JP2712092B2 - Voltage reactive power monitoring and control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention monitors the magnitude of the bus voltage of a power system (hereinafter, the term voltage means the magnitude of the voltage) and the reactive power flow. The present invention relates to a technique for improving the stability of a power system in a voltage reactive power monitoring and control device that performs control.

(Prior art) Conventionally, the phase-adjusting capacitor, the reactor, and the transformer are controlled so that the bus voltage of the power system and the reactive power flow flowing through the transmission line and the transformer are maintained within predetermined operation target values. Tap, generator, synchronous phaser (rotary condenser)
And the like, and independently controlling the voltage reactive power adjusting device and controlling the device such that the voltage stability of the power system is equal to or higher than a predetermined level.

Moreover, these were performed by a human system without a control device.

(Problems to be Solved by the Invention) As described above, in the conventional device, monitoring and control are performed so as to maintain the bus voltage and the reactive power flow within a predetermined operation target value range, and the voltage stability is maximized. And the monitoring and control are performed independently so that the bus voltage and the reactive power flow are within the range of the operation target value. If it is controlled, the voltage stability may be degraded, or if adjustment / control is performed to maintain the voltage stability, the bus voltage and the reactive power flow may fall outside the range of the operation target value. was there.

The present invention has been made in view of the above circumstances, and has a control condition that the bus voltage and the reactive power flow of the power system are maintained within or around an operation target value, and the voltage stability of the power system is maximized. It is an object of the present invention to provide a voltage reactive power monitoring and control device capable of controlling a voltage reactive power adjusting device so as to be equal to or higher than a predetermined level.

[Configuration of the Invention] (Means for Solving the Problems) In order to achieve the above object, a voltage reactive power monitoring and control device of the present invention includes a state estimating means for determining a value of a state variable of a power system, The means for calculating the ratio of the change in node power to the change (hereinafter abbreviated as dp / dV) and the degree to which the dp / dV changes when the voltage reactive power adjusting device is adjusted by a unit amount (hereinafter abbreviated as the sensitivity coefficient) It comprises a means for calculating (hereinafter abbreviated as sensitivity coefficient calculating means) and a means for calculating an adjustment amount of a voltage reactive power adjusting device for improving voltage stability (hereinafter abbreviated as voltage stability improvement adjustment amount calculating means). .

(Operation) Using the measurement data of the state of the power system transmitted by the information transmission device, the state estimating means determines the value of the state variable of the power system. Next, dp / dV representing the state of the voltage stability of the power system is calculated by dp / dV calculation means, and the sensitivity coefficient for dp / dV of the voltage reactive power adjusting device is calculated by the sensitivity coefficient calculation means. Finally, the adjustment amount of the voltage reactive power device for improving the voltage stability is determined by the voltage stability improvement adjustment amount calculating means using the sensitivity coefficient.

(Example) Hereinafter, an example is described with reference to drawings.

FIG. 1 is a structural example showing the processing contents of a voltage reactive power monitoring and control device according to the present invention, and FIG. 2 is an overall structural example.

Referring to FIG. 2, reference numeral 1 denotes a power system, which includes a measuring device 2 and a voltage reactive power adjusting device 3. Reference numeral 4 denotes an information transmission device on the transmission / reception side, reference numeral 5 denotes an electronic computer, which performs processing described later, and reference numeral 6 denotes a display input device.

 And the overall operation is as follows.

First, the state quantities of the power system such as the bus voltage, the power flow, the generator output, the load power, and the ON / OFF state of the circuit breaker measured by the measuring device 2 are input to the electronic computer 5 by the information transmission device 4. The electronic computer 5 calculates the adjustment amount for improving the voltage stability of the power system while satisfying the constraints on the bus voltage and the reactive power flow by various means shown in FIG. A control signal for the adjusting device 3 is sent to the voltage reactive power adjusting device 3 via the information transmission device 4 and the voltage of the power system and the reactive power flow are controlled, so that the voltage stability of the power system is improved. . The display / input device 6 is used for displaying a control amount and the like and inputting parameters such as an upper and lower limit value of voltage operation.

FIG. 1 is a diagram showing an example of the configuration of the means of the present invention processed by the computer 5, and 11 is a power system information input means,
12 is state estimation means, 13 is dp / dV calculation means, 14 is voltage stability evaluation means, 15 is sensitivity coefficient calculation means for calculating the sensitivity coefficient of voltage reactive power adjustment equipment for dp / dV, 16 is voltage stability improvement The adjustment amount calculating means 17 is a control signal sending means.

