Impacts of the SSSC control modes on small-signal and transient stability of a power system

In order to accomplish specific compensation objectives a static synchronous series compensator (SSSC) may be controlled by several ways. The most common control modes of the SSSC are: (1) constant voltage mode, (2) constant impedance emulation mode, and (3) constant power control mode. Moreover, to improve the dynamic performance of the system, a SSSC may be equipped with supplementary controllers, such as damping controls. Therefore, this paper investigates the impacts of different SSSC control modes on small-signal and transient stability of a power system. The performance of different input signals to the power oscillation damping (POD) controller is also assessed. The stability analysis and the design of the SSSC controllers are based on modal analysis, non-linear simulations, pole placement technique, and time and frequency response techniques. The results obtained allow to conclude that the usage of the SSSC in the constant impedance emulation mode is the most beneficial strategy to improve both the small-signal and transient stability.     

Constraints violation handling of SSSC with multi‐control modes in Newton–Raphson load flow algorithm

The static synchronous series compensator (SSSC ) is an important component of flexible AC transmission systems (FACTS ) devices. SSSC can be used to control the active and reactive power flow in transmission lines. This paper presents a simplified model for SSSC in Newton–Raphson (NR ) load flow algorithm. It also presents strategies for handling the operating constraints of SSSC including the series‐injected voltage and current passing through this device. The presented strategies are based on modifying the specified active and reactive powers with the maximum limits of the operating constraints. However, the SSSC is simply implemented in NR load flow algorithm based on the power injection approach. In this model, the SSSC is represented as injected loads as a function of the desired power flow through the transmission line. The main advantages of this model are avoiding the modification of Jacobin matrix and reducing the complexities of incorporating SSSC in the load flow algorithm. Moreover, the resistance of SSSC is considered in this model. Standard IEEE 14‐bus and 30‐bus test systems are used to verify the performance of the developed model and strategies handling the constraints of the SSSC model. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Optimal siting and sizing of demand response in a transmission constrained system with high wind penetration

This paper describes algorithms that use demand-side management to address large-scale integration of wind power. In particular, demand response (DR) is used to manage wind power intermittency by shifting the time that electrical power system loads occur in response to real-time prices and wind availability. An economic dispatch with transmission, DR capacity and operational constraints is used to model the operation of a transmission constrained system with a high penetration of wind power. This optimization model is used to determine the optimal sizing and distribution of DR given a fixed budget for customer incentives and the installation of enabling technology. We demonstrate the effectiveness of the operational model based on a simple PJM 5-bus system and an IEEE 118-bus system. Simulation results show that transmission constraints have a greater effect on sizing of DR capacity than the location of wind power, which means that buses electrically close to congested lines tend to have higher incentives to deploy DR resources than other buses. The second part of the work examines optimal siting of technology that enables DR based on the frequency of DR based load changes, which are generally a function of the network location.     

Separation of power systems into a unique set of zones based on transmission usage of network tariffs and transmission loss tariffs

Transmission usage of network tariffs (TUNT) and transmission loss tariffs (TLT) are among the most important pricing mechanisms that are utilized to recover main transmission costs in today’s electricity markets. Separation of entire power network into different tariff zones is a common approach which simplifies the tariff mechanisms particularly for large power systems. Zonal distribution of nodal tariffs that is calculated based on classical weighted-average procedures can be different given the difference between the calculation methodologies of the TUNTs and TLTs. However, correlation between nodal TUNTs and TLTs can be very strong, particularly when they are determined based on marginal pricing methodologies. This paper proposes an approach which separates a power system into a unique set of zones considering the nodal distribution of TUNTs and TLTs. In this approach, mismatches between the nodal elements of TUNTs and TLTs zones are iteratively eliminated until a unique zonal tariff sets are created. Application of the proposed zoning approach is discussed on the zonal TUNTs and TLTs of the Turkish power system. Numerical verification of the proposed zoning methodology is made with the IEEE 24 Bus System. Unique set of tariff zones can be represented on a map which will provide significant and consistent indication about the transmission enforcement requirements of the network in a simplest and efficient manner.     

