is smaller than a threshold value 2, the state variable is initialized again, partitioned sate estimation is carried out again, and if the bad data proportion is larger than the threshold value 2, alarm is given, and sampling is carried out again; the measurement residual for the threshold value 1 is 3%; and the measurement residual for the threshold value 2 is set to be 10%. The state estimation method for the offshore oilfield group power grid can be applied to the EMS of the oilfield group power grid.

Description

A kind of method for estimating state of offshore oilfield group electrical network

Technical field

The present invention relates to a kind of Power Network Status Estimation method, particularly produce and the method for estimating state of the offshore oilfield group electrical network in network system field for offshore oil and gas about a kind of.

Background technology

Offshore oilfield group electrical network is one and is dispersed on ocean, the independent micro-grid system being formed by distributed power generation, platform transformer station/load, extra large cable etc., be the important infrastructure of marine oil and gas exploitation, its safe and highly efficient operation has important effect for promoting offshore oil and gas production reliability and efficiency.And EMS (EMS) is one of key technology ensureing in offshore oilfield group electrical network, there is very important effect.There is no so far the state estimation about offshore oilfield group electrical network, and the state estimation of offshore oilfield group electrical network is one of Core Feature of offshore oilfield group electrical network EMS, its function is the various measurement informations according to Oilfield Group electrical network, estimates the current running status of electrical network.

The land Power Network Status Estimation of existing tradition can not adapt to the needs of offshore oilfield group Power Network Status Estimation well, its reason is: offshore oilfield electrical network and land electrical network difference are larger, mainly contain following characteristics: in offshore oilfield electrical network, in electrical network, measure quantity few, accuracy in measurement is not high; Oilfield electric net is the looped network of small scale and independent operating, ruuning situation more complicated; The generating set of oilfield electric net is gas turbine, is subject to the impact of field produces and scale enlargement, and system operation mode is changeable; Between the different produce oil platforms of oilfield electric net, be connected by a submarine cable, easily occur the situation of split operation.Because oilfield electric net has above feature, therefore bring huge challenge to state estimation: 1, in oilfield electric net, measure quantity few, precision is low, may cause system unobservable, or state estimation program cannot restrain.2, oilfield electric net small scale, after being disturbed, system state change is fast, thus claimed condition estimation routine will have the speed of service faster, reflects in real time the running status of system.3, oilfield electric net generating set is gas turbine, and because gas turbine inertia is little, start or shutdown are very large on the impact of system mode, is therefore not suitable for use amount measurement sudden change and detects the error message of searching in measurement.4, between the different produce oil platforms of oilfield electric net, be connected by a submarine cable, easily occur the situation of split operation, cause the normally running status of estimating system of traditional state estimation program.

Summary of the invention

For the problems referred to above, the object of this invention is to provide a kind of method for estimating state of offshore oilfield group electrical network, the method energy effecting reaction goes out operation of power networks state, and estimated speed is very fast.

For achieving the above object, the present invention takes following technical scheme: a kind of method for estimating state of offshore oilfield group electrical network, it comprises the following steps: 1) from EMS, obtain the network parameter of offshore oilfield group network system, and these network parameters are input in the common information model of offshore oilfield group electrical network; Wherein, EMS is EMS; 2) SCADA from EMS reads metric data, and metric data comprises that remote measurement measurement and remote signalling measure; Wherein remote measurement measurement mainly comprises that voltage magnitude measurement, generator active power measurement, generator reactive power measurement, the measurement of load active power, reactive load power measurement, the measurement of circuit head end active power, the measurement of circuit head end reactive power, the measurement of line end active power, the measurement of line end reactive power and line current amplitude measure; Remote signalling measures and mainly comprises that the measurement of switch, disconnecting link folding condition and load tap changer position measure; Wherein, each measuring point at least will comprise three contents: measuring point type, survey period and measuring value; 3) by described step 2) in obtain metric data weight assignment be 1; 4) introduce node Injection Current as state variable, and introduce relay protection and measure as measurement amount, make constraints linearisation: I=YU, by state variable initialization; 5) using each oil field platform electrical network as Yi Ge district, according to measurement residuals weighting one Norm minimum value z ^*solving state variable, uses respectively interior point method to calculate measurement residuals weighting one Norm minimum value z to each district ^*=h (x ^*), wherein x ^*it is state variable to be solved; 6), if maximum measurement residuals is less than threshold 1 in step 5), preserve and output state estimated result; If maximum measurement residuals is greater than threshold 1, be bad data by the data markers of residual error maximum, and be 0 by bad data weight assignment, judge the ratio of bad data, if bad data ratio is less than threshold 2, reinitialize state variable and again carry out subregion state estimation, if bad data ratio is greater than threshold 2, reporting to the police and resampling; Wherein to get measurement residuals be 3% to threshold 1; Threshold 2 is set as 10%.