 Hereinafter, a method of realizing each means will be described in detail.

The power system information input means 11 receives various measured values related to the power system, that is, a bus (hereinafter also referred to as a node) voltage,
Active power flow and reactive power flow flowing through transmission lines and transformers,
Input the power system state quantities such as the active power output and reactive power output of the generator, the tap position of the transformer, the on / off state of the circuit breaker, etc. from the information transmission device, and convert them to engineering units so that they can be used by the following means. Is performed.

Next, the state estimating means 12 calculates the value x ₀ (that is, V ₀ ) of the state variable x of the power system (the magnitude V of the node voltage and its phase angle δ) from the state quantity of the power system to which the means 11 has performed the input processing. ,
δ ₀ ). The determination method is a well-known technique, and a description thereof will be omitted.

The dp / dV calculation means 13 uses the value x _{0 of the} state variable to calculate the ratio of the change of the node power p to the change of the voltage, that is, dp, from the change amount of the node voltage when the total demand power is increased.
_j (x) / dV _j is obtained as follows. When the total demand power increases, the load power of each node increases in proportion to the total demand, and the generator output increases at a certain distribution ratio. Further, the ratio of the reactive power of the load to the active power of the load can be regarded as constant regardless of the total demand power. Therefore, the distribution ratio of generator output i is KG _i , the ratio of load j to total demand is KL _j , load j
Assuming that the ratio of the reactive power to the active power is _PFj , when the total demand power increases by ΔL, the change amounts of the active power and the reactive power of each node are as follows.

ΔP _i = KG _i · ΔL (1) ΔP _j = KL _j · ΔL (2) ΔQ _j = PF _j · ΔP _j (3) where ΔP: amount of change in active power of the node ΔP: invalidity of the node power variation i: generator node _{= i 1, i 2, ~i} m j: load node = j _1, j _2, a to j _n.

Now, the power equation representing the state of the power system is: p _i (x) = 0 (4) p _j (x) = 0 (5) q _j (x) = 0 (6) p (x): node active power function vector q (x): is a function vector node reactive power, when the total power demand changes by [Delta] L, the state variable is changed from x ₀ to x ₀ + [Delta] x _0,
[Δx ₀ ] = [H] ⁻¹ [ΔP _i , ΔP _j , ΔQ _j ] ^T ... (7) [] by the first order term of the Taylor expansion of the equations (4), (5), and (6). Represents a matrix or vector.

−1: means an inverse matrix.

 T: means transposition of matrix or vector.

Δx ₀ : amount of change of state variable x [H]: Jacobian matrix, whose elements are ∂p (x) ∂x | _{x = x0} and ∂q (x) ∂x | _{x = x0} . Here, equation (7) of the voltage variable V _j dp _j / dV _j the variation value if [Delta] V _0j of j nodes of the _{Δx 0, dp j / dV j} = ΔP j / ΔV 0j ... (8)

The voltage stability evaluation means 14 evaluates the current state of the voltage stability of the power system and determines whether or not control for improving the voltage stability is necessary. In general, the voltage stability of the power system is dp _j /
It can be evaluated by the value of dV _j . That is, the third
As shown in the figure, dp _j / dV _j is a positive value in the stable voltage range,
The value is zero at the stability limit and a negative value in the unstable region. The larger the value, the better the voltage stability, and the smaller the value, the worse the stability. The minimum value of dp _j / dV _j calculated by the dp / dV calculation means 13 is obtained and compared with the threshold ε. When the minimum value is larger than the threshold value ε, the voltage stability is high and no improvement is necessary, so the processing is terminated here. When the voltage is small, the voltage stability is low, and therefore the voltage stability needs to be improved, and the process of the sensitivity coefficient calculating means 15 is started.

The sensitivity coefficient calculating means 15 calculates the dp _j /
Calculate the sensitivity coefficient for dV _j . A commonly used voltage reactive power adjusting device effective for improving voltage stability is a reactive power supply source such as a phase adjusting capacitor, a reactive power output of a generator and a synchronous phase adjuster. The sensitivity coefficient of the voltage reactive power adjusting device to dp _j / dV _j is dp _j when the reactive power q _k supplied by the voltage reactive power adjusting device k connected to the k node changes by ΔQ _k. the variation / dV _j delta determined by (dp _j / dV _j). That is, It is.

