JPH0681424B2 - System stabilization method - Google Patents

Description

Description: TECHNICAL FIELD The present invention is intended to prevent the occurrence of an accident in a power system in which the generators cannot maintain synchronization with each other and the system becomes unstable and collapses. The present invention relates to a system stabilizing device.

[Prior art]

Conventionally, an apparatus of this type has been shown in FIG. In Fig. 1, PS is a power system, A is an accident detection end, B is a power plant to be controlled, 1 is a central processing unit (hereinafter CP
(Abbreviated as U), an accident signal F ₀ is sent from the detection end A to the CPU 1, and conversely a cutoff signal CB is sent from the CPU 1 to the power plant B.

Next, the operation will be described. When an accident occurs on the power transmission line L, a protection relay (not shown) at the detection end A detects the accident.
Send accident signal F ₀ to CPU1. In response to this, the CPU 1 determines whether or not it is necessary to shut off a part of the generator by collating with the preliminary power flow collation X ₁ or the predetermined accident condition collation X _2, and if it is necessary, The cutoff signal CB is sent to the power plant B.

Since the conventional system stabilizer is configured as described above, if the number of accident detection ends increases, more information will be transmitted and it will be difficult to set conditions. Was unable to distinguish the accident points, and it was difficult to accurately determine if the interruption amount was different depending on the accident point in the same transmission line.

On the other hand, as one method to overcome the drawbacks of these conventional devices,
An accident determination method applying the energy method has been proposed. One example thereof will be described with reference to FIG. Fig. 2 shows an example of applying the system to a system in which three groups of acceleration, deceleration, and no acceleration / deceleration are applied when the behavior of the generator group due to the accident in the central part of the system is applied. Shall be partially blocked.

In Fig. 2, G _1i is one with K generators that accelerate, G _2i is one N power plant with generator units that decelerate, and G _3i is L generators without acceleration / deceleration. Of the inertial constant, mechanical input value, and electrical output value of M _1i , P _m1i , P _e1i , M _2i , P _m2i ,
_Let P _e2i , M _3i , P _m3i , P _e3i , and the respective back angles be δ _1i , δ _2i , δ _3i . Note that M _2i , P _m2i , and _{Pe 2i} are GS _2i
Is the total value of the generator units that make up the GS _2i, and δ _2i is the average value of the rear angles of the generator units that make up the GS _2i weighted by the inertia constant.

Reference numeral 2 indicates a central processing unit (hereinafter abbreviated as CPU), information A _i indicates information sent from the generator G 1 _i to CPU 2, and information B _i
i indicates the information sent from the power plant GS _2i to the CPU 2, and the information C _i
Indicates the information sent from the generator G _3i to the CPU 2. Specifically, each information includes an inertia constant, a mechanical input value, an electrical output value, etc., and is transmitted to the CPU 2 via the measuring and transmitting devices T _1i , T _2i , T _3i .

Based on this information, the CPU 2 determines the stabilizing control amount by the energy method as follows.

In the system model shown in Fig. 2, the angle center From the standpoint of synchronous equilibrium with respect to, the energy function E _T during the accident is derived as follows.

E _T = E _KT + E _PT (2) However, kinetic energy Potential energy The subscript s represents the stable equilibrium point (operating state before the accident), and the subscript t _f represents the accident duration.

In general, the accident duration t _f is a very short time of several tens of msec, so the generator angle during the accident hardly changes.

That is, Is established. Therefore, the potential energy term E _{PT in} Eq. (2) can be ignored, and the energy during accident E _T
Is As shown in, only the term of kinetic energy E _XT needs to be considered. Also, δ _1i , δ _2i , δ _3i are In the end, the information A _i (i = 1 to K), B _i
(I = 1~N), can be calculated C _{i (i} = 1~L) than an accident in the energy E _T.

E calculated from this accident information and Eqs. (4) and (5)
_T and, pre-configured, or Yotsute that compares the magnitude relation between Potenshiyaru E _c of unstable equilibrium point to be calculated from the accident after the clearing information, The stability is determined as shown in. If Eq. (7) holds, E _T (M ' ₂ ) ≤ E _c (M' ₂ ) (8) K _S : Find the smallest K _S that satisfies the cutoff rate of the generator group that is decelerating, and output the cutoff signal CB to this amount of generator unit to stabilize the system.

By using the method applying the energy method as described above, it is possible to accurately determine the control amount necessary for stabilization based on the limited information such as the inertia constant of each generator, mechanical input and electrical output. The drawbacks described above can be eliminated.

However, the energy during an accident and the potential of an unstable equilibrium point handled by the Energy Law are the energy amounts of the entire system under consideration, so when applying this to a stabilizing device, it is inevitable that the energy shown in Fig. 2 will be applied. This will result in a centralized system configuration that collects information for all systems in one CPU2. In this centralized system configuration, the transmission system becomes large-scale and complicated, and it becomes difficult to perform face-to-face testing and maintenance / inspection. Further, if the transmission system fails even in one place, the whole system goes down, so that the reliability of the stabilization control becomes low. Therefore, it can be said that the centralized type is a system configuration that is quite difficult in actual operation.