In described step 5), described measurement residuals comprises disconnected point and the measurement residuals of branch road and the measurement residuals of connected node in the platform of each oil field, and the measurement residuals of every extra large cable tie point.

In described step 5), described state variable method for solving is as follows: (1) is according to target function h (x ^*) solve one group of state variable, target setting function h (x ^*) be:

$\begin{array}{c}h\left(x^{*}\right)=\min \underset{i=1}{\overset{N}{\mathrm{\Σ}}}K\_P_i*{\mathrm{\Δp}}_i+K\_Q_i*\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\Δq}}_i+K\_U_i*\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\Δu}}_i\\ +\underset{m=1}{\overset{M}{\mathrm{\Σ}}}K\_P_{\mathrm{ij}}\left[m\right]*\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\mathrm{\Δp}}_{\mathrm{ij}}\left[m\right]+\underset{m=1}{\overset{M}{\mathrm{\Σ}}}K\_Q_{\mathrm{ij}}\left[m\right]*\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\mathrm{\Δq}}_{\mathrm{ij}}\left[m\right]+\underset{m=1}{\overset{M}{\mathrm{\Σ}}}K\_I_{\mathrm{ij}}\left[m\right]*\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\mathrm{\Δi}}_{\mathrm{ij}}\left[m\right]\end{array},$

State variable to be estimated has node voltage abscissa U _ix, node voltage ordinate U _iy, node Injection Current abscissa I _ixwith node Injection Current ordinate I _iy; (2) between the state variable voltage and current obtaining through step (1), need to meet trend constraint and inequality constraints:

Trend constraint YU-I=0,

(G ₁₁U _1x-B ₁₁U _1y)+…+(G _1nU _nx-B _1nU _ny)-I _1x＝0

(G ₁₁U _1y-B ₁₁U _1x)+…+(G _1nU _ny-B _1nU _nx)-I _1y＝0

·

·

(G _n1U _1x-B _n1U _1y)+…+(G _nnU _nx-B _nnU _ny)-I _nx＝0

(G _n1U _1y-B _n1U _1x)+…+(G _nnU _ny-B _nnU _nx)-I _ny＝0

Inequality constraints:

-Δp _i≤P _i-(U _ixI _ix+U _iyI _iy)≤Δp _i

-Δq _i≤Q _i-(U _iyI _ix-U _ixI _iy)≤Δq _i

${-\mathrm{\Δu}}_i\≤U_i^2-({U_{\mathrm{ix}}}^2+{U_{\mathrm{iy}}}^2)\≤{\mathrm{\Δu}}_i$

${-\mathrm{\Δp}}_{\mathrm{ij}}\≤P_{\mathrm{ij}}-[(U_{\mathrm{ix}}^2+U_{\mathrm{iy}}^2)g-U_{\mathrm{ix}}{U}_{\mathrm{jx}}g-U_{\mathrm{iy}}{U}_{\mathrm{jy}}g-U_{\mathrm{iy}}{U}_{\mathrm{jx}}b+U_{\mathrm{ix}}{U}_{\mathrm{jy}}b]\≤{\mathrm{\Δp}}_{\mathrm{ij}}$

${-\mathrm{\Δq}}_{\mathrm{ij}}\≤Q_{\mathrm{ij}}-[-(U_{\mathrm{ix}}^2+U_{\mathrm{iy}}^2)(b+y_c)-U_{\mathrm{iy}}{U}_{\mathrm{jx}}g+U_{\mathrm{ix}}{U}_{\mathrm{jy}}g+U_{\mathrm{ix}}{U}_{\mathrm{jx}}b+U_{\mathrm{iy}}{U}_{\mathrm{jy}}b]\≤{\mathrm{\Δq}}_{\mathrm{ij}}$