Here, the partial differential value of dp _j / dV _j can be approximated as follows.

∂V _k / ∂q _k is as follows.

_{B k, k = ∂V k /} ∂q k = ΔV qk / ΔQ k ... (11) [Δx q] = [H] -1 · [0,0, ... Δq k, 0, ...] T ... (12 ) ΔV _qk is the amount of change in the state variable V _k of the voltage of the k node in [Δx _q ].

The voltage stability improvement adjustment amount calculation means 16 determines an adjustment amount of the voltage reactive power adjustment device for improving the voltage stability. As shown in FIG. 3, the larger the value of dp / dV, the higher the voltage stability. Therefore, under the constraint that the bus voltage and the reactive power flow are within the upper and lower limits as the operation target value, Δ (dp _j / dV _j ) to determine the adjustment amount ΔQ _k of the voltage reactive power adjusting device that maximizes the weighted sum. That is, the objective function Constraints Limit of adjustment amount ΔQ _k ≦ ΔQ _k ≦ ▲ ▼ _k (16) Limit of voltage ΔV _jj ≦ ΔV _jj ≦ ▲ ▼ _jj (17) Limit of reactive power flow ΔQ _iikk ≦ ΔQ _iikk ≦ ▲ ▼ _iikk … (18 ΔQ _iikk : Reactive power flow of the branch to be monitored, that is, the reactive power flow of the branch between node ii and node kk ΔV _jj : Voltage of node jj to be monitored B _{jj, k} = ∂V _jj / ∂Q _k ( 19) C _{iikk, k} = ∂Q _iikk / ∂Q _k (20) W _j : A weighting coefficient is used to find ΔQ _k that maximizes the objective function JQ.

The control signal transmitting means 17 converts the adjustment amount ΔQ _k of the voltage reactive power adjusting device for improving the voltage stability determined by the voltage stability improvement adjustment amount calculating means 16 into a control amount, and controls the information transmission device 4. A control signal to the voltage reactive power adjusting device is transmitted via the control signal.

According to the above embodiment, by controlling the voltage reactive power adjusting device, it is possible to perform an operation with increased voltage stability while maintaining the voltage and power flow of the power system at appropriate values, and to stably provide high-quality power. Can be supplied with reliability.

For the purpose of shortening the processing time, instead of maximizing the value of the objective function JQ in equation (13) of the above embodiment, dp / dV
Even if the voltage / reactive power adjusting device is controlled so that the value of dp _j1 / dV _j1 of the node J ₁ having the smallest value satisfies the constraint condition and is maximized, the initial purpose is achieved. That is, the objective function Constraints Adjustment amount limit ΔQ _k ≦ ΔQ _k ≦ ▲ ▼ _k (24) Voltage limit ΔV _jj ≦ ΔV _jj ≦ ▲ ▼ _jj (25) Restriction of reactive power flow ΔQ _iikk ≦ ΔQ _iikk ≦ ▲ ▼ _iikk … (26 ΔQ _iikk : Reactive power flow of the branch to be monitored, that is, the reactive power flow of the branch between node ii and node kk ΔV _jj : Voltage of node jj to be monitored B _{jj, k} = ∂V _jj / ∂Q _k ( 27) In C _{iikk, k} = ∂ΔQ _iikk / ∂Q _k (28), ΔQ _k that maximizes the objective function JQ _j1 may be obtained.

In the case of an emergency where the recovery of voltage stability is not sufficient even if the full capacity of the voltage regulator is used by the methods of the above two embodiments, the entire power system is not collapsed and some loads are limited. There is a method of restoring most of the remaining voltage stability by performing a power outage. In order to obtain the load cutoff amount ΔP _k at this time, as in the case of the above embodiment, the objective function Constraints Adjustment amount limitation ΔQ _k ≦ ΔQ _k ≦ ▲ ▼ _k (32) Voltage limitation ΔV _jj ≦ ΔV _jj ≦ ▲ ▼ _jj (33) Restriction of reactive power flow ΔQ _iikk ≦ ΔQ _iikk ≦ ▲ ▼ _iikk … (34 ΔQ _iikk : reactive power flow of the monitored branch, that is, reactive power flow of the branch between node ii and node kk _{F jj, k = ∂V jj /} ∂p k ... (36) G iikk, k = ∂Q iikk / ∂p k ... (37) k: Maximum in the load cut-off node, the objective function JP equation (21) seek ΔP _k to. The load is limited according to the determined ΔP _k .

