Cenergy Ukraine, School Street, Zaporizhia (2026)

09/06/2022

The household photovoltaic system is generally installed on the roof of the house, and its metal surface area is large, the distance from the ground is high, and the position is prominent, so it is easy to become the target of lightning attack in thunderstorm weather. If there is no reliable lightning protection grounding after the completion of the power station construction, the probability of being struck by lightning will become extremely high, and it will even cause the danger of electricity consumption and the occurrence of fire, resulting in unnecessary personal and property losses.

Therefore, in order to improve the effectiveness of lightning protection for household systems, in addition to meeting the requirements of conventional lightning protection measures, the following points need to be considered:

1) If the system has a large capacity or is located in a high-incidence area of lightning strikes, it is necessary to add a lightning rod beside the phalanx to improve the lightning protection level of the system;

2) There are other metal facilities on the roof, the DC circuit should be kept as far away as possible, the photovoltaic support should not be in contact with it, and it is recommended to add a lightning rod on the roof;

3) The serial loop area of the system should be as small as possible to reduce the intensity of induction lightning;

4) It is recommended to make a separate lightning protection network for the photovoltaic system to prevent lightning from invading the photovoltaic system through the building lightning protection network.

31/05/2022

There is a smooth switching control strategy for microgrids with high power quality and no need for long-distance communication lines.

The microgrid is mainly composed of multiple parallel distributed generation units and a pre-synchronized unit. A unified grid-connected current control structure is proposed for the interface inverter in the distributed generation unit, which has the following advantages:
①The inverter can automatically switch between the current control mode in grid-connected operation state and the voltage control mode in islanded operation state without islanding detection, so as to ensure the quality of load power supply;
②The proposed unified grid-connected current control structure can effectively suppress the harmonics in grid-connected current and capacitor voltage;
③ When the grid frequency fluctuates, the inverter can still output the corresponding active and reactive power according to the command value, and can synchronize with the grid without a phase-locked loop or a frequency-locked loop in the grid-connected operation state.

In addition, the proposed pre-synchronization unit can realize the pre-synchronization control of the microgrid voltage and the grid voltage without relying on the remote communication line, and reduce the inrush current when the islanding operation state is changed to the grid-connected operation state. Finally, the control parameters are optimized and the effectiveness and feasibility of the proposed control strategy are verified by experiments.

30/05/2022

Inverter distributed generation (IIDG) is an important application method of renewable energy in the distribution network, and its stable operation depends on the control strategy and the distribution network system it is connected to. When a transient event occurs in the distribution network, the transient response of IIDG is complex, and it is prone to fluctuation or oscillation of output power and power angle.

Based on the IIDG control system and its mathematical model connected to the power grid, the power angle characteristic curve is analyzed, and its transient stability criterion is proposed based on the power angle curve cluster.

The grid-connected parameters and rated power that affect the transient stability of IIDG are systematically analyzed, and the effects of different parameters on the transient stability are compared.

By describing the transient process, a transient stability iterative judgment method is proposed, which iteratively calculates the power angle change of IIDG under transient events and judges its transient stability.

A simulation example is established in PSCAD/EMTDC to verify the transient stability mechanism of IIDG, and the effectiveness and accuracy of the transient stability iterative determination method are proved by changing the network parameters of the grid.

26/05/2022

As an important protection device in the low-voltage power distribution system, the leakage circuit breaker is mainly used to prevent the occurrence of leakage fire accidents and protect the safety of personal electric shock. When the electromagnetic leakage circuit breaker is disturbed by the external magnetic field, it will cause the change or even damage of the leakage protection working characteristics.

Through the optimized design of the internal wiring of the electromagnetic leakage circuit breaker and the magnetic shielding design of the magnetic release, the influence of the external magnetic field and internal load current on the electromagnetic leakage circuit breaker is effectively reduced, and the ability of resisting space magnetic field interference is improved. , and verified by experiments.

12/05/2022

At present, high efficiency and energy saving are becoming the key development strategy of the motor industry.

The booming emerging industries such as smart grid and smart transportation pose higher challenges to the control and protection of motor systems.

The understanding and application of intelligent concepts in the field of motors are deepening, and they also provide new development opportunities for traditional industrial motors.

10/05/2022

The high-voltage direct current (HVDC) relay contact system has a compact structure, and it is difficult to improve the breaking performance of the contacts by using grids or gas-generating materials.

The external magnetic field of the magnetic blowing system can speed up the movement speed of the arc and improve the arc extinguishing ability.

07/05/2022

Large-scale distributed new energy sources are connected to the distribution grid through inverters, and complex interactions are formed between grid-connected inverters and weak power grids, and the problem of harmonic degradation is prominent.

One of the keys to the harmonic degradation analysis is the establishment of the impedance model of the grid-connected inverter.

06/05/2022

As the core equipment of the power system, the power transformer is of great significance for the safe and stable operation of the power system.

On-line fault diagnosis of power transformers is an important method to realize real-time status analysis of power transformers.

Dissolved gas analysis in oil is the most commonly used method of on-line fault diagnosis of power transformers.

05/05/2022

In the context of energy interconnection, multiple integrated resources represented by energy storage, demand response, and distributed generation (DG) will be deeply involved in the operation of the power grid.

As the integrator of multiple types of distributed resources in local areas, the distribution network needs to optimize and control the multi-integrated distributed resources including DG, energy storage, and controllable loads through effective means to improve the flexibility of the distribution network.

29/04/2022

Establishing a model of grid-connected photovoltaic power generation system is the basis for studying its interaction process with the power grid.

The transient characteristics of photovoltaic systems are not only affected by environmental factors such as weather conditions and power grid conditions, but also depend on the internal structure and control strategies of commercial inverters.

28/04/2022

In the distribution grid system with distributed power generation, the coordination planning of the source grid not only needs to consider the economic cost, but also the security and coordination issues.

Considering the safety, the line congestion compensation cost is added to the traditional economic objective function, and the safety of distributed power generation and power grid lines are considered separately, and a "safety factor" is defined as the system safety objective function to improve its safety capability;

Considering the coordination, considering the transmission coordination and structural coordination between the source and the grid, a "coordination factor" is proposed as the coordination objective function to enhance the coordination ability of both sides.

27/04/2022

Compared with traditional distribution transformers, the hybrid distribution transformer (HDT) contains a pulse-width modulation converter that can regulate a portion of the transmitted power.

Thus, it not only performs the basic functions of voltage level conversion and power transmission of traditional distribution transformers, but also can dynamically control the load voltage and current of the grid in real time, which is of great application importance for the implementation of an active distribution.

У порівнянні з традиційними розподільними трансформаторами гібридний розподільний трансформатор (HDT) містить перетворювач з широтно-імпульсною модуляцією, який може регулювати частину потужності, що передається.

Таким чином, він не тільки виконує основні функції перетворення рівня напруги та передачі потужності традиційних розподільних трансформаторів, але також може динамічно керувати напругою навантаження та струмом мережі в режимі реального часу, що має важливе прикладне значення для реалізації активної розподільної мережі.

Cenergy Ukraine

09/06/2022

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