Wherein, G, B is that the electricity in node admittance matrix Y is led and susceptance; Δ p _ifor node injects active power residual error, Δ q _ifor node injects reactive power residual error, Δ u _ifor node voltage amplitude residual error, Δ p _ijfor branch road two ends active power residual error, Δ q _ijfor branch road two ends reactive power residual error;

Node injects active power residual error ${\mathrm{\Δp}}_i=|P_i-(U_{\mathrm{ix}}{I}_{\mathrm{ix}}+U_{\mathrm{iy}}{I}_{\mathrm{iy}})|,$

Node injects reactive power residual error ${\mathrm{\Δq}}_i=|Q_i-(U_{\mathrm{iy}}{I}_{\mathrm{ix}}-U_{\mathrm{ix}}{I}_{\mathrm{iy}})|,$

Node voltage amplitude residual error ${\mathrm{\Δu}}_i=|U_i^2-({U_{\mathrm{ix}}}^2+{U_{\mathrm{iy}}}^2)|,$

Branch road two ends active power residual error ${\mathrm{\Δp}}_{\mathrm{ij}}\left[m\right]=|P_{\mathrm{ij}}-[(U_{\mathrm{ix}}^2+U_{\mathrm{iy}}^2)g-U_{\mathrm{ix}}{U}_{\mathrm{jx}}g-U_{\mathrm{iy}}{U}_{\mathrm{jy}}g-U_{\mathrm{iy}}{U}_{\mathrm{jx}}b+U_{\mathrm{ix}}{U}_{\mathrm{jy}}b\left]\right|,$

Branch road two ends reactive power residual error: ${\mathrm{\Δq}}_{\mathrm{ij}}\left[m\right]=|Q_{\mathrm{ij}}-[-(U_{\mathrm{ix}}^2+U_{\mathrm{iy}}^2)(b+y_c)-U_{\mathrm{iy}}{U}_{\mathrm{jx}}g+U_{\mathrm{ix}}{U}_{\mathrm{jy}}g+U_{\mathrm{ix}}{U}_{\mathrm{jx}}b+U_{\mathrm{iy}}{U}_{\mathrm{jy}}b\left]\right|,$

Branch current amplitude residual error: ${\mathrm{\Δi}}_{\mathrm{ij}}\left[m\right]=|I_{\mathrm{ij}}-\sqrt{[{U_{\mathrm{ix}}(y_{i0}+y_{\mathrm{ij}})-U_{\mathrm{jx}}{y}_{\mathrm{ij}}]}^2+[U_{\mathrm{iy}}(y_{i0}+y_{\mathrm{ij}})-U_{\mathrm{jy}}{y}_{\mathrm{ij}}{]}^2}|;$

In formula, P _ithat the active power that node i is injected measures; Q _ithat the reactive power that node i is injected measures; U _ithe voltage that is node i measures; P _ijthat the active power of branch road from i effluent toward j side measures; Q _ijthat the reactive power of branch road from i effluent toward j side measures; I _ijthe current measurement of branch road from i effluent toward j side; (3) state variable that meets step (2) constraints also will meet its corresponding target function minimum, and then this group state variable is carried out to state estimation.

The present invention is owing to taking above technical scheme, it has the following advantages: 1, the present invention is owing to adopting calculation method of divided area, first respectively each subregion (being each oil field platform) electrical network is carried out to state estimation, then reject bad data by state estimation in this locality, improve the computational speed of state estimation, the in real time virtual condition of reflection system, for the modules such as optimal load flow are below carried out element task.2, the present invention, owing to adopting node Injection Current as state variable, can make constraints linearisation, thereby can better process current measurement, and improve the computational speed of state estimation program.The present invention can be applied in the EMS (EMS) of extra large oily electrical network, also can be applied to electric power system supervision, analysis and control system based on real-time measurement amount.

Brief description of the drawings

Fig. 1 is overall flow schematic diagram of the present invention.