The same control as in the above embodiment is also applied to voltage stability improvement control that includes a transformer tap, a rotary capacitor (synchronous phase adjuster), a phase adjustment reactor, and an SVC (Static Var Controller) as voltage reactive power adjustment equipment. It is clear that the method can be used.

Although the four embodiments described above are examples in which the voltage reactive power adjusting device is actually controlled, this embodiment is a method of displaying the result on the display input / output device without performing control. In the case of this embodiment, the operator performs adjustment of the voltage reactive power adjusting device and a load cutoff command with reference to the display result.

[Effects of the Invention] As described above, according to the present invention, the voltage stability of the power system is improved by controlling the voltage reactive power adjusting device while maintaining the voltage and the power flow of the power system at appropriate values. It is operable and has a great effect on stably supplying high-quality electric power with high reliability. Further, if the control is performed only by the voltage reactive power adjusting device in a normal state, and the load is limited in an emergency, the effect is further enhanced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the configuration of an embodiment of a voltage reactive power monitoring and control device according to the present invention. FIG.
The figure illustrates the concept of voltage stability. DESCRIPTION OF SYMBOLS 1 ... Electric power system 2 ... Measuring device 3 ... Voltage reactive power adjusting device 4 ... Information transmission device 5 ... Computer 6 ... Display / input device

Claims (5)

(57) [Claims] 1. A voltage reactive power monitoring and control device for detecting a state quantity from a power system and inputting it to an electronic computer via an information transmission device to monitor and control a magnitude of a bus voltage and a reactive power flow. Means for determining the state of the power system based on system information transmitted via the information transmission device; and total demand P for the system based on the determined system state.
Means for determining a PV curve indicating the relationship between the voltage and the system voltage V, and determining a ratio of a change in power to a change in voltage indicating the voltage stability state (gradient of the PV curve) from the PV curve. Means for judging the stability of the voltage based on the magnitude and sign of the value of the slope of the PV curve, and when the judgment result of the stability is unstable, it is necessary to improve the stability. Means for determining the adjustment amount of the voltage reactive power adjusting device, and a condition that the bus voltage and the reactive power flow at a plurality of points in the power system are within a predetermined range, and the stability of the power system is maximum or predetermined. Means for controlling voltage reactive power adjusting devices provided at a plurality of locations in the power system so as to be at or above the level. 2. The voltage reactive power monitoring and control device according to claim 1, wherein when the voltage stability of the power system cannot be maintained at a predetermined level or more only by controlling the voltage reactive power adjusting device, the load is also cut off to perform voltage reduction. A voltage reactive power monitoring and control device comprising means for setting the stability to a predetermined level or more. 3. The voltage reactive power monitoring and control device according to claim 1, further comprising means for outputting a control amount to a display device, in addition to means for controlling the voltage reactive power adjusting devices at a plurality of locations. Voltage reactive power monitoring and control device. 4. The voltage reactive power monitoring and control device according to claim 2, wherein when the voltage stability of the power system cannot be maintained at a predetermined level or more only by controlling the voltage reactive power adjusting device, the load is also cut off and the voltage is reduced. A voltage reactive power monitoring and control device comprising means for outputting a control amount to a display device in addition to means for making the stability equal to or higher than a predetermined level. 5. A voltage reactive power monitoring and control device for detecting a state quantity from a power system and inputting it to an electronic computer via an information transmission device to monitor and control the magnitude of the bus voltage and the reactive power flow. Means for determining the state of the power system based on system information transmitted via the information transmission device; and total demand P for the system based on the determined system state.
Means for determining a PV curve indicating the relationship between the voltage and the system voltage V, and determining a ratio of a change in power to a change in voltage indicating the voltage stability state (gradient of the PV curve) from the PV curve. Means for judging the stability of the voltage based on the magnitude and sign of the value of the slope of the PV curve, and when the judgment result of the stability is unstable, it is necessary to improve the stability. A voltage reactive power monitoring and control device comprising: means for determining an adjustment amount of a voltage reactive power adjusting device; and means for outputting the adjustment amount to a display device.