Real‐time calculation of power system bus voltage using a hybrid approach combining the Newton–Raphson method and dynamic programming

The calculation of the magnitudes and phase angles of the bus voltage is a challenging task in real‐time applications for power systems. Voltage profile, which denotes the present conditions of a power system, is determined by executing the traditional AC power flow program or by searching the supervisory control and data acquisition system. The AC power flow program is not suitable for several real‐time applications, such as contingency analysis and security control calculations, because of its complexity and convergence problems. Fast computation is the major concern in such applications. In this paper, a new method based on sensitivity factors, referred to as Jacobian‐based distribution factors (JBDFs), is proposed for calculating the magnitudes and phase angles of bus voltages. This method requires setting up JBDFs and deriving optimal solution paths of bus voltage for non‐swing buses through dynamic programming under base‐case loading conditions. Under real‐time conditions, the proposed method initially calculates real and reactive power line flows via JBDFs, and then computes the voltage magnitudes and phase angles of non‐swing buses through the derived optimal solution paths. The excellence of the proposed hybrid calculation method is verified by IEEE test systems. Simulation results demonstrate that the proposed method exhibits fast computation and high accuracy. Thus, the method is suitable for real‐time applications. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Optimal siting and sizing of distributed generation accompanied by reconfiguration of distribution networks for maximum loss reduction by using a new UVDA-based heuristic method

A great number of methods have been proposed for distributed generation (DG) placement in distribution networks to minimize the power loss of Medium Voltage (MV) lines. However, very few researches have been done for network configuration in parallel with the DG siting and sizing for the maximum system loss reduction. In this paper, a heuristic method based on “uniform voltage distribution based constructive reconfiguration algorithm” (UVDA) is proposed for the simultaneous reconfiguration and DG siting and sizing. The results obtained from the application of the proposed method on two well-known distribution networks and a real network clearly verify the robustness of the contributed technique. The simulation results demonstrate that the proposed approach is able to find the best solution of the problem found so far. Also, the presented method is applicable to real large-scale distribution systems to find the optimal solution in a very short period of time.     

Optimal integration of DGs into radialdistribution network in the presence ofplug-in electric vehicles to minimize dailyactive power losses and to improve thevoltage profile of the system using bioinspiredoptimization algorithms

Purpose: The increase in plug-in electric vehicles (PEVs) is likely to see a noteworthy impact on the distribution system due to high electric power consumption during charging and uncertainty in charging behavior. To address this problem, the present work mainly focuses on optimal integration of distributed generators (DG) into radial distribution systems in the presence of PEV loads with their charging behavior under daily load pattern including load models by considering the daily (24 h) power loss and voltage improvement of the system as objectives for better system performance. Design/methodology/approach: To achieve the desired outcomes, an efficient weighted factor multi-objective function is modeled. Particle Swarm Optimization (PSO) and Butterfly Optimization (BO) algorithms are selected and implemented to minimize the objectives of the system. A repetitive backward-forward sweep-based load flow has been introduced to calculate the daily power loss and bus voltages of the radial distribution system. The simulations are carried out using MATLAB software. Findings: The simulation outcomes reveal that the proposed approach definitely improved the system performance in all aspects. Among PSO and BO, BO is comparatively successful in achieving the desired objectives. Originality/value: The main contribution of this paper is the formulation of the multi-objective function that can address daily active power loss and voltage deviation under 24-h load pattern including grouping of residential, industrial and commercial loads. Introduction of repetitive backward-forward sweep-based load flow and the modeling of PEV load with two different charging scenarios.     

Development of a new two-input PSS to control low-frequency oscillation in interconnecting power systems and the study of a low-frequency oscillation model

In Japan, large and small power systems were interconnected over time and thus ultimately grew into a large-scale national power system. A highly important stability problem arising from large-scale power system interconnections is low-frequency oscillation (about 0.3 Hz to 0.5 Hz) of interconnected systems. The ΔP-type PSS has been applied to all generators in trunk power systems as a measure to improve the damping of local mode oscillation (about 1 Hz). However, it is difficult for this PSS to improve the damping of low-frequency oscillation because of the hardware and the design of PSS control constants. Therefore it has become necessary to develop a new two-input PSS. This paper explains the development of this two-input PSS and the study of a low-frequency oscillation model. This paper can be summarized as follows:

• 1 (1) The effect of control over low-frequency oscillation is affected by the kinds of PSS detecting signals. The Δω-type or Δf-type detecting signals used for lead-phase compensation are suitable for this purpose.
• 2 (2) It is possible to cause low-frequency oscillation studies in a one-machine infinite-bus power system model with medium loads.
• 3 (3) According to the simulation of a three-machine and actual large-power system models, dynamic stability was largely increased by this two-input PSS used for generators.