Embodiment

Below in conjunction with drawings and Examples, the present invention is described in detail.

As shown in Figure 1, the invention provides a kind of method for estimating state of offshore oilfield group electrical network, it comprises the following steps:

1) initialization: the network parameter that obtains offshore oilfield group network system from existing EMS (EMS), this network parameter comprise the resistance, reactance of extra large cable, over the ground electricity lead, no-load voltage ratio and the impedance of susceptance and transformer over the ground, and these network parameters are input in the common information model (CIM model) of existing offshore oilfield group electrical network.

2) SCADA(data acquisition and the supervisor control from EMS) read metric data, metric data comprises that remote measurement measurement and remote signalling measure; Wherein remote measurement measurement mainly comprises that voltage magnitude measurement, generator active power measurement, generator reactive power measurement, the measurement of load active power, reactive load power measurement, the measurement of circuit head end active power, the measurement of circuit head end reactive power, the measurement of line end active power, the measurement of line end reactive power and line current amplitude measure; Remote signalling measures and mainly comprises that the measurement of switch, disconnecting link folding condition and load tap changer position measure.Wherein, each measuring point at least will comprise three contents: measuring point type, survey period and measuring value.

3) by step 2) in obtain metric data weight assignment be 1;

4) introduce node Injection Current as state variable, because the quantity measuring in oilfield electric net system is few, measure as measurement amount so introduce relay protection.It is lower and contain more current measurement that relay protection measures accuracy in measurement, therefore node Injection Current is introduced to state variable, simplifies the measurement equation of system, and make constraints linearisation: I=YU, thereby simplify the iterative process of optimizing in calculating, accelerated the speed of calculating.By state variable initialization, order:

U _x＝1；U _y＝0；

$I_x=\frac{{\mathrm{PU}}_x+{\mathrm{QU}}_y}{U_x^2+U_y^2};$ $I_y=\frac{{\mathrm{PU}}_y-{\mathrm{QU}}_x}{U_x^2+U_y^2},$

Wherein P, Q are respectively active power and the reactive power that node injects; U _xfor node voltage abscissa; U _yfor node voltage ordinate; I _xfor node Injection Current abscissa; I _yfor node Injection Current ordinate.

5) using each oil field platform electrical network as Yi Ge district, according to measurement residuals weighting one Norm minimum value z ^*solving state variable, uses respectively interior point method to calculate measurement residuals weighting one Norm minimum value z to each district ^*=h (x ^*), wherein x ^*it is state variable to be solved; Measurement residuals comprises disconnected point and the measurement residuals of branch road and the measurement residuals of connected node in the platform of each oil field, and the measurement residuals of every extra large cable tie point.

6), if maximum measurement residuals is less than threshold 1 in step 5), preserve and output state estimated result; If maximum measurement residuals is greater than threshold 1, be bad data by the data markers of residual error maximum, and be 0 by bad data weight assignment, judge the ratio of bad data, if bad data ratio is less than threshold 2, reinitialize state variable and again carry out subregion state estimation, if bad data ratio is greater than threshold 2, reporting to the police and resampling.Wherein threshold 1 is got measurement residuals, and representative value is 3%; Threshold 2 is rule of thumb set as 10%.

Above-mentioned steps 5) in, state variable method for solving is as follows:

(1) according to target function h (x ^*) solve one group of state variable, target setting function h (x ^*) be:

$\begin{array}{c}h\left(x^{*}\right)=\min \underset{i=1}{\overset{N}{\mathrm{\Σ}}}K\_P_i*{\mathrm{\Δp}}_i+K\_Q_i*\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\Δq}}_i+K\_U_i*\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\Δu}}_i\\ +\underset{m=1}{\overset{M}{\mathrm{\Σ}}}K\_P_{\mathrm{ij}}\left[m\right]*\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\mathrm{\Δp}}_{\mathrm{ij}}\left[m\right]+\underset{m=1}{\overset{M}{\mathrm{\Σ}}}K\_Q_{\mathrm{ij}}\left[m\right]*\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\mathrm{\Δq}}_{\mathrm{ij}}\left[m\right]+\underset{m=1}{\overset{M}{\mathrm{\Σ}}}K\_I_{\mathrm{ij}}\left[m\right]*\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\mathrm{\Δi}}_{\mathrm{ij}}\left[m\right]\end{array},$