[Outline of Invention]

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and one characteristic generator of acceleration and one deceleration of each representative generator by appropriately characterizing a system phenomenon and appropriately dispersing an energy function. It is an object of the present invention to provide a system stabilizing device having a separate distributed system configuration in which a power plant having a generator is completely independent in a one-to-one pair.

The basic principle of the invention will now be described.

Accidents that cause large disturbances such as generators that are accelerating and generators that are decelerating at the level of all machines, leading to system collapse, are mainly in the central part of the system, especially Limited to accidents involving ultra-high voltage backbone lines. Therefore, if the system stabilizing device is designed for such an accident, it is possible to substantially meet the specification target of the device.

The behavior of the system shown in FIG. 2 with respect to the above-mentioned accident in the central part of the backbone system has the following features.

During the accident of the generator group without acceleration / deceleration, P _e3i (i = 1 to _L ) is
Almost no reduction. Therefore, the angle δ _3i (i = 1
The movement of (-L) is almost the same as the movement of the angle center δ ₀ of the entire system. That is, _3i - ₀ 0 (i = 1 to L) (9) holds.

The accelerating power of the generators that accelerate during the accident is almost the same for each generator. Therefore, ₁ (substituting) _1i (i = 1 to K) (10) holds. Here, δ ₁ (substituting) is an angle of one unit arbitrarily selected from the group of accelerating generators. However, the inertia constant M ₁ (alternative) of this generator is Shall be given in. Hereinafter, this generator will be referred to as a representative generator.

The deceleration force of the generator group that slows down during the accident is almost the same for each generator. Therefore, the angle center between the representative generator and each power plant holding the reduction gear generator When defined as, δ _0i δ ₀ (i = 1 to N) (13) substantially holds.

Utilizing the characteristics of each of these system phenomena, the energy function E _T of the entire system given by equation (4) is transformed. First,
Using equation (9), And simplify. From the equation (10), the first term on the right side of the equation (14) is Can be written. Furthermore, from equation (11), the right side of equation (15) is Will be transformed. From equations (15) and (16), equation (14) can be expressed as follows, The first term on the right side is Is multiplied by N, so when expressed using Σ You can write the whole right side of the above equation It comes down as follows.

By substituting equation (13) into equation (17), the total system energy function becomes Can be written.

Focusing on the right side of Eq. (18), it can be seen that it is the sum of the two-machine system energy functions defined between the representative generator G ₁ (substitute) and a certain deceleration-side power plant GS _2i . That is, a total of N pairs of energy functions with respect to the center of angle of the two-machine system model shown in FIG. 3 is given as the energy function of the entire system. The two-machine system energy function defined for each pair is hereinafter referred to as an individual energy function, and will be referred to as E _Ki .

Therefore, the individual energy function E _Ki is given within {} on the right side of the equation (18) as shown below.

Then, by substituting the function of Expression (12) into the above expression, the individual energy function E _Ki can be expressed as follows.

On the other hand, as described above, for accidents in the central part of the backbone system, ₁ (substituting) _-2i constant (i = 1 to N) (20) holds. Therefore, E _Ki is (M ₁ ( _subs ) / M _2i ) / (M
_It can be seen that it is proportional to ₁ (generation) + M _2i ). That is, the energy function E _T of the whole system is (M ₁ (substituting) · M _2i ) / (M ₁ (substituting)
It can be said that the individual energy function E _Ki is proportionally distributed by + M _2i ).

Based on this idea, the individual critical energy E _ci is
Critical energy of the whole system (potential of unstable equilibrium point)
From E _cT , It can be obtained by the following formula. In equation (21), the individual critical energy E _ci is the critical energy E of the entire system.
_CT It is derived based on the assumption that it is given by prorating.

Individual accident energy E _Ki calculated by equation (19)
And the individual critical energy E _ci calculated from the information set in advance or after clearing the accident using Eq. (21)
By comparing the large and small functions of and, even in individual pairs, the stable discrimination of the energy method can be applied. Ie The stability determination principle can be applied independently to the representative power source G ₁ (substituting) and each deceleration side power station GS _2i . If Eq. (23) holds, E _Ki (M ' _2i ) ≤ E _ci (M' _2i ) (24) Ni: Number of units of deceleration side power plant GS _2i M _2ij : Inertia constant of each unit of 〃 k _si ： _Find the smallest k _si that satisfies 〃 _breaking ratio and this amount at deceleration side power plant M _2i It is also possible to stabilize by turning off the generator unit of the minute.

Example of Invention

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 uses the individual energy function described above,
It is a block diagram of a system stabilizing device having an individual distributed system configuration. In FIG. 4, G ₁ (substituting) is one representative generator GS _2i (i selected arbitrarily from the accelerating generator group.
= 1 to N) represents a power plant that holds a decelerating generator unit, and each inertia constant, mechanical input value, electrical output value, back angle is M ₁ (substitution), P _m1 (substitution), P
_e1 (substitution), δ ₁ (substitution), M ₂ (substitution), P _m2i , P _e2i , δ
_2i (i = 1 to N). In addition, M _2i , P
_m2i, P _E2i the total value of each generator Yunitsuto constituting the GS _2i, [delta] _2i is an average value weighted by the inertia constants behind angle of each generator Yunitsuto constituting the GS _2i.

Further, 3i (i = 1 to N) is a central processing unit (hereinafter abbreviated as CPU)
A indicates information sent from the representative generator G ₁ (substitute) to the CPU 3i (i = 1 to N). Specifically, the information A includes an inertia constant M ₁ (substitute), a mechanical input value P _m1 (substitute), and an electrical output value P.
includes _e1 (cash) or the like, via a measurement and transmission unit T ₁ (cash)
Transmitted to CPU3i.

The CPU 3i is the information A and the inertia constant M _2i and mechanical input value input from the measuring device T _2i installed at the end of each deceleration power plant GS _2i.
Based on each information of P _m2i , the individual energy function E _Ki is calculated by the following equation at the same time as the accident occurs.

However, t _f : The duration of the accident.

E _Ki calculated by equation (25) and individual critical energy E set in advance (or calculated from information after clearing the accident)
By comparing with _ci , stability determination and stabilization control amount determination are performed as shown in equations (22) to (24), and if unstable, the cutoff signal CB _i is output and stabilization is performed. The number of power generation is cut off by the amount necessary for. Note that equation (25) is the angle δ ₁ (substitute) and δ _2i of equation (19). Can be obtained by substituting and organizing.

The above-described stability determination, stabilization control amount determination, and generator shutoff are performed independently for each pair to prevent out-of-step of the accelerating generator group and the decelerating generator group.

In the above embodiment, an individual pair is formed for each deceleration-side power plant, but it is also possible to handle several neighboring power plants together. In this way, the number of individual pairs can be reduced.

〔The invention's effect〕

As described above, according to the present invention, since the stabilization control amount by the energy method can be determined in the system configuration that is individually decentralized, highly accurate stabilization control can be performed with limited information, and further, It has the effect of obtaining a simple and highly reliable system stabilization that is easy to perform tests, maintenance and inspections.

[Brief description of drawings]

FIG. 1 is a block diagram of a conventional system stabilizing device, FIG. 2 is a system configuration diagram of a conventional system stabilizing device using the energy method, FIG. 3 is a system model diagram giving an individual energy function, FIG. 4 FIG. 3 is a block diagram of a system stabilizing device according to an embodiment of the present invention. 1,2,3i (i = 1 to N) ... Central processing unit (CPU), G _1i (i
= 1 to K), G _2i (i = 1 to N), G _3i (i = 1 to L) generator group, T _1i (i = 1 to K), T _2i (i = 1 to N), T _3i
(I = 1 to L) ... Measuring and transmitting device. The same reference numerals in the drawings denote the same parts.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kunio Matsuzawa 1-3-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Tokyo Electric Power Co., Inc. (72) Inventor Hitoshi Otsuka 1-3-1, Uchiyuki-cho, Chiyoda-ku, Tokyo East Inside Kyoden Electric Co., Ltd. (72) Inventor Tadahiro Goda 1-2-2 Wadazaki-cho, Hyogo-ku, Kobe-shi, Hyogo Inside Mitsubishi Electric Corporation Control Works (72) Hideharu Oshida Wadazaki-cho, Hyogo-ku, Kobe-shi, Hyogo 1-2 1-2 Mitsubishi Electric Co., Ltd. Control Works (72) Inventor Shogo Nishida 1-2-1 Wadazaki-cho, Hyogo-ku, Kobe, Hyogo Prefecture Inside Mitsubishi Electric Co., Ltd. Control Works

Claims (3)

[Claims] 1. The amount of energy accumulated during an accident by connecting a generator group to a system that is divided into three groups, namely, acceleration, deceleration, and no acceleration / deceleration due to a short-circuit accident and a ground fault accident that occur in the system. By comparing the magnitude relationship between the unstable equilibrium point of the system and the potential of the generator group that accelerates and decelerates the generator group by predicting the presence or absence of step-out by the above determination. In the system stabilization method that maintains the synchronization between the generators by shutting off a part of the generator group that slows down, the According to the phenomenon,
One representative generator arbitrarily selected from the generator group to be accelerated and each power plant having a generator unit to be decelerated are set as one-to-one independent units and accumulated for each unit. A system stabilization method characterized in that energy during an accident and critical energy are controlled so as to be separately dispersed. 2. The energy during an accident is (However, i = 1,2 ..., M ₁ (substituting) is the inertia constant of any one selected from the accelerating generator group, M _2i is the inertia constant of each decelerating generator group, ₁ (substituting) Is the back angle of one of the accelerating generator groups, and δ _2i is the back angle of the decelerating generator group.) The system stabilizing method according to claim 1, wherein 3. The critical energy is (However, i = 1,2 ..., M ₁ (substituting) is the inertia constant of any one selected from the accelerating generator group, M _2i is the inertia constant of each decelerating generator group, and E _CT is the system It is the total critical energy.) The method for stabilizing the system according to claim 1, wherein