State variable to be estimated has node voltage abscissa U _ix, node voltage ordinate U _iy, node Injection Current abscissa I _ixwith node Injection Current ordinate I ^iy;

(2) between the state variable voltage and current obtaining through step (1), need to meet trend constraint and inequality constraints, meet following constraints:

Trend constraint YU-I=0,

(G ₁₁U _1x-B ₁₁U _1y)+…+(G _1nU _nx-B _1nU _ny)-I _1x＝0

(G ₁₁U _1y-B ₁₁U _1x)+…+(G _1nU _ny-B _1nU _nx)-I _1y＝0

·

·

(G _n1U _1x-B _n1U _1y)+…+(G _nnU _nx-B _nnU _ny)-I _nx＝0

(G _n1U _1y-B _n1U _1x)+…+(G _nnU _ny-B _nnU _nx)-I _ny＝0

Inequality constraints:

-Δp _i≤P _i-(U _ixI _ix+U _iyI _iy)≤Δp _i

-Δq _i≤Q _i-(U _iyI _ix-U _ixI _iy)≤Δq _i

${-\mathrm{\Δu}}_i\≤U_i^2-({U_{\mathrm{ix}}}^2+{U_{\mathrm{iy}}}^2)\≤{\mathrm{\Δu}}_i$

${-\mathrm{\Δp}}_{\mathrm{ij}}\≤P_{\mathrm{ij}}-[(U_{\mathrm{ix}}^2+U_{\mathrm{iy}}^2)g-U_{\mathrm{ix}}{U}_{\mathrm{jx}}g-U_{\mathrm{iy}}{U}_{\mathrm{jy}}g-U_{\mathrm{iy}}{U}_{\mathrm{jx}}b+U_{\mathrm{ix}}{U}_{\mathrm{jy}}b]\≤{\mathrm{\Δp}}_{\mathrm{ij}}$

${-\mathrm{\Δq}}_{\mathrm{ij}}\≤Q_{\mathrm{ij}}-[-(U_{\mathrm{ix}}^2+U_{\mathrm{iy}}^2)(b+y_c)-U_{\mathrm{iy}}{U}_{\mathrm{jx}}g+U_{\mathrm{ix}}{U}_{\mathrm{jy}}g+U_{\mathrm{ix}}{U}_{\mathrm{jx}}b+U_{\mathrm{iy}}{U}_{\mathrm{jy}}b]\≤{\mathrm{\Δq}}_{\mathrm{ij}}$

Wherein, G, B is that the electricity in node admittance matrix Y is led and susceptance; Δ p _ifor node injects active power residual error, Δ q _ifor node injects reactive power residual error, Δ u _ifor node voltage amplitude residual error, Δ p _ijfor branch road two ends active power residual error, Δ q _ijfor branch road two ends reactive power residual error.

Wherein, node injects active power residual error ${\mathrm{\Δp}}_i=|P_i-(U_{\mathrm{ix}}{I}_{\mathrm{ix}}+U_{\mathrm{iy}}{I}_{\mathrm{iy}})|,$

Node injects reactive power residual error ${\mathrm{\Δq}}_i=|Q_i-(U_{\mathrm{iy}}{I}_{\mathrm{ix}}-U_{\mathrm{ix}}{I}_{\mathrm{iy}})|,$

Node voltage amplitude residual error ${\mathrm{\Δu}}_i=|U_i^2-({U_{\mathrm{ix}}}^2+{U_{\mathrm{iy}}}^2)|,$

Branch road two ends active power residual error ${\mathrm{\Δp}}_{\mathrm{ij}}\left[m\right]=|P_{\mathrm{ij}}-[(U_{\mathrm{ix}}^2+U_{\mathrm{iy}}^2)g-U_{\mathrm{ix}}{U}_{\mathrm{jx}}g-U_{\mathrm{iy}}{U}_{\mathrm{jy}}g-U_{\mathrm{iy}}{U}_{\mathrm{jx}}b+U_{\mathrm{ix}}{U}_{\mathrm{jy}}b\left]\right|,$

Branch road two ends reactive power residual error: ${\mathrm{\Δq}}_{\mathrm{ij}}\left[m\right]=|Q_{\mathrm{ij}}-[-(U_{\mathrm{ix}}^2+U_{\mathrm{iy}}^2)(b+y_c)-U_{\mathrm{iy}}{U}_{\mathrm{jx}}g+U_{\mathrm{ix}}{U}_{\mathrm{jy}}g+U_{\mathrm{ix}}{U}_{\mathrm{jx}}b+U_{\mathrm{iy}}{U}_{\mathrm{jy}}b\left]\right|,$

Branch current amplitude residual error: ${\mathrm{\Δi}}_{\mathrm{ij}}\left[m\right]=|I_{\mathrm{ij}}-\sqrt{[{U_{\mathrm{ix}}(y_{i0}+y_{\mathrm{ij}})-U_{\mathrm{jx}}{y}_{\mathrm{ij}}]}^2+[U_{\mathrm{iy}}(y_{i0}+y_{\mathrm{ij}})-U_{\mathrm{jy}}{y}_{\mathrm{ij}}{]}^2}|;$

Wherein, P _ithat the active power that node i is injected measures; Q _ithat the reactive power that node i is injected measures; U _ithe voltage that is node i measures; P _ijthat the active power of branch road from i effluent toward j side measures; Q _ijthat the reactive power of branch road from i effluent toward j side measures; I _ijthe current measurement of branch road from i effluent toward j side.

(3) state variable that meets step (2) constraints also will meet its corresponding target function minimum, and then this group state variable is carried out to state estimation.

The various embodiments described above are only for illustrating the present invention; the connection of each parts and structure all can change to some extent; on the basis of technical solution of the present invention; all improvement and equivalents that according to the principle of the invention, the connection to indivedual parts and structure are carried out, all should not get rid of outside protection scope of the present invention.

Claims (2)

1. a method for estimating state for offshore oilfield group electrical network, it comprises the following steps:

1) from EMS, obtain the network parameter of offshore oilfield group network system, and these network parameters are input in the common information model of offshore oilfield group electrical network; Wherein, EMS is EMS;

2) SCADA from EMS reads metric data, and metric data comprises that remote measurement measurement and remote signalling measure; Wherein remote measurement measurement mainly comprises that voltage magnitude measurement, generator active power measurement, generator reactive power measurement, the measurement of load active power, reactive load power measurement, the measurement of circuit head end active power, the measurement of circuit head end reactive power, the measurement of line end active power, the measurement of line end reactive power and line current amplitude measure; Remote signalling measures and mainly comprises that the measurement of switch, disconnecting link folding condition and load tap changer position measure; Wherein, each measuring point at least will comprise three contents: measuring point type, survey period and measuring value;

3) by described step 2) in obtain metric data weight assignment be 1;

4) introduce node Injection Current as state variable, and introduce relay protection and measure as measurement amount, make constraints linearisation: I=YU, by state variable initialization; Wherein, Y is node admittance matrix; I is node Injection Current; U is node voltage;

5) using each oil field platform electrical network as Yi Ge district, according to measurement residuals weighting one Norm minimum value z ^*solving state variable, uses respectively interior point method to calculate measurement residuals weighting one Norm minimum value z to each district ^*=h (x ^*), wherein x ^*it is state variable to be solved; H (x ^*) be target function;

6) if step 5) in maximum measurement residuals be less than threshold 1, preserve and output state estimated result; If maximum measurement residuals is greater than threshold 1, be bad data by the data markers of residual error maximum, and be 0 by bad data weight assignment, judge the ratio of bad data, if bad data ratio is less than threshold 2, reinitialize state variable and again carry out subregion state estimation, if bad data ratio is greater than threshold 2, reporting to the police and resampling; Wherein to get measurement residuals be 3% to threshold 1; Threshold 2 is set as 10%.

2. the method for estimating state of a kind of offshore oilfield group electrical network as claimed in claim 1, it is characterized in that: described step 5) in, described measurement residuals comprises disconnected point and the measurement residuals of branch road and the measurement residuals of connected node in the platform of each oil field, and the measurement residuals of every extra large cable